MARS ROVER LENTICULAR 3D PUZZLE 50pc NASA Curiosity selfie portrait outer space

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Seller: sidewaysstairsco ✉️ (1,180) 100%, Location: Santa Ana, California, US, Ships to: US & many other countries, Item: 195728471603 MARS ROVER LENTICULAR 3D PUZZLE 50pc NASA Curiosity selfie portrait outer space. Critics of the puzzle piece symbol instead advocate for a gold-colored or red infinity symbol representing diversity. They removed the puzzle piece from their cover in February 2018.". (wikipedia.org). Check out our other new and used items>>>>>HERE! (click me) FOR SALE: An awesome, NASA rover-themed lenticular 3D jigsaw puzzle 2020 DISCOVERY "ROVER ON MARS" PUZZLE BY PRIME 3D (9" X 6") DETAILS: It's a Curiosity rover selfie puzzle! The Discovery "Rover on Mars" 50-piece lenticular jigsaw puzzle features a graphic that utilizes an official self-portrait of Curiosity the rover referred to as "Buckskin". The belly selfie of Curiosity seen 'round the world offers a unique, upward low-angle view that reveals its flat undercarriage - something you don't normally see. And what makes the puzzle image even more awesome is that Prime 3D Global utilized their high-quality lenticular printing technology to make it "3D" art. Curiosity created its selfie by stitching together 92 component self images taken while out drilling rock for samples at Buckskin; a site in the "Marias Pass" area of lower Mount Sharp. Today Curiosity has remained on Mars for nearly 11 years, is still operational, and still provides NASA with assistance and data. Prime 3D Global also printed the beautiful graphic on a separate lenticular card and attached it to the front of the box to showcase the puzzle's main feature. This small "3D" art jigsaw puzzle would look great framed! Hang on a deserving wall or display on a shelf or mantel. Perfect for a space-themed bar or man cave. A must have for the lenticular art and space fanatic especially those who collect all things NASA! Brand: Discovery Title: "Rover on Mars" Year: 2020 Piece Count: 50 Completed Size: 9 x 6 in. (22.9 x 15.2 cm) Manufacturer: Prime 3D Global Country: China CONDITION: New in box. Box may have shelf wear. Please see photos. To ensure safe delivery all items are carefully packaged before shipping out. THANK YOU FOR LOOKING. QUESTIONS? JUST ASK. *ALL PHOTOS AND TEXT ARE INTELLECTUAL PROPERTY OF SIDEWAYS STAIRS CO. ALL RIGHTS RESERVED.* "A Mars rover is a motor vehicle designed to travel on the surface of Mars. Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control. They serve a different purpose than orbital spacecraft like Mars Reconnaissance Orbiter. A more recent development is the Mars helicopter. As of May 2021, there have been six successful robotically operated Mars rovers; the first five, managed by the American NASA Jet Propulsion Laboratory, were (by date of Mars landing): Sojourner (1997), Spirit (2004–2010), Opportunity (2004–2018), Curiosity (2012–present), and Perseverance (2021–present). The sixth, managed by the China National Space Administration, is Zhurong (2021–present). On January 24, 2016, NASA reported that then current studies on Mars by Opportunity and Curiosity would be searching for evidence of ancient life, including a biosphere based on autotrophic, chemotrophic or chemolithoautotrophic microorganisms, as well as ancient water, including fluvio-lacustrine environments (plains related to ancient rivers or lakes) that may have been habitable.[1][2][3][4][5] The search for evidence of habitability, taphonomy (related to fossils), and organic carbon on Mars is now a primary NASA objective.[1][6] The Soviet probes, Mars 2 and Mars 3, were physically tethered probes; Sojourner was dependent on the Mars Pathfinder base station for communication with Earth; Opportunity, Spirit and Curiosity were on their own. As of February 2023, Curiosity is still active, while Spirit, Opportunity, and Sojourner completed their missions before losing contact. On February 18, 2021, Perseverance, the newest American Mars rover, successfully landed. On May 14, 2021, China's Zhurong became the first non-American rover to successfully operate on Mars. Missions See also: List of missions to Mars Multiple rovers have been dispatched to Mars: Rover and lander captured by HiRISE from NASA's MRO on June 6, 2021 Zhurong rover and lander captured by HiRISE from NASA's MRO on 6 June 2021 Active     Curiosity of the Mars Science Laboratory (MSL) mission by NASA, was launched November 26, 2011[7][8] and landed at the Aeolis Palus plain near Aeolis Mons (informally "Mount Sharp")[9][10][11][12] in Gale Crater on August 6, 2012.[13][14][15] The Curiosity rover is still operational as of February 2023.     Perseverance, NASA rover based on the successful Curiosity design. Launched with the Mars 2020 mission on July 30, 2020, it landed on February 18, 2021.[16] It carried the Mars Helicopter Ingenuity attached to its belly.     Zhurong launched with the Tianwen-1 CNSA Mars mission on July 23, 2020, landed on May 14, 2021 in the southern region of Utopia Planitia, and deployed on May 22, 2021, while dropping a remote selfie camera on 1 June, 2021.[17][18] As of February 2023, it is suspected that Zhurong has failed to wake up after the Mars winter and its mission has ended.[19] Past Sojourner disembarks Mars Pathfinder base station lander on the surface of planet Mars     Sojourner rover, Mars Pathfinder, landed successfully on July 4, 1997. Communications were lost on September 27, 1997. Sojourner had traveled a distance of just over 100 meters (330 ft).[20]     Spirit (MER-A), Mars Exploration Rover (MER), launched on June 10, 2003,[21] and landed on January 4, 2004. Nearly 6 years after the original mission limit, Spirit had covered a total distance of 7.73 km (4.80 mi) but its wheels became trapped in sand.[22] The last communication received from the rover was on March 22, 2010, and NASA ceased attempts to re-establish communication on May 25, 2011.[23]     Opportunity (MER-B), Mars Exploration Rover, launched on July 7, 2003[21] and landed on January 25, 2004. Opportunity surpassed the previous records for longevity at 5,352 sols (5498 Earth days from landing to mission end; 15 Earth years or 8 Martian years) and covered 45.16 km (28.06 mi). The rover sent its last status on 10 June 2018 when a global 2018 Mars dust storm blocked the sunlight needed to recharge its batteries.[24] After hundreds of attempts to reactivate the rover, NASA declared the mission complete on February 13, 2019. Failed     Mars 2, PrOP-M rover, 1971, Mars 2 landing failed taking Prop-M with it. The Mars 2 and 3 spacecraft from the Soviet Union had identical 4.5 kg Prop-M rovers. They were to move on skis while connected to the landers with cables.[25]     Mars 3, PrOP-M rover, landed successfully on December 2, 1971. 4.5 kilograms (9.9 lb) rover tethered to the Mars 3 lander. Lost when the Mars 3 lander stopped communicating about 110 seconds after landing.[25] The loss of communication may have been due to the extremely powerful Martian dust storm taking place at the time or an issue with the Mars 3 orbiter's ability to relay communications. Planned     The European-Russian ExoMars rover Rosalind Franklin was confirmed technically ready for launch in March 2022 and planned to launch in September 2022, but due to the suspension of cooperation with Roscosmos this is delayed and a fast-track study was started to determine alternative launch options.[26] Proposed     The JAXA Melos rover was supposed to be launched in 2022. JAXA has not given an update since 2015.     NASA Mars Geyser Hopper     ISRO has proposed a Mars rover as part of Mangalyaan-3, its third Mars mission in 2030.[27] Undeveloped     Marsokhod was proposed to be a part of Russian Mars 96 mission.     Astrobiology Field Laboratory, proposed in the 2000-2010 period as a follow on to MSL.[28]     Mars Astrobiology Explorer-Cacher (MAX-C), cancelled 2011[29][30]     Mars Surveyor 2001 rover[31]     Mars Tumbleweed Rover, a spherical wind-propelled rover.[32][33]     In 2018, a kind of cushion-air rover was proposed,[34] which in contrast with traditional hovercraft does not use blowers to pressurize the gas in the chamber but rather uses stored pressurized CO2 obtained from a freezing process which does not require mechanical compression.[35] Timeline of rover surface operations Examples of instruments Curiosity's (MSL) rover "hand" featuring a suite of instruments on a rotating "wrist". Mount Sharp is in the background (September 8, 2012). Opportunity's first self-portrait including the camera mast on Mars (February 14−20, 2018 / sols 4998−5004). It was taken with its microscopic imager instrument. Examples of instruments onboard landed rovers include:     Alpha particle X-ray spectrometer (MPF + MER + MSL)     CheMin (MSL)     Chemistry and Camera complex (MSL)     Dynamic Albedo of Neutrons (MSL)     Hazcam (MER + MSL + M20)     MarsDial (MER + MSL + M20)     Materials Adherence Experiment (MPF)     MIMOS II (MER)     Mini-TES (MER)     Mars Hand Lens Imager (MSL)     Navcam (MER + MSL + M20+TW1)     Pancam (MER)     Rock Abrasion Tool (MER)     Radiation assessment detector (MSL)     Rover Environmental Monitoring Station (MSL)     Sample Analysis at Mars (MSL)     EDL cameras on Rover (MSL + M20+TW1)     Cachecam (M20)     Mastcam-Z (M20)     MEDA (M20)     Microphones (M20+TW1)     MOXIE (M20)     PIXL (M20)     RIMFAX (M20)     SHERLOC (M20)     SuperCam (M20)     Remote Camera (TW1) Mars landing locations Map of Mars The image above contains clickable links (view • discuss) Interactive image map of the global topography of Mars, overlain with locations of Mars Lander and Rover sites. Hover your mouse over the image to see the names of over 60 prominent geographic features, and click to link to them. Coloring of the base map indicates relative elevations, based on data from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. Whites and browns indicate the highest elevations (+12 to +8 km); followed by pinks and reds (+8 to +3 km); yellow is 0 km; greens and blues are lower elevations (down to −8 km). Axes are latitude and longitude; Polar regions are noted. (See also: Mars map; Mars Memorials map / list) (   Active ROVER •   Inactive •   Active LANDER •   Inactive •   Future ) Beagle 2 ← Beagle 2 (2003) Bradbury Landing Curiosity (2012) → Deep Space 2 Deep Space 2 (1999) → InSight Landing InSight (2018) → Mars 2 Mars 2 (1971) → Mars 3 ← Mars 3 (1971) Mars 6 Mars 6 (1973) → Mars Polar Lander Polar Lander (1999) ↓ Challenger Memorial Station ↑ Opportunity (2004) Mars 2020 ← Perseverance (2021) Green Valley ← Phoenix (2008) Schiaparelli EDM Schiaparelli EDM (2016) → Carl Sagan Memorial Station ← Sojourner (1997) Columbia Memorial Station Spirit (2004) ↑ Tianwen-1 ↓Zhurong (2021) Thomas Mutch Memorial Station Viking 1 (1976) → Gerald Soffen Memorial Station Viking 2 (1976) → Mars Landing Sites (December 16, 2020) NASA Mars rover goals Circa the 2010s, NASA had established certain goals for the rover program. NASA distinguishes between "mission" objectives and "science" objectives. Mission objectives are related to progress in space technology and development processes. Science objectives are met by the instruments during their mission in space. The science instruments are chosen and designed based on the science objectives and goals. The primary goal of the Spirit and Opportunity rovers was to investigate "the history of water on Mars".[36] The four science goals of NASA's long-term Mars Exploration Program are:     Determine whether life ever arose on Mars     Characterize the climate of Mars     Characterize the geology of Mars     Prepare for human exploration of Mars" (wikipedia.org) "Curiosity is a car-sized Mars rover designed to explore the Gale crater on Mars as part of NASA's Mars Science Laboratory (MSL) mission.[2] Curiosity was launched from Cape Canaveral (CCAFS) on November 26, 2011, at 15:02:00 UTC and landed on Aeolis Palus inside Gale crater on Mars on August 6, 2012, 05:17:57 UTC.[3][4][5] The Bradbury Landing site was less than 2.4 km (1.5 mi) from the center of the rover's touchdown target after a 560 million km (350 million mi) journey.[6][7] Mission goals include an investigation of the Martian climate and geology, assessment of whether the selected field site inside Gale has ever offered environmental conditions favorable for microbial life (including investigation of the role of water), and planetary habitability studies in preparation for human exploration.[8][9] In December 2012, Curiosity's two-year mission was extended indefinitely,[10] and on August 5, 2017, NASA celebrated the fifth anniversary of the Curiosity rover landing.[11][12] On August 6, 2022, a detailed overview of accomplishments by the Curiosity rover for the last ten years was reported.[13] The rover is still operational, and as of 24 April 2023, Curiosity has been active on Mars for 3808 sols (3913 total days; 10 years, 261 days) since its landing (see current status). The NASA/JPL Mars Science Laboratory/Curiosity Project Team was awarded the 2012 Robert J. Collier Trophy by the National Aeronautic Association "In recognition of the extraordinary achievements of successfully landing Curiosity on Mars, advancing the nation's technological and engineering capabilities, and significantly improving humanity's understanding of ancient Martian habitable environments."[14] Curiosity's rover design serves as the basis for NASA's 2021 Perseverance mission, which carries different scientific instruments. Mission Further information: Timeline of Mars Science Laboratory Goals and objectives Animation of the Curiosity rover, showing its capabilities As established by the Mars Exploration Program, the main scientific goals of the MSL mission are to help determine whether Mars could ever have supported life, as well as determining the role of water, and to study the climate and geology of Mars.[8][9] The mission results will also help prepare for human exploration.[9] To contribute to these goals, MSL has eight main scientific objectives:[15] Biological     Determine the nature and inventory of organic carbon compounds     Investigate the chemical building blocks of life (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur)     Identify features that may represent the effects of biological processes (biosignatures and biomolecules) Geological and geochemical     Investigate the chemical, isotopic, and mineralogical composition of the Martian surface and near-surface geological materials     Interpret the processes that have formed and modified rocks and soils Planetary process     Assess long-timescale (i.e., 4-billion-year) Martian atmospheric evolution processes     Determine present state, distribution, and cycling of water and carbon dioxide Surface radiation     Characterize the broad spectrum of surface radiation, including galactic and cosmic radiation, solar proton events and secondary neutrons. As part of its exploration, it also measured the radiation exposure in the interior of the spacecraft as it traveled to Mars, and it is continuing radiation measurements as it explores the surface of Mars. This data would be important for a future crewed mission.[16] About one year into the surface mission, and having assessed that ancient Mars could have been hospitable to microbial life, the MSL mission objectives evolved to developing predictive models for the preservation process of organic compounds and biomolecules; a branch of paleontology called taphonomy.[17] The region it is set to explore has been compared to the Four Corners region of the North American west.[18] Name A NASA panel selected the name Curiosity following a nationwide student contest that attracted more than 9,000 proposals via the Internet and mail. A sixth-grade student from Kansas, 12-year-old Clara Ma from Sunflower Elementary School in Lenexa, Kansas, submitted the winning entry. As her prize, Ma won a trip to NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, where she signed her name directly onto the rover as it was being assembled.[19] Ma wrote in her winning essay:     Curiosity is an everlasting flame that burns in everyone's mind. It makes me get out of bed in the morning and wonder what surprises life will throw at me that day. Curiosity is such a powerful force. Without it, we wouldn't be who we are today. Curiosity is the passion that drives us through our everyday lives. We have become explorers and scientists with our need to ask questions and to wonder.[19] Cost Adjusted for inflation, Curiosity has a life-cycle cost of US$3.2 billion in 2020 dollars. By comparison, the 2021 Perseverance rover has a life-cycle cost of US$2.9 billion.[20] Rover and lander specifications See also: Comparison of embedded computer systems on board the Mars rovers Two Jet Propulsion Laboratory engineers stand with three vehicles, providing a size comparison of three generations of Mars rovers. Front and center left is the flight spare for the first Mars rover, Sojourner, which landed on Mars in 1997 as part of the Mars Pathfinder Project. On the left is a Mars Exploration Rover (MER) test vehicle that is a working sibling to Spirit and Opportunity, which landed on Mars in 2004. On the right is a test rover for the Mars Science Laboratory, which landed as Curiosity on Mars in 2012. Sojourner is 65 cm (26 in) long. The Mars Exploration Rovers (MER) are 1.6 m (5 ft 3 in) long. Curiosity on the right is 3 m (9.8 ft) long. Curiosity is 2.9 m (9 ft 6 in) long by 2.7 m (8 ft 10 in) wide by 2.2 m (7 ft 3 in) in height,[21] larger than Mars Exploration Rovers, which are 1.5 m (4 ft 11 in) long and have a mass of 174 kg (384 lb) including 6.8 kg (15 lb) of scientific instruments.[22][23][24] In comparison to Pancam on the Mars Exploration Rovers, the MastCam-34 has 1.25× higher spatial resolution and the MastCam-100 has 3.67× higher spatial resolution.[25] Curiosity has an advanced payload of scientific equipment on Mars.[26] It is the fourth NASA robotic rover sent to Mars since 1996. Previous successful Mars rovers are Sojourner from the Mars Pathfinder mission (1997), and Spirit (2004–2010) and Opportunity (2004–2018) rovers from the Mars Exploration Rover mission. Curiosity comprised 23% of the mass of the 3,893 kg (8,583 lb) spacecraft at launch. The remaining mass was discarded in the process of transport and landing.     Dimensions: Curiosity has a mass of 899 kg (1,982 lb) including 80 kg (180 lb) of scientific instruments.[22] The rover is 2.9 m (9 ft 6 in) long by 2.7 m (8 ft 10 in) wide by 2.2 m (7 ft 3 in) in height.[21] The main box-like chassis forms the Warm Electronics Box (WEB).[27]: 52  Radioisotope pellet within a graphite shell that fuels the generator Radioisotope Power System for Curiosity at Kennedy Space Center     Power source: Curiosity is powered by a radioisotope thermoelectric generator (RTG), like the successful Viking 1 and Viking 2 Mars landers in 1976.[28][29]     Radioisotope power systems (RPSs) are generators that produce electricity from the decay of radioactive isotopes, such as plutonium-238, which is a non-fissile isotope of plutonium. Heat given off by the decay of this isotope generates electrical power using thermocouples, providing consistent power during all seasons and through the day and night. Waste heat is also used via pipes to warm systems, freeing electrical power for the operation of the vehicle and instruments.[28][29] Curiosity's RTG is fueled by 4.8 kg (11 lb) of plutonium-238 dioxide supplied by the U.S. Department of Energy.[30]     Curiosity's RTG is the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), designed and built by Rocketdyne and Teledyne Energy Systems under contract to the U.S. Department of Energy,[31] and fueled and tested by the Idaho National Laboratory.[32] Based on legacy RTG technology, it represents a more flexible and compact development step,[33] and is designed to produce 110 watts of electrical power and about 2,000 watts of thermal power at the start of the mission.[28][29] The MMRTG produces less power over time as its plutonium fuel decays: at its minimum lifetime of 14 years, electrical power output is down to 100 watts.[34][35] The power source generates 9 MJ (2.5 kWh) of electrical energy each day, much more than the solar panels of the now retired Mars Exploration Rovers, which generated about 2.1 MJ (0.58 kWh) each day. The electrical output from the MMRTG charges two rechargeable lithium-ion batteries. This enables the power subsystem to meet peak power demands of rover activities when the demand temporarily exceeds the generator's steady output level. Each battery has a capacity of about 42 ampere hours.     Heat rejection system: The temperatures at the landing site vary seasonally and the thermal system warms the rover as needed. The thermal system does so in several ways: passively, through the dissipation to internal components; by electrical heaters strategically placed on key components; and by using the rover heat rejection system (HRS).[27] It uses fluid pumped through 60 m (200 ft) of tubing in the rover body so that sensitive components are kept at optimal temperatures.[36] The fluid loop serves the additional purpose of rejecting heat when the rover has become too warm, and it can also gather waste heat from the power source by pumping fluid through two heat exchangers that are mounted alongside the RTG. The HRS also has the ability to cool components if necessary.[36]     Computers: The two identical on-board rover computers, called Rover Compute Element (RCE) contain radiation hardened memory to tolerate the extreme radiation from space and to safeguard against power-off cycles. The computers run the VxWorks real-time operating system (RTOS). Each computer's memory includes 256 kilobytes (kB) of EEPROM, 256 megabytes (MB) of dynamic random-access memory (DRAM), and 2 gigabytes (GB) of flash memory.[37] For comparison, the Mars Exploration Rovers used 3 MB of EEPROM, 128 MB of DRAM, and 256 MB of flash memory.[38]     The RCE computers use the RAD750 Central processing unit (CPU), which is a successor to the RAD6000 CPU of the Mars Exploration Rovers.[39][40] The IBM RAD750 CPU, a radiation-hardened version of the PowerPC 750, can execute up to 400 Million instructions per second (MIPS), while the RAD6000 CPU is capable of up to only 35 MIPS.[41][42] Of the two on-board computers, one is configured as backup and will take over in the event of problems with the main computer.[37] On February 28, 2013, NASA was forced to switch to the backup computer due to a problem with the active computer's flash memory, which resulted in the computer continuously rebooting in a loop. The backup computer was turned on in safe mode and subsequently returned to active status on March 4, 2013.[43] The same problem happened in late March, resuming full operations on March 25, 2013.[44]     The rover has an inertial measurement unit (IMU) that provides 3-axis information on its position, which is used in rover navigation.[37] The rover's computers are constantly self-monitoring to keep the rover operational, such as by regulating the rover's temperature.[37] Activities such as taking pictures, driving, and operating the instruments are performed in a command sequence that is sent from the flight team to the rover.[37] The rover installed its full surface operations software after the landing because its computers did not have sufficient main memory available during flight. The new software essentially replaced the flight software.[7]     The rover has four processors. One of them is a SPARC processor that runs the rover's thrusters and descent-stage motors as it descended through the Martian atmosphere. Two others are PowerPC processors: the main processor, which handles nearly all of the rover's ground functions, and that processor's backup. The fourth one, another SPARC processor, commands the rover's movement and is part of its motor controller box. All four processors are single core.[45] Curiosity transmits to Earth directly or via three relay satellites in Mars orbit. Communications     Communications: Curiosity is equipped with significant telecommunication redundancy by several means: an X band transmitter and receiver that can communicate directly with Earth, and an Ultra high frequency (UHF) Electra-Lite software-defined radio for communicating with Mars orbiters.[27] Communication with orbiters is the main path for data return to Earth, since the orbiters have both more power and larger antennas than the lander, allowing for faster transmission speeds.[27] Telecommunication included a small deep space transponder on the descent stage and a solid-state power amplifier on the rover for X-band. The rover also has two UHF radios,[27] the signals of which orbiting relay satellites are capable of relaying back to Earth. Signals between Earth and Mars take an average of 14 minutes, 6 seconds.[46] Curiosity can communicate with Earth directly at speeds up to 32 kbit/s, but the bulk of the data transfer is being relayed through the Mars Reconnaissance Orbiter and Odyssey orbiter. Data transfer speeds between Curiosity and each orbiter may reach 2000 kbit/s and 256 kbit/s, respectively, but each orbiter is able to communicate with Curiosity for only about eight minutes per day (0.56% of the time).[47] Communication from and to Curiosity relies on internationally agreed space data communications protocols as defined by the Consultative Committee for Space Data Systems.[48]     Jet Propulsion Laboratory (JPL) is the central data distribution hub where selected data products are provided to remote science operations sites as needed. JPL is also the central hub for the uplink process, though participants are distributed at their respective home institutions.[27] At landing, telemetry was monitored by three orbiters, depending on their dynamic location: the 2001 Mars Odyssey, Mars Reconnaissance Orbiter and ESA's Mars Express satellite.[49] As of February 2019, the MAVEN orbiter is being positioned to serve as a relay orbiter while continuing its science mission.[50] Mobility systems     Mobility systems: Curiosity is equipped with six 50 cm (20 in) diameter wheels in a rocker-bogie suspension. These are scaled versions of those used on Mars Exploration Rovers (MER).[27] The suspension system also served as landing gear for the vehicle, unlike its smaller predecessors.[51][52] Each wheel has cleats and is independently actuated and geared, providing for climbing in soft sand and scrambling over rocks. Each front and rear wheel can be independently steered, allowing the vehicle to turn in place as well as execute arcing turns.[27] Each wheel has a pattern that helps it maintain traction but also leaves patterned tracks in the sandy surface of Mars. That pattern is used by on-board cameras to estimate the distance traveled. The pattern itself is Morse code for "JPL" (·--- ·--· ·-··).[53] The rover is capable of climbing sand dunes with slopes up to 12.5°.[54] Based on the center of mass, the vehicle can withstand a tilt of at least 50° in any direction without overturning, but automatic sensors limit the rover from exceeding 30° tilts.[27] After six years of use, the wheels are visibly worn with punctures and tears.[55]     Curiosity can roll over obstacles approaching 65 cm (26 in) in height,[26] and it has a ground clearance of 60 cm (24 in).[56] Based on variables including power levels, terrain difficulty, slippage and visibility, the maximum terrain-traverse speed is estimated to be 200 m (660 ft) per day by automatic navigation.[26] The rover landed about 10 km (6.2 mi) from the base of Mount Sharp,[57] (officially named Aeolis Mons) and it is expected to traverse a minimum of 19 km (12 mi) during its primary two-year mission.[58] It can travel up to 90 m (300 ft) per hour but average speed is about 30 m (98 ft) per hour.[58] The vehicle is 'driven' by several operators led by Vandi Verma, group leader of Autonomous Systems, Mobility and Robotic Systems at JPL,[59][60] who also cowrote the PLEXIL language used to operate the rover.[61][62][63] Landing Further information: Bradbury Landing Curiosity landed in Quad 51 (nicknamed Yellowknife) of Aeolis Palus in the crater Gale.[64][65][66][67] The landing site coordinates are: 4.5895°S 137.4417°E.[68][69] The location was named Bradbury Landing on August 22, 2012, in honor of science fiction author Ray Bradbury.[6] Gale, an estimated 3.5 to 3.8 billion-year-old impact crater, is hypothesized to have first been gradually filled in by sediments; first water-deposited, and then wind-deposited, possibly until it was completely covered. Wind erosion then scoured out the sediments, leaving an isolated 5.5 km (3.4 mi) mountain, Aeolis Mons ("Mount Sharp"), at the center of the 154 km (96 mi) wide crater. Thus, it is believed that the rover may have the opportunity to study two billion years of Martian history in the sediments exposed in the mountain. Additionally, its landing site is near an alluvial fan, which is hypothesized to be the result of a flow of ground water, either before the deposition of the eroded sediments or else in relatively recent geologic history.[70][71] According to NASA, an estimated 20,000 to 40,000 heat-resistant bacterial spores were on Curiosity at launch, and as many as 1,000 times that number may not have been counted.[72] Curiosity and surrounding area as viewed by MRO/HiRISE. North is left. (August 14, 2012; enhanced colors) Rover's landing system Main article: Mars Science Laboratory–Landing NASA video describing the landing procedure. NASA dubbed the landing as "Seven Minutes of Terror" Previous NASA Mars rovers became active only after the successful entry, descent and landing on the Martian surface. Curiosity, on the other hand, was active when it touched down on the surface of Mars, employing the rover suspension system for the final set-down.[73] Curiosity transformed from its stowed flight configuration to a landing configuration while the MSL spacecraft simultaneously lowered it beneath the spacecraft descent stage with a 20 m (66 ft) tether from the "sky crane" system to a soft landing—wheels down—on the surface of Mars.[74][75][76][77] After the rover touched down it waited 2 seconds to confirm that it was on solid ground then fired several pyrotechnic fasteners activating cable cutters on the bridle to free itself from the spacecraft descent stage. The descent stage then flew away to a crash landing, and the rover prepared itself to begin the science portion of the mission.[78] Travel status As of December 9, 2020, the rover was 23.32 km (14.49 mi) away from its landing site.[79] As of April 17, 2020, the rover has been driven on fewer than 800 of its 2736 sols (Martian days). Duplicate MAGGIE Rover Scarecrow rover Curiosity has two full sized, vehicle system test bed (VSTB), a twin rover used for testing and problem solving, MAGGIE rover (Mars Automated Giant Gizmo for Integrated Engineering) with a computer brain and a Scarecrow rover without a computer brain. They are housed at the JPL Mars Yard for problem solving on simulated Mars terrain.[80][81] Scientific instruments Instrument location diagram The general sample analysis strategy begins with high-resolution cameras to look for features of interest. If a particular surface is of interest, Curiosity can vaporize a small portion of it with an infrared laser and examine the resulting spectra signature to query the rock's elemental composition. If that signature is intriguing, the rover uses its long arm to swing over a microscope and an X-ray spectrometer to take a closer look. If the specimen warrants further analysis, Curiosity can drill into the boulder and deliver a powdered sample to either the Sample Analysis at Mars (SAM) or the CheMin analytical laboratories inside the rover.[82][83][84] The MastCam, Mars Hand Lens Imager (MAHLI), and Mars Descent Imager (MARDI) cameras were developed by Malin Space Science Systems and they all share common design components, such as on-board digital image processing boxes, 1600 × 1200 charge-coupled device (CCDs), and an RGB Bayer pattern filter.[85][86][87][88][25][89] In total, the rover carries 17 cameras: HazCams (8), NavCams (4), MastCams (2), MAHLI (1), MARDI (1), and ChemCam (1).[90] Mast Camera (MastCam) The turret at the end of the robotic arm holds five devices. The MastCam system provides multiple spectra and true-color imaging with two cameras.[86] The cameras can take true-color images at 1600×1200 pixels and up to 10 frames per second hardware-compressed video at 720p (1280×720).[91] One MastCam camera is the Medium Angle Camera (MAC), which has a 34 mm (1.3 in) focal length, a 15° field of view, and can yield 22 cm/pixel (8.7 in/pixel) scale at 1 km (0.62 mi). The other camera in the MastCam is the Narrow Angle Camera (NAC), which has a 100 mm (3.9 in) focal length, a 5.1° field of view, and can yield 7.4 cm/pixel (2.9 in/pixel) scale at 1 km (0.62 mi).[86] Malin also developed a pair of MastCams with zoom lenses,[92] but these were not included in the rover because of the time required to test the new hardware and the looming November 2011 launch date.[93] However, the improved zoom version was selected to be incorporated on the Mars 2020 mission as Mastcam-Z.[94] Each camera has eight gigabytes of flash memory, which is capable of storing over 5,500 raw images, and can apply real time lossless data compression.[86] The cameras have an autofocus capability that allows them to focus on objects from 2.1 m (6 ft 11 in) to infinity.[25] In addition to the fixed RGBG Bayer pattern filter, each camera has an eight-position filter wheel. While the Bayer filter reduces visible light throughput, all three colors are mostly transparent at wavelengths longer than 700 nm, and have minimal effect on such infrared observations.[86] Chemistry and Camera complex (ChemCam) Main article: Chemistry and Camera complex The internal spectrometer (left) and the laser telescope (right) for the mast First laser spectrum of chemical elements from ChemCam on Curiosity ("Coronation" rock, August 19, 2012) ChemCam is a suite of two remote sensing instruments combined as one: a laser-induced breakdown spectroscopy (LIBS) and a Remote Micro Imager (RMI) telescope. The ChemCam instrument suite was developed by the French CESR laboratory and the Los Alamos National Laboratory.[95][96][97] The flight model of the mast unit was delivered from the French CNES to Los Alamos National Laboratory.[98] The purpose of the LIBS instrument is to provide elemental compositions of rock and soil, while the RMI gives ChemCam scientists high-resolution images of the sampling areas of the rocks and soil that LIBS targets.[95][99] The LIBS instrument can target a rock or soil sample up to 7 m (23 ft) away, vaporizing a small amount of it with about 50 to 75 5-nanosecond pulses from a 1067 nm infrared laser and then observes the spectrum of the light emitted by the vaporized rock.[100] ChemCam has the ability to record up to 6,144 different wavelengths of ultraviolet, visible, and infrared light.[101] Detection of the ball of luminous plasma is done in the visible, near-UV and near-infrared ranges, between 240 nm and 800 nm.[95] The first initial laser testing of the ChemCam by Curiosity on Mars was performed on a rock, N165 ("Coronation" rock), near Bradbury Landing on August 19, 2012.[102][103][104] The ChemCam team expects to take approximately one dozen compositional measurements of rocks per day.[105] Using the same collection optics, the RMI provides context images of the LIBS analysis spots. The RMI resolves 1 mm (0.039 in) objects at 10 m (33 ft) distance, and has a field of view covering 20 cm (7.9 in) at that distance.[95] Navigation cameras (NavCams) Main article: Navcam First full-resolution Navcam images The rover has two pairs of black and white navigation cameras mounted on the mast to support ground navigation.[106][107] The cameras have a 45° angle of view and use visible light to capture stereoscopic 3-D imagery.[107][108] Rover Environmental Monitoring Station (REMS) Main article: Rover Environmental Monitoring Station REMS comprises instruments to measure the Mars environment: humidity, pressure, temperatures, wind speeds, and ultraviolet radiation.[109] It is a meteorological package that includes an ultraviolet sensor provided by the Spanish Ministry of Education and Science. The investigative team is led by Javier Gómez-Elvira of the Spanish Astrobiology Center and includes the Finnish Meteorological Institute as a partner.[110][111] All sensors are located around three elements: two booms attached to the rover's mast, the Ultraviolet Sensor (UVS) assembly located on the rover top deck, and the Instrument Control Unit (ICU) inside the rover body. REMS provides new clues about the Martian general circulation, micro scale weather systems, local hydrological cycle, destructive potential of UV radiation, and subsurface habitability based on ground-atmosphere interaction.[110] Hazard avoidance cameras (HazCams) Main article: Hazcam The rover has four pairs of black and white navigation cameras called hazcams, two pairs in the front and two pairs in the back.[106][112] They are used for autonomous hazard avoidance during rover drives and for safe positioning of the robotic arm on rocks and soils.[112] Each camera in a pair is hardlinked to one of two identical main computers for redundancy; only four out of the eight cameras are in use at any one time. The cameras use visible light to capture stereoscopic three-dimensional (3-D) imagery.[112] The cameras have a 120° field of view and map the terrain at up to 3 m (9.8 ft) in front of the rover.[112] This imagery safeguards against the rover crashing into unexpected obstacles, and works in tandem with software that allows the rover to make its own safety choices.[112] Mars Hand Lens Imager (MAHLI) Main article: Mars Hand Lens Imager Mars Hand Lens Imager (MAHLI) Alpha Particle X-Ray Spectrometer (APXS) MAHLI is a camera on the rover's robotic arm, and acquires microscopic images of rock and soil. MAHLI can take true-color images at 1600×1200 pixels with a resolution as high as 14.5 µm per pixel. MAHLI has an 18.3 to 21.3 mm (0.72 to 0.84 in) focal length and a 33.8–38.5° field of view.[87] MAHLI has both white and ultraviolet Light-emitting diode (LED) illumination for imaging in darkness or fluorescence imaging. MAHLI also has mechanical focusing in a range from infinite to millimeter distances.[87] This system can make some images with focus stacking processing.[113] MAHLI can store either the raw images or do real time lossless predictive or JPEG compression. The calibration target for MAHLI includes color references, a metric bar graphic, a 1909 VDB Lincoln penny, and a stair-step pattern for depth calibration.[114] Alpha Particle X-ray Spectrometer (APXS) See also: Alpha particle X-ray spectrometer The APXS instrument irradiates samples with alpha particles and maps the spectra of X-rays that are re-emitted for determining the elemental composition of samples.[115] Curiosity's APXS was developed by the Canadian Space Agency (CSA).[115] MacDonald Dettwiler (MDA), the Canadian aerospace company that built the Canadarm and RADARSAT, were responsible for the engineering design and building of the APXS. The APXS science team includes members from the University of Guelph, the University of New Brunswick, the University of Western Ontario, NASA, the University of California, San Diego and Cornell University.[116] The APXS instrument takes advantage of particle-induced X-ray emission (PIXE) and X-ray fluorescence, previously exploited by the Mars Pathfinder and the two Mars Exploration Rovers.[115][117] Curiosity's CheMin Spectrometer on Mars (September 11, 2012), with sample inlet seen closed and open Chemistry and Mineralogy (CheMin) Main article: CheMin First X-ray diffraction view of Martian soil (Curiosity at Rocknest, October 17, 2012)[118] CheMin is the Chemistry and Mineralogy X-ray powder diffraction and fluorescence instrument.[119] CheMin is one of four spectrometers. It can identify and quantify the abundance of the minerals on Mars. It was developed by David Blake at NASA Ames Research Center and the Jet Propulsion Laboratory,[120] and won the 2013 NASA Government Invention of the year award.[121] The rover can drill samples from rocks and the resulting fine powder is poured into the instrument via a sample inlet tube on the top of the vehicle. A beam of X-rays is then directed at the powder and the crystal structure of the minerals deflects it at characteristic angles, allowing scientists to identify the minerals being analyzed.[122] On October 17, 2012, at "Rocknest", the first X-ray diffraction analysis of Martian soil was performed. The results revealed the presence of several minerals, including feldspar, pyroxenes and olivine, and suggested that the Martian soil in the sample was similar to the "weathered basaltic soils" of Hawaiian volcanoes.[118] The paragonetic tephra from a Hawaiian cinder cone has been mined to create Martian regolith simulant for researchers to use since 1998.[123][124] Sample Analysis at Mars (SAM) Main article: Sample Analysis at Mars First night-time pictures on Mars (white-light left/UV right) (Curiosity viewing Sayunei rock, January 22, 2013) The SAM instrument suite analyzes organics and gases from both atmospheric and solid samples. It consists of instruments developed by the NASA Goddard Space Flight Center, the Laboratoire Inter-Universitaire des Systèmes Atmosphériques (LISA) (jointly operated by France's CNRS and Parisian universities), and Honeybee Robotics, along with many additional external partners.[83][125][126] The three main instruments are a Quadrupole Mass Spectrometer (QMS), a gas chromatograph (GC) and a tunable laser spectrometer (TLS). These instruments perform precision measurements of oxygen and carbon isotope ratios in carbon dioxide (CO2) and methane (CH4) in the atmosphere of Mars in order to distinguish between their geochemical or biological origin.[83][126][127][128] First use of Curiosity's Dust Removal Tool (DRT) (January 6, 2013); Ekwir_1 rock before/after cleaning (left) and closeup (right) Dust Removal Tool (DRT) The Dust Removal Tool (DRT) is a motorized, wire-bristle brush on the turret at the end of Curiosity's arm. The DRT was first used on a rock target named Ekwir_1 on January 6, 2013. Honeybee Robotics built the DRT.[129] Radiation assessment detector (RAD) Main article: Radiation assessment detector The role of the Radiation assessment detector (RAD) instrument is to characterize the broad spectrum of radiation environment found inside the spacecraft during the cruise phase and while on Mars. These measurements have never been done before from the inside of a spacecraft in interplanetary space. Its primary purpose is to determine the viability and shielding needs for potential human explorers, as well as to characterize the radiation environment on the surface of Mars, which it started doing immediately after MSL landed in August 2012.[130] Funded by the Exploration Systems Mission Directorate at NASA Headquarters and Germany's Space Agency (DLR), RAD was developed by Southwest Research Institute (SwRI) and the extraterrestrial physics group at Christian-Albrechts-Universität zu Kiel, Germany.[130][131] Dynamic Albedo of Neutrons (DAN) Main article: Dynamic Albedo of Neutrons The DAN instrument employs a neutron source and detector for measuring the quantity and depth of hydrogen or ice and water at or near the Martian surface.[132] The instrument consists of the detector element (DE) and a 14.1 MeV pulsing neutron generator (PNG). The die-away time of neutrons is measured by the DE after each neutron pulse from the PNG. DAN was provided by the Russian Federal Space Agency[133][134] and funded by Russia.[135] Mars Descent Imager (MARDI) MARDI camera MARDI is fixed to the lower front left corner of the body of Curiosity. During the descent to the Martian surface, MARDI took color images at 1600×1200 pixels with a 1.3-millisecond exposure time starting at distances of about 3.7 km (2.3 mi) to near 5 m (16 ft) from the ground, at a rate of four frames per second for about two minutes.[88][136] MARDI has a pixel scale of 1.5 m (4 ft 11 in) at 2 km (1.2 mi) to 1.5 mm (0.059 in) at 2 m (6 ft 7 in) and has a 90° circular field of view. MARDI has eight gigabytes of internal buffer memory that is capable of storing over 4,000 raw images. MARDI imaging allowed the mapping of surrounding terrain and the location of landing.[88] JunoCam, built for the Juno spacecraft, is based on MARDI.[137] First use of Curiosity's scooper as it sifts a load of sand at Rocknest (October 7, 2012) Robotic arm First drill tests (John Klein rock, Yellowknife Bay, February 2, 2013).[138] The rover has a 2.1 m (6 ft 11 in) long robotic arm with a cross-shaped turret holding five devices that can spin through a 350° turning range.[139][140] The arm makes use of three joints to extend it forward and to stow it again while driving. It has a mass of 30 kg (66 lb) and its diameter, including the tools mounted on it, is about 60 cm (24 in).[141] It was designed, built, and tested by MDA US Systems, building upon their prior robotic arm work on the Mars Surveyor 2001 Lander, the Phoenix lander, and the two Mars Exploration Rovers, Spirit and Opportunity.[142] Two of the five devices are in-situ or contact instruments known as the X-ray spectrometer (APXS), and the Mars Hand Lens Imager (MAHLI camera). The remaining three are associated with sample acquisition and sample preparation functions: a percussion drill; a brush; and mechanisms for scooping, sieving, and portioning samples of powdered rock and soil.[139][141] The diameter of the hole in a rock after drilling is 1.6 cm (0.63 in) and up to 5 cm (2.0 in) deep.[140][143] The drill carries two spare bits.[143][144] The rover's arm and turret system can place the APXS and MAHLI on their respective targets, and also obtain powdered sample from rock interiors, and deliver them to the SAM and CheMin analyzers inside the rover.[140] Since early 2015 the percussive mechanism in the drill that helps chisel into rock has had an intermittent electrical short.[145] On December 1, 2016, the motor inside the drill caused a malfunction that prevented the rover from moving its robotic arm and driving to another location.[146] The fault was isolated to the drill feed brake,[147] and internal debris is suspected of causing the problem.[145] By December 9, 2016, driving and robotic arm operations were cleared to continue, but drilling remained suspended indefinitely.[148] The Curiosity team continued to perform diagnostics and testing on the drill mechanism throughout 2017,[149] and resumed drilling operations on May 22, 2018.[150] Media, cultural impact and legacy Further information: Timeline of Mars Science Laboratory § Current status Celebration erupts at NASA with the rover's successful landing on Mars (August 6, 2012). Live video showing the first footage from the surface of Mars was available at NASA TV, during the late hours of August 6, 2012, PDT, including interviews with the mission team. The NASA website momentarily became unavailable from the overwhelming number of people visiting it,[151] and a 13-minute NASA excerpt of the landings on its YouTube channel was halted an hour after the landing by an automated DMCA takedown notice from Scripps Local News, which prevented access for several hours.[152] Around 1,000 people gathered in New York City's Times Square, to watch NASA's live broadcast of Curiosity's landing, as footage was being shown on the giant screen.[153] Bobak Ferdowsi, Flight Director for the landing, became an Internet meme and attained Twitter celebrity status, with 45,000 new followers subscribing to his Twitter account, due to his Mohawk hairstyle with yellow stars that he wore during the televised broadcast.[154][155] On August 13, 2012, U.S. President Barack Obama, calling from aboard Air Force One to congratulate the Curiosity team, said, "You guys are examples of American know-how and ingenuity. It's really an amazing accomplishment".[156] (Video (07:20)) Scientists at the Getty Conservation Institute in Los Angeles, California, viewed the CheMin instrument aboard Curiosity as a potentially valuable means to examine ancient works of art without damaging them. Until recently, only a few instruments were available to determine the composition without cutting out physical samples large enough to potentially damage the artifacts. CheMin directs a beam of X-rays at particles as small as 400 μm (0.016 in)[157] and reads the radiation scattered back to determine the composition of the artifact in minutes. Engineers created a smaller, portable version named the X-Duetto. Fitting into a few briefcase-sized boxes, it can examine objects on site, while preserving their physical integrity. It is now being used by Getty scientists to analyze a large collection of museum antiques and the Roman ruins of Herculaneum, Italy.[158] Prior to the landing, NASA and Microsoft released Mars Rover Landing, a free downloadable game on Xbox Live that uses Kinect to capture body motions, which allows users to simulate the landing sequence.[159] U.S. flag medallion Plaque with President Obama and Vice President Biden's signatures NASA gave the general public the opportunity from 2009 until 2011 to submit their names to be sent to Mars. More than 1.2 million people from the international community participated, and their names were etched into silicon using an electron-beam machine used for fabricating micro devices at JPL, and this plaque is now installed on the deck of Curiosity.[160] In keeping with a 40-year tradition, a plaque with the signatures of President Barack Obama and Vice President Joe Biden was also installed. Elsewhere on the rover is the autograph of Clara Ma, the 12-year-old girl from Kansas who gave Curiosity its name in an essay contest, writing in part that "curiosity is the passion that drives us through our everyday lives".[161] On August 6, 2013, Curiosity audibly played "Happy Birthday to You" in honor of the one Earth year mark of its Martian landing, the first time for a song to be played on another planet. This was also the first time music was transmitted between two planets.[162] On June 24, 2014, Curiosity completed a Martian year — 687 Earth days — after finding that Mars once had environmental conditions favorable for microbial life.[163] Curiosity served as the basis for the design of the Perseverance rover for the Mars 2020 rover mission. Some spare parts from the build and ground test of Curiosity are being used in the new vehicle, but it will carry a different instrument payload.[164] In 2014, project chief engineer wrote a book detailing the development of the Curiosity rover. "Mars Rover Curiosity: An Inside Account from Curiosity's Chief Engineer, is a first hand account of the development and landing of the Curiosity Rover.[165] On August 5, 2017, NASA celebrated the fifth anniversary of the Curiosity rover mission landing, and related exploratory accomplishments, on the planet Mars.[11][12] (Videos: Curiosity's First Five Years (02:07); Curiosity's POV: Five Years Driving (05:49); Curiosity's Discoveries About Gale Crater (02:54)) As reported in 2018, drill samples taken in 2015 uncovered organic molecules of benzene and propane in 3 billion year old rock samples in Gale. Images 2:27 Descent of Curiosity (video-02:26; August 6, 2012) Interactive 3D model of the rover (with extended arm) Components of Curiosity     Mast head with ChemCam, MastCam-34, MastCam-100, NavCam     Mast head with ChemCam, MastCam-34, MastCam-100, NavCam     One of the six wheels on Curiosity     One of the six wheels on Curiosity     High-gain (right) and low-gain (left) antennas     High-gain (right) and low-gain (left) antennas     UV sensor     UV sensor Orbital images     Curiosity descending under its parachute (6 August 2012; MRO/HiRISE).     Curiosity descending under its parachute (6 August 2012; MRO/HiRISE).     Curiosity's parachute flapping in Martian wind (12 August 2012 to 13 January 2013; MRO).     Curiosity's parachute flapping in Martian wind (12 August 2012 to 13 January 2013; MRO).     Gale crater - surface materials (false colors; THEMIS; 2001 Mars Odyssey).     Gale crater - surface materials (false colors; THEMIS; 2001 Mars Odyssey).     Curiosity's landing site is on Aeolis Palus near Mount Sharp (north is down).     Curiosity's landing site is on Aeolis Palus near Mount Sharp (north is down).     Mount Sharp rises from the middle of Gale; the green dot marks Curiosity's landing site (north is down).     Mount Sharp rises from the middle of Gale; the green dot marks Curiosity's landing site (north is down).     Green dot is Curiosity's landing site; upper blue is Glenelg; lower blue is base of Mount Sharp.     Green dot is Curiosity's landing site; upper blue is Glenelg; lower blue is base of Mount Sharp.     Curiosity's landing ellipse. Quad 51, called Yellowknife, marks the area where Curiosity actually landed.     Curiosity's landing ellipse. Quad 51, called Yellowknife, marks the area where Curiosity actually landed.     Quad 51, a 1-mile-by-1-mile section of the crater Gale - Curiosity landing site is noted.     Quad 51, a 1-mile-by-1-mile section of the crater Gale - Curiosity landing site is noted.     MSL debris field - parachute landed 615 m from Curiosity (3-D: rover and parachute) (17 August 2012; MRO).     MSL debris field - parachute landed 615 m from Curiosity (3-D: rover and parachute) (17 August 2012; MRO).     Curiosity's landing site, Bradbury Landing, as seen by MRO/HiRISE (14 August 2012)     Curiosity's landing site, Bradbury Landing, as seen by MRO/HiRISE (14 August 2012)     Curiosity's first tracks viewed by MRO/HiRISE (6 September 2012)     Curiosity's first tracks viewed by MRO/HiRISE (6 September 2012)     First-year and first-mile map of Curiosity's traverse on Mars (1 August 2013) (3-D).     First-year and first-mile map of Curiosity's traverse on Mars (1 August 2013) (3-D). Rover images     Ejected heat shield as viewed by Curiosity descending to Martian surface (6 August 2012)     Ejected heat shield as viewed by Curiosity descending to Martian surface (6 August 2012)     Curiosity's first image after landing (6 August 2012). The rover's wheel can be seen.     Curiosity's first image after landing (6 August 2012). The rover's wheel can be seen.     Curiosity's first image after landing (without clear dust cover, 6 August 2012)     Curiosity's first image after landing (without clear dust cover, 6 August 2012)     Curiosity landed on 6 August 2012 near the base of Aeolis Mons (or "Mount Sharp")[169]     Curiosity landed on 6 August 2012 near the base of Aeolis Mons (or "Mount Sharp")[169]     Curiosity's first color image of the Martian landscape, taken by MAHLI (6 August 2012)     Curiosity's first color image of the Martian landscape, taken by MAHLI (6 August 2012)     Curiosity's self-portrait – with closed dust cover (7 September 2012)     Curiosity's self-portrait – with closed dust cover (7 September 2012)     Curiosity's self-portrait (7 September 2012; color-corrected)     Curiosity's self-portrait (7 September 2012; color-corrected)     Calibration target of MAHLI (9 September 2012; alternate 3-D version)     Calibration target of MAHLI (9 September 2012; alternate 3-D version)     U.S. Lincoln penny on Mars (Curiosity; 10 September 2012) (3-D; 2 October 2013)     U.S. Lincoln penny on Mars (Curiosity; 10 September 2012)     (3-D; 2 October 2013)     U.S. Lincoln penny on Mars (Curiosity; 4 September 2018)     U.S. Lincoln penny on Mars (Curiosity; 4 September 2018)     Wheels on Curiosity. Mount Sharp is visible in the background. (MAHLI, 9 September 2012)     Wheels on Curiosity. Mount Sharp is visible in the background. (MAHLI, 9 September 2012)     Curiosity's tracks on first test drive (22 August 2012), after parking 6 m (20 ft) from original landing site[6]     Curiosity's tracks on first test drive (22 August 2012), after parking 6 m (20 ft) from original landing site[6]     Comparison of color versions (raw, natural, white balance) of Aeolis Mons on Mars (23 August 2012)     Comparison of color versions (raw, natural, white balance) of Aeolis Mons on Mars (23 August 2012)     Curiosity's view of Aeolis Mons (9 August 2012; white-balanced image)     Curiosity's view of Aeolis Mons (9 August 2012; white-balanced image)     Layers at the base of Aeolis Mons. The dark rock in inset is the same size as Curiosity.     Layers at the base of Aeolis Mons. The dark rock in inset is the same size as Curiosity. Self-portraits Self-portraits of Curiosity rover on Mount Sharp "Rocknest" (October 2012) "John Klein" (May 2013) "Windjana" (May 2014) "Mojave" (January 2015) "Buckskin" (August 2015) "Big Sky" (October 2015) "Namib" (January 2016) "Murray" (September 2016) "Vera Rubin" (January 2018) "Dust Storm" (June 2018) "Vera Rubin" (January 2019) "Aberlady" (May 2019) "Glen Etive" (October 2019) "Hutton" (February 2020) "Mary Anning" (November 2020) "Mont Mercou" (March 2021) "Greenheugh Pediment" (November 2021) See also: List of rocks on Mars#Curiosity Wide images Curiosity's first 360° color panorama image (August 8, 2012)[169][170] Curiosity's view of Mount Sharp (September 20, 2012; raw color version) Curiosity's view of the Rocknest area. South is at center, north is at both ends. Mount Sharp dominates the horizon, while Glenelg is left-of-center and rover tracks are right-of-center (November 16, 2012; white balanced; raw color version; high-res panoramic). Curiosity's view from Rocknest looking east toward Point Lake (center) on the way to Glenelg (November 26, 2012; white balanced; raw color version) Curiosity's view of "Mount Sharp" (September 9, 2015) Curiosity's view of Mars sky at sunset (February 2013; Sun simulated by artist) Curiosity's view of Glen Torridon near Mount Sharp, the rover's highest-resolution 360° panoramic image of over 1.8 billion pixels (at full size) from over 1000 photos taken between November 24 and December 1, 2019 Locations Curiosity Traverse Path showing its current location" (wikipedia.org) "Mars is the fourth planet from the Sun and the third largest and massive terrestrial object in the Solar System. Mars has a thin atmosphere and a crust primarily composed of elements similar to Earth's crust, as well as a core made of iron and nickel. Mars has surface features such as impact craters, valleys, dunes, and polar ice caps. Mars has two small, irregularly shaped moons, Phobos and Deimos. Some of the most notable surface features on Mars include Olympus Mons, the largest volcano and highest-known mountain in the Solar System, and Valles Marineris, one of the largest canyons in the Solar System. The Borealis basin in the Northern Hemisphere covers approximately 40% of the planet and may be a large impact feature.[21] Days and seasons on Mars are comparable to those of Earth, as the planets have a similar rotation period and tilt of the rotational axis relative to the ecliptic plane. Liquid water on the surface of Mars cannot exist due to low atmospheric pressure, which is less than 1% of the atmospheric pressure on Earth.[22][23] Both of Mars's polar ice caps appear to be made largely of water.[24][25] In the distant past, Mars was likely wetter, and thus possibly more suited for life. It is not known whether life has ever existed on Mars. Mars has been explored by several uncrewed spacecraft, beginning with Mariner 4 in 1965. NASA's Viking 1 lander transmitted the first images from the Martian surface in 1976. Two countries have successfully deployed rovers on Mars, the United States first doing so with Sojourner in 1997 and China with Zhurong in 2021.[26] There are also planned future missions to Mars, such as a NASA-ESA Mars Sample Return set to happen in 2026, and the Rosalind Franklin rover mission, which was intended to launch in 2018 but was delayed to 2024 at the earliest, with a more likely launch date at 2028. Mars can be viewed from Earth with the naked eye, as can its reddish coloring. This appearance, due to the iron oxide prevalent on its surface, has led to Mars often being called the Red Planet.[27][28] It is among the brightest objects in Earth's sky, with an apparent magnitude that reaches −2.94, comparable to that of Jupiter and surpassed only by Venus, the Moon and the Sun.[16] Mars has been observed since ancient times. Over the millennia it has been featured in culture and the arts in ways that have reflected humanity's growing knowledge of it. Historical observations Main article: History of Mars observation The history of observations of Mars is marked by the oppositions of Mars when the planet is closest to Earth and hence is most easily visible, which occur every couple of years. Even more notable are the perihelic oppositions of Mars, which are distinguished because Mars is close to perihelion, making it even closer to Earth.[29] Ancient and medieval observations The ancient Sumerians named Mars Nergal, the god of war and plague. During Sumerian times, Nergal was a minor deity of little significance, but, during later times, his main cult center was the city of Nineveh.[30] In Mesopotamian texts, Mars is referred to as the "star of judgement of the fate of the dead."[31] The existence of Mars as a wandering object in the night sky was also recorded by the ancient Egyptian astronomers and, by 1534 BCE, they were familiar with the retrograde motion of the planet.[32] By the period of the Neo-Babylonian Empire, the Babylonian astronomers were making regular records of the positions of the planets and systematic observations of their behavior. For Mars, they knew that the planet made 37 synodic periods, or 42 circuits of the zodiac, every 79 years. They invented arithmetic methods for making minor corrections to the predicted positions of the planets.[33][34] In Ancient Greece, the planet was known as Πυρόεις.[35] Commonly, the Greek name for the planet now referred to as Mars, was Ares. It was the Romans who named the planet Mars, for their god of war, often represented by the sword and shield of the planet's namesake.[36] In the fourth century BCE, Aristotle noted that Mars disappeared behind the Moon during an occultation, indicating that the planet was farther away.[37] Ptolemy, a Greek living in Alexandria,[38] attempted to address the problem of the orbital motion of Mars. Ptolemy's model and his collective work on astronomy was presented in the multi-volume collection later called the Almagest (from the Arabic for "greatest"), which became the authoritative treatise on Western astronomy for the next fourteen centuries.[39] Literature from ancient China confirms that Mars was known by Chinese astronomers by no later than the fourth century BCE.[40] In the East Asian cultures, Mars is traditionally referred to as the "fire star" (Chinese: 火星), based on the Wuxing system.[41][42][43] During the seventeenth century A.D., Tycho Brahe measured the diurnal parallax of Mars that Johannes Kepler used to make a preliminary calculation of the relative distance to the planet.[44] From Brahe's observations of Mars, Kepler deduced that the planet orbited the Sun not in a circle, but in an ellipse. Moreover, Kepler showed that Mars sped up as it approached the Sun and slowed down as it moved farther away, in a manner that later physicists would explain as a consequence of the conservation of angular momentum.[45]: 433–437  When the telescope became available, the diurnal parallax of Mars was again measured in an effort to determine the Sun-Earth distance. This was first performed by Giovanni Domenico Cassini in 1672. The early parallax measurements were hampered by the quality of the instruments.[46] The only occultation of Mars by Venus observed was that of 13 October 1590, seen by Michael Maestlin at Heidelberg.[47] In 1610, Mars was viewed by Italian astronomer Galileo Galilei, who was first to see it via telescope.[48] The first person to draw a map of Mars that displayed any terrain features was the Dutch astronomer Christiaan Huygens.[49] Martian "canals" Main article: Martian canals By the 19th century, the resolution of telescopes reached a level sufficient for surface features to be identified. On 5 September 1877, a perihelic opposition of Mars occurred. The Italian astronomer Giovanni Schiaparelli used a 22-centimetre (8.7 in) telescope in Milan to help produce the first detailed map of Mars. These maps notably contained features he called canali, which were later shown to be an optical illusion. These canali were supposedly long, straight lines on the surface of Mars, to which he gave names of famous rivers on Earth. His term, which means "channels" or "grooves", was popularly mistranslated in English as "canals".[50][51] Influenced by the observations, the orientalist Percival Lowell founded an observatory which had 30- and 45-centimetre (12- and 18-in) telescopes. The observatory was used for the exploration of Mars during the last good opportunity in 1894 and the following less favorable oppositions. He published several books on Mars and life on the planet, which had a great influence on the public.[52][53] The canali were independently observed by other astronomers, like Henri Joseph Perrotin and Louis Thollon in Nice, using one of the largest telescopes of that time.[54][55] The seasonal changes (consisting of the diminishing of the polar caps and the dark areas formed during Martian summer) in combination with the canals led to speculation about life on Mars, and it was a long-held belief that Mars contained vast seas and vegetation. As bigger telescopes were used, fewer long, straight canali were observed. During observations in 1909 by Antoniadi with an 84-centimetre (33 in) telescope, irregular patterns were observed, but no canali were seen.[56] Physical characteristics Comparison: Earth and Mars Animation (00:40) showing major features of Mars Video (01:28) showing how three NASA orbiters mapped the gravity field of Mars Mars is approximately half the diameter of Earth, with a surface area only slightly less than the total area of Earth's dry land.[2] Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's mass, resulting in about 38% of Earth's surface gravity. The red-orange appearance of the Martian surface is caused by ferric oxide, or rust.[57] It can look like butterscotch;[58] other common surface colors include golden, brown, tan, and greenish, depending on the minerals present.[58] Internal structure Like Earth, Mars has differentiated into a dense metallic core overlaid by less dense materials.[59][60] Current models of its interior imply a core consisting primarily of iron and nickel with about 16–17% sulfur.[61] This iron(II) sulfide core is thought to be twice as rich in lighter elements as Earth's.[62] The core is surrounded by a silicate mantle that formed many of the tectonic and volcanic features on the planet, but it appears to be dormant. Besides silicon and oxygen, the most abundant elements in the Martian crust are iron, magnesium, aluminium, calcium, and potassium. The average thickness of the planet's crust is about 50 kilometres (31 mi), with a maximum thickness of 125 kilometres (78 mi).[62] By comparison, Earth's crust averages 40 kilometres (25 mi) in thickness.[63][64] Mars is seismically active. In 2019, it was reported that InSight (now offline) had detected and recorded over 450 marsquakes and related events.[65][66] In 2021 it was reported that based on eleven low-frequency marsquakes detected by the InSight lander the core of Mars was indeed liquid and had a radius of about 1830±40 km and a temperature around 1900–2000 K. The Martian core radius is abnormally large, accounting for more than half the radius of Mars and about half the size of the Earth's core. To this, it has been suggested that the core contains some amount of lighter elements like oxygen and hydrogen in addition to the iron–nickel alloy and about 15% of sulfur.[67][68] The core of Mars is overlaid by the rocky mantle, which does not seem to have a thermally insulating layer analogous to the Earth's lower mantle.[68] The Martian mantle appears to be solid down to the depth of about 500 km, where the low-velocity zone (partially melted asthenosphere) begins.[69] Below the asthenosphere the velocity of seismic waves starts to grow again; and at the depth of about 1050 km lies the boundary of the transition zone extending down to the core.[68] Surface geology Main article: Geology of Mars Geologic map of Mars (USGS, 2014)[70] Mars is a terrestrial planet with a surface that consists of minerals containing silicon and oxygen, metals, and other elements that typically make up rock. The Martian surface is primarily composed of tholeiitic basalt,[71] although parts are more silica-rich than typical basalt and may be similar to andesitic rocks on Earth, or silica glass. Regions of low albedo suggest concentrations of plagioclase feldspar, with northern low albedo regions displaying higher than normal concentrations of sheet silicates and high-silicon glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Localized concentrations of hematite and olivine have been found.[72] Much of the surface is deeply covered by finely grained iron(III) oxide dust.[73] Although Mars has no evidence of a structured global magnetic field,[74] observations show that parts of the planet's crust have been magnetized, suggesting that alternating polarity reversals of its dipole field have occurred in the past. This paleomagnetism of magnetically susceptible minerals is similar to the alternating bands found on Earth's ocean floors. One theory, published in 1999 and re-examined in October 2005 (with the help of the Mars Global Surveyor), is that these bands suggest plate tectonic activity on Mars four billion years ago, before the planetary dynamo ceased to function and the planet's magnetic field faded.[75] Scientists have theorized that during the Solar System's formation Mars was created as the result of a random process of run-away accretion of material from the protoplanetary disk that orbited the Sun. Mars has many distinctive chemical features caused by its position in the Solar System. Elements with comparatively low boiling points, such as chlorine, phosphorus, and sulfur, are much more common on Mars than Earth; these elements were probably pushed outward by the young Sun's energetic solar wind.[76] After the formation of the planets, all were subjected to the so-called "Late Heavy Bombardment". About 60% of the surface of Mars shows a record of impacts from that era,[77][78][79] whereas much of the remaining surface is probably underlain by immense impact basins caused by those events. There is evidence of an enormous impact basin in the Northern Hemisphere of Mars, spanning 10,600 by 8,500 kilometres (6,600 by 5,300 mi), or roughly four times the size of the Moon's South Pole – Aitken basin, the largest impact basin yet discovered.[80] This theory suggests that Mars was struck by a Pluto-sized body about four billion years ago. The event, thought to be the cause of the Martian hemispheric dichotomy, created the smooth Borealis basin that covers 40% of the planet.[81][82] The geological history of Mars can be split into many periods, but the following are the three primary periods:[83][84]     Noachian period: Formation of the oldest extant surfaces of Mars, 4.5 to 3.5 billion years ago. Noachian age surfaces are scarred by many large impact craters. The Tharsis bulge, a volcanic upland, is thought to have formed during this period, with extensive flooding by liquid water late in the period. Named after Noachis Terra.[85]     Hesperian period: 3.5 to between 3.3 and 2.9 billion years ago. The Hesperian period is marked by the formation of extensive lava plains. Named after Hesperia Planum.[85]     Amazonian period: between 3.3 and 2.9 billion years ago to the present. Amazonian regions have few meteorite impact craters but are otherwise quite varied. Olympus Mons formed during this period, with lava flows elsewhere on Mars. Named after Amazonis Planitia.[85] Geological activity is still taking place on Mars. The Athabasca Valles is home to sheet-like lava flows created about 200 mya. Water flows in the grabens called the Cerberus Fossae occurred less than 20 Mya, indicating equally recent volcanic intrusions.[86] The Mars Reconnaissance Orbiter has captured images of avalanches.[87][88] Soil Main article: Martian soil Curiosity's view of Martian soil and boulders after crossing the "Dingo Gap" sand dune The Phoenix lander returned data showing Martian soil to be slightly alkaline and containing elements such as magnesium, sodium, potassium and chlorine. These nutrients are found in soils on Earth. They are necessary for growth of plants.[89] Experiments performed by the lander showed that the Martian soil has a basic pH of 7.7, and contains 0.6% of the salt perchlorate,[90][91] concentrations that are toxic to humans.[92][93] Streaks are common across Mars and new ones appear frequently on steep slopes of craters, troughs, and valleys. The streaks are dark at first and get lighter with age. The streaks can start in a tiny area, then spread out for hundreds of metres. They have been seen to follow the edges of boulders and other obstacles in their path. The commonly accepted theories include that they are dark underlying layers of soil revealed after avalanches of bright dust or dust devils.[94] Several other explanations have been put forward, including those that involve water or even the growth of organisms.[95][96] Hydrology Main article: Water on Mars Martian plain covered by water ice, precipitated through adhering to dry ice, observed by Viking 2 lander Proportion of water ice present in the upper meter of the Martian surface for lower (top) and higher (bottom) latitudes Water in its liquid form cannot exist on the surface of Mars due to low atmospheric pressure, which is less than 1% that of Earth,[22] except at the lowest of elevations for short periods.[60][97] The two polar ice caps appear to be made largely of water.[24][25] The volume of water ice in the south polar ice cap, if melted, would be enough to cover the entire surface of the planet with a depth of 11 metres (36 ft).[98] Large quantities of ice are thought to be trapped within the thick cryosphere of Mars. Radar data from Mars Express and the Mars Reconnaissance Orbiter (MRO) show large quantities of ice at both poles,[99][100] and at middle latitudes.[101] The Phoenix lander directly sampled water ice in shallow Martian soil on 31 July 2008.[102] Landforms visible on Mars strongly suggest that liquid water has existed on the planet's surface. Huge linear swathes of scoured ground, known as outflow channels, cut across the surface in about 25 places. These are thought to be a record of erosion caused by the catastrophic release of water from subsurface aquifers, though some of these structures have been hypothesized to result from the action of glaciers or lava.[103][104] One of the larger examples, Ma'adim Vallis, is 700 kilometres (430 mi) long, much greater than the Grand Canyon, with a width of 20 kilometres (12 mi) and a depth of 2 kilometres (1.2 mi) in places. It is thought to have been carved by flowing water early in Mars's history.[105] The youngest of these channels are thought to have formed only a few million years ago.[106] Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic networks of valleys are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by runoff resulting from precipitation in early Mars history. Subsurface water flow and groundwater sapping may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases.[107] Along crater and canyon walls, there are thousands of features that appear similar to terrestrial gullies. The gullies tend to be in the highlands of the Southern Hemisphere and to face the Equator; all are poleward of 30° latitude. A number of authors have suggested that their formation process involves liquid water, probably from melting ice,[108][109] although others have argued for formation mechanisms involving carbon dioxide frost or the movement of dry dust.[110][111] No partially degraded gullies have formed by weathering and no superimposed impact craters have been observed, indicating that these are young features, possibly still active.[109] Other geological features, such as deltas and alluvial fans preserved in craters, are further evidence for warmer, wetter conditions at an interval or intervals in earlier Mars history.[112] Such conditions necessarily require the widespread presence of crater lakes across a large proportion of the surface, for which there is independent mineralogical, sedimentological and geomorphological evidence.[113] Further evidence that liquid water once existed on the surface of Mars comes from the detection of specific minerals such as hematite and goethite, both of which sometimes form in the presence of water.[114] Polar caps Main article: Martian polar ice caps North polar early summer water ice cap (1999); a seasonal layer of carbon dioxide ice forms in winter and disappears in summer. South polar midsummer ice cap (2000); the south cap has a permanent carbon dioxide ice cap covered with water ice.[115] Mars has two permanent polar ice caps. During a pole's winter, it lies in continuous darkness, chilling the surface and causing the deposition of 25–30% of the atmosphere into slabs of CO2 ice (dry ice).[116] When the poles are again exposed to sunlight, the frozen CO2 sublimes. These seasonal actions transport large amounts of dust and water vapor, giving rise to Earth-like frost and large cirrus clouds. Clouds of water-ice were photographed by the Opportunity rover in 2004.[117] The caps at both poles consist primarily (70%[citation needed]) of water ice. Frozen carbon dioxide accumulates as a comparatively thin layer about one metre thick on the north cap in the northern winter only, whereas the south cap has a permanent dry ice cover about eight metres thick. This permanent dry ice cover at the south pole is peppered by flat floored, shallow, roughly circular pits, which repeat imaging shows are expanding in some places and retreating in others.[118] The northern polar cap has a diameter of about 1,000 kilometres (620 mi),[119] and contains about 1.6 million cubic kilometres (5.7×1016 cu ft) of ice, which, if spread evenly on the cap, would be 2 kilometres (1.2 mi) thick.[120] (This compares to a volume of 2.85 million cubic kilometres (1.01×1017 cu ft) for the Greenland ice sheet.) The southern polar cap has a diameter of 350 kilometres (220 mi) and a thickness of 3 kilometres (1.9 mi).[121] The total volume of ice in the south polar cap plus the adjacent layered deposits has been estimated at 1.6 million cubic km.[122] Both polar caps show spiral troughs, which recent analysis of SHARAD ice penetrating radar has shown are a result of katabatic winds that spiral due to the Coriolis effect.[123][124] The seasonal frosting of areas near the southern ice cap results in the formation of transparent 1-metre-thick slabs of dry ice above the ground. With the arrival of spring, sunlight warms the subsurface and pressure from subliming CO2 builds up under a slab, elevating and ultimately rupturing it. This leads to geyser-like eruptions of CO2 gas mixed with dark basaltic sand or dust. This process is rapid, observed happening in the space of a few days, weeks or months, a rate of change rather unusual in geology – especially for Mars. The gas rushing underneath a slab to the site of a geyser carves a spiderweb-like pattern of radial channels under the ice, the process being the inverted equivalent of an erosion network formed by water draining through a single plughole.[125][126] Observations and findings of water evidence Main article: Chronology of discoveries of water on Mars In 2004, Opportunity detected the mineral jarosite. This forms only in the presence of acidic water, showing that water once existed on Mars.[127][128] The Spirit rover found concentrated deposits of silica in 2007 that indicated wet conditions in the past, and in December 2011, the mineral gypsum, which also forms in the presence of water, was found on the surface by NASA's Mars rover Opportunity.[129][130][131] It is estimated that the amount of water in the upper mantle of Mars, represented by hydroxyl ions contained within Martian minerals, is equal to or greater than that of Earth at 50–300 parts per million of water, which is enough to cover the entire planet to a depth of 200–1,000 metres (660–3,280 ft).[132][133] A cross-section of underground water ice is exposed at the steep slope that appears bright blue in this enhanced-color view from the MRO. On 18 March 2013, NASA reported evidence from instruments on the Curiosity rover of mineral hydration, likely hydrated calcium sulfate, in several rock samples including the broken fragments of "Tintina" rock and "Sutton Inlier" rock as well as in veins and nodules in other rocks like "Knorr" rock and "Wernicke" rock.[134][135] Analysis using the rover's DAN instrument provided evidence of subsurface water, amounting to as much as 4% water content, down to a depth of 60 centimetres (24 in), during the rover's traverse from the Bradbury Landing site to the Yellowknife Bay area in the Glenelg terrain.[134] In September 2015, NASA announced that they had found strong evidence of hydrated brine flows in recurring slope lineae, based on spectrometer readings of the darkened areas of slopes.[136][137][138] These streaks flow downhill in Martian summer, when the temperature is above −23° Celsius, and freeze at lower temperatures.[139] These observations supported earlier hypotheses, based on timing of formation and their rate of growth, that these dark streaks resulted from water flowing just below the surface.[140] However, later work suggested that the lineae may be dry, granular flows instead, with at most a limited role for water in initiating the process.[141] A definitive conclusion about the presence, extent, and role of liquid water on the Martian surface remains elusive.[142][143] Researchers suspect much of the low northern plains of the planet were covered with an ocean hundreds of meters deep, though this theory remains controversial.[144] In March 2015, scientists stated that such an ocean might have been the size of Earth's Arctic Ocean. This finding was derived from the ratio of protium to deuterium in the modern Martian atmosphere compared to that ratio on Earth. The amount of Martian deuterium is eight times the amount that exists on Earth, suggesting that ancient Mars had significantly higher levels of water. Results from the Curiosity rover had previously found a high ratio of deuterium in Gale Crater, though not significantly high enough to suggest the former presence of an ocean. Other scientists caution that these results have not been confirmed, and point out that Martian climate models have not yet shown that the planet was warm enough in the past to support bodies of liquid water.[145] Near the northern polar cap is the 81.4 kilometres (50.6 mi) wide Korolev Crater, which the Mars Express orbiter found to be filled with approximately 2,200 cubic kilometres (530 cu mi) of water ice.[146] In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior (which is 12,100 cubic kilometres[147]).[148][149] During observations from 2018 through 2021, the ExoMars Trace Gas Orbiter spotted indications of water, probably subsurface ice, in the Valles Marineris canyon system.[150] Geography and names Main article: Geography of Mars Further information: Areoid See also: Category:Surface features of Mars A MOLA-based topographic map showing highlands (red and orange) dominating the Southern Hemisphere of Mars, lowlands (blue) the northern. Volcanic plateaus delimit regions of the northern plains, whereas the highlands are punctuated by several large impact basins. Terminology of Martian geological features Terminology of Martian geological features Although better remembered for mapping the Moon, Johann Heinrich Mädler and Wilhelm Beer were the first areographers. They began by establishing that most of Mars's surface features were permanent and by more precisely determining the planet's rotation period. In 1840, Mädler combined ten years of observations and drew the first map of Mars.[151] Features on Mars are named from a variety of sources. Albedo features are named for classical mythology. Craters larger than roughly 50 km are named for deceased scientists and writers and others who have contributed to the study of Mars. Smaller craters are named for towns and villages of the world with populations of less than 100,000. Large valleys are named for the word "Mars" or "star" in various languages; smaller valleys are named for rivers.[152] Large albedo features retain many of the older names but are often updated to reflect new knowledge of the nature of the features. For example, Nix Olympica (the snows of Olympus) has become Olympus Mons (Mount Olympus).[153] The surface of Mars as seen from Earth is divided into two kinds of areas, with differing albedo. The paler plains covered with dust and sand rich in reddish iron oxides were once thought of as Martian "continents" and given names like Arabia Terra (land of Arabia) or Amazonis Planitia (Amazonian plain). The dark features were thought to be seas, hence their names Mare Erythraeum, Mare Sirenum and Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum.[154] The permanent northern polar ice cap is named Planum Boreum. The southern cap is called Planum Australe.[155] Mars's equator is defined by its rotation, but the location of its Prime Meridian was specified, as was Earth's (at Greenwich), by choice of an arbitrary point; Mädler and Beer selected a line for their first maps of Mars in 1830. After the spacecraft Mariner 9 provided extensive imagery of Mars in 1972, a small crater (later called Airy-0), located in the Sinus Meridiani ("Middle Bay" or "Meridian Bay"), was chosen by Merton Davies, Harold Masursky, and Gérard de Vaucouleurs for the definition of 0.0° longitude to coincide with the original selection.[156][157][158] Because Mars has no oceans and hence no "sea level", a zero-elevation surface had to be selected as a reference level; this is called the areoid[159] of Mars, analogous to the terrestrial geoid.[160] Zero altitude was defined by the height at which there is 610.5 Pa (6.105 mbar) of atmospheric pressure.[161] This pressure corresponds to the triple point of water, and it is about 0.6% of the sea level surface pressure on Earth (0.006 atm).[162] For mapping purposes, the United States Geological Survey divides the surface of Mars into thirty cartographic quadrangles, each named for a classical albedo feature it contains.[163] In April 2023, The New York Times reported an updated global map of Mars based on images from the Hope spacecraft.[164] A related, but much more detailed, global Mars map was released by NASA on 16 April 2023.[165] Volcanoes Main article: Volcanology of Mars Viking 1 image of Olympus Mons. The volcano and related terrain are approximately 550 km (340 mi) across. The shield volcano Olympus Mons (Mount Olympus) is an extinct volcano in the vast upland region Tharsis, which contains several other large volcanoes. The edifice is over 600 km (370 mi) wide.[166][167] Because the mountain is so large, with complex structure at its edges, allocating a height to it is difficult. Its local relief, from the foot of the cliffs which form its northwest margin to its peak, is over 21 km (13 mi),[167] a little over twice the height of Mauna Kea as measured from its base on the ocean floor. The total elevation change from the plains of Amazonis Planitia, over 1,000 km (620 mi) to the northwest, to the summit approaches 26 km (16 mi),[168] roughly three times the height of Mount Everest, which in comparison stands at just over 8.8 kilometres (5.5 mi). Consequently, Olympus Mons is either the tallest or second-tallest mountain in the Solar System; the only known mountain which might be taller is the Rheasilvia peak on the asteroid Vesta, at 20–25 km (12–16 mi).[169] Impact topography The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. It is possible that, four billion years ago, the Northern Hemisphere of Mars was struck by an object one-tenth to two-thirds the size of Earth's Moon. If this is the case, the Northern Hemisphere of Mars would be the site of an impact crater 10,600 by 8,500 kilometres (6,600 by 5,300 mi) in size, or roughly the area of Europe, Asia, and Australia combined, surpassing Utopia Planitia and the Moon's South Pole–Aitken basin as the largest impact crater in the Solar System.[170][171][172] Mars is scarred by a number of impact craters: a total of 43,000 craters with a diameter of 5 kilometres (3.1 mi) or greater have been found.[173] The largest exposed crater is Hellas, which is 2,300 kilometres (1,400 mi) wide and 7,000 metres (23,000 ft) deep, and is a light albedo feature clearly visible from Earth.[174][175] There are other notable impact features, such as Argyre, which is around 1,800 kilometres (1,100 mi) in diameter,[176] and Isidis, which is around 1,500 kilometres (930 mi) in diameter.[177] Due to the smaller mass and size of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period comets, i.e., those that lie within the orbit of Jupiter.[178] Martian craters can have a morphology that suggests the ground became wet after the meteor impacted.[179] Tectonic sites Valles Marineris, taken by the Viking 1 probe The large canyon, Valles Marineris (Latin for "Mariner Valleys", also known as Agathodaemon in the old canal maps[180]), has a length of 4,000 kilometres (2,500 mi) and a depth of up to 7 kilometres (4.3 mi). The length of Valles Marineris is equivalent to the length of Europe and extends across one-fifth the circumference of Mars. By comparison, the Grand Canyon on Earth is only 446 kilometres (277 mi) long and nearly 2 kilometres (1.2 mi) deep. Valles Marineris was formed due to the swelling of the Tharsis area, which caused the crust in the area of Valles Marineris to collapse. In 2012, it was proposed that Valles Marineris is not just a graben, but a plate boundary where 150 kilometres (93 mi) of transverse motion has occurred, making Mars a planet with possibly a two-tectonic plate arrangement.[181][182] Holes and caves Images from the Thermal Emission Imaging System (THEMIS) aboard NASA's Mars Odyssey orbiter have revealed seven possible cave entrances on the flanks of the volcano Arsia Mons.[183] The caves, named after loved ones of their discoverers, are collectively known as the "seven sisters".[184] Cave entrances measure from 100 to 252 metres (328 to 827 ft) wide and they are estimated to be at least 73 to 96 metres (240 to 315 ft) deep. Because light does not reach the floor of most of the caves, they may extend much deeper than these lower estimates and widen below the surface. "Dena" is the only exception; its floor is visible and was measured to be 130 metres (430 ft) deep. The interiors of these caverns may be protected from micrometeoroids, UV radiation, solar flares and high energy particles that bombard the planet's surface.[185][186] Atmosphere Main article: Atmosphere of Mars see caption Edge-on view of Mars atmosphere by Viking 1 probe Mars lost its magnetosphere 4 billion years ago,[187] possibly because of numerous asteroid strikes,[188] so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer.[189] Both Mars Global Surveyor and Mars Express have detected ionised atmospheric particles trailing off into space behind Mars,[187][190] and this atmospheric loss is being studied by the MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmospheric pressure on the surface today ranges from a low of 30 Pa (0.0044 psi) on Olympus Mons to over 1,155 Pa (0.1675 psi) in Hellas Planitia, with a mean pressure at the surface level of 600 Pa (0.087 psi).[191] The highest atmospheric density on Mars is equal to that found 35 kilometres (22 mi)[192] above Earth's surface. The resulting mean surface pressure is only 0.6% of Earth's 101.3 kPa (14.69 psi). The scale height of the atmosphere is about 10.8 kilometres (6.7 mi),[193] which is higher than Earth's 6 kilometres (3.7 mi), because the surface gravity of Mars is only about 38% of Earth's.[194] The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water.[2][195][189] The atmosphere is quite dusty, containing particulates about 1.5 µm in diameter which give the Martian sky a tawny color when seen from the surface.[196] It may take on a pink hue due to iron oxide particles suspended in it.[27] The concentration of methane in the Martian atmosphere fluctuates from about 0.24 ppb during the northern winter to about 0.65 ppb during the summer.[197] Estimates of its lifetime range from 0.6 to 4 years,[198][199] so its presence indicates that an active source of the gas must be present. Methane could be produced by non-biological process such as serpentinization involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars,[200] or by Martian life.[201] Escaping atmosphere on Mars (carbon, oxygen, and hydrogen) by MAVEN in UV[202] Compared to Earth, its higher concentration of atmospheric CO2 and lower surface pressure may be why sound is attenuated more on Mars, where natural sources are rare apart from the wind. Using acoustic recordings collected by the Perseverance rover, researchers concluded that the speed of sound there is approximately 240 m/s for frequencies below 240 Hz, and 250 m/s for those above.[203][204] Auroras have been detected on Mars.[205][206][207] Because Mars lacks a global magnetic field, the types and distribution of auroras there differ from those on Earth;[208] rather than being mostly restricted to polar regions as is the case on Earth, a Martian aurora can encompass the planet.[209] In September 2017, NASA reported radiation levels on the surface of the planet Mars were temporarily doubled, and were associated with an aurora 25 times brighter than any observed earlier, due to a massive, and unexpected, solar storm in the middle of the month.[209][210] Climate Main article: Climate of Mars Detail of a Martian dust storm, as viewed from orbit Mars without a dust storm in June 2001 (on left) and with a global dust storm in July 2001 (on right), as seen by Mars Global Surveyor Of all the planets in the Solar System, the seasons of Mars are the most Earth-like, due to the similar tilts of the two planets' rotational axes. The lengths of the Martian seasons are about twice those of Earth's because Mars's greater distance from the Sun leads to the Martian year being about two Earth years long. Martian surface temperatures vary from lows of about −110 °C (−166 °F) to highs of up to 35 °C (95 °F) in equatorial summer.[17] The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low thermal inertia of Martian soil.[211] The planet is 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight.[212][213] If Mars had an Earth-like orbit, its seasons would be similar to Earth's because its axial tilt is similar to Earth's. The comparatively large eccentricity of the Martian orbit has a significant effect. Mars is near perihelion when it is summer in the Southern Hemisphere and winter in the north, and near aphelion when it is winter in the Southern Hemisphere and summer in the north. As a result, the seasons in the Southern Hemisphere are more extreme and the seasons in the northern are milder than would otherwise be the case. The summer temperatures in the south can be warmer than the equivalent summer temperatures in the north by up to 30 °C (54 °F).[214] Mars has the largest dust storms in the Solar System, reaching speeds of over 160 km/h (100 mph). These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase the global temperature.[215] Dust storms on Mars 18 November 2012 25 November 2012 6 June 2018[216] 29 September 2022 Locations of the Opportunity and Curiosity rovers are noted. Orbit and rotation Main article: Orbit of Mars See also: Timekeeping on Mars Mars circling the Sun further and slower than Earth Orbit of Mars and other Inner Solar System planets Mars's average distance from the Sun is roughly 230 million km (143 million mi), and its orbital period is 687 (Earth) days. The solar day (or sol) on Mars is only slightly longer than an Earth day: 24 hours, 39 minutes, and 35.244 seconds.[217] A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours.[2] The axial tilt of Mars is 25.19° relative to its orbital plane, which is similar to the axial tilt of Earth.[2] As a result, Mars has seasons like Earth, though on Mars they are nearly twice as long because its orbital period is that much longer. In the present day epoch, the orientation of the north pole of Mars is close to the star Deneb.[20] Mars has a relatively pronounced orbital eccentricity of about 0.09; of the seven other planets in the Solar System, only Mercury has a larger orbital eccentricity. It is known that in the past, Mars has had a much more circular orbit. At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today.[218] Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years.[219] Mars approaches Earth in a synodic period of 779.94 days. Earth orbits the Sun the closest to Mars's orbit around the Sun, and Mars orbit is the second closest to Earth after the orbit of Venus. Therefore, their closest approaches, the inferior conjunctions, are the second closest for Earth after those with Venus, and the closest for Mars to any other planet. The gravitational potential difference, and thus the delta-v needed to transfer between Mars and Earth is the second lowest for Earth and the lowest for Mars to any other planet, while transfers can possibly be optimized with Venus flybys.[220][221] Habitability and search for life Main article: Life on Mars Curiosity rover’s robotic arm showing drill in place, February 2013 During the late nineteenth century, it was widely accepted in the astronomical community that Mars had life-supporting qualities, including the presence of oxygen and water.[222] However, in 1894 W. W. Campbell at Lick Observatory observed the planet and found that "if water vapor or oxygen occur in the atmosphere of Mars it is in quantities too small to be detected by spectroscopes then available".[222] That observation contradicted many of the measurements of the time and was not widely accepted.[222] Campbell and V. M. Slipher repeated the study in 1909 using better instruments, but with the same results. It wasn't until the findings were confirmed by W. S. Adams in 1925 that the myth of the Earth-like habitability of Mars was finally broken.[222] However, even in the 1960s, articles were published on Martian biology, putting aside explanations other than life for the seasonal changes on Mars. Detailed scenarios for the metabolism and chemical cycles for a functional ecosystem were being published as late as 1962.[223] The current understanding of planetary habitability – the ability of a world to develop environmental conditions favorable to the emergence of life – favors planets that have liquid water on their surface. Most often this requires the orbit of a planet to lie within the habitable zone, which for the Sun is estimated to extend from within the orbit of Earth to about that of Mars.[224] During perihelion, Mars dips inside this region, but Mars's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface may have been too salty and acidic to support regular terrestrial life.[225] The environmental conditions on Mars are a challenge to sustaining organic life: the planet has little heat transfer across its surface, it has poor insulation against bombardment by the solar wind due to the absence of a magnetosphere and has insufficient atmospheric pressure to retain water in a liquid form (water instead sublimes to a gaseous state). Mars is nearly, or perhaps totally, geologically dead; the end of volcanic activity has apparently stopped the recycling of chemicals and minerals between the surface and interior of the planet.[226] see caption Scoop of Mars soil by Curiosity, October 2012 In situ investigations have been performed on Mars by the Viking landers, Spirit and Opportunity rovers, Phoenix lander, and Curiosity rover. Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there remains unknown. The Viking probes of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites and had positive results, including a temporary increase of CO2 production on exposure to water and nutrients. This sign of life was later disputed by scientists, resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that Viking may have found life.[227] Tests conducted by the Phoenix Mars lander have shown that the soil has an alkaline pH and it contains magnesium, sodium, potassium and chloride.[228] The soil nutrients may be able to support life, but life would still have to be shielded from the intense ultraviolet light.[229] A 2014 analysis of Martian meteorite EETA79001 found chlorate, perchlorate, and nitrate ions in sufficiently high concentration to suggest that they are widespread on Mars. UV and X-ray radiation would turn chlorate and perchlorate ions into other, highly reactive oxychlorines, indicating that any organic molecules would have to be buried under the surface to survive.[230] Radiation levels on the surface are on average 0.64 millisieverts of radiation per day, and significantly less than the radiation of 1.84 millisieverts per day or 22 millirads per day during the flight to and from Mars.[231][232] For comparison the radiation levels in Low Earth Orbit, where Earth's space stations orbit, are around 0.5 millisieverts of radiation per day.[233] Hellas Planitia has the lowest surface radiation at about 0.342 millisieverts per day, featuring lava tubes southwest of Hadriacus Mons with potentially levels as low as 0.064 millisieverts per day.[234] Estimated surface radiation dosage map in rem on a colour scale of 0.027 to 0.055 rem per day (a rem is 10 millisievert) Scientists have proposed that carbonate globules found in meteorite ALH84001, which is thought to have originated from Mars, could be fossilized microbes extant on Mars when the meteorite was blasted from the Martian surface by a meteor strike some 15 million years ago. This proposal has been met with skepticism, and an exclusively inorganic origin for the shapes has been proposed.[235] Small quantities of methane and formaldehyde detected by Mars orbiters are both claimed to be possible evidence for life, as these chemical compounds would quickly break down in the Martian atmosphere.[236][237] Alternatively, these compounds may instead be replenished by volcanic or other geological means, such as serpentinite.[200] Impact glass, formed by the impact of meteors, which on Earth can preserve signs of life, has also been found on the surface of the impact craters on Mars.[238][239] Likewise, the glass in impact craters on Mars could have preserved signs of life, if life existed at the site.[240][241][242] Moons Main articles: Moons of Mars, Phobos (moon), and Deimos (moon) Enhanced-color HiRISE image of Phobos, showing a series of mostly parallel grooves and crater chains, with Stickney crater at right Enhanced-color HiRISE image of Deimos (not to scale), showing its smooth blanket of regolith Mars has two relatively small (compared to Earth's) natural moons, Phobos (about 22 kilometres (14 mi) in diameter) and Deimos (about 12 kilometres (7.5 mi) in diameter), which orbit close to the planet. The origin of both moons is unclear, although a popular theory states that they were asteroids captured into Martian orbit.[243] Both satellites were discovered in 1877 by Asaph Hall and were named after the characters Phobos (the deity of panic and fear) and Deimos (the deity of terror and dread), twins from Greek mythology who accompanied their father Ares, god of war, into battle.[244] Mars was the Roman equivalent to Ares. In modern Greek, the planet retains its ancient name Ares (Aris: Άρης).[171] From the surface of Mars, the motions of Phobos and Deimos appear different from that of the Earth's satellite, the Moon. Phobos rises in the west, sets in the east, and rises again in just 11 hours. Deimos, being only just outside synchronous orbit – where the orbital period would match the planet's period of rotation – rises as expected in the east, but slowly. Because the orbit of Phobos is below synchronous altitude, tidal forces from Mars are gradually lowering its orbit. In about 50 million years, it could either crash into Mars's surface or break up into a ring structure around the planet.[245] The origin of the two satellites is not well understood. Their low albedo and carbonaceous chondrite composition have been regarded as similar to asteroids, supporting a capture theory. The unstable orbit of Phobos would seem to point toward a relatively recent capture. But both have circular orbits, near the equator that is unusual for captured objects and the required capture dynamics are complex. Accretion early in the history of Mars is plausible, but would not account for a composition resembling asteroids rather than Mars itself, if that is confirmed.[246] A third possibility for their origin as satellites of Mars is the involvement of a third body or a type of impact disruption. More-recent lines of evidence for Phobos having a highly porous interior,[247] and suggesting a composition containing mainly phyllosilicates and other minerals known from Mars,[248] point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the prevailing theory for the origin of Earth's satellite. Although the visible and near-infrared (VNIR) spectra of the moons of Mars resemble those of outer-belt asteroids, the thermal infrared spectra of Phobos are reported to be inconsistent with chondrites of any class.[248] It is also possible that Phobos and Deimos are fragments of an older moon, formed by debris from a large impact on Mars, and then destroyed by a more recent impact upon the satellite.[249] Mars may have yet-undiscovered moons, smaller than 50 to 100 metres (160 to 330 ft) in diameter, and a dust ring is predicted to exist between Phobos and Deimos.[250] Exploration Main article: Exploration of Mars Map of Mars The image above contains clickable links (view • discuss) Interactive image map of the global topography of Mars, overlain with locations of Mars Lander and Rover sites. Hover your mouse over the image to see the names of over 60 prominent geographic features, and click to link to them. Coloring of the base map indicates relative elevations, based on data from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. Whites and browns indicate the highest elevations (+12 to +8 km); followed by pinks and reds (+8 to +3 km); yellow is 0 km; greens and blues are lower elevations (down to −8 km). Axes are latitude and longitude; Polar regions are noted. (See also: Mars map; Mars Memorials map / list) (   Active ROVER •   Inactive •   Active LANDER •   Inactive •   Future ) Beagle 2 ← Beagle 2 (2003) Bradbury Landing Curiosity (2012) → Deep Space 2 Deep Space 2 (1999) → InSight Landing InSight (2018) → Mars 2 Mars 2 (1971) → Mars 3 ← Mars 3 (1971) Mars 6 Mars 6 (1973) → Mars Polar Lander Polar Lander (1999) ↓ Challenger Memorial Station ↑ Opportunity (2004) Mars 2020 ← Perseverance (2021) Green Valley ← Phoenix (2008) Schiaparelli EDM Schiaparelli EDM (2016) → Carl Sagan Memorial Station ← Sojourner (1997) Columbia Memorial Station Spirit (2004) ↑ Tianwen-1 ↓Zhurong (2021) Thomas Mutch Memorial Station Viking 1 (1976) → Gerald Soffen Memorial Station Viking 2 (1976) → Dozens of crewless spacecraft, including orbiters, landers, and rovers, have been sent to Mars by the Soviet Union, the United States, Europe, India, the United Arab Emirates, and China to study the planet's surface, climate, and geology.[251] NASA's Mariner 4 was the first spacecraft to visit Mars; launched on 28 November 1964, it made its closest approach to the planet on 15 July 1965. Mariner 4 detected the weak Martian radiation belt, measured at about 0.1% that of Earth, and captured the first images of another planet from deep space.[252] Once spacecraft visited the planet during NASA's Mariner missions in the 1960s and 1970s, many previous concepts of Mars were radically broken. After the results of the Viking life-detection experiments, the hypothesis of a dead planet was generally accepted.[253] The data from Mariner 9 and Viking allowed better maps of Mars to be made, and the Mars Global Surveyor mission, which launched in 1996 and operated until late 2006, produced complete, extremely detailed maps of the Martian topography, magnetic field and surface minerals.[254] These maps are available online at websites including Google Mars. Both the Mars Reconnaissance Orbiter and Mars Express continued exploring with new instruments and supporting lander missions. NASA provides two online tools: Mars Trek, which provides visualizations of the planet using data from 50 years of exploration, and Experience Curiosity, which simulates traveling on Mars in 3-D with Curiosity.[255][256] see caption Ingenuity helicopter on Mars, preparing for its first flight, April 2021 As of 2023, Mars is host to thirteen functioning spacecraft. Eight are in orbit: 2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, MAVEN, ExoMars Trace Gas Orbiter, the Hope orbiter, and the Tianwen-1 orbiter.[257][258] Another five are on the surface: the Mars Science Laboratory Curiosity rover, the Perseverance rover, the Ingenuity helicopter, the Tianwen-1 lander, and the Zhurong rover.[259] Planned missions to Mars include the Rosalind Franklin rover mission, designed to search for evidence of past life, which was intended to be launched in 2018 but has been repeatedly delayed, with a launch date pushed to 2024 at the earliest, with a more likely one sometime in 2028.[260][261][262] A current concept for a joint NASA-ESA mission to return samples from Mars would launch in 2026.[263][264] Several plans for a human mission to Mars have been proposed throughout the 20th and 21st centuries, but none have come to fruition. The NASA Authorization Act of 2017 directed NASA to study the feasibility of a crewed Mars mission in the early 2030s; the resulting report eventually concluded that this would be unfeasible.[265][266] In addition, in 2021, China was planning to send a crewed Mars mission in 2033.[267] Privately held companies such as SpaceX have also proposed plans to send humans to Mars, with the eventual goal to settle on the planet.[268] The moon Phobos has been proposed as an anchor point for a space elevator.[269] Astronomy on Mars Main article: Astronomy on Mars See also: Solar eclipses on Mars Phobos transits the Sun, as viewed by the Perseverance rover on 2 April 2022 With the presence of various orbiters, landers, and rovers, it is possible to practice astronomy from Mars. Although Mars's moon Phobos appears about one-third the angular diameter of the full moon on Earth, Deimos appears more or less star-like, looking only slightly brighter than Venus does from Earth.[270] Various phenomena seen from Earth have also been observed from Mars, such as meteors and auroras.[271] The apparent sizes of the moons Phobos and Deimos are much smaller than that of the Sun; thus, their partial "eclipses" of the Sun are best considered transits (see transit of Deimos and Phobos from Mars).[272][273] Transits of Mercury and Venus have been observed from Mars. A transit of Earth will be seen from Mars on 10 November 2084.[274] Viewing see caption Mars seen through an 16-inch amateur telescope, at 2020 opposition The mean apparent magnitude of Mars is +0.71 with a standard deviation of 1.05.[16] Because the orbit of Mars is eccentric, the magnitude at opposition from the Sun can range from about −3.0 to −1.4.[275] The minimum brightness is magnitude +1.86 when the planet is near aphelion and in conjunction with the Sun.[16] At its brightest, Mars (along with Jupiter) is second only to Venus in luminosity.[16] Mars usually appears distinctly yellow, orange, or red. When farthest away from Earth, it is more than seven times farther away than when it is closest. Mars is usually close enough for particularly good viewing once or twice at 15-year or 17-year intervals.[276] As Mars approaches opposition, it begins a period of retrograde motion, which means it will appear to move backwards in a looping curve with respect to the background stars. This retrograde motion lasts for about 72 days, and Mars reaches its peak luminosity in the middle of this interval.[277] The point at which Mars's geocentric longitude is 180° different from the Sun's is known as opposition, which is near the time of closest approach to Earth. The time of opposition can occur as much as 8.5 days away from the closest approach. The distance at close approach varies between about 54 and 103 million km (34 and 64 million mi) due to the planets' elliptical orbits, which causes comparable variation in angular size.[278][279] The most recent Mars opposition occurred on 13 October 2020, at a distance of about 63 million km (39 million mi).[280] The average time between the successive oppositions of Mars, its synodic period, is 780 days; but the number of days between the dates of successive oppositions can range from 764 to 812.[219] Mars comes into opposition from Earth every 2.1 years. The planets come into opposition near Mars's perihelion in 2003, 2018 and 2035, with the 2020 and 2033 events being particularly close to perihelic opposition.[29][281] Mars made its closest approach to Earth and maximum apparent brightness in nearly 60,000 years, 55,758,006 km (0.37271925 AU; 34,646,419 mi), magnitude −2.88, on 27 August 2003, at 09:51:13 UTC. This occurred when Mars was one day from opposition and about three days from its perihelion, making it particularly easy to see from Earth. The last time it came so close is estimated to have been on 12 September 57,617 BC, the next time being in 2287.[282] This record approach was only slightly closer than other recent close approaches.[219] Optical ground-based telescopes are typically limited to resolving features about 300 kilometres (190 mi) across when Earth and Mars are closest because of Earth's atmosphere.[283] In culture Main articles: Mars in culture and Mars in fiction See also: Planets in astrology § Mars The War of the Worlds by H. G. Wells, 1897, depicts an invasion of Earth by fictional Martians. Mars is named after the Roman god of war. This association between Mars and war dates back at least to Babylonian astronomy, in which the planet was named for the god Nergal, deity of war and destruction.[284][285] It persisted into modern times, as exemplified by Gustav Holst's orchestral suite The Planets, whose famous first movement labels Mars "the bringer of war".[286] The planet's symbol, a circle with a spear pointing out to the upper right, is also used as a symbol for the male gender.[287] The symbol dates from at latest the 11th century, though a possible predecessor has been found in the Greek Oxyrhynchus Papyri.[288] The idea that Mars was populated by intelligent Martians became widespread in the late 19th century. Schiaparelli's "canali" observations combined with Percival Lowell's books on the subject put forward the standard notion of a planet that was a drying, cooling, dying world with ancient civilizations constructing irrigation works.[289] Many other observations and proclamations by notable personalities added to what has been termed "Mars Fever".[290] High-resolution mapping of the surface of Mars revealed no artifacts of habitation, but pseudoscientific speculation about intelligent life on Mars still continues. Reminiscent of the canali observations, these speculations are based on small scale features perceived in the spacecraft images, such as "pyramids" and the "Face on Mars".[291] In his book Cosmos, planetary astronomer Carl Sagan wrote: "Mars has become a kind of mythic arena onto which we have projected our Earthly hopes and fears."[51] The depiction of Mars in fiction has been stimulated by its dramatic red color and by nineteenth-century scientific speculations that its surface conditions might support not just life but intelligent life.[292] This gave way to many science fiction stories involving these concepts, such as H. G. Wells' The War of the Worlds, in which Martians seek to escape their dying planet by invading Earth, Ray Bradbury's The Martian Chronicles, in which human explorers accidentally destroy a Martian civilization, as well as Edgar Rice Burroughs' Barsoom series, C. S. Lewis' novel Out of the Silent Planet (1938),[293] and a number of Robert A. Heinlein stories before the mid-sixties.[294] Since then, depictions of Martians have also extended to animation. A comic figure of an intelligent Martian, Marvin the Martian, appeared in Haredevil Hare (1948) as a character in the Looney Tunes animated cartoons of Warner Brothers, and has continued as part of popular culture to the present.[295] After the Mariner and Viking spacecraft had returned pictures of Mars as it really is, a lifeless and canal-less world, these ideas about Mars were abandoned; for many science-fiction authors, the new discoveries initially seemed like a constraint, but eventually the post-Viking knowledge of Mars became itself a source of inspiration for works like Kim Stanley Robinson's Mars trilogy." (wikipedia.org) "The Solar System[c] is the gravitationally bound system of the Sun and the objects that orbit it. It formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority (99.86%) of the system's mass is in the Sun, with most of the remaining mass contained in the planet Jupiter. The planetary system around the Sun contains eight planets. The four inner system planets—Mercury, Venus, Earth and Mars—are terrestrial planets, being composed primarily of rock and metal. The four giant planets of the outer system are substantially larger and more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the next two, Uranus and Neptune, are ice giants, being composed mostly of volatile substances with relatively high melting points compared with hydrogen and helium, such as water, ammonia, and methane. All eight planets have nearly circular orbits that lie near the plane of Earth's orbit, called the ecliptic. There are an unknown number of smaller dwarf planets and innumerable small Solar System bodies orbiting the Sun.[d] Six of the major planets, the six largest possible dwarf planets, and many of the smaller bodies are orbited by natural satellites, commonly called "moons" after Earth's Moon. Two natural satellites, Jupiter's moon Ganymede and Saturn's moon Titan, are larger than Mercury, the smallest terrestrial planet, though less massive, and Jupiter's moon Callisto is nearly as large. Each of the giant planets and some smaller bodies are encircled by planetary rings of ice, dust and moonlets. The asteroid belt, which lies between the orbits of Mars and Jupiter, contains objects composed of rock, metal and ice. Beyond Neptune's orbit lie the Kuiper belt and scattered disc, which are populations of objects composed mostly of ice and rock. In the outer reaches of the Solar System lies a class of minor planets called detached objects. There is considerable debate as to how many such objects there will prove to be.[9] Some of these objects are large enough to have rounded under their own gravity and thus to be categorized as dwarf planets. Astronomers generally accept about nine objects as dwarf planets: the asteroid Ceres, the Kuiper-belt objects Pluto, Orcus, Haumea, Quaoar, and Makemake, and the scattered-disc objects Gonggong, Eris, and Sedna.[d] Various small-body populations, including comets, centaurs and interplanetary dust clouds, freely travel between the regions of the Solar System. The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region of interplanetary medium in the interstellar medium known as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere. The Solar System is located 26,000 light-years from the center of the Milky Way galaxy in the Orion Arm, which contains most of the visible stars in the night sky. The nearest stars are within the so-called Local Bubble, with the closest, Proxima Centauri, at 4.2441 light-years.... Inner Solar System Overview of the Inner Solar System up to the Jovian System The inner Solar System is the region comprising the terrestrial planets and the asteroid belt.[87] Composed mainly of silicates and metals,[88] the objects of the inner Solar System are relatively close to the Sun; the radius of this entire region is less than the distance between the orbits of Jupiter and Saturn. This region is also within the frost line, which is a little less than 5 AU (750 million km; 460 million mi) from the Sun.[28] Inner planets Main article: Terrestrial planet The four terrestrial planets Mercury, Venus, Earth and Mars The four terrestrial or inner planets have dense, rocky compositions, few or no moons, and no ring systems. They are composed largely of refractory minerals such as the silicates—which form their crusts and mantles—and metals such as iron and nickel which form their cores. Three of the four inner planets (Venus, Earth and Mars) have atmospheres substantial enough to generate weather; all have impact craters and tectonic surface features, such as rift valleys and volcanoes. The term inner planet should not be confused with inferior planet, which designates those planets that are closer to the Sun than Earth is (i.e. Mercury and Venus).[89] Mercury Main article: Mercury (planet) Mercury (0.307–0.588 AU (45.9–88.0 million km; 28.5–54.7 million mi) from the Sun[90]) is the closest planet to the Sun. The smallest planet in the Solar System (0.055 MEarth), Mercury has no natural satellites. The dominant geological features are impact craters or basins with ejecta blankets, the remains of early volcanic activity including magma flows, and lobed ridges or rupes that were probably produced by a period of contraction early in the planet's history.[91] Mercury's very tenuous atmosphere consists of solar-wind particles trapped by Mercury's magnetic field, as well as atoms blasted off its surface by the solar wind.[92][93] Its relatively large iron core and thin mantle have not yet been adequately explained. Hypotheses include that its outer layers were stripped off by a giant impact, or that it was prevented from fully accreting by the young Sun's energy.[94][95] There have been searches for "Vulcanoids", asteroids in stable orbits between Mercury and the Sun, but none have been discovered.[96][97] Venus Main article: Venus Venus (0.718–0.728 AU (107.4–108.9 million km; 66.7–67.7 million mi) from the Sun[90]) is close in size to Earth (0.815 MEarth) and, like Earth, has a thick silicate mantle around an iron core, a substantial atmosphere, and evidence of internal geological activity. It is much drier than Earth, and its atmosphere is ninety times as dense. Venus has no natural satellites. It is the hottest planet, with surface temperatures over 400 °C (752 °F), mainly due to the amount of greenhouse gases in the atmosphere.[98] The planet has no magnetic field that would prevent depletion of its substantial atmosphere, which suggests that its atmosphere is being replenished by volcanic eruptions.[99] A relatively young planetary surface displays extensive evidence of volcanic activity, but is devoid of plate tectonics. It may undergo resurfacing episodes on a time scale of 700 million years.[100] Earth Main article: Earth Earth (0.983–1.017 AU (147.1–152.1 million km; 91.4–94.5 million mi) from the Sun) is the largest and densest of the inner planets, the only one known to have current geological activity, and the only place where life is known to exist.[101] Its liquid hydrosphere is unique among the terrestrial planets, and it is the only planet where plate tectonics has been observed.[102] Earth's atmosphere is radically different from those of the other planets, having been altered by the presence of life to contain 21% free oxygen.[103][104] The planetary magnetosphere shields the surface from solar and cosmic radiation, limiting atmospheric stripping and maintaining habitability.[105] It has one natural satellite, the Moon, the only large satellite of a terrestrial planet in the Solar System. Mars Main article: Mars Mars (1.382–1.666 AU (206.7–249.2 million km; 128.5–154.9 million mi) from the Sun) is smaller than Earth and Venus (0.107 MEarth). It has an atmosphere of mostly carbon dioxide with a surface pressure of 6.1 millibars (0.088 psi; 0.18 inHg); roughly 0.6% of that of Earth but sufficient to support weather phenomena.[106] Its surface, peppered with volcanoes, such as Olympus Mons, and rift valleys, such as Valles Marineris, shows geological activity that may have persisted until as recently as 2 million years ago.[107] Its red color comes from iron oxide (rust) in its soil.[108] Mars has two tiny natural satellites (Deimos and Phobos) thought to be either captured asteroids,[109] or ejected debris from a massive impact early in Mars's history.[110] Asteroid belt Main articles: Asteroid belt and Asteroid Linear map of the inner Solar System, showing many asteroid populations Asteroids except for the largest, Ceres, are classified as small Solar System bodies[d] and are composed mainly of refractory rocky and metallic minerals, with some ice.[111][112] They range from a few metres to hundreds of kilometres in size. Asteroids smaller than one meter are usually called meteoroids and micrometeoroids (grain-sized), with the exact division between the two categories being debated over the years.[113] As of 2017, the IAU designates asteroids having diameter between about 30 micrometres and 1 metre as micrometeroids, and terms smaller particles "dust".[114] The asteroid belt occupies the orbit between Mars and Jupiter, between 2.3 and 3.3 AU (340 and 490 million km; 210 and 310 million mi) from the Sun. It is thought to be remnants from the Solar System's formation that failed to coalesce because of the gravitational interference of Jupiter.[115] The asteroid belt contains tens of thousands, possibly millions, of objects over one kilometre in diameter.[116] Despite this, the total mass of the asteroid belt is unlikely to be more than a thousandth of that of Earth.[46] The asteroid belt is very sparsely populated; spacecraft routinely pass through without incident.[117] Ceres Main article: Ceres (dwarf planet) Ceres (2.77 AU (414 million km; 257 million mi) from the Sun) is the largest asteroid, a protoplanet, and a dwarf planet.[d] It has a diameter of slightly under 1,000 km (620 mi) and a mass large enough for its own gravity to pull it into a spherical shape. Ceres was considered a planet when it was discovered in 1801, but as further observations revealed additional asteroids, it became common to consider it as one of the minor rather than major planets.[118] It was then reclassified again as a dwarf planet in 2006 when the IAU definition of planet was established.[119]: 218  Pallas and Vesta Main articles: 2 Pallas and 4 Vesta Pallas (2.77 AU from the Sun) and Vesta (2.36 AU from the Sun) are the largest asteroids in the asteroid belt, after Ceres. They are the other two protoplanets that survive more or less intact. At about 520 km (320 mi) in diameter, they were large enough to have developed planetary geology in the past, but both have suffered large impacts and been battered out of being round.[120][121][122] Fragments from impacts upon these two bodies survive elsewhere in the asteroid belt, as the Pallas family and Vesta family. Both were considered planets upon their discoveries in 1802 and 1807 respectively, and then like Ceres generally considered as minor planets with the discovery of more asteroids. Some authors today have begun to consider Pallas and Vesta as planets again, along with Ceres, under geophysical definitions of the term.[5] Asteroid groups Asteroids in the asteroid belt are divided into asteroid groups and families based on their orbital characteristics. Kirkwood gaps are sharp dips in the distribution of asteroid orbits that correspond to orbital resonances with Jupiter.[123] Asteroid moons are asteroids that orbit larger asteroids. They are not as clearly distinguished as planetary moons, sometimes being almost as large as their partners (e.g. that of 90 Antiope). The asteroid belt includes main-belt comets, which may have been the source of Earth's water.[124] Jupiter trojans are located in either of Jupiter's L4 or L5 points (gravitationally stable regions leading and trailing a planet in its orbit); the term trojan is also used for small bodies in any other planetary or satellite Lagrange point. Hilda asteroids are in a 2:3 resonance with Jupiter; that is, they go around the Sun three times for every two Jupiter orbits.[125] The inner Solar System contains near-Earth asteroids, many of which cross the orbits of the inner planets.[126] Some of them are potentially hazardous objects.[127] Outer Solar System Plot of objects around the Kuiper belt and other asteroid populations, the J, S, U and N denotes Jupiter, Saturn, Uranus and Neptune The outer region of the Solar System is home to the giant planets and their large moons. The centaurs and many short-period comets also orbit in this region. Due to their greater distance from the Sun, the solid objects in the outer Solar System contain a higher proportion of volatiles, such as water, ammonia, and methane than those of the inner Solar System because the lower temperatures allow these compounds to remain solid.[16] Outer planets Main article: Giant planet The outer planets Jupiter, Saturn, Uranus and Neptune, compared to the inner planets Earth, Venus, Mars, and Mercury at the bottom right The four outer planets, also called giant planets or Jovian planets, collectively make up 99% of the mass known to orbit the Sun.[f] Jupiter and Saturn are together more than 400 times the mass of Earth and consist overwhelmingly of the gases hydrogen and helium, hence their designation as gas giants.[128] Uranus and Neptune are far less massive—less than 20 Earth masses (MEarth) each—and are composed primarily of ices. For these reasons, some astronomers suggest they belong in their own category, ice giants.[129] All four giant planets have rings, although only Saturn's ring system is easily observed from Earth. The term superior planet designates planets outside Earth's orbit and thus includes both the outer planets and Mars.[89] The ring–moon systems of Jupiter, Saturn, and Uranus are like miniature versions of the Solar System; that of Neptune is significantly different, having been disrupted by the capture of its largest moon Triton.[130] Jupiter Main article: Jupiter Jupiter (4.951–5.457 AU (740.7–816.4 million km; 460.2–507.3 million mi) from the Sun[90]), at 318 MEarth, is 2.5 times the mass of all the other planets put together. It is composed largely of hydrogen and helium. Jupiter's strong internal heat creates semi-permanent features in its atmosphere, such as cloud bands and the Great Red Spot. The planet possesses a 4.2–14 Gauss strength magnetosphere that spans 22–29 million km, making it, in certain respects, the largest object in the Solar System.[131] Jupiter has 95 known satellites. The four largest, Ganymede, Callisto, Io, and Europa, are called the Galilean moons: they show similarities to the terrestrial planets, such as volcanism and internal heating.[132] Ganymede, the largest satellite in the Solar System, is larger than Mercury; Callisto is almost as large.[133] Saturn Main article: Saturn Saturn (9.075–10.07 AU (1.3576–1.5065 billion km; 843.6–936.1 million mi) from the Sun[90]), distinguished by its extensive ring system, has several similarities to Jupiter, such as its atmospheric composition and magnetosphere. Although Saturn has 60% of Jupiter's volume, it is less than a third as massive, at 95 MEarth. Saturn is the only planet of the Solar System that is less dense than water. The rings of Saturn are made up of small ice and rock particles.[134] Saturn has 83 confirmed satellites composed largely of ice. Two of these, Titan and Enceladus, show signs of geological activity;[135] they, as well as five other Saturnian moons (Iapetus, Rhea, Dione, Tethys, and Mimas), are large enough to be round. Titan, the second-largest moon in the Solar System, is bigger than Mercury and the only satellite in the Solar System to have a substantial atmosphere.[136][137] Uranus Main article: Uranus Uranus (18.27–20.06 AU (2.733–3.001 billion km; 1.698–1.865 billion mi) from the Sun[90]), at 14 MEarth, has the lowest mass of the outer planets. Uniquely among the planets, it orbits the Sun on its side; its axial tilt is over ninety degrees to the ecliptic. This gives the planet extreme seasonal variation as each pole points toward and then away from the Sun.[138] It has a much colder core than the other giant planets and radiates very little heat into space.[139] As a consequence, it has the coldest planetary atmosphere in the Solar System.[140] Uranus has 27 known satellites, the largest ones being Titania, Oberon, Umbriel, Ariel, and Miranda.[141] Like the other giant planets, it possesses a ring system and magnetosphere.[142] Neptune Main article: Neptune Neptune (29.89–30.47 AU (4.471–4.558 billion km; 2.778–2.832 billion mi) from the Sun[90]), though slightly smaller than Uranus, is more massive (17 MEarth) and hence more dense. It radiates more internal heat than Uranus, but not as much as Jupiter or Saturn.[143] Neptune has 14 known satellites. The largest, Triton, is geologically active, with geysers of liquid nitrogen.[144] Triton is the only large satellite with a retrograde orbit, which indicates that it did not form with Neptune, but was probably captured from the Kuiper belt.[145] Neptune is accompanied in its orbit by several minor planets, termed Neptune trojans, that either lead or trail the planet by about one-sixth of the way around the Sun, positions known as Lagrange points.[146] Centaurs Main article: Centaur (small Solar System body) The centaurs are icy comet-like bodies whose orbits have semi-major axes greater than Jupiter's (5.5 AU (820 million km; 510 million mi)) and less than Neptune's (30 AU (4.5 billion km; 2.8 billion mi)). These are former Kuiper belt and scattered disc objects that were gravitationally perturbed closer to the Sun by the outer planets, and are expected to become comets or get ejected out of the Solar System.[45] While most centaurs are inactive and asteroid-like, some exhibit clear cometary activity, such as the first centaur discovered, 2060 Chiron, which has been classified as a comet (95P) because it develops a coma just as comets do when they approach the Sun.[147] The largest known centaur, 10199 Chariklo, has a diameter of about 250 km (160 mi) and is one of the only few minor planets known to possess a ring system." (wikipedia.org) "Outer space, commonly shortened to space, is an infinite expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty; it is a near-perfect vacuum[1] containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is 2.7 kelvins (−270 °C; −455 °F).[2] The plasma between galaxies is thought to account for about half of the baryonic (ordinary) matter in the universe, having a number density of less than one hydrogen atom per cubic metre and a kinetic temperature of millions of kelvins.[3] Local concentrations of matter have condensed into stars and galaxies. Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space. Most of the remaining mass-energy in the observable universe is made up of an unknown form, dubbed dark matter and dark energy.[4][5][6][7] Outer space does not begin at a definite altitude above Earth's surface. The Kármán line, an altitude of 100 km (62 mi) above sea level,[8][9] is conventionally used as the start of outer space in space treaties and for aerospace records keeping. Certain portions of the upper stratosphere and the mesosphere are sometimes referred to as "near space". The framework for international space law was established by the Outer Space Treaty, which entered into force on 10 October 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons have been tested in Earth orbit. Humans began the physical exploration of space during the 20th century with the advent of high-altitude balloon flights. This was followed by crewed rocket flights and, then, crewed Earth orbit, first achieved by Yuri Gagarin of the Soviet Union in 1961. The economic cost of putting objects, including humans, into space is very high, limiting human spaceflight to low Earth orbit and the Moon. On the other hand, uncrewed spacecraft have reached all of the known planets in the Solar System. Outer space represents a challenging environment for human exploration because of the hazards of vacuum and radiation. Microgravity has a negative effect on human physiology that causes both muscle atrophy and bone loss. Formation and state Main article: Big Bang This is an artist's concept of the metric expansion of space, where a volume of the Universe is represented at each time interval by the circular sections. At left is depicted the rapid inflation from the initial state, followed thereafter by steadier expansion to the present day, shown at right. A black background with luminous shapes of various sizes scattered randomly about. They typically have white, red or blue hues. Part of the Hubble Ultra-Deep Field image showing a typical section of space containing galaxies interspersed by deep vacuum. Given the finite speed of light, this view covers the past 13 billion years of the history of outer space. The size of the whole universe is unknown, and it might be infinite in extent.[10] According to the Big Bang theory, the very early Universe was an extremely hot and dense state about 13.8 billion years ago[11] which rapidly expanded. About 380,000 years later the Universe had cooled sufficiently to allow protons and electrons to combine and form hydrogen—the so-called recombination epoch. When this happened, matter and energy became decoupled, allowing photons to travel freely through the continually expanding space.[12] Matter that remained following the initial expansion has since undergone gravitational collapse to create stars, galaxies and other astronomical objects, leaving behind a deep vacuum that forms what is now called outer space.[13] As light has a finite velocity, this theory also constrains the size of the directly observable universe.[12] The present day shape of the universe has been determined from measurements of the cosmic microwave background using satellites like the Wilkinson Microwave Anisotropy Probe. These observations indicate that the spatial geometry of the observable universe is "flat", meaning that photons on parallel paths at one point remain parallel as they travel through space to the limit of the observable universe, except for local gravity.[14] The flat Universe, combined with the measured mass density of the Universe and the accelerating expansion of the Universe, indicates that space has a non-zero vacuum energy, which is called dark energy.[15] Estimates put the average energy density of the present day Universe at the equivalent of 5.9 protons per cubic meter, including dark energy, dark matter, and baryonic matter (ordinary matter composed of atoms). The atoms account for only 4.6% of the total energy density, or a density of one proton per four cubic meters.[16] The density of the Universe is clearly not uniform; it ranges from relatively high density in galaxies—including very high density in structures within galaxies, such as planets, stars, and black holes—to conditions in vast voids that have much lower density, at least in terms of visible matter.[17] Unlike matter and dark matter, dark energy seems not to be concentrated in galaxies: although dark energy may account for a majority of the mass-energy in the Universe, dark energy's influence is 5 orders of magnitude smaller than the influence of gravity from matter and dark matter within the Milky Way.[18] Environment The interplanetary dust cloud illuminated and visible as zodiacal light, with its parts the false dawn,[19] gegenschein and the rest of its band, which is visually crossed by the Milky Way Outer space is the closest known approximation to a perfect vacuum. It has effectively no friction, allowing stars, planets, and moons to move freely along their ideal orbits, following the initial formation stage. The deep vacuum of intergalactic space is not devoid of matter, as it contains a few hydrogen atoms per cubic meter.[20] By comparison, the air humans breathe contains about 1025 molecules per cubic meter.[21][22] The low density of matter in outer space means that electromagnetic radiation can travel great distances without being scattered: the mean free path of a photon in intergalactic space is about 1023 km, or 10 billion light years.[23] In spite of this, extinction, which is the absorption and scattering of photons by dust and gas, is an important factor in galactic and intergalactic astronomy.[24] Stars, planets, and moons retain their atmospheres by gravitational attraction. Atmospheres have no clearly delineated upper boundary: the density of atmospheric gas gradually decreases with distance from the object until it becomes indistinguishable from outer space.[25] The Earth's atmospheric pressure drops to about 0.032 Pa at 100 kilometres (62 miles) of altitude,[26] compared to 100,000 Pa for the International Union of Pure and Applied Chemistry (IUPAC) definition of standard pressure. Above this altitude, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar wind. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather.[27] The temperature of outer space is measured in terms of the kinetic activity of the gas,[28] as it is on Earth. The radiation of outer space has a different temperature than the kinetic temperature of the gas, meaning that the gas and radiation are not in thermodynamic equilibrium.[29][30] All of the observable universe is filled with photons that were created during the Big Bang, which is known as the cosmic microwave background radiation (CMB). (There is quite likely a correspondingly large number of neutrinos called the cosmic neutrino background.[31]) The current black body temperature of the background radiation is about 3 K (−270 °C; −454 °F).[32] The gas temperatures in outer space can vary widely. For example, the temperature in the Boomerang Nebula is 1 K,[33] while the solar corona reaches temperatures over 1.2–2.6 million K.[34] Magnetic fields have been detected in the space around just about every class of celestial object. Star formation in spiral galaxies can generate small-scale dynamos, creating turbulent magnetic field strengths of around 5–10 μG. The Davis–Greenstein effect causes elongated dust grains to align themselves with a galaxy's magnetic field, resulting in weak optical polarization. This has been used to show ordered magnetic fields exist in several nearby galaxies. Magneto-hydrodynamic processes in active elliptical galaxies produce their characteristic jets and radio lobes. Non-thermal radio sources have been detected even among the most distant, high-z sources, indicating the presence of magnetic fields.[35] Outside a protective atmosphere and magnetic field, there are few obstacles to the passage through space of energetic subatomic particles known as cosmic rays. These particles have energies ranging from about 106 eV up to an extreme 1020 eV of ultra-high-energy cosmic rays.[36] The peak flux of cosmic rays occurs at energies of about 109 eV, with approximately 87% protons, 12% helium nuclei and 1% heavier nuclei. In the high energy range, the flux of electrons is only about 1% of that of protons.[37] Cosmic rays can damage electronic components and pose a health threat to space travelers.[38] According to astronauts, like Don Pettit, space has a burned/metallic odor that clings to their suits and equipment, similar to the scent of an arc welding torch.[39][40] Effect on biology and human bodies Main articles: Effect of spaceflight on the human body, Bioastronautics, Uncontrolled decompression, and Weightlessness See also: Astrobiology, Astrobotany, Plants in space, and Animals in space The lower half shows a blue planet with patchy white clouds. The upper half has a man in a white spacesuit and maneuvering unit against a black background. Because of the hazards of a vacuum, astronauts must wear a pressurized space suit while off-Earth and outside their spacecraft. Despite the harsh environment, several life forms have been found that can withstand extreme space conditions for extended periods. Species of lichen carried on the ESA BIOPAN facility survived exposure for ten days in 2007.[41] Seeds of Arabidopsis thaliana and Nicotiana tabacum germinated after being exposed to space for 1.5 years.[42] A strain of Bacillus subtilis has survived 559 days when exposed to low Earth orbit or a simulated martian environment.[43] The lithopanspermia hypothesis suggests that rocks ejected into outer space from life-harboring planets may successfully transport life forms to another habitable world. A conjecture is that just such a scenario occurred early in the history of the Solar System, with potentially microorganism-bearing rocks being exchanged between Venus, Earth, and Mars.[44] Even at relatively low altitudes in the Earth's atmosphere, conditions are hostile to the human body. The altitude where atmospheric pressure matches the vapor pressure of water at the temperature of the human body is called the Armstrong line, named after American physician Harry G. Armstrong. It is located at an altitude of around 19.14 km (11.89 mi). At or above the Armstrong line, fluids in the throat and lungs boil away. More specifically, exposed bodily liquids such as saliva, tears, and liquids in the lungs boil away. Hence, at this altitude, human survival requires a pressure suit, or a pressurized capsule.[45] Out in space, sudden exposure of an unprotected human to very low pressure, such as during a rapid decompression, can cause pulmonary barotrauma—a rupture of the lungs, due to the large pressure differential between inside and outside the chest.[46] Even if the subject's airway is fully open, the flow of air through the windpipe may be too slow to prevent the rupture.[47] Rapid decompression can rupture eardrums and sinuses, bruising and blood seep can occur in soft tissues, and shock can cause an increase in oxygen consumption that leads to hypoxia.[48] As a consequence of rapid decompression, oxygen dissolved in the blood empties into the lungs to try to equalize the partial pressure gradient. Once the deoxygenated blood arrives at the brain, humans lose consciousness after a few seconds and die of hypoxia within minutes.[49] Blood and other body fluids boil when the pressure drops below 6.3 kPa, and this condition is called ebullism.[50] The steam may bloat the body to twice its normal size and slow circulation, but tissues are elastic and porous enough to prevent rupture. Ebullism is slowed by the pressure containment of blood vessels, so some blood remains liquid.[51][52] Swelling and ebullism can be reduced by containment in a pressure suit. The Crew Altitude Protection Suit (CAPS), a fitted elastic garment designed in the 1960s for astronauts, prevents ebullism at pressures as low as 2 kPa.[53] Supplemental oxygen is needed at 8 km (5 mi) to provide enough oxygen for breathing and to prevent water loss, while above 20 km (12 mi) pressure suits are essential to prevent ebullism.[54] Most space suits use around 30–39 kPa of pure oxygen, about the same as on the Earth's surface. This pressure is high enough to prevent ebullism, but evaporation of nitrogen dissolved in the blood could still cause decompression sickness and gas embolisms if not managed.[55] Humans evolved for life in Earth gravity, and exposure to weightlessness has been shown to have deleterious effects on human health. Initially, more than 50% of astronauts experience space motion sickness. This can cause nausea and vomiting, vertigo, headaches, lethargy, and overall malaise. The duration of space sickness varies, but it typically lasts for 1–3 days, after which the body adjusts to the new environment. Longer-term exposure to weightlessness results in muscle atrophy and deterioration of the skeleton, or spaceflight osteopenia. These effects can be minimized through a regimen of exercise.[56] Other effects include fluid redistribution, slowing of the cardiovascular system, decreased production of red blood cells, balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, and puffiness of the face.[57] During long-duration space travel, radiation can pose an acute health hazard. Exposure to high-energy, ionizing cosmic rays can result in fatigue, nausea, vomiting, as well as damage to the immune system and changes to the white blood cell count. Over longer durations, symptoms include an increased risk of cancer, plus damage to the eyes, nervous system, lungs and the gastrointestinal tract.[58] On a round-trip Mars mission lasting three years, a large fraction of the cells in an astronaut's body would be traversed and potentially damaged by high energy nuclei.[59] The energy of such particles is significantly diminished by the shielding provided by the walls of a spacecraft and can be further diminished by water containers and other barriers. The impact of the cosmic rays upon the shielding produces additional radiation that can affect the crew. Further research is needed to assess the radiation hazards and determine suitable countermeasures.... Interplanetary space Main article: Interplanetary medium At lower left, a white coma stands out against a black background. Nebulous material streams away to the top and left, slowly fading with distance. The sparse plasma (blue) and dust (white) in the tail of comet Hale–Bopp are being shaped by pressure from solar radiation and the solar wind, respectively. Interplanetary space is defined by the solar wind, a continuous stream of charged particles emanating from the Sun that creates a very tenuous atmosphere (the heliosphere) for billions of kilometers into space. This wind has a particle density of 5–10 protons/cm3 and is moving at a velocity of 350–400 km/s (780,000–890,000 mph).[105] Interplanetary space extends out to the heliopause where the influence of the galactic environment starts to dominate over the magnetic field and particle flux from the Sun.[83] The distance and strength of the heliopause varies depending on the activity level of the solar wind.[106] The heliopause in turn deflects away low-energy galactic cosmic rays, with this modulation effect peaking during solar maximum.[107] The volume of interplanetary space is a nearly total vacuum, with a mean free path of about one astronomical unit at the orbital distance of the Earth. This space is not completely empty, and is sparsely filled with cosmic rays, which include ionized atomic nuclei and various subatomic particles. There is also gas, plasma and dust,[108] small meteors, and several dozen types of organic molecules discovered to date by microwave spectroscopy.[109] A cloud of interplanetary dust is visible at night as a faint band called the zodiacal light.[110] Interplanetary space contains the magnetic field generated by the Sun.[105] There are also magnetospheres generated by planets such as Jupiter, Saturn, Mercury and the Earth that have their own magnetic fields. These are shaped by the influence of the solar wind into the approximation of a teardrop shape, with the long tail extending outward behind the planet. These magnetic fields can trap particles from the solar wind and other sources, creating belts of charged particles such as the Van Allen radiation belts. Planets without magnetic fields, such as Mars, have their atmospheres gradually eroded by the solar wind.[111] Interstellar space Main article: Interstellar medium "Interstellar space" redirects here. For the album, see Interstellar Space. Patchy orange and blue nebulosity against a black background, with a curved orange arc wrapping around a star at the center. Bow shock formed by the magnetosphere of the young star LL Orionis (center) as it collides with the Orion Nebula flow Interstellar space is the physical space within a galaxy beyond the influence each star has upon the encompassed plasma.[84] The contents of interstellar space are called the interstellar medium. Approximately 70% of the mass of the interstellar medium consists of lone hydrogen atoms; most of the remainder consists of helium atoms. This is enriched with trace amounts of heavier atoms formed through stellar nucleosynthesis. These atoms are ejected into the interstellar medium by stellar winds or when evolved stars begin to shed their outer envelopes such as during the formation of a planetary nebula.[112] The cataclysmic explosion of a supernova generates an expanding shock wave consisting of ejected materials that further enrich the medium.[113] The density of matter in the interstellar medium can vary considerably: the average is around 106 particles per m3,[114] but cold molecular clouds can hold 108–1012 per m3.[29][112] A number of molecules exist in interstellar space, as can tiny 0.1 μm dust particles.[115] The tally of molecules discovered through radio astronomy is steadily increasing at the rate of about four new species per year. Large regions of higher density matter known as molecular clouds allow chemical reactions to occur, including the formation of organic polyatomic species. Much of this chemistry is driven by collisions. Energetic cosmic rays penetrate the cold, dense clouds and ionize hydrogen and helium, resulting, for example, in the trihydrogen cation. An ionized helium atom can then split relatively abundant carbon monoxide to produce ionized carbon, which in turn can lead to organic chemical reactions.[116] The local interstellar medium is a region of space within 100 parsecs (pc) of the Sun, which is of interest both for its proximity and for its interaction with the Solar System. This volume nearly coincides with a region of space known as the Local Bubble, which is characterized by a lack of dense, cold clouds. It forms a cavity in the Orion Arm of the Milky Way galaxy, with dense molecular clouds lying along the borders, such as those in the constellations of Ophiuchus and Taurus. (The actual distance to the border of this cavity varies from 60 to 250 pc or more.) This volume contains about 104–105 stars and the local interstellar gas counterbalances the astrospheres that surround these stars, with the volume of each sphere varying depending on the local density of the interstellar medium. The Local Bubble contains dozens of warm interstellar clouds with temperatures of up to 7,000 K and radii of 0.5–5 pc.[117] When stars are moving at sufficiently high peculiar velocities, their astrospheres can generate bow shocks as they collide with the interstellar medium. For decades it was assumed that the Sun had a bow shock. In 2012, data from Interstellar Boundary Explorer (IBEX) and NASA's Voyager probes showed that the Sun's bow shock does not exist. Instead, these authors argue that a subsonic bow wave defines the transition from the solar wind flow to the interstellar medium.[118][119] A bow shock is the third boundary of an astrosphere after the termination shock and the astropause (called the heliopause in the Solar System).[119] Intergalactic space Structure of the Universe Large-scale matter distribution in a cubic section of the universe. The blue fiber structures represent the matter and the empty regions in between represent the cosmic voids of the intergalactic medium. Main articles: Warm–hot intergalactic medium, Intracluster medium, and Intergalactic dust Intergalactic space is the physical space between galaxies. Studies of the large-scale distribution of galaxies show that the Universe has a foam-like structure, with groups and clusters of galaxies lying along filaments that occupy about a tenth of the total space. The remainder forms huge voids that are mostly empty of galaxies. Typically, a void spans a distance of 7–30 megaparsecs.[120] Surrounding and stretching between galaxies, there is a rarefied plasma[121] that is organized in a galactic filamentary structure.[122] This material is called the intergalactic medium (IGM). The density of the IGM is 5–200 times the average density of the Universe.[123] It consists mostly of ionized hydrogen; i.e. a plasma consisting of equal numbers of electrons and protons. As gas falls into the intergalactic medium from the voids, it heats up to temperatures of 105 K to 107 K,[3] which is high enough so that collisions between atoms have enough energy to cause the bound electrons to escape from the hydrogen nuclei; this is why the IGM is ionized. At these temperatures, it is called the warm–hot intergalactic medium (WHIM). (Although the plasma is very hot by terrestrial standards, 105 K is often called "warm" in astrophysics.) Computer simulations and observations indicate that up to half of the atomic matter in the Universe might exist in this warm–hot, rarefied state.[123][124][125] When gas falls from the filamentary structures of the WHIM into the galaxy clusters at the intersections of the cosmic filaments, it can heat up even more, reaching temperatures of 108 K and above in the so-called intracluster medium (ICM)." (wikipedia.org) "A rover (or sometimes planetary rover) is a planetary surface exploration device designed to move across the solid surface on a planet or other planetary mass celestial bodies. Some rovers have been designed as land vehicles to transport members of a human spaceflight crew; others have been partially or fully autonomous robots. Rovers are typically created to land on another planet (other than Earth) via a lander-style spacecraft,[1] tasked to collect information about the terrain, and to take crust samples such as dust, soil, rocks, and even liquids. They are essential tools in space exploration. Features Rovers arrive on spacecraft and are used in conditions very distinct from those on the Earth, which makes some demands on their design. Reliability Rovers have to withstand high levels of acceleration, high and low temperatures, pressure, dust, corrosion, cosmic rays, remaining functional without repair for a needed period of time. Mars rover Sojourner in cruise configuration Autonomy Rovers which land on celestial bodies far from the Earth, such as the Mars Exploration Rovers, cannot be remotely controlled in real-time since the speed at which radio signals travel is far too slow for real-time or near-real-time communication. For example, sending a signal from Mars to Earth takes between 3 and 21 minutes. These rovers are thus capable of operating autonomously with little assistance from ground control as far as navigation and data acquisition are concerned, although they still require human input for identifying promising targets in the distance to which to drive, and determining how to position itself to maximize solar energy.[2] Giving a rover some rudimentary visual identification capabilities to make simple distinctions can allow engineers to speed up the reconnaissance.[2] During the NASA Sample Return Robot Centennial Challenge, a rover, named Cataglyphis, successfully demonstrated autonomous navigation, decision-making, and sample detection, retrieval, and return capabilities.[3] Non-wheeled approaches Other rover designs that do not use wheeled approaches are possible. Mechanisms that utilize "walking" on robotic legs, hopping, rolling, etc. are possible. For example, Stanford University researchers have proposed "Hedgehog", a small cube-shaped rover that can controllably hop—or even spin out of a sandy sinkhole by corkscrewing upward to escape—for surface exploration of low gravity celestial bodies.[4] History Landing sites of sample return and rover missions Lunokhod 0 (No.201) The Soviet rover was intended to be the first roving remote-controlled robot on the Moon, but crashed during a failed start of the launcher 19 February 1969. Lunokhod 1 Main article: Lunokhod 1 The Lunokhod 1 Lunar Rover The Lunokhod 1 rover landed on the Moon in November 1970.[5] It was the first roving remote-controlled robot to land on any celestial body. The Soviet Union launched Lunokhod 1 aboard the Luna 17 spacecraft on November 10, 1970, and it entered lunar orbit on November 15. The spacecraft soft-landed in the Sea of Rains region on November 17. The lander had dual ramps from which Lunokhod 1 could descend to the lunar surface, which it did at 06:28 UT. From November 17, 1970, to November 22, 1970, the rover drove 197 m, and during 10 communication sessions returned 14 close up pictures of the Moon and 12 panoramic views. It also analyzed the lunar soil. The last successful communications session with Lunokhod 1 was on September 14, 1971. Having worked for 11 months,[6] Lunokhod 1 held the durability record for space rovers for more than 30 years, until a new record was set by the Mars Exploration Rovers. Apollo Lunar Roving Vehicle Main article: Apollo Lunar Roving Vehicle Apollo 15 Lunar Roving Vehicle NASA included Lunar Roving Vehicles in three Apollo missions: Apollo 15 (which landed on the Moon July 30, 1971), Apollo 16 (which landed April 21, 1972), and Apollo 17 (which landed December 11, 1972).[7] Lunokhod 2 Main article: Lunokhod 2 The Lunokhod 2 lunar rover The Lunokhod 2 was the second of two uncrewed lunar rovers landed on the Moon by the Soviet Union as part of the Lunokhod program. The rover became operational on the Moon on January 16, 1973.[8] It was the second roving remote-controlled robot to land on any celestial body. The Soviet Union launched Lunokhod 2 aboard the Luna 21 spacecraft on January 8, 1973, and the spacecraft soft-landed in the eastern edge of the Mare Serenitatis region on January 15, 1973. Lunokhod 2 descended from the lander's dual ramps to the lunar surface at 01:14 UT on January 16, 1973. Lunokhod 2 operated for about four months, covered 39 km (24 mi) of terrain, including hilly upland areas and rilles, and sent back 86 panoramic images and over 80,000 TV pictures.[9][10][11] Based on wheel rotations Lunokhod 2 was thought to have covered 37 km (23 mi) but Russian scientists at the Moscow State University of Geodesy and Cartography (MIIGAiK) have revised that to an estimated distance of about 42.1–42.2 km (26.2–26.2 mi) based on Lunar Reconnaissance Orbiter (LRO) images of the lunar surface.[12][13] Subsequent discussions with their American counterparts ended with an agreed-upon final distance of 39 km (24 mi), which has stuck since.[14][15] PrOP-M Main articles: PrOP-M, Mars 2, and Mars 3 The Soviet Mars 2 and Mars 3 landers each had a small 4.5 kg Mars rover on board, which would have moved across the surface on skis while connected to the lander with a 15-meter umbilical. Two small metal rods were used for autonomous obstacle avoidance, as radio signals from Earth would have taken too long to drive the rovers using remote control. The rover was planned to be placed on the surface after landing by a manipulator arm and to move in the field of view of the television cameras and stop to make measurements every 1.5 meters. The rover tracks in the Martian soil would also have been recorded to determine material properties. Because of the crash landing of Mars 2 and the communication failure (15 seconds post landing) of Mars 3, neither rover was deployed. Lunokhod 3 The Soviet rover was intended to be the third roving remote-controlled robot on the Moon in 1977. The mission was canceled due to lack of launcher availability and funding, although the rover was built. Marsokhod Main article: Marsokhod The Marsokhod was a Soviet rover (hybrid, with both controls telecommand and automatic) aimed at Mars, part of the Mars 4NM and scheduled to commence after 1973 (according to the plans of 1970). It was to be launched by a N1 rocket, which never flew successfully.[16] Sojourner Main articles: Sojourner (rover) and Mars Pathfinder Sojourner on Mars in 1997 The Mars Pathfinder mission included Sojourner, the first rover to successfully deploy on another planet. NASA, the space agency of the United States, launched Mars Pathfinder on 4 December 1996; it landed on Mars in a region called Chryse Planitia on 4 July 1997.[17] From its landing until the final data transmission on 27 September 1997, Mars Pathfinder returned 16,500 images from the lander and 550 images from Sojourner, as well as data from more than 15 chemical analyses of rocks and soil and extensive data on winds and other weather factors.[17] Beagle 2 Planetary Undersurface Tool Beagle 2 was designed to explore Mars with a small "mole" (Planetary Undersurface Tool, or PLUTO), to be deployed by the arm. PLUTO had a compressed spring mechanism designed to enable it to move across the surface at a rate of 20 mm per second and to burrow into the ground, collecting a subsurface sample in a cavity in its tip. Beagle 2 failed while attempting to land on Mars in 2003. Mars Exploration Rover Spirit Main article: Spirit (rover) Mars Exploration Rover Spirit is a robotic rover on Mars, active from 2004 to 2010. It was one of two rovers of NASA's ongoing Mars Exploration Rover mission. It landed successfully on Mars at 04:35 Ground UTC on January 4, 2004, three weeks before its twin, Opportunity (MER-B), landed on the other side of the planet. Its name was chosen through a NASA-sponsored student essay competition. The rover became stuck in late 2009, and its last communication with Earth was sent on March 22, 2010. Mars Exploration Rover Opportunity Main article: Opportunity (rover) Opportunity is a robotic rover on the planet Mars, active from 2004 to early 2019. Launched from Earth on July 7, 2003, it landed on the Martian Meridiani Planum on January 25, 2004, at 05:05 Ground UTC (about 13:15 local time), three weeks after its twin Spirit (MER-A) touched down on the other side of the planet. On July 28, 2014, NASA announced that Opportunity, after having traveled over 40 km (25 mi) on the planet Mars, has set a new "off-world" record as the rover having driven the greatest distance, surpassing the previous record held by the Soviet Union's Lunokhod 2 rover that had traveled 39 km (24 mi).[18][19] (related image) Chang'e 3's Yutu Rover Main article: Yutu (rover) Chang'e 3 is a Chinese Moon mission that includes a robotic lunar rover Yutu, named after the pet rabbit of Chang'e, the goddess of the Moon in Chinese mythology. Launched in 2013 with the Chang'e 3 mission, it is China's first lunar rover, the first soft landing on the Moon since 1976 and the first rover to operate there since the Soviet Lunokhod 2 ceased operations on 11 May 1973.[20] It was deployed on the Moon on December 14, 2013, and the rover encountered operational difficulties toward the end of the second lunar day[21] after surviving and recovering successfully the first 14-day lunar night (about a month on the Moon),[22] and was unable to move after the end of the second lunar night, though it continued to gather useful information for some months afterward.[23] In October 2015, Yutu set the record for the longest operational period for a rover on the Moon.[24] On 31 July 2016, Yutu ceased to operate after a total of 31 months, well beyond its original expected lifespan of three months.[25] Active rover missions Active Mars rover locations in context Map of Mars The image above contains clickable links (view • discuss) Interactive image map of the global topography of Mars, overlain with locations of Mars Lander and Rover sites. Hover your mouse over the image to see the names of over 60 prominent geographic features, and click to link to them. Coloring of the base map indicates relative elevations, based on data from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. Whites and browns indicate the highest elevations (+12 to +8 km); followed by pinks and reds (+8 to +3 km); yellow is 0 km; greens and blues are lower elevations (down to −8 km). Axes are latitude and longitude; Polar regions are noted. (See also: Mars map; Mars Memorials map / list) (   Active ROVER •   Inactive •   Active LANDER •   Inactive •   Future ) Beagle 2 ← Beagle 2 (2003) Bradbury Landing Curiosity (2012) → Deep Space 2 Deep Space 2 (1999) → InSight Landing InSight (2018) → Mars 2 Mars 2 (1971) → Mars 3 ← Mars 3 (1971) Mars 6 Mars 6 (1973) → Mars Polar Lander Polar Lander (1999) ↓ Challenger Memorial Station ↑ Opportunity (2004) Mars 2020 ← Perseverance (2021) Green Valley ← Phoenix (2008) Schiaparelli EDM Schiaparelli EDM (2016) → Carl Sagan Memorial Station ← Sojourner (1997) Columbia Memorial Station Spirit (2004) ↑ Tianwen-1 ↓Zhurong (2021) Thomas Mutch Memorial Station Viking 1 (1976) → Gerald Soffen Memorial Station Viking 2 (1976) → Mars Science Laboratory Rover Curiosity Main article: Curiosity (rover) Mars Science Laboratory Curiosity rover On 26 November 2011, NASA's Mars Science Laboratory mission was successfully launched for Mars. The mission successfully landed the robotic Curiosity rover on the surface of Mars in August 2012. The rover is currently helping to determine whether Mars could ever have supported life, and search for evidence of past or present life on Mars.[26][27] Yutu-2 (Chang'e 4 rover) Main article: Chang'e 4 Chinese mission launched 7 December 2018, landed and deployed rover 3 January 2019 on the far side of the Moon. It was the first ever rover that operates on the far side of the Moon. In December 2019, Yutu 2 broke the lunar longevity record, previously held by the Soviet Union's Lunokhod 1 rover,[28] which operated on the lunar surface for eleven lunar days (321 Earth days) and traversed a total distance of 10.54 km (6.55 mi).[29] In February 2020, Chinese astronomers reported, for the first time, a high-resolution image of a lunar ejecta sequence, and, as well, direct analysis of its internal architecture. These were based on observations made by the Lunar Penetrating Radar (LPR) on board the Yutu-2 rover while studying the far side of the Moon.[30][31] Mars 2020 Perseverance rover Main article: Mars 2020 Mars 2020 Perseverance rover design infographic detailing cameras The Perseverance rover of the Mars 2020 mission is a Mars rover developed by NASA which was launched in 2020 and landed on Mars on February 18, 2021. It is intended to investigate an astrobiologically relevant ancient environment on Mars, investigate its surface geological processes and history, including the assessment of its past habitability and potential for preservation of biosignatures within accessible geological materials.[32] Tianwen-1 Zhurong Main articles: Tianwen-1 and Zhurong (rover) Tianwen-1, a CNSA project, launched on July 23, 2020, and successfully reached Mars orbit on February 10, 2021. The Zhurong rover landed on Mars on May 14, 2021, and was deployed from lander on 22 May 2021.[33] It will conduct scientific missions. Planned rover missions     This section needs to be updated. Please help update this article to reflect recent events or newly available information. (August 2018) Chandrayaan 3 Main article: Chandrayaan-3 Chandrayaan-3 is a planned mission by India, consisting of a lunar lander and a rover. It would be a re-attempt to demonstrate soft landing, following the failure of Chandrayaan-2's Vikram lander. ExoMars Rosalind Franklin Main article: Rosalind Franklin (rover) The European Space Agency (ESA) has designed and carried out early prototyping and testing of the Rosalind Franklin rover. As of 2022, the rover is scheduled for launch in late 2028." (wikipedia.org) "Mars Science Laboratory (MSL) is a robotic space probe mission to Mars launched by NASA on November 26, 2011,[2] which successfully landed Curiosity, a Mars rover, in Gale Crater on August 6, 2012.[3][9][10][11] The overall objectives include investigating Mars' habitability, studying its climate and geology, and collecting data for a human mission to Mars.[12] The rover carries a variety of scientific instruments designed by an international team.[13] Overview Hubble view of Mars: Gale crater can be seen. Slightly left and south of center, it is a small dark spot with dust trailing southward from it. MSL successfully carried out the most accurate Martian landing of any known spacecraft at the time, hitting a small target landing ellipse of only 7 by 20 km (4.3 by 12.4 mi),[14] in the Aeolis Palus region of Gale Crater. In the event, MSL achieved a landing 2.4 km (1.5 mi) east and 400 m (1,300 ft) north of the center of the target.[15][16] This location is near the mountain Aeolis Mons (a.k.a. "Mount Sharp").[17][18] The rover mission is set to explore for at least 687 Earth days (1 Martian year) over a range of 5 by 20 km (3.1 by 12.4 mi).[19] The Mars Science Laboratory mission is part of NASA's Mars Exploration Program, a long-term effort for the robotic exploration of Mars that is managed by the Jet Propulsion Laboratory of California Institute of Technology. The total cost of the MSL project is about US$2.5 billion.[20][21] Previous successful U.S. Mars rovers include Sojourner from the Mars Pathfinder mission and the Mars Exploration Rovers Spirit and Opportunity. Curiosity is about twice as long and five times as heavy as Spirit and Opportunity,[22] and carries over ten times the mass of scientific instruments.[23] Goals and objectives MSL self-portrait from Gale Crater sol 85 (October 31, 2012). For results and findings, see Timeline of Mars Science Laboratory. The MSL mission has four scientific goals: Determine the landing site's habitability including the role of water, the study of the climate and the geology of Mars. It is also useful preparation for a future human mission to Mars. To contribute to these goals, MSL has eight main scientific objectives:[24] Biological     (1) Determine the nature and inventory of organic carbon compounds     (2) Investigate the chemical building blocks of life (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur)     (3) Identify features that may represent the effects of biological processes (biosignatures) Geological and geochemical     (4) Investigate the chemical, isotopic, and mineralogical composition of the Martian surface and near-surface geological materials     (5) Interpret the processes that have formed and modified rocks and soils Planetary process     (6) Assess long-timescale (i.e., 4-billion-year) Martian atmospheric evolution processes     (7) Determine present state, distribution, and cycling of water and carbon dioxide Surface radiation     (8) Characterize the broad spectrum of surface radiation, including cosmic radiation, solar particle events and secondary neutrons. As part of its exploration, it also measured the radiation exposure in the interior of the spacecraft as it traveled to Mars, and it is continuing radiation measurements as it explores the surface of Mars. This data would be important for a future human mission.[25] About one year into the surface mission, and having assessed that ancient Mars could have been hospitable to microbial life, the MSL mission objectives evolved to developing predictive models for the preservation process of organic compounds and biomolecules; a branch of paleontology called taphonomy.[26] Specifications Spacecraft Mars Science Laboratory in final assembly Diagram of the MSL spacecraft: 1- Cruise stage; 2- Backshell; 3- Descent stage; 4- Curiosity rover; 5- Heat shield; 6- Parachute The spacecraft flight system had a mass at launch of 3,893 kg (8,583 lb), consisting of an Earth-Mars fueled cruise stage (539 kg (1,188 lb)), the entry-descent-landing (EDL) system (2,401 kg (5,293 lb) including 390 kg (860 lb) of landing propellant), and a 899 kg (1,982 lb) mobile rover with an integrated instrument package.[1][27] The MSL spacecraft includes spaceflight-specific instruments, in addition to utilizing one of the rover instruments — Radiation assessment detector (RAD) — during the spaceflight transit to Mars.     MSL EDL Instrument (MEDLI): The MEDLI project's main objective is to measure aerothermal environments, sub-surface heat shield material response, vehicle orientation, and atmospheric density.[28] The MEDLI instrumentation suite was installed in the heatshield of the MSL entry vehicle. The acquired data will support future Mars missions by providing measured atmospheric data to validate Mars atmosphere models and clarify the lander design margins on future Mars missions. MEDLI instrumentation consists of three main subsystems: MEDLI Integrated Sensor Plugs (MISP), Mars Entry Atmospheric Data System (MEADS) and the Sensor Support Electronics (SSE). Rover Color-coded rover diagram Main article: Curiosity (rover) § Specifications Curiosity rover has a mass of 899 kg (1,982 lb), can travel up to 90 m (300 ft) per hour on its six-wheeled rocker-bogie system, is powered by a multi-mission radioisotope thermoelectric generator (MMRTG), and communicates in both X band and UHF bands.     Computers: The two identical on-board rover computers, called "Rover Compute Element" (RCE), contain radiation-hardened memory to tolerate the extreme radiation from space and to safeguard against power-off cycles. Each computer's memory includes 256 KB of EEPROM, 256 MB of DRAM, and 2 GB of flash memory.[29] This compares to 3 MB of EEPROM, 128 MB of DRAM, and 256 MB of flash memory used in the Mars Exploration Rovers.[30]     The RCE computers use the RAD750 CPU (a successor to the RAD6000 CPU used in the Mars Exploration Rovers) operating at 200 MHz.[31][32][33] The RAD750 CPU is capable of up to 400 MIPS, while the RAD6000 CPU is capable of up to 35 MIPS.[34][35] Of the two on-board computers, one is configured as backup, and will take over in the event of problems with the main computer.[29]     The rover has an Inertial Measurement Unit (IMU) that provides 3-axis information on its position, which is used in rover navigation.[29] The rover's computers are constantly self-monitoring to keep the rover operational, such as by regulating the rover's temperature.[29] Activities such as taking pictures, driving, and operating the instruments are performed in a command sequence that is sent from the flight team to the rover.[29] The rover's computers run VxWorks, a real-time operating system from Wind River Systems. During the trip to Mars, VxWorks ran applications dedicated to the navigation and guidance phase of the mission, and also had a pre-programmed software sequence for handling the complexity of the entry-descent-landing. Once landed, the applications were replaced with software for driving on the surface and performing scientific activities.[36][37][38]     See also: Comparison of embedded computer systems on board the Mars rovers Goldstone antenna can receive signals Wheels of a working sibling to Curiosity. The Morse code pattern (for "JPL") is represented by small (dot) and large (dash) holes in three horizontal lines on the wheels. The code on each line is read from right to left.     Communications: Curiosity is equipped with several means of communication, for redundancy. An X band Small Deep Space Transponder for communication directly to Earth via the NASA Deep Space Network[39] and a UHF Electra-Lite software-defined radio for communicating with Mars orbiters.[27]: 46  The X-band system has one radio, with a 15 W power amplifier, and two antennas: a low-gain omnidirectional antenna that can communicate with Earth at very low data rates (15 bit/s at maximum range), regardless of rover orientation, and a high-gain antenna that can communicate at speeds up to 32 kbit/s, but must be aimed. The UHF system has two radios (approximately 9 W transmit power[27]: 81 ), sharing one omnidirectional antenna. This can communicate with the Mars Reconnaissance Orbiter (MRO) and 2001 Mars Odyssey orbiter (ODY) at speeds up to 2 Mbit/s and 256 kbit/s, respectively, but each orbiter is only able to communicate with Curiosity for about 8 minutes per day.[40] The orbiters have larger antennas and more powerful radios, and can relay data to Earth faster than the rover could do directly. Therefore most of the data returned by Curiosity (MSL) is via the UHF relay links with MRO and ODY. The data return during the first 10 days was approximately 31 megabytes per day.     Typically 225 kbit/day of commands are transmitted to the rover directly from Earth, at a data rate of 1–2 kbit/s, during a 15-minute (900 second) transmit window, while the larger volumes of data collected by the rover are returned via satellite relay.[27]: 46  The one-way communication delay with Earth varies from 4 to 22 minutes, depending on the planets' relative positions, with 12.5 minutes being the average.[41]     At landing, telemetry was monitored by the 2001 Mars Odyssey orbiter, Mars Reconnaissance Orbiter and ESA's Mars Express. Odyssey is capable of relaying UHF telemetry back to Earth in real time. The relay time varies with the distance between the two planets and took 13:46 minutes at the time of landing.[42][43]     Mobility systems: Curiosity is equipped with six wheels in a rocker-bogie suspension, which also served as landing gear for the vehicle, unlike its smaller predecessors.[44][45] The wheels are significantly larger (50 centimeters (20 in) diameter) than those used on previous rovers. Each wheel has cleats and is independently actuated and geared, providing for climbing in soft sand and scrambling over rocks. The four corner wheels can be independently steered, allowing the vehicle to turn in place as well as execute arcing turns.[27] Each wheel has a pattern that helps it maintain traction and leaves patterned tracks in the sandy surface of Mars. That pattern is used by on-board cameras to judge the distance traveled. The pattern itself is Morse code for "JPL" (•−−− •−−• •−••).[46] Based on the center of mass, the vehicle can withstand a tilt of at least 50 degrees in any direction without overturning, but automatic sensors will limit the rover from exceeding 30-degree tilts.[27] Instruments Main instruments APXS – Alpha Particle X-ray Spectrometer ChemCam – Chemistry and Camera complex CheMin – Chemistry and Mineralogy DAN – Dynamic Albedo of Neutrons Hazcam – Hazard Avoidance Camera MAHLI – Mars Hand Lens Imager MARDI – Mars Descent Imager MastCam – Mast Camera MEDLI – MSL EDL Instrument Navcam – Navigation Camera RAD – Radiation assessment detector REMS – Rover Environmental Monitoring Station SAM – Sample Analysis at Mars Main article: Curiosity (rover) § Instruments The shadow of Curiosity and Aeolis Mons ("Mount Sharp") The general analysis strategy begins with high resolution cameras to look for features of interest. If a particular surface is of interest, Curiosity can vaporize a small portion of it with an infrared laser and examine the resulting spectra signature to query the rock's elemental composition. If that signature intrigues, the rover will use its long arm to swing over a microscope and an X-ray spectrometer to take a closer look. If the specimen warrants further analysis, Curiosity can drill into the boulder and deliver a powdered sample to either the SAM or the CheMin analytical laboratories inside the rover.[47][48][49]     Alpha Particle X-ray Spectrometer (APXS): This device can irradiate samples with alpha particles and map the spectra of X-rays that are re-emitted for determining the elemental composition of samples.     CheMin: CheMin is short for 'Chemistry and Mineralogy', and it is an X-ray diffraction and X-ray fluorescence analyzer.[50][51][52] It will identify and quantify the minerals present in rocks and soil and thereby assess the involvement of water in their formation, deposition, or alteration.[51] In addition, CheMin data will be useful in the search for potential mineral biosignatures, energy sources for life or indicators for past habitable environments.[50][51]     Sample Analysis at Mars (SAM): The SAM instrument suite will analyze organics and gases from both atmospheric and solid samples.[48][49] This include oxygen and carbon isotope ratios in carbon dioxide (CO2) and methane (CH4) in the atmosphere of Mars in order to distinguish between their geochemical or biological origin.[48][53][54][55][56] Comparison of Radiation Doses – includes the amount detected on the trip from Earth to Mars by the RAD on the MSL (2011–2013).[57][58][59]     Radiation Assessment Detector (RAD): This instrument was the first of ten MSL instruments to be turned on. Both en route and on the planet's surface, it will characterize the broad spectrum of radiation encountered in the Martian environment. Turned on after launch, it recorded several radiation spikes caused by the Sun.[60] On May 31, 2013, NASA scientists reported that a possible human mission to Mars may involve a great radiation risk based on the amount of energetic particle radiation detected by the RAD on the Mars Science Laboratory while traveling from the Earth to Mars in 2011–2012.[57][58][59] The RAD on Curiosity.     Dynamic Albedo of Neutrons (DAN): A pulsed neutron source and detector for measuring hydrogen or ice and water at or near the Martian surface.[61][62] On August 18, 2012 (sol 12) the Russian science instrument, DAN, was turned on,[63] marking the success of a Russian-American collaboration on the surface of Mars and the first working Russian science instrument on the Martian surface since Mars 3 stopped transmitting over forty years ago.[64] The instrument is designed to detect subsurface water.[63]     Rover Environmental Monitoring Station (REMS): Meteorological package and an ultraviolet sensor provided by Spain and Finland.[65] It measures humidity, pressure, temperatures, wind speeds, and ultraviolet radiation.[65]     Cameras: Curiosity has seventeen cameras overall.[66] 12 engineering cameras (Hazcams and Navcams) and five science cameras. MAHLI, MARDI, and MastCam cameras were developed by Malin Space Science Systems and they all share common design components, such as on-board electronic imaging processing boxes, 1600×1200 CCDs, and a RGB Bayer pattern filter.[67][68][69][70][71][72]         MastCam: This system provides multiple spectra and true-color imaging with two cameras.         Mars Hand Lens Imager (MAHLI): This system consists of a camera mounted to a robotic arm on the rover, used to acquire microscopic images of rock and soil. It has white and ultraviolet LEDs for illumination.     ChemCam: Designed by Roger Wiens is a system of remote sensing instruments used to erode the Martian surface up to 10 meters away and measure the different components that make up the land.[73] The payload includes the first laser-induced breakdown spectroscopy (LIBS) system to be used for planetary science, and Curiosity's fifth science camera, the remote micro-imager (RMI). The RMI provides black-and-white images at 1024×1024 resolution in a 0.02 radian (1.1-degree) field of view.[74] This is approximately equivalent to a 1500 mm lens on a 35 mm camera. MARDI views the surface     Mars Descent Imager (MARDI): During part of the descent to the Martian surface, MARDI acquired 4 color images per second, at 1600×1200 pixels, with a 0.9-millisecond exposure time. Images were taken 4 times per second, starting shortly before heatshield separation at 3.7 km altitude, until a few seconds after touchdown. This provided engineering information about both the motion of the rover during the descent process, and science information about the terrain immediately surrounding the rover. NASA descoped MARDI in 2007, but Malin Space Science Systems contributed it with its own resources.[75] After landing it could take 1.5 mm (0.059 in) per pixel views of the surface,[76] the first of these post-landing photos were taken by August 27, 2012 (sol 20).[77]     Engineering cameras: There are 12 additional cameras that support mobility:         Hazard avoidance cameras (Hazcams): The rover has a pair of black and white navigation cameras (Hazcams) located on each of its four corners.[78] These provide closed-up views of potential obstacles about to go under the wheels.         Navigation cameras (Navcams): The rover uses two pairs of black and white navigation cameras mounted on the mast to support ground navigation.[78] These provide a longer-distance view of the terrain ahead. History MSL's cruise stage being tested at the Jet Propulsion Laboratory near Pasadena, California The Mars Science Laboratory was recommended by United States National Research Council Decadal Survey committee as the top priority middle-class Mars mission in 2003.[79] NASA called for proposals for the rover's scientific instruments in April 2004,[80] and eight proposals were selected on December 14 of that year.[80] Testing and design of components also began in late 2004, including Aerojet's designing of a monopropellant engine with the ability to throttle from 15–100 percent thrust with a fixed propellant inlet pressure.[80] Cost overruns, delays, and launch By November 2008 most hardware and software development was complete, and testing continued.[81] At this point, cost overruns were approximately $400 million. In the attempts to meet the launch date, several instruments and a cache for samples were removed and other instruments and cameras were simplified to simplify testing and integration of the rover.[82][83] The next month, NASA delayed the launch to late 2011 because of inadequate testing time.[84][85][86] Eventually the costs for developing the rover reached $2.47 billion, that for a rover that initially had been classified as a medium-cost mission with a maximum budget of $650 million, yet NASA still had to ask for an additional $82 million to meet the planned November launch. As of 2012, the project suffered an 84 percent overrun.[87] MSL launched on an Atlas V rocket from Cape Canaveral on November 26, 2011.[88] On January 11, 2012, the spacecraft successfully refined its trajectory with a three-hour series of thruster-engine firings, advancing the rover's landing time by about 14 hours. When MSL was launched, the program's director was Doug McCuistion of NASA's Planetary Science Division.[89] Curiosity successfully landed in the Gale Crater at 05:17:57.3 UTC on August 6, 2012,[3][9][10][11] and transmitted Hazcam images confirming orientation.[11] Due to the Mars-Earth distance at the time of landing and the limited speed of radio signals, the landing was not registered on Earth for another 14 minutes.[11] The Mars Reconnaissance Orbiter sent a photograph of Curiosity descending under its parachute, taken by its HiRISE camera, during the landing procedure. Six senior members of the Curiosity team presented a news conference a few hours after landing, they were: John Grunsfeld, NASA associate administrator; Charles Elachi, director, JPL; Peter Theisinger, MSL project manager; Richard Cook, MSL deputy project manager; Adam Steltzner, MSL entry, descent and landing (EDL) lead; and John Grotzinger, MSL project scientist.[90] Naming Between March 23 and 29, 2009, the general public ranked nine finalist rover names (Adventure, Amelia, Journey, Perception, Pursuit, Sunrise, Vision, Wonder, and Curiosity)[91] through a public poll on the NASA website.[92] On May 27, 2009, the winning name was announced to be Curiosity. The name had been submitted in an essay contest by Clara Ma, a sixth-grader from Kansas.[92][93][94]     Curiosity is the passion that drives us through our everyday lives. We have become explorers and scientists with our need to ask questions and to wonder.     — Clara Ma, NASA/JPL Name the Rover contest Landing site selection Aeolis Mons rises from the middle of Gale Crater – Green dot marks the Curiosity rover landing site in Aeolis Palus[95][96] – North is down Over 60 landing sites were evaluated, and by July 2011 Gale crater was chosen. A primary goal when selecting the landing site was to identify a particular geologic environment, or set of environments, that would support microbial life. Planners looked for a site that could contribute to a wide variety of possible science objectives. They preferred a landing site with both morphologic and mineralogical evidence for past water. Furthermore, a site with spectra indicating multiple hydrated minerals was preferred; clay minerals and sulfate salts would constitute a rich site. Hematite, other iron oxides, sulfate minerals, silicate minerals, silica, and possibly chloride minerals were suggested as possible substrates for fossil preservation. Indeed, all are known to facilitate the preservation of fossil morphologies and molecules on Earth.[97] Difficult terrain was favored for finding evidence of livable conditions, but the rover must be able to safely reach the site and drive within it.[98] Engineering constraints called for a landing site less than 45° from the Martian equator, and less than 1 km above the reference datum.[99] At the first MSL Landing Site workshop, 33 potential landing sites were identified.[100] By the end of the second workshop in late 2007, the list was reduced to six;[101][102] in November 2008, project leaders at a third workshop reduced the list to these four landing sites:[103][104][105][106] Name     Location     Elevation     Notes Eberswalde Crater Delta     23.86°S 326.73°E     −1,450 m (−4,760 ft)     Ancient river delta.[107] Holden Crater Fan     26.37°S 325.10°E     −1,940 m (−6,360 ft)     Dry lake bed.[108] Gale Crater     4.49°S 137.42°E     −4,451 m (−14,603 ft)     Features 5 km (3.1 mi) tall mountain of layered material near center.[109] Selected.[95] Mawrth Vallis Site 2     24.01°N 341.03°E     −2,246 m (−7,369 ft)     Channel carved by catastrophic floods.[110] A fourth landing site workshop was held in late September 2010,[111] and the fifth and final workshop May 16–18, 2011.[112] On July 22, 2011, it was announced that Gale Crater had been selected as the landing site of the Mars Science Laboratory mission. Launch The MSL launched from Cape Canaveral Launch vehicle The Atlas V launch vehicle is capable of launching up to 8,290 kg (18,280 lb) to geostationary transfer orbit.[113] The Atlas V was also used to launch the Mars Reconnaissance Orbiter and the New Horizons probe.[5][114] The first and second stages, along with the solid rocket motors, were stacked on October 9, 2011, near the launch pad.[115] The fairing containing MSL was transported to the launch pad on November 3, 2011.[116] Launch event MSL was launched from Cape Canaveral Air Force Station Space Launch Complex 41 on November 26, 2011, at 15:02 UTC via the Atlas V 541 provided by United Launch Alliance.[117] This two stage rocket includes a 3.8 m (12 ft) Common Core Booster (CCB) powered by one RD-180 engine, four solid rocket boosters (SRB), and one Centaur second stage with a 5 m (16 ft) diameter payload fairing.[118] The NASA Launch Services Program coordinated the launch via the NASA Launch Services (NLS) I Contract.[119] Cruise Animation of Mars Science Laboratory's trajectory    Earth ·    Mars ·   Mars Science Laboratory Cruise stage The cruise stage carried the MSL spacecraft through the void of space and delivered it to Mars. The interplanetary trip covered the distance of 352 million miles in 253 days.[120] The cruise stage has its own miniature propulsion system, consisting of eight thrusters using hydrazine fuel in two titanium tanks.[121] It also has its own electric power system, consisting of a solar array and battery for providing continuous power. Upon reaching Mars, the spacecraft stopped spinning and a cable cutter separated the cruise stage from the aeroshell.[121] Then the cruise stage was diverted into a separate trajectory into the atmosphere.[122][123] In December 2012, the debris field from the cruise stage was located by the Mars Reconnaissance Orbiter. Since the initial size, velocity, density and impact angle of the hardware are known, it will provide information on impact processes on the Mars surface and atmospheric properties.[124] Mars transfer orbit The MSL spacecraft departed Earth orbit and was inserted into a heliocentric Mars transfer orbit on November 26, 2011, shortly after launch, by the Centaur upper stage of the Atlas V launch vehicle.[118] Prior to Centaur separation, the spacecraft was spin-stabilized at 2 rpm for attitude control during the 36,210 km/h (22,500 mph) cruise to Mars.[125] During cruise, eight thrusters arranged in two clusters were used as actuators to control spin rate and perform axial or lateral trajectory correction maneuvers.[27] By spinning about its central axis, it maintained a stable attitude.[27][126][127] Along the way, the cruise stage performed four trajectory correction maneuvers to adjust the spacecraft's path toward its landing site.[128] Information was sent to mission controllers via two X-band antennas.[121] A key task of the cruise stage was to control the temperature of all spacecraft systems and dissipate the heat generated by power sources, such as solar cells and motors, into space. In some systems, insulating blankets kept sensitive science instruments warmer than the near-absolute zero temperature of space. Thermostats monitored temperatures and switched heating and cooling systems on or off as needed." (wikipedia.org) "Science, technology, engineering, and mathematics (STEM) is an umbrella term used to group together the distinct but related technical disciplines of science, technology, engineering, and mathematics. The term is typically used in the context of education policy or curriculum choices in schools. It has implications for workforce development, national security concerns (as a shortage of STEM-educated citizens can reduce effectiveness in this area) and immigration policy, with regards to admitting foreign students and tech workers.[1] There is no universal agreement on which disciplines are included in STEM; in particular whether or not the science in STEM includes social sciences, such as psychology, sociology, economics, and political science. In the United States, these are typically included by organizations such as the National Science Foundation (NSF),[1] the Department of Labor's O*Net online database for job seekers,[2] and the Department of Homeland Security.[3] In the United Kingdom, the social sciences are categorized separately and are instead grouped together with humanities and arts to form another counterpart acronym HASS (Humanities, Arts, and Social Sciences), rebranded in 2020 as SHAPE (Social Sciences, Humanities and the Arts for People and the Economy).[4][5] Some sources also use HEAL (health, education, administration, and literacy) as the counterpart of STEM.[6] Terminology History In the early 1990s, the acronym STEM was used by a variety of educators in preference to SMET, including Charles E. Vela, the founder and director of the Center for the Advancement of Hispanics in Science and Engineering Education (CAHSEE).[7][8][9] Moreover, the CAHSEE started a summer program for talented under-represented students in the Washington, D.C., area called the STEM Institute. Based on the program's recognized success and his expertise in STEM education,[10] Charles Vela was asked to serve on numerous NSF and Congressional panels in science, mathematics and engineering education;[11] it is through this manner that NSF was first introduced to the acronym STEM. One of the first NSF projects to use the acronym was STEMTEC, the Science, Technology, Engineering and Math Teacher Education Collaborative at the University of Massachusetts Amherst, which was founded in 1998.[12] In 2001, at the urging of Dr. Peter Faletra, the Director of Workforce Development for Teachers and Scientists at the Office of Science, the acronym was adopted by Rita Colwell and other science administrators in the National Science Foundation (NSF). The Office of Science was also an early adopter of the STEM acronym.[13] Other variations A-STEM (arts, science, technology, engineering, and mathematics);[14] more focus and based on humanism and arts. eSTEM (environmental STEM)[15][16] GEMS (girls in engineering, math, and science); used for programs to encourage women to enter these fields.[17][18] MINT (mathematics, informatics, natural sciences, and technology)[19] SHTEAM (science, humanities, technology, engineering, arts, and mathematics)[20] SMET (science, mathematics, engineering, and technology); previous name[21] STEAM (science, technology, engineering, arts, and mathematics)[22]     STEAM (science, technology, engineering, agriculture, and mathematics); add agriculture[23]     STEAM (science, technology, engineering, and applied mathematics); more focus on applied mathematics[24] STEEM (science, technology, engineering, economics, and mathematics); adds economics as a field[25] STEMIE (science, technology, engineering, mathematics, invention and entrepreneurship); adds Inventing and Entrepreneurship as means to apply STEM to real world problem solving and markets.[26] STEMM (science, technology, engineering, mathematics, and medicine)[27] STM (scientific, technical, and mathematics[28] or science, technology, and medicine)[29] STREAM (science, technology, robotics, engineering, arts, and mathematics); adds robotics and arts as fields[" (wikipedia.org) "Lenticular printing is a technology in which lenticular lenses (a technology also used for 3D displays) are used to produce printed images with an illusion of depth, or the ability to change or move as they are viewed from different angles. Examples include flip and animation effects such as winking eyes, and modern advertising graphics whose messages change depending on the viewing angle. Colloquial terms for lenticular prints include "flickers", "winkies", "wiggle pictures", and "tilt cards". The trademarks Vari-Vue and Magic Motion are often used for lenticular pictures, without regard to the actual manufacturer. Process How a lenticular lens works Lenticular printing is a multi-step process which consists of creating a lenticular image from at least two images, and placing it behind a lenticular lens. It can be used to create frames of animation, for a motion effect; offsetting the various layers at different increments, for a 3D effect; or simply to show sets of alternative images that appear to transform into each other. Once the images are collected, they are arranged in individual frame files, then digitally combined into a single file in a process called interlacing. The interlaced image may be printed directly on the back (smooth side) of the lens, or on a substrate (ideally a synthetic paper) which is laminated to the lens. When printing on the backside of the lens, the critical registration of the fine "slices" of interlaced images must be absolutely correct during the lithographic or screen printing process to avoid "ghosting" and poor image definition. The combined lenticular print shows two or more images by changing the angle from which the print is viewed. If a sequence of images is used, it can even show a short animation. Though normally produced in sheet form by interlacing simple images or colors throughout the artwork, lenticular images can also be created in roll form with 3D effects or multi-color changes. Alternatively, several images of the same object, taken from slightly different angles, can be used to create a lenticular print with a stereoscopic 3D effect. 3D effects can be achieved only in a lateral (side-by-side) orientation, as each of the viewer's eyes must see them from a slightly different angle to achieve the stereoscopic effect. Other effects, like morphs, motion, and zooms work better (with less ghosting or latent effects) in top-to-bottom orientation, but can be achieved in both orientations. There are many commercial processes in the manufacture of lenticular images, which can be made from PVC, APET, acrylic, and PETG, as well as other materials. While PETG and APET are the most common, other materials are becoming popular to accommodate outdoor use and special forming due to the increasing use of lenticular images on items such as gift cards. Lithographic lenticular printing allows for the flat side of the lenticular sheet to have ink placed directly onto the lens, while high-resolution photographic lenticulars typically have the image laminated to the lens.[citation needed] Lenticular images saw a surge in popularity in the first decade of the 21st century, appearing on the cover of the May 2006 issue of Rolling Stone, trading cards, sports posters, and signs in stores that help to attract buyers.[citation needed] Construction Images are interlaced on the substrate Each image is arranged (slicing) into strips, which are then interlaced with one or more similarly arranged images (splicing). These are printed on the back of a piece of plastic, with a series of thin lenses molded into the opposite side. Alternatively, the images can be printed on paper, which is then bonded to the plastic. With the new technology, lenses are printed in the same printing operation as the interlaced image, either on both sides of a flat sheet of transparent material, or on the same side of a sheet of paper, the image being covered with a transparent sheet of plastic or with a layer of transparent, which in turn is printed with several layers of varnish to create the lenses. The lenses are accurately aligned with the interlaces of the image, so that light reflected off each strip is refracted in a slightly different direction, but the light from all pixels originating from the same original image is sent in the same direction. The end result is that a single eye looking at the print sees a single whole image, but two eyes will see different images, which leads to stereoscopic 3D perception. Types of lenticular prints There are three distinct types of lenticular prints, distinguished by how great a change in angle of view is required to change the image: Transforming prints     Here two or more very different pictures are used, and the lenses are designed to require a relatively large change in angle of view to switch from one image to another. This allows viewers to easily see the original images, since small movements cause no change. Larger movement of the viewer or the print causes the image to flip from one image to another (the "flip effect"). An example of this is the lenticular print of hockey player Mario Tremblay at Centre Mario-Tremblay in Alma, Quebec where he is transformed from a minor hockey playing boy as an Alma Eagle into the professional hockey playing man, four years later, as a Montreal Canadien.[1] Animated prints     Here the distance between different angles of view is "medium", so that while both eyes usually see the same picture, moving a little bit switches to the next picture in the series. Two or more sequential images are used, with only small differences between each image and the next. This can be used to create an image that moves ("motion effect"), or can create a "zoom" or "morph" effect, in which part of the image expands in size or changes shape as the angle of view changes. The movie poster of the film Species II, shown in this article, is an example of this technique. Stereoscopic effects     Here the change in viewing angle needed to change images is small, so that each eye sees a slightly different view. This creates a 3D effect without requiring special glasses, using two or more images. For example, the Dolby-Philips Lenticular 3D display produces 28 different images. Motorized lenticular With static (non-motorized) lenticular, the viewer either moves the piece or moves past the piece in order to see the graphic effects. With motorized lenticular, a motor moves the graphics behind the lens, enabling the graphic effects while both the viewer and the display remain stationary. History Predecessors Tabula scalata Main article: Tabula scalata Corrugated images that change when viewed from different angles predate the development of lenticular printing. A few examples from the paleolithic era exist in French caves.[2][3] Tabula scalata or "turning pictures" were popular in England since the 16th century.[4] Extant double paintings, with two distinct images on a corrugated panel, are known from the 17th century.[5][6] H.C.J. Deeks used a similar technique with minute vertical corrugations pressed into photographic paper and then exposed to two different images from two different angles.[7] Under a 1906 patent H.C.J. Deeks & Co marketed a Puzzle Post Card or Photochange Post Card. In 1907 a Colorchange Post Card followed, featuring identical pictures on each side of the corrugations that were sprayed with different "liquid pigment or coloring matter" on (parts of) each side.[8] Barrier grid autostereograms and animation Main article: Barrier grid animation and stereography Berthier's diagram: A-B=glass plate, with a-b=opaque lines, P=Picture, O=Eyes, c-n=blocked and allowed views (Le Cosmos 05-1896) The oldest known publication about using a line sheet as a parallax barrier to produce an autostereogram is found in an article by Auguste Berthier in the French scientific magazine "Le Cosmos" of May 1896.[9] Berthier's idea was hardly noticed, but American inventor Frederic Eugene Ives had more success with his very similar parallax stereogram since 1901. He also patented the technique for a "Changeable sign, picture, &c." in 1903, which showed different pictures from different angles (instead of one stereoscopic image from the right angle and distance). Léon Gaumont introduced Ives' pictures in France and encouraged Eugène Estanave to work on the technique. Estanave patented a barrier grid technique for animated autostereograms. Animated portrait photographs with line sheets were marketed for a while, mostly in the 1910s and 1920s. In the US "Magic Moving Picture" postcards with simple 3 phase animation or changing pictures were marketed after 1906. Maurice Bonnett improved barrier grid autostereography in the 1930s with his relièphographie technique and scanning cameras. On 11 April 1898 John Jacobson filed an application for US patent No. 624,043 (granted 2 May 1899) for a Stereograph of an interlaced stereoscopic picture and "a transparent mount for said picture having a corrugated or channeled surface".[10] The corrugated lines or channels were not yet really lenticular, but this is the first known autostereogram that used a corrugated transparent surface rather than the opaque lines of most barrier grid stereograms. Gabriel Lippmann's integral photography Main article: Integral imaging French Nobel Prize winning physicist Gabriel Lippmann represented Eugène Estanave at several presentations of Estanave's works at the French Academy of Sciences. On 2 March 1908 Lippmann presented his own ideas for "photographie intégrale", based on insect eyes. He suggested to use a screen of tiny lenses. Spherical segments should be pressed into a sort of film with photographic emulsion on the other side. The screen would be placed inside a lightproof holder and on a tripod for stability. When exposed each tiny lens would function as a camera and record the surroundings from a slightly different angle than neighboring lenses. When developed and lit from behind the lenses should project the life-size image of the recorded subject in space. He could not yet present concrete results in March 1908, but by the end of 1908 he claimed to have exposed some Integral photography plates and to have seen the "resulting single, full-sized image". However, the technique remained experimental since no material or technique seemed to deliver the optical quality desired. At the time of his death in 1921 Lippmann reportedly had a system with only twelve lenses.[11] Early lenticular methods On 11 April 1898, John Jacobson filed an application for US patent No. 624,043 (granted 2 May 1899) for a Stereograph of an interlaced stereoscopic picture and "a transparent mount for said picture having a corrugated or channeled surface".[10] In 1912, Louis Chéron described in his French patent 443,216 a screen with long vertical lenses that would be sufficient for recording "stereoscopic depth and the shifting of the relations of objects to each other as the viewer moved", while he suggested pinholes for integral photography.[11] In June 1912, Swiss Nobel Prize winning physiologist Walter Rudolf Hess applied for a US patent for a Stereoscopic picture with a "celluloid covering having a surface composed of cylindrical lens elements".[12] US patent 1,128,979 (published 16 February 1915) was one of several patents in different countries he would register for this technique. The company Stereo-Photographie A.G., registered in Zürich in 1914 and 1915, would produce pictures on transparencies through Hess' process. Few examples of these pictures are still known to have survived. They are circa 3 1/6 × 4 inches black and white pictures (with discolored or intentional hues) and labeled on their passe-partouts "Stereo-Photo nach W.R. Hess - Stereo-Photographie A.G. Zürich. Patente: "Schweiz / Deutschland / Frankreich / Italien / England / Oesterreich / Vereinigte Staaten angemeldet". The Société française de photographie has three lenticular "Stereo-photo" plates in their collection, three more were on auction in 2017.[13][11][14] Herbert E. Ives, son of Frederic Eugene Ives, was one of several researchers who worked on lenticular sheets in the 1920s. These were basically simpler versions of Lippmann's integral photography and had a linear array of small plano-convex cylindrical lenses (lenticules).[15] The first successful commercial application of the lenticular technique was not used for 3D or motion display but for color movies. Eastman Kodak's 1928 Kodacolor film was based on Keller-Dorian cinematography. It used 16 mm black and white sensitive film embossed with 600 lenses per square inch for use with a filter with RGB stripes.[16] In the 1930s several US patents relating to lenticular techniques were granted, mostly for color film.[17] On 15 December 1936, Douglas F. Winnek Coffey was granted US patent 2,063,985 (application 24 May 1935) for an "Apparatus for making a composite stereograph".[18] The description does not include changing pictures or animation concepts. Further history During World War II, research for military purposes was done into 3D imaging, including lenticular technologies. Mass production of plastics and the technique of injection moulding came about around the same period and enabled commercially viable production of lenticular sheets for novelty toys and advertisements.[19] Victor Anderson and Vari-Vue Victor G. Anderson worked for the Sperry Corporation during World War II where 3D imaging was used for military instructional products, for instance on how to use a bomb sight. After the war Anderson started his company Pictorial Productions Inc. A patent application for a Process in the assembling of changeable picture display devices was filed on 1 March 1952 and granted on 3 December 1957 (US patent 2,815,310. Anderson stated in 1996 that the company's first product was the I Like Ike button.[19] The presidential campaign button's image changed from the slogan "I Like Ike" (in black letters on white) into a black and white picture of Ike Eisenhower when viewed from different angles.[20] It was copyrighted on 14 May 1952.[21] In December 1953 the company registered their trademark Vari-Vue.[22] Vari-Vue further popularized lenticular images during the 1950s and 1960s. By the late sixties, the company marketed about two thousand stock products including twelve-inch-square (30 cm) moving pattern and color sheets, large images (many religious), billboards, and novelty toys.[citation needed] The company went bankrupt in 1986.[23] Xograph Look magazine of 25 February 1964 introduced the publisher's "parallax panoramagram" technology with 8 million copies of a 10x12 cm black and white card with a photographic 3D image of an Edison bust surrounded by some inventions. A 10 x 12 cm full color picture of a model promoting Kodel followed on 7 April. The technique was soon trademarked as "xograph" by Cowles' daughter company Visual Panographics Inc. Magazines like Look and Venture published xographs until the mid 1970s. Some baseball cards were produced as xographs.[24][25] Images produced by the company ranged from just a few millimeters (0.1 inch) to 28 by 19.5 inches (71 by 50 cm).[citation needed] Other early companies In the 1960s, more companies manufactured lenticular products, including Hallmark Cards (registering the Magic Motion trademark in 1964[26]), Reflexa (Nürnberg, Germany), Toppan (Tokyo, Japan) and Dai-Nippon (Japan).[15] OptiGraphics Corporation of Grand Prairie, Texas[27] was formed in 1970 and—under the guidance of Victor Anderson, working well into his 80s. The company trademarked Magic Motion in 1976.[28] Optigraphics produced the lenticular prizes for Cracker Jack in the 1980s, 7-Eleven Slurpee lenticular sports coins from 1983 to 1987,[29] and in 1986 it produced the first set of 3D traditional baseball cards marketed as Sportflics, which ultimately led to the creation of Pinnacle Brands.[30] In 1999 Performance Companies bought OptiGraphics after Pinnacle Trading Card Company went bankrupt in 1998.[27] While lenticular images were very popular in the 1960s and 1970s, by the 1980s OptiGraphics was the only significant manufacturer left in the US.[15] 21st century The techniques for lenticular printing were further improved in the 21st century. Lenticular full motion video effects or "motion print" enabled viewing of up to 60 video frames within a print. Common and notable products Political campaign and pop star "flasher" badges After their first presidential campaign badge I like Ike in 1952, Pictorial Productions Inc. made many more similar political campaign buttons, including presidential campaign badge like Don't blame me! - I voted democratic (1956), John F. Kennedy - The Man for the 60s (1960), I Like Ben (1963) and I'm for Nixon (1968?).[31] Official "flasher" badges for pop stars like Elvis Presley were manufactured by Vari-Vue at least since 1956,[32] including badges for Beatles, Rolling Stones' and other bands in the 1960s. Cheerios and Cracker Jack prizes Pictorial Productions/Vari-Vue produced small animated picture cards for Cheerios in the 1950s, of which founder Victor Anderson claimed to have produced 40 million. He also stated that the cards were originally stuck to the outside of the packaging and were only put inside the boxes after too many cards were stolen before the boxes reached the store shelves.[19] Many different lenticular "tilt cards" were produced as prizes in Cracker Jack boxes. These were first produced by Vari-Vue (1950s-1970s), later by Toppan Printing, Ltd. (1980s), and Optigraphics Corporation (1980s-1990s).[33] Novelty toys In 1958 Victor Anderson patented an Ocular Toy: an eye glass mount with lenticular winking eyes.[34] Lenticular images were used in many small and cheap plastic toys, often as gumball machine prizes. These include: miniature toy televisions with an animated lenticular screen, charms in the shape of animals with lenticular faces, "flicker rings", etcetera. In 1960 Takara's Dakkochan - a little plastic golliwog toy with lenticular eyes - originally intended for toddlers, became very popular with Japanese teenagers as a fashion accessory worn around the arm.[35] Postcards Around 1966 several companies started producing lenticular postcards. Common themes are winking girls, religious scenes, animals, dioramas with dolls, touristic sites and pin-up models wearing clothes when viewed from one angle and nude when viewed from another angle. Covers for books, music albums and movies The lenticular picture on the album cover for the Rolling Stones' 1967 LP Their Satanic Majesties Request was manufactured by Vari-Vue, as well as the postcards and other promotional items that accompanied the release.[36] Other lenticular LP covers include Johnny Cash's The Holy Land (1969)[37] and The Stranglers' The Raven.[38] In the 2010s lenticular covers for LPs became a bit more common, especially for deluxe re-releases.[39] Saturnalia 1973 LP with lenticular label that switches from "Magical love" to a logo. In 1973 the band Saturnalia had lenticular labels on their Magical Love picture disc lp.[40] From around the mid-1990s some lenticular cd covers were produced (mostly for limited editions), including Pet Shop Boys' Alternative (1995) with an image of Chris changing into Neil,[41] The Sacrilicious Sounds of the Supersuckers (1995),[42] Tool's Ænima (1996), Velvet Underground's Loaded 2CD version (1997),[43] Kraftwerk Expo2000 (1999) and David Bowie's Hours (1999).[44] Ministry's 2007 The last sucker had an image of George W. Bush changing into a monstrous, alien-like face.[45] In the 2010s lenticular covers for movies on DVD and Blu-ray became quite common. Lenticular covers have also been used as a collectible cover variant for comic books since the 1990s; Marvel, DC, and other publishers have created such covers with animated or 3-D effects.[46] Lentograph In August 1967 the trademark Lentograph was filed by Victor Anderson 3D Studios, Inc. (registered in October 1968).[47][48] Lentographs were marketed as relatively large lenticular plates (16 x 12 inches / 12 × 8 inches), often found in an illuminated brass frame. Commonly found are 3D pictures of Paul Cunningham's biblical displays with sculpted figurines in dramatic poses based on paintings (Plate 501-508), a family of teddy bears in a domestic scene, Plate No. 106 Evening Flowers, Plate No. 115 Goldilocks and 3 bears, Plate No. 124 Bijou (a white poodle), Plate No. 121 Midday Respite (a taxidermied young deer in a forest setting), Plate No. 213 Red Riding Hood. Also known are a harbor scene (Plate No. 114), Plate No. 118 Japanese Floral, Plate No. 123 Faustus (a yorky dog) and Plate No. 212 of a covered bridge.[49] Lenticular postage stamps In 1967 Bhutan introduced lenticular 3D postage stamps as one of the many unusual stamp designs of the Bhutan Stamp Agency initiated by American businessman Burt Kerr Todd.[50][51] Countries like Ajman, Yemen, Manama, Umm Al Qiwain and North Korea released lenticular stamps in the 1970s. Animated lenticular stamps have been issued since the early 1980s by countries like North Korea.[52] In 2004 full motion lenticular postage stamps were issued in New Zealand. Over the years many other countries have produced stamps with similar lenticular full motion effects, mostly depicting sport events.[52] In 2010 Communications agency KesselsKramer produced the "Smallest Shortest Film" on a Dutch stamp, directed by Anton Corbijn and featuring actress Carice van Houten.[53] In 2012, Design Consultancy GBH.London created the UK's first 'Motion Stamps' for Royal Mail's Special Stamp Issue, The Genius of Gerry Anderson. The minisheet featured four fully lenticular stamps based on Gerry and Sylvia Anderson's Thunderbirds TV series. The Stamps and their background border used 48 frame 'MotionPrint’ technology and were produced by Outer Aspect from New Zealand. In August 2018 the United States Postal Service introduced "The Art of Magic" lenticular stamp, sold in a souvenir sheet of three. The stamp was designed to celebrate the art of magic and "by rotating each stamp, you can see a white rabbit popping out of a black top hat."[54] In August 2019 the United States Postal Service introduced a second stamp with lenticular technology, this time featuring the dinosaur Tyrannosaurus Rex. The USPS explained that "two of the four designs show movement when rotated. See the skeletal remains with and without flesh and watch as an approaching T. rex suddenly lunges forward."[55] Books In 2012, Dan Kainen's first "photicular" book Safari was published, with processed video images animated by having a lens sheet slide by turning the page,[56] much like Rufus Butler Seder's "scanimation" process. It was followed by Ocean (2014), Polar (2015), Jungle (2016), Wild (2017), Dinosaur (2018) and Outback (2019). Related techniques Han-O-Disc manufactured for Light Fantastic with metal flake outside and Dufex process print within. Han-O-Disc record with diffraction grating 'Rainbow' film (outside ring), color shifting Rowlux (middle ring) and "silver balls" Rowlux film (center of record). A related product, produced by a small company in New Jersey, was Rowlux. Unlike the Vari-Vue product, Rowlux used a microprismatic lens structure made by a process they patented in 1972,[57] and no paper print. Instead, the plastic (polycarbonate, flexible PVC and later PETG) was dyed with translucent colors, and the film was usually thin and flexible (from 0.002" or 0.051 mm in thickness). While not a true lenticular process, the Dufex Process (manufactured by F.J. Warren Ltd.)[58] does use a form of lens structure to animate the image. The process consists of imprinting a metallic foil with an image. The foil is then laminated onto a thin sheet of card stock that has been coated with a thick layer of wax. The heated lamination press has the Dufex embossing plate on its upper platen, which has been engraved with 'lenses' at different angles, designed to match the artwork and reflect light at different intensities depending on angle of view. Lenticular cinema and television Since at least the early 1930s many researchers have tried to develop lenticular cinema. Herbert E. Ives presented an apparatus on 31 October 1930 with small autostereoscopic motion pictures viewable by only small groups at a time. Ives would continue to improve his system over the years. However, producing autostereoscopic movies was deemed too costly for commercial purposes. A November 1931 New York Times article entitled New screens gives depth to movies describes a lenticular system by Douglas F. Winnek and also mentions an optical appliance fitted near the screen by South African astronomer R.T.A. Innes.[59] Lenticular arrays have also been used for 3D autostereoscopic television, which produces the illusion of 3D vision without the use of special glasses. At least as early as 1954 patents for lenticular television were filed,[60] but it lasted until 2010 before a range of 3D televisions became available. Some of these systems used cylindrical lenses slanted from the vertical, or spherical lenses arranged in a honeycomb pattern, to provide a better resolution. While over 40 million 3D televisions were sold in 2012 (including systems that required glasses),[61] by 2016 very little 3D content was offered and manufacturers had stopped producing 3D TV sets. While the need to wear glasses for the more affordable systems seemed to have been a letdown for customers, affordable autostereoscopic televisions were seen as a future solution.[62] Further information: 3D television Manufacturing process Printing Lenticular front sheeting and image-processing software are both sold for home computer printing, where the interlaced image backing is inkjet printed in photo resolution and affixed behind the lenticular sheet. [63] Creation of lenticular images on a commercial scale requires printing presses that are adapted to print on sensitive thermoplastic materials. Lithographic offset printing is typically used, to ensure the images are good quality. Printing presses for lenticulars must be capable of adjusting image placement in 10-µm steps, to allow good alignment of the image to the lens array. Typically, ultraviolet-cured inks are used. These dry very quickly by direct conversion of the liquid ink to a solid form, rather than by evaporation of liquid solvents from a mixture. Powerful (400-watt-per-square-inch or 0.083 hp/cm2) ultraviolet (UV) lamps have been used to rapidly cure the ink. This allowed lenticular images to be printed at high speed. In some cases, electron beam lithography has been used instead. The curing of the ink was then initiated directly by an electron beam scanned across the surface. Defects Design defects Double images on the relief and in depth Double images are usually caused by an exaggeration of the 3D effect from some angles of view, or an insufficient number of frames. Poor design can lead to doubling, small jumps, or a fuzzy image, especially on objects in relief or in depth. For some visuals, where the foreground and background are fuzzy or shaded, this exaggeration can prove to be an advantage. In most cases, the detail and precision required do not allow this. Image ghosting Ghosting occurs due to poor treatment of the source images, and also due to transitions where demand for an effect goes beyond the limits and technical possibilities of the system. This causes some of the images to remain visible when they should disappear. These effects can depend on the lighting of the lenticular print. Prepress defects Synchronization of the print (master) with the pitch This effect is also known as "banding". Poor calibration of the material can cause the passage from one image to another to not be simultaneous over the entire print. The image transition progresses from one side of the print to the other, giving the impression of a veil or curtain crossing the visual. This phenomenon is felt less for the 3D effects, but is manifested by a jump of the transverse image. In some cases, the transition starts in several places and progresses from each starting point towards the next, giving the impression of several curtains crossing the visual, as described above. Discordant harmonics This phenomenon is unfortunately very common, and is explained either by incorrect calibration of the support or by incorrect parametrization of the prepress operations. It is manifested in particular by streaks that appear parallel to the lenticules during transitions from one visual to the other. Printing defects Color synchronization One of the main difficulties in lenticular printing is color synchronization. The causes are varied, they may come from a malleable material, incorrect printing conditions and adjustments, or again a dimensional differential of the engraving of the offset plates in each color. This poor marking is shown by doubling of the visual; a lack of clarity; a streak of color or wavy colors (especially for four-color shades) during a change of phase by inclination of the visual. Synchronization of parallelism of the printing to the lenticules The origin of this problem is a fault in the printing and forcibly generates a phase defect. The passage from one visual to another must be simultaneous over the entire format. But when this problem occurs, there is a lag in the effects on the diagonals. At the end of one diagonal of the visual, there is one effect, and at the other end, there is another. Phasing In most cases, the phasing problem comes from imprecise cutting of the material, as explained below. Nevertheless, poor printing and rectification conditions may also be behind it. In theory, for a given angle of observation, one and the same visual must appear, for the entire batch. As a general rule, the angle of vision is around 45°, and this angle must be in agreement with the sequence provided by the master. If the images have a tendency to double perpendicularly (for 3D) or if the images provided for observation to the left appear to the right (top/bottom), then there is a phasing problem. Cutting defects Defects, in the way the lenticular lens has been cut, can lead to phase errors between the lens and the image. Two examples, taken from the same production batch: First image     Second image The first image shows a cut which removed about 150 µm of the first lens, and which shows irregular cutting of the lenticular lenses. The second image shows a cut which removed about 30 µm of the first lens. Defects in cutting such as these lead to a serious phase problem. In the printing press the image being printed is aligned relative to the edges of the sheet of material. If the sheet is not always cut in the same place relative to the first lenticule, a phase error is introduced between the lenses and the image slices. " (wikipedia.org) "A 3D display is a display device capable of conveying depth to the viewer. Many 3D displays are stereoscopic displays, which produce a basic 3D effect by means of stereopsis, but can cause eye strain and visual fatigue. Newer 3D displays such as holographic and light field displays produce a more realistic 3D effect by combining stereopsis and accurate focal length for the displayed content. Newer 3D displays in this manner cause less visual fatigue than classical stereoscopic displays. As of 2021, the most common type of 3D display is a stereoscopic display, which is the type of display used in almost all virtual reality equipment. 3D displays can be near-eye displays like in VR headsets, or they can be in a device further away from the eyes like a 3D-enabled mobile device or 3D movie theater. The term “3D display” can also be used to refer to a volumetric display which may generate content that can be viewed from all angles. History The first 3D display was created by Sir Charles Wheatstone in 1832.[1] It was a stereoscopic display that had rudimentary ability for representing depth. Stereoscopic displays Main article: Stereoscopy Stereoscopic displays are commonly referred to as “stereo displays,” “stereo 3D displays,” “stereoscopic 3D displays,” or sometimes erroneously as just “3D displays.” The basic technique of stereo displays is to present offset images that are displayed separately to the left and right eye. Both of these 2D offset images are then combined in the brain to give the perception of 3D depth. Although the term "3D" is ubiquitously used, it is important to note that the presentation of dual 2D images is distinctly different from displaying a light field, and is also different from displaying an image in three-dimensional space. The most notable difference to real 3D displays is that the observer's head and eyes movements will not increase information about the 3D objects being displayed. For example, holographic displays do not have such limitations. It is an overstatement of capability to refer to dual 2D images as being "3D". The accurate term "stereoscopic" is more cumbersome than the common misnomer "3D", which has been entrenched after many decades of unquestioned misuse. Although most stereoscopic displays do not qualify as real 3D displays, all real 3D displays are often referred to as also stereoscopic displays because they meet the lower criteria of being stereoscopic as well. Based on the principles of stereopsis, described by Sir Charles Wheatstone in the 1830s, stereoscopic technology provides a different image to the viewer's left and right eyes. The following are some of the technical details and methodologies employed in some of the more notable stereoscopic systems that have been developed. Side-by-side images "The early bird catches the worm" Stereograph published in 1900 by North-Western View Co. of Baraboo, Wisconsin, digitally restored. Traditional stereoscopic photography consists of creating a 3D illusion starting from a pair of 2D images, a stereogram. The easiest way to enhance depth perception in the brain is to provide the eyes of the viewer with two different images, representing two perspectives of the same object, with a minor deviation exactly equal to the perspectives that both eyes naturally receive in binocular vision. If eyestrain and distortion are to be avoided, each of the two 2D images preferably should be presented to each eye of the viewer so that any object at infinite distance seen by the viewer should be perceived by that eye while it is oriented straight ahead, the viewer's eyes being neither crossed nor diverging. When the picture contains no object at infinite distance, such as a horizon or a cloud, the pictures should be spaced correspondingly closer together. The side-by-side method is extremely simple to create, but it can be difficult or uncomfortable to view without optical aids. Stereoscope and stereographic cards Main article: Stereoscope A stereoscope is a device for viewing stereographic cards, which are cards that contain two separate images that are printed side by side to create the illusion of a three-dimensional image. Transparency viewers Main article: Slide viewer § Stereo slide viewer A View-Master Model E of the 1950s Pairs of stereo views printed on a transparent base are viewed by transmitted light. One advantage of transparency viewing is the opportunity for a wider, more realistic dynamic range than is practical with prints on an opaque base; another is that a wider field of view may be presented since the images, being illuminated from the rear, may be placed much closer to the lenses. The practice of viewing film-based stereoscopic transparencies dates to at least as early as 1931, when Tru-Vue began to market sets of stereo views on strips of 35 mm film that were fed through a hand-held Bakelite viewer. In 1939, a modified and miniaturized variation of this technology, employing cardboard disks containing seven pairs of small Kodachrome color film transparencies, was introduced as the View-Master. Head-mounted displays Main articles: Head-mounted display and Virtual retinal display The user typically wears a helmet or glasses with two small LCD or OLED displays with magnifying lenses, one for each eye. The technology can be used to show stereo films, images or games. Head-mounted displays may also be coupled with head-tracking devices, allowing the user to "look around" the virtual world by moving their head, eliminating the need for a separate controller. Owing to rapid advancements in computer graphics and the continuing miniaturization of video and other equipment these devices are beginning to become available at more reasonable cost. Head-mounted or wearable glasses may be used to view a see-through image imposed upon the real world view, creating what is called augmented reality. This is done by reflecting the video images through partially reflective mirrors. The real world can be seen through the partial mirror. A recent development in holographic-waveguide or "waveguide-based optics" allows a stereoscopic images to be superimposed on real world without the uses of bulky reflective mirror.[2][3] Head-mounted projection displays Head-mounted projection displays (HMPD) is similar to head-mounted displays but with images projected to and displayed on a retroreflective screen, The advantage of this technology over head-mounted display is that the focusing and vergence issues didn't require fixing with corrective eye lenses. For image generation, Pico-projectors are used instead of LCD or OLED screens.[4][5] Anaglyph Main article: Anaglyph 3D The archetypal 3D glasses, with modern red and cyan color filters, similar to the red/green and red/blue lenses used to view early anaglyph films. In an anaglyph, the two images are superimposed in an additive light setting through two filters, one red and one cyan. In a subtractive light setting, the two images are printed in the same complementary colors on white paper. Glasses with colored filters in each eye separate the appropriate image by canceling the filter color out and rendering the complementary color black. A compensating technique, commonly known as Anachrome, uses a slightly more transparent cyan filter in the patented glasses associated with the technique. Process reconfigures the typical anaglyph image to have less parallax. An alternative to the usual red and cyan filter system of anaglyph is ColorCode 3-D, a patented anaglyph system which was invented in order to present an anaglyph image in conjunction with the NTSC television standard, in which the red channel is often compromised. ColorCode uses the complementary colors of yellow and dark blue on-screen, and the colors of the glasses' lenses are amber and dark blue. Polarization systems Resembling sunglasses, RealD circular polarized glasses are now the standard for theatrical releases and theme park attractions. Main article: Polarized 3D system To present a stereoscopic picture, two images are projected superimposed onto the same screen through different polarizing filters. The viewer wears eyeglasses which also contain a pair of polarizing filters oriented differently (clockwise/counterclockwise with circular polarization or at 90 degree angles, usually 45 and 135 degrees,[6] with linear polarization). As each filter passes only that light which is similarly polarized and blocks the light polarized differently, each eye sees a different image. This is used to produce a three-dimensional effect by projecting the same scene into both eyes, but depicted from slightly different perspectives. Additionally, since both lenses have the same color, people with one dominant eye, where one eye is used more, are able to see the colors properly, previously negated by the separation of the two colors. Circular polarization has an advantage over linear polarization, in that the viewer does not need to have their head upright and aligned with the screen for the polarization to work properly. With linear polarization, turning the glasses sideways causes the filters to go out of alignment with the screen filters causing the image to fade and for each eye to see the opposite frame more easily. For circular polarization, the polarizing effect works regardless of how the viewer's head is aligned with the screen such as tilted sideways, or even upside down. The left eye will still only see the image intended for it, and vice versa, without fading or crosstalk. Polarized light reflected from an ordinary motion picture screen typically loses most of its polarization. So an expensive silver screen or aluminized screen with negligible polarization loss has to be used. All types of polarization will result in a darkening of the displayed image and poorer contrast compared to non-3D images. Light from lamps is normally emitted as a random collection of polarizations, while a polarization filter only passes a fraction of the light. As a result, the screen image is darker. This darkening can be compensated by increasing the brightness of the projector light source. If the initial polarization filter is inserted between the lamp and the image generation element, the light intensity striking the image element is not any higher than normal without the polarizing filter, and overall image contrast transmitted to the screen is not affected. Eclipse method A pair of LCD shutter glasses used to view XpanD 3D films. The thick frames conceal the electronics and batteries. Main article: Active shutter 3D system With the eclipse method, a shutter blocks light from each appropriate eye when the converse eye's image is projected on the screen. The display alternates between left and right images, and opens and closes the shutters in the glasses or viewer in synchronization with the images on the screen. This was the basis of the Teleview system which was used briefly in 1922.[7][8] A variation on the eclipse method is used in LCD shutter glasses. Glasses containing liquid crystal that will let light through in synchronization with the images on the cinema, television or computer screen, using the concept of alternate-frame sequencing. This is the method used by nVidia, XpanD 3D, and earlier IMAX systems. A drawback of this method is the need for each person viewing to wear expensive, electronic glasses that must be synchronized with the display system using a wireless signal or attached wire. The shutter-glasses are heavier than most polarized glasses, though lighter models are no heavier than some sunglasses or deluxe polarized glasses.[9] However these systems do not require a silver screen for projected images. Liquid crystal light valves work by rotating light between two polarizing filters. Due to these internal polarizers, LCD shutter-glasses darken the display image of any LCD, plasma, or projector image source, which has the result that images appear dimmer and contrast is lower than for normal non-3D viewing. This is not necessarily a usage problem; for some types of displays which are already very bright with poor grayish black levels, LCD shutter glasses may actually improve the image quality. Interference filter technology Main article: Anaglyph 3D § Interference filter systems Dolby 3D uses specific wavelengths of red, green, and blue for the right eye, and different wavelengths of red, green, and blue for the left eye. Eyeglasses which filter out the very specific wavelengths allow the wearer to see a 3D image. This technology eliminates the expensive silver screens required for polarized systems such as RealD, which is the most common 3D display system in theaters. It does, however, require much more expensive glasses than the polarized systems. It is also known as spectral comb filtering or wavelength multiplex visualization The recently introduced Omega 3D/Panavision 3D system also uses this technology, though with a wider spectrum and more "teeth" to the "comb" (5 for each eye in the Omega/Panavision system). The use of more spectral bands per eye eliminates the need to color process the image, required by the Dolby system. Evenly dividing the visible spectrum between the eyes gives the viewer a more relaxed "feel" as the light energy and color balance is nearly 50-50. Like the Dolby system, the Omega system can be used with white or silver screens. But it can be used with either film or digital projectors, unlike the Dolby filters that are only used on a digital system with a color correcting processor provided by Dolby. The Omega/Panavision system also claims that their glasses are cheaper to manufacture than those used by Dolby.[10] In June 2012, the Omega 3D/Panavision 3D system was discontinued by DPVO Theatrical, who marketed it on behalf of Panavision, citing "challenging global economic and 3D market conditions".[citation needed] Although DPVO dissolved its business operations, Omega Optical continues promoting and selling 3D systems to non-theatrical markets. Omega Optical’s 3D system contains projection filters and 3D glasses. In addition to the passive stereoscopic 3D system, Omega Optical has produced enhanced anaglyph 3D glasses. The Omega’s red/cyan anaglyph glasses use complex metal oxide thin film coatings and high quality annealed glass optics. Autostereoscopy Main article: Autostereoscopy The Nintendo 3DS uses parallax barrier autostereoscopy to display a 3D image. In this method, glasses are not necessary to see the stereoscopic image. Lenticular lens and parallax barrier technologies involve imposing two (or more) images on the same sheet, in narrow, alternating strips, and using a screen that either blocks one of the two images' strips (in the case of parallax barriers) or uses equally narrow lenses to bend the strips of image and make it appear to fill the entire image (in the case of lenticular prints). To produce the stereoscopic effect, the person must be positioned so that one eye sees one of the two images and the other sees the other. The optical principles of multiview auto-stereoscopy have been known for over a century.[11] Both images are projected onto a high-gain, corrugated screen which reflects light at acute angles. In order to see the stereoscopic image, the viewer must sit within a very narrow angle that is nearly perpendicular to the screen, limiting the size of the audience. Lenticular was used for theatrical presentation of numerous shorts in Russia from 1940 to 1948[12] and in 1946 for the feature-length film Robinzon Kruzo[13] Though its use in theatrical presentations has been rather limited, lenticular has been widely used for a variety of novelty items and has even been used in amateur 3D photography.[14][15] Recent use includes the Fujifilm FinePix Real 3D with an autostereoscopic display that was released in 2009. Other examples for this technology include autostereoscopic LCD displays on monitors, notebooks, TVs, mobile phones and gaming devices, such as the Nintendo 3DS. Other Main article: Stereoscopy The Pulfrich effect is a psychophysical percept wherein lateral motion of an object in the field of view is interpreted by the visual cortex as having a depth component, due to a relative difference in signal timings between the two eyes. Prismatic glasses make cross-viewing easier as well as over/under-viewing possible, examples include the KMQ viewer. Volumetric display Main article: Volumetric display Volumetric 3D display Volumetric displays use some physical mechanism to display points of light within a volume. Such displays use voxels instead of pixels. Volumetric displays include multiplanar displays, which have multiple display planes stacked up, and rotating panel displays, where a rotating panel sweeps out a volume. Other technologies have been developed to project light dots in the air above a device. An infrared laser is focused on the destination in space, generating a small bubble of plasma which emits visible light. Light field / holographic display A light field display tries to recreate a "light field" on the surface of the display. In contrast to a 2D display which shows a distinct color on each pixel, a light field display shows a distinct color on each pixel for each direction that the light ray emits to. This way, eyes from different positions will see different pictures on the display, creating parallax and thus creating a sense of 3D. A light field display is like a glass window, people see 3D objects behind the glass, despite that all light rays they see come from (through) the glass. The light field in front of the display can be created in two ways: 1) by emitting different light rays in different directions at each point on the display; 2) by recreating a wavefront in front of the display. Displays using the first method are called ray-based or light field displays. Displays using the second method are called wavefront-based or holographic displays. Wavefront-based displays work in the same way as holograms. Compared to ray-based displays, a wavefront-based display not only reconstructs the light field, but also reconstructs the curvature of the plane waves, and the phase differences of the waves in different directions.[16] Integral photography is one of the ray-based methods with full-parallax information. However, there are also ray-based techniques developed with horizontal-parallax-only.[16] Holographic displays Main articles: Holographic display and Computer-generated holography Holographic display is a display technology that has the ability to provide all four eye mechanisms: binocular disparity, motion parallax, accommodation and convergence. The 3D objects can be viewed without wearing any special glasses and no visual fatigue will be caused to human eyes. In 2013, a Silicon valley Company LEIA Inc started manufacturing holographic displays well suited for mobile devices (watches, smartphones or tablets) using a multi-directional backlight and allowing a wide full-parallax angle view to see 3D content without the need of glasses.[17] Their first product was part of a mobile phone (Red Hydrogen One) and later on in their own Android tablet.[citation needed] Integral imaging Main article: Integral imaging Integral imaging is an autostereoscopic or multiscopic 3D display, meaning that it displays a 3D image without the use of special glasses on the part of the viewer. It achieves this by placing an array of microlenses (similar to a lenticular lens) in front of the image, where each lens looks different depending on viewing angle. Thus rather than displaying a 2D image that looks the same from every direction, it reproduces a 3D light field, creating stereo images that exhibit parallax when the viewer moves. Compressive light field displays A new display technology called "compressive light field" is being developed. These prototype displays use layered LCD panels and compression algorithms at the time of display. Designs include dual[18] and multilayer[19][20][21] devices that are driven by algorithms such as computed tomography and Non-negative matrix factorization and non-negative tensor factorization." (wikipedia.org) "In geometry, a three-dimensional space (3D space, 3-space or, rarely, tri-dimensional space) is a mathematical space in which three values (coordinates) are required to determine the position of a point. Most commonly, it is the three-dimensional Euclidean space, the Euclidean n-space of dimension n=3 that models physical space. More general three-dimensional spaces are called 3-manifolds. Technically, a tuple of n numbers can be understood as the Cartesian coordinates of a location in a n-dimensional Euclidean space. The set of these n-tuples is commonly denoted R n , {\displaystyle \mathbb {R} ^{n},} {\displaystyle \mathbb {R} ^{n},} and can be identified to the pair formed by a n-dimensional Euclidean space and a Cartesian coordinate system. When n = 3, this space is called the three-dimensional Euclidean space (or simply "Euclidean space" when the context is clear).[1] It serves as a model of the physical universe (when relativity theory is not considered), in which all known matter exists. While this space remains the most compelling and useful way to model the world as it is experienced,[2] it is only one example of a large variety of spaces in three dimensions called 3-manifolds. In this classical example, when the three values refer to measurements in different directions (coordinates), any three directions can be chosen, provided that vectors in these directions do not all lie in the same 2-space (plane). Furthermore, in this case, these three values can be labeled by any combination of three chosen from the terms width/breadth, height/depth, and length. History Books XI to XIII of Euclid's Elements dealt with three-dimensional geometry. Book XI develops notions of orthogonality and parallelism of lines and planes, and defines solids including parallelpipeds, pyramids, prisms, spheres, octahedra, icosahedra and dodecahedra. Book XII develops notions of similarity of solids. Book XIII describes the construction of the five regular Platonic solids in a sphere. In the 17th century, three-dimensional space was described with Cartesian coordinates, with the advent of analytic geometry developed by René Descartes in his work La Géométrie and Pierre de Fermat in the manuscript Ad locos planos et solidos isagoge (Introduction to Plane and Solid Loci), which was unpublished during Fermat's lifetime. However, only Fermat's work dealt with three-dimensional space. In the 19th century, developments of the geometry of three-dimensional space came with William Rowan Hamilton's development of the quaternions. In fact, it was Hamilton who coined the terms scalar and vector, and they were first defined within his geometric framework for quaternions. Three dimensional space could then be described by quaternions q = a + u i + v j + w k {\displaystyle q=a+ui+vj+wk} {\displaystyle q=a+ui+vj+wk} which had vanishing scalar component, that is, a = 0 {\displaystyle a=0} a=0. While not explicitly studied by Hamilton, this indirectly introduced notions of basis, here given by the quaternion elements i , j , k {\displaystyle i,j,k} i,j,k, as well as the dot product and cross product, which correspond to (the negative of) the scalar part and the vector part of the product of two vector quaternions. It was not until Josiah Willard Gibbs that these two products were identified in their own right, and the modern notation for the dot and cross product were introduced in his classroom teaching notes, found also in the 1901 textbook Vector Analysis written by Edwin Bidwell Wilson based on Gibbs' lectures. Also during the 19th century came developments in the abstract formalism of vector spaces, with the work of Hermann Grassmann and Giuseppe Peano, the latter of whom first gave the modern definition of vector spaces as an algebraic structure." (wikipedia.org) "The National Aeronautics and Space Administration (NASA /ˈnæsə/) is an independent agency of the U.S. federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA), to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science.[5][6][7] NASA has since led most American space exploration, including Project Mercury, Project Gemini, the 1968–1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. NASA supports the International Space Station and oversees the development of the Orion spacecraft and the Space Launch System for the crewed lunar Artemis program, Commercial Crew spacecraft, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown management for uncrewed NASA launches. NASA's science is focused on better understanding Earth through the Earth Observing System;[8] advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program;[9] exploring bodies throughout the Solar System with advanced robotic spacecraft such as New Horizons and planetary rovers such as Perseverance;[10] and researching astrophysics topics, such as the Big Bang, through the James Webb Space Telescope, and the Great Observatories and associated programs.[11] Management Leadership Administrator Bill Nelson (2021–present) The agency's administration is located at NASA Headquarters in Washington, DC, and provides overall guidance and direction.[12] Except under exceptional circumstances, NASA civil service employees are required to be US citizens.[13] NASA's administrator is nominated by the President of the United States subject to the approval of the US Senate,[14] and serves at the President's pleasure as a senior space science advisor. The current administrator is Bill Nelson, appointed by President Joe Biden, since May 3, 2021.[15] Strategic plan NASA operates with four FY2022 strategic goals.[16]     Expand human knowledge through new scientific discoveries     Extend human presence to the Moon and on towards Mars for sustainable long-term exploration, development, and utilization     Catalyze economic growth and drive innovation to address national challenges     Enhance capabilities and operations to catalyze current and future mission success Budget Further information: Budget of NASA NASA budget requests are developed by NASA and approved by the administration prior to submission to the U.S. Congress. Authorized budgets are those that have been included in enacted appropriations bills that are approved by both houses of Congress and enacted into law by the U.S. president.[17] NASA fiscal year budget requests and authorized budgets are provided below. Year     Budget Request in bil. US$     Authorized Budget in bil. US$     U.S. Government Employees 2018     $19.092[18]     $20.736[19]     17,551[20] 2019     $19.892[19]     $21.500[21]     17,551[22] 2020     $22.613[21]     $22.629[23]     18,048[24] 2021     $25.246[23]     $23.271[25]     18,339[26] 2022     $24.802[25]     $24.041[27]     18,400 est Organization NASA funding and priorities are developed through its six Mission Directorates. Mission Directorate     Associate Administrator     % of NASA Budget (FY22)[25] Aeronautics Research (ARMD)     Robert A. Pearce[28]     4% Exploration Systems Development (ESDMD)     James Free[29]     28% Space Operations (SOMD)     Kathy Lueders[29]     17% Science (SMD)     Dr. Nicola Fox[30]     32% Space Technology (STMD)     James L. Reuter[31]     5% Mission Support (MSD)     Robert Gibbs[32]     14% Center-wide activities such as the Chief Engineer and Safety and Mission Assurance organizations are aligned to the headquarters function. The MSD budget estimate includes funds for these HQ functions. The administration operates 10 major field centers with several managing additional subordinate facilities across the country. Each is led by a Center Director (data below valid as of September 1, 2022). Field Center     Primary Location     Center Director Ames Research Center     Mountain View, California     Dr. Eugene L. Tu[33] Armstrong Flight Research Center     Palmdale, California     Brad Flick (acting)[34] Glenn Research Center     Cleveland, Ohio     Dr. James A. Kenyon (acting)[35] Goddard Space Flight Center     Greenbelt, Maryland     Dr. Makenzie Lystrup[36] Jet Propulsion Laboratory     La Canada-Flintridge, California     Laurie Leshin[37] Johnson Space Center     Houston, Texas     Vanessa E. Wyche[38] Kennedy Space Center     Merritt Island, Florida     Janet Petro[39] Langley Research Center     Hampton, Virginia     Clayton Turner[40] Marshall Space Flight Center     Huntsville, Alabama     Jody Singer[41] Stennis Space Center     Hancock County, Mississippi     Richard J. Gilbrech[42] History Establishment of NASA Further information: Creation of NASA, NASA's Space Place, and Science Mission Directorate Short 2018 documentary about NASA produced for its 60th anniversary Beginning in 1946, the National Advisory Committee for Aeronautics (NACA) began experimenting with rocket planes such as the supersonic Bell X-1.[43] In the early 1950s, there was challenge to launch an artificial satellite for the International Geophysical Year (1957–1958). An effort for this was the American Project Vanguard. After the Soviet space program's launch of the world's first artificial satellite (Sputnik 1) on October 4, 1957, the attention of the United States turned toward its own fledgling space efforts. The US Congress, alarmed by the perceived threat to national security and technological leadership (known as the "Sputnik crisis"), urged immediate and swift action; President Dwight D. Eisenhower counseled more deliberate measures. The result was a consensus that the White House forged among key interest groups, including scientists committed to basic research; the Pentagon which had to match the Soviet military achievement; corporate America looking for new business; and a strong new trend in public opinion looking up to space exploration.[44] On January 12, 1958, NACA organized a "Special Committee on Space Technology", headed by Guyford Stever.[7] On January 14, 1958, NACA Director Hugh Dryden published "A National Research Program for Space Technology", stating,[45]     It is of great urgency and importance to our country both from consideration of our prestige as a nation as well as military necessity that this challenge [Sputnik] be met by an energetic program of research and development for the conquest of space ... It is accordingly proposed that the scientific research be the responsibility of a national civilian agency ... NACA is capable, by rapid extension and expansion of its effort, of providing leadership in space technology.[45] While this new federal agency would conduct all non-military space activity, the Advanced Research Projects Agency (ARPA) was created in February 1958 to develop space technology for military application.[46] On July 29, 1958, Eisenhower signed the National Aeronautics and Space Act, establishing NASA.[47] When it began operations on October 1, 1958, NASA absorbed the 43-year-old NACA intact; its 8,000 employees, an annual budget of US$100 million, three major research laboratories (Langley Aeronautical Laboratory, Ames Aeronautical Laboratory, and Lewis Flight Propulsion Laboratory) and two small test facilities.[48] Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA. A significant contributor to NASA's entry into the Space Race with the Soviet Union was the technology from the German rocket program led by Wernher von Braun, who was now working for the Army Ballistic Missile Agency (ABMA), which in turn incorporated the technology of American scientist Robert Goddard's earlier works.[49] Earlier research efforts within the US Air Force[48] and many of ARPA's early space programs were also transferred to NASA.[50] In December 1958, NASA gained control of the Jet Propulsion Laboratory, a contractor facility operated by the California Institute of Technology.[48] Past administrators Further information: Administrator of NASA NASA's first administrator was Dr. T. Keith Glennan who was appointed by President Dwight D. Eisenhower. During his term (1958–1961) he brought together the disparate projects in American space development research.[51] James Webb led the agency during the development of the Apollo program in the 1960s.[52] James C. Fletcher has held the position twice; first during the Nixon administration in the 1970s and then at the request of Ronald Reagan following the Challenger disaster.[53] Daniel Goldin held the post for nearly 10 years and is the longest serving administrator to date. He is best known for pioneering the "faster, better, cheaper" approach to space programs.[54] Bill Nelson is currently serving as the 14th administrator of NASA. Insignia Further information: NASA insignia The NASA seal was approved by Eisenhower in 1959, and slightly modified by President John F. Kennedy in 1961.[55][56] NASA's first logo was designed by the head of Lewis' Research Reports Division, James Modarelli, as a simplification of the 1959 seal.[57] In 1975, the original logo was first dubbed "the meatball" to distinguish it from the newly designed "worm" logo which replaced it. The "meatball" returned to official use in 1992.[57] The "worm" was brought out of retirement by administrator Jim Bridenstine in 2020.[58] Facilities Further information: NASA facilities NASA Headquarters in Washington, DC provides overall guidance and political leadership to the agency's ten field centers, through which all other facilities are administered.[59] Aerial views of the NASA Ames (left) and NASA Armstrong (right) centers Ames Research Center (ARC) at Moffett Field is located in the Silicon Valley of central California and delivers wind-tunnel research on the aerodynamics of propeller-driven aircraft along with research and technology in aeronautics, spaceflight, and information technology.[60] It provides leadership in astrobiology, small satellites, robotic lunar exploration, intelligent/adaptive systems and thermal protection. Armstrong Flight Research Center (AFRC) is located inside Edwards Air Force Base and is the home of the Shuttle Carrier Aircraft (SCA), a modified Boeing 747 designed to carry a Space Shuttle orbiter back to Kennedy Space Center after a landing at Edwards AFB. The center focuses on flight testing of advanced aerospace systems. Glenn Research Center is based in Cleveland, Ohio and focuses on air-breathing and in-space propulsion and cryogenics, communications, power energy storage and conversion, microgravity sciences, and advanced materials.[61] View of GSFC campus (left) and Kraft Mission Control Center at JSC (right) Goddard Space Flight Center (GSFC), located in Greenbelt, Maryland develops and operates uncrewed scientific spacecraft.[62] GSFC also operates two spaceflight tracking and data acquisition networks (the Space Network and the Near Earth Network), develops and maintains advanced space and Earth science data information systems, and develops satellite systems for the National Oceanic and Atmospheric Administration (NOAA).[62] Johnson Space Center (JSC) is the NASA center for human spaceflight training, research and flight control.[63] It is home to the United States Astronaut Corps and is responsible for training astronauts from the US and its international partners, and includes the Christopher C. Kraft Jr. Mission Control Center.[64] JSC also operates the White Sands Test Facility in Las Cruces, New Mexico to support rocket testing. View of JPL (left) and the Langley Research Center (right) Jet Propulsion Laboratory (JPL), located in the San Gabriel Valley area of Los Angeles County, C and builds and operates robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions.[65] It is also responsible for operating NASA's Deep Space Network (DSN). Langley Research Center (LaRC), located in Hampton, Virginia devotes two-thirds of its programs to aeronautics, and the rest to space. LaRC researchers use more than 40 wind tunnels to study improved aircraft and spacecraft safety, performance, and efficiency. The center was also home to early human spaceflight efforts including the team chronicled in the Hidden Figures story.[66] Aerial view of Kennedy Space Center showing VAB and Launch Complex 39 View of the SLS exiting the VAB at KSC (left) and of the MSFC test stands (right) Kennedy Space Center (KSC), located west of Cape Canaveral Space Force Station in Florida, has been the launch site for every United States human space flight since 1968. KSC also manages and operates uncrewed rocket launch facilities for America's civil space program from three pads at Cape Canaveral.[67] Marshall Space Flight Center (MSFC), located on the Redstone Arsenal near Huntsville, Alabama, is one of NASA's largest centers and is leading the development of the Space Launch System in support of the Artemis program. Marshall is NASA's lead center for International Space Station (ISS) design and assembly; payloads and related crew training; and was the lead for Space Shuttle propulsion and its external tank.[68] Stennis Space Center, originally the "Mississippi Test Facility", is located in Hancock County, Mississippi, on the banks of the Pearl River at the Mississippi–Louisiana border.[69] Commissioned in October 1961, it is currently used for rocket testing by over 30 local, state, national, international, private, and public companies and agencies.[70][71] It also contains the NASA Shared Services Center.[72] Past human spaceflight programs X-15 (1954–1968) Further information: North American X-15 X-15 in powered flight NASA inherited NACA's X-15 experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force and Navy. Three planes were built starting in 1955. The X-15 was drop-launched from the wing of one of two NASA Boeing B-52 Stratofortresses, NB52A tail number 52-003, and NB52B, tail number 52-008 (known as the Balls 8). Release took place at an altitude of about 45,000 feet (14 km) and a speed of about 500 miles per hour (805 km/h).[73] Twelve pilots were selected for the program from the Air Force, Navy, and NACA. A total of 199 flights were made between June 1959 and December 1968, resulting in the official world record for the highest speed ever reached by a crewed powered aircraft (current as of 2014), and a maximum speed of Mach 6.72, 4,519 miles per hour (7,273 km/h).[74] The altitude record for X-15 was 354,200 feet (107.96 km).[75] Eight of the pilots were awarded Air Force astronaut wings for flying above 260,000 feet (80 km), and two flights by Joseph A. Walker exceeded 100 kilometers (330,000 ft), qualifying as spaceflight according to the International Aeronautical Federation. The X-15 program employed mechanical techniques used in the later crewed spaceflight programs, including reaction control system jets for controlling the orientation of a spacecraft, space suits, and horizon definition for navigation.[75] The reentry and landing data collected were valuable to NASA for designing the Space Shuttle.[76] Mercury (1958–1963) Further information: Project Mercury Mercury-patch-g.png L. Gordon Cooper, photographed by a slow-scan television camera aboard Faith 7 (May 16, 1963) In 1958, NASA formed an engineering group, the Space Task Group, to manage their human spaceflight programs under the direction of Robert Gilruth. Their earliest programs were conducted under the pressure of the Cold War competition between the US and the Soviet Union. NASA inherited the US Air Force's Man in Space Soonest program, which considered many crewed spacecraft designs ranging from rocket planes like the X-15, to small ballistic space capsules.[77] By 1958, the space plane concepts were eliminated in favor of the ballistic capsule,[78] and NASA renamed it Project Mercury. The first seven astronauts were selected among candidates from the Navy, Air Force and Marine test pilot programs. On May 5, 1961, astronaut Alan Shepard became the first American in space aboard a capsule he named Freedom 7, launched on a Redstone booster on a 15-minute ballistic (suborbital) flight.[79] John Glenn became the first American to be launched into orbit, on an Atlas launch vehicle on February 20, 1962, aboard Friendship 7.[80] Glenn completed three orbits, after which three more orbital flights were made, culminating in L. Gordon Cooper's 22-orbit flight Faith 7, May 15–16, 1963.[81] Katherine Johnson, Mary Jackson, and Dorothy Vaughan were three of the human computers doing calculations on trajectories during the Space Race.[82][83][84] Johnson was well known for doing trajectory calculations for John Glenn's mission in 1962, where she was running the same equations by hand that were being run on the computer.[82] Mercury's competition from the Soviet Union (USSR) was the single-pilot Vostok spacecraft. They sent the first man in space, cosmonaut Yuri Gagarin, into a single Earth orbit aboard Vostok 1 in April 1961, one month before Shepard's flight.[85] In August 1962, they achieved an almost four-day record flight with Andriyan Nikolayev aboard Vostok 3, and also conducted a concurrent Vostok 4 mission carrying Pavel Popovich.[86] Gemini (1961–1966) Further information: Project Gemini GeminiPatch.png Richard Gordon performs a spacewalk to attach a tether to the Agena Target Vehicle on Gemini 11, 1966. Based on studies to grow the Mercury spacecraft capabilities to long-duration flights, developing space rendezvous techniques, and precision Earth landing, Project Gemini was started as a two-man program in 1961 to overcome the Soviets' lead and to support the planned Apollo crewed lunar landing program, adding extravehicular activity (EVA) and rendezvous and docking to its objectives. The first crewed Gemini flight, Gemini 3, was flown by Gus Grissom and John Young on March 23, 1965.[87] Nine missions followed in 1965 and 1966, demonstrating an endurance mission of nearly fourteen days, rendezvous, docking, and practical EVA, and gathering medical data on the effects of weightlessness on humans.[88][89] Under the direction of Soviet Premier Nikita Khrushchev, the USSR competed with Gemini by converting their Vostok spacecraft into a two- or three-man Voskhod. They succeeded in launching two crewed flights before Gemini's first flight, achieving a three-cosmonaut flight in 1964 and the first EVA in 1965.[90] After this, the program was canceled, and Gemini caught up while spacecraft designer Sergei Korolev developed the Soyuz spacecraft, their answer to Apollo. Apollo (1960–1972) Further information: Apollo program Apollo program.svg Buzz Aldrin on the Moon, 1969 (photograph by Neil Armstrong) The U.S. public's perception of the Soviet lead in the Space Race (by putting the first man into space) motivated President John F. Kennedy[91] to ask the Congress on May 25, 1961, to commit the federal government to a program to land a man on the Moon by the end of the 1960s, which effectively launched the Apollo program.[92] Apollo was one of the most expensive American scientific programs ever. It cost more than $20 billion in 1960s dollars[93] or an estimated $236 billion in present-day US dollars.[94] (In comparison, the Manhattan Project cost roughly $30.1 billion, accounting for inflation.)[94][95] The Apollo program used the newly developed Saturn I and Saturn V rockets, which were far larger than the repurposed ICBMs of the previous Mercury and Gemini programs.[96] They were used to launch the Apollo spacecraft, consisting of the Command and Service Module (CSM) and the Lunar Module (LM). The CSM ferried astronauts from Earth to Moon orbit and back, while the Lunar Module would land them on the Moon itself.[note 1] The planned first crew of 3 astronauts were killed due to a fire during a 1967 preflight test for the Apollo 204 mission (later renamed Apollo 1).[97] The second crewed mission, Apollo 8, brought astronauts for the first time in a flight around the Moon in December 1968.[98] Shortly before, the Soviets had sent an uncrewed spacecraft around the Moon.[99] The next two missions (Apollo 9 and Apollo 10) practiced rendezvous and docking maneuvers required to conduct the Moon landing.[100][101] The Apollo 11 mission, launched in July 1969, landed the first humans on the Moon. Astronauts Neil Armstrong and Buzz Aldrin walked on the lunar surface, conducting experiments and sample collection, while Michael Collins orbited above in the CSM.[102] Six subsequent Apollo missions (12 through 17) were launched; five of them were successful, while one (Apollo 13) was aborted after an in-flight emergency nearly killed the astronauts. Throughout these seven Apollo spaceflights, twelve men walked on the Moon. These missions returned a wealth of scientific data and 381.7 kilograms (842 lb) of lunar samples. Topics covered by experiments performed included soil mechanics, meteoroids, seismology, heat flow, lunar ranging, magnetic fields, and solar wind.[103] The Moon landing marked the end of the space race; and as a gesture, Armstrong mentioned mankind when he stepped down on the Moon.[104] On July 3, 1969, the Soviets suffered a major setback on their Moon program when the rocket known as the N-1 had exploded in a fireball at its launch site at Baikonur in Kazakhstan, destroying one of two launch pads. Each of the first four launches of N-1 resulted in failure before the end of the first stage flight effectively denying the Soviet Union the capacity to deliver the systems required for a crewed lunar landing.[105] Apollo set major milestones in human spaceflight. It stands alone in sending crewed missions beyond low Earth orbit, and landing humans on another celestial body.[106] Apollo 8 was the first crewed spacecraft to orbit another celestial body, while Apollo 17 marked the last moonwalk and the last crewed mission beyond low Earth orbit. The program spurred advances in many areas of technology peripheral to rocketry and crewed spaceflight, including avionics, telecommunications, and computers. Apollo sparked interest in many fields of engineering and left many physical facilities and machines developed for the program as landmarks. Many objects and artifacts from the program are on display at various locations throughout the world, notably at the Smithsonian's Air and Space Museums. Skylab (1965–1979) Further information: Skylab Skylab Program Patch.png Skylab in 1974, seen from the departing Skylab 4 CSM Skylab was the United States' first and only independently built space station.[107] Conceived in 1965 as a workshop to be constructed in space from a spent Saturn IB upper stage, the 169,950 lb (77,088 kg) station was constructed on Earth and launched on May 14, 1973, atop the first two stages of a Saturn V, into a 235-nautical-mile (435 km) orbit inclined at 50° to the equator. Damaged during launch by the loss of its thermal protection and one electricity-generating solar panel, it was repaired to functionality by its first crew. It was occupied for a total of 171 days by 3 successive crews in 1973 and 1974.[107] It included a laboratory for studying the effects of microgravity, and a solar observatory.[107] NASA planned to have the in-development Space Shuttle dock with it, and elevate Skylab to a higher safe altitude, but the Shuttle was not ready for flight before Skylab's re-entry and demise on July 11, 1979.[108] To reduce cost, NASA modified one of the Saturn V rockets originally earmarked for a canceled Apollo mission to launch Skylab, which itself was a modified Saturn V fuel tank. Apollo spacecraft, launched on smaller Saturn IB rockets, were used for transporting astronauts to and from the station. Three crews, consisting of three men each, stayed aboard the station for periods of 28, 59, and 84 days. Skylab's habitable volume was 11,290 cubic feet (320 m3), which was 30.7 times bigger than that of the Apollo Command Module.[108] Space Transportation System (1969–1972) Further information: Space Transportation System In February 1969, President Richard Nixon appointed a space task group headed by Vice President Spiro Agnew to recommend human spaceflight projects beyond Apollo. The group responded in September with the Integrated Program Plan (IPP), intended to support space stations in Earth and lunar orbit, a lunar surface base, and a human Mars landing. These would be supported by replacing NASA's existing expendable launch systems with a reusable infrastructure including Earth orbit shuttles, space tugs, and a nuclear-powered trans-lunar and interplanetary shuttle. Despite the enthusiastic support of Agnew and NASA Administrator Thomas O. Paine, Nixon realized public enthusiasm, which translated into Congressional support, for the space program was waning as Apollo neared its climax, and vetoed most of these plans, except for the Earth orbital shuttle, and a deferred Earth space station.[109] Apollo–Soyuz (1972–1975) Further information: Apollo–Soyuz ASTP patch.png Soviet and American crews with spacecraft model, 1975 On May 24, 1972, US President Richard M. Nixon and Soviet Premier Alexei Kosygin signed an agreement calling for a joint crewed space mission, and declaring intent for all future international crewed spacecraft to be capable of docking with each other.[110] This authorized the Apollo–Soyuz Test Project (ASTP), involving the rendezvous and docking in Earth orbit of a surplus Apollo command and service module with a Soyuz spacecraft. The mission took place in July 1975. This was the last US human spaceflight until the first orbital flight of the Space Shuttle in April 1981.[111] The mission included both joint and separate scientific experiments and provided useful engineering experience for future joint US–Russian space flights, such as the Shuttle–Mir program[112] and the International Space Station. Space Shuttle (1972–2011) Further information: Space Shuttle program Shuttle Patch.svg Launch of Space Shuttle Discovery at the start of STS-120 The Space Shuttle was the only vehicle in the Space Transportation System to be developed, and became the major focus of NASA in the late 1970s and the 1980s. Originally planned as a frequently launchable, fully reusable vehicle, the design was changed to use an expendable external propellant tank to reduce development cost, and four Space Shuttle orbiters were built by 1985. The first to launch, Columbia, did so on April 12, 1981, the 20th anniversary of the first human spaceflight.[113] The Shuttle flew 135 missions and carried 355 astronauts from 16 countries, many on multiple trips. Its major components were a spaceplane orbiter with an external fuel tank and two solid-fuel launch rockets at its side. The external tank, which was bigger than the spacecraft itself, was the only major component that was not reused. The shuttle could orbit in altitudes of 185–643 km (115–400 miles)[114] and carry a maximum payload (to low orbit) of 24,400 kg (54,000 lb).[115] Missions could last from 5 to 17 days and crews could be from 2 to 8 astronauts.[114] On 20 missions (1983–1998) the Space Shuttle carried Spacelab, designed in cooperation with the European Space Agency (ESA). Spacelab was not designed for independent orbital flight, but remained in the Shuttle's cargo bay as the astronauts entered and left it through an airlock.[116] On June 18, 1983, Sally Ride became the first American woman in space, on board the Space Shuttle Challenger STS-7 mission.[117] Another famous series of missions were the launch and later successful repair of the Hubble Space Telescope in 1990 and 1993, respectively.[118] In 1995, Russian-American interaction resumed with the Shuttle–Mir missions (1995–1998). Once more an American vehicle docked with a Russian craft, this time a full-fledged space station. This cooperation has continued with Russia and the United States as two of the biggest partners in the largest space station built: the International Space Station (ISS).[119] The strength of their cooperation on this project was even more evident when NASA began relying on Russian launch vehicles to service the ISS during the two-year grounding of the shuttle fleet following the 2003 Space Shuttle Columbia disaster. The Shuttle fleet lost two orbiters and 14 astronauts in two disasters: Challenger in 1986, and Columbia in 2003.[120] While the 1986 loss was mitigated by building the Space Shuttle Endeavour from replacement parts, NASA did not build another orbiter to replace the second loss.[120] NASA's Space Shuttle program had 135 missions when the program ended with the successful landing of the Space Shuttle Atlantis at the Kennedy Space Center on July 21, 2011. The program spanned 30 years with 355 separate astronauts sent into space, many on multiple missions.[121] Constellation (2005–2010) Further information: Constellation program Constellation logo white.svg Artist's rendering of Altair lander on the Moon While the Space Shuttle program was still suspended after the loss of Columbia, President George W. Bush announced the Vision for Space Exploration including the retirement of the Space Shuttle after completing the International Space Station. The plan was enacted into law by the NASA Authorization Act of 2005 and directs NASA to develop and launch the Crew Exploration Vehicle (later called Orion) by 2010, return Americans to the Moon by 2020, land on Mars as feasible, repair the Hubble Space Telescope, and continue scientific investigation through robotic solar system exploration, human presence on the ISS, Earth observation, and astrophysics research. The crewed exploration goals prompted NASA's Constellation program.[122] On December 4, 2006, NASA announced it was planning a permanent Moon base.[123] The goal was to start building the Moon base by 2020, and by 2024, have a fully functional base that would allow for crew rotations and in-situ resource utilization. However, in 2009, the Augustine Committee found the program to be on an "unsustainable trajectory."[124] In February 2010, President Barack Obama's administration proposed eliminating public funds for it.[125] Journey to Mars (2010–2017) An artist's conception, from NASA, of an astronaut planting a US flag on Mars. A human mission to Mars has been discussed as a possible NASA mission since the 1960s. Concepts for how the first human landing site on Mars might evolve over the course of multiple human expeditions President Obama's plan was to develop American private spaceflight capabilities to get astronauts to the International Space Station, replace Russian Soyuz capsules, and use Orion capsules for ISS emergency escape purposes. During a speech at the Kennedy Space Center on April 15, 2010, Obama proposed a new heavy-lift vehicle (HLV) to replace the formerly planned Ares V.[126] In his speech, Obama called for a crewed mission to an asteroid as soon as 2025, and a crewed mission to Mars orbit by the mid-2030s.[126] The NASA Authorization Act of 2010 was passed by Congress and signed into law on October 11, 2010.[127] The act officially canceled the Constellation program.[127] The NASA Authorization Act of 2010 required a newly designed HLV be chosen within 90 days of its passing; the launch vehicle was given the name Space Launch System. The new law also required the construction of a beyond low earth orbit spacecraft.[128] The Orion spacecraft, which was being developed as part of the Constellation program, was chosen to fulfill this role.[129] The Space Launch System is planned to launch both Orion and other necessary hardware for missions beyond low Earth orbit.[130] The SLS is to be upgraded over time with more powerful versions. The initial capability of SLS is required to be able to lift 70 t (150,000 lb) (later 95 t or 209,000 lb) into LEO. It is then planned to be upgraded to 105 t (231,000 lb) and then eventually to 130 t (290,000 lb).[129][131] The Orion capsule first flew on Exploration Flight Test 1 (EFT-1), an uncrewed test flight that was launched on December 5, 2014, atop a Delta IV Heavy rocket.[131] NASA undertook a feasibility study in 2012 and developed the Asteroid Redirect Mission as an uncrewed mission to move a boulder-sized near-Earth asteroid (or boulder-sized chunk of a larger asteroid) into lunar orbit. The mission would demonstrate ion thruster technology and develop techniques that could be used for planetary defense against an asteroid collision, as well as a cargo transport to Mars in support of a future human mission. The Moon-orbiting boulder might then later be visited by astronauts. The Asteroid Redirect Mission was cancelled in 2017 as part of the FY2018 NASA budget, the first one under President Donald Trump.[132] Past robotic exploration programs Further information: List of uncrewed NASA missions NASA has conducted many uncrewed and robotic spaceflight programs throughout its history. Uncrewed robotic programs launched the first American artificial satellites into Earth orbit for scientific and communications purposes and sent scientific probes to explore the planets of the Solar System, starting with Venus and Mars, and including "grand tours" of the outer planets. More than 1,000 uncrewed missions have been designed to explore the Earth and the Solar System.[133] Early efforts The first US uncrewed satellite was Explorer 1, which started as an ABMA/JPL project during the early part of the Space Race. It was launched in January 1958, two months after Sputnik. At the creation of NASA, the Explorer project was transferred to the agency and still continues. Its missions have been focusing on the Earth and the Sun, measuring magnetic fields and the solar wind, among other aspects.[134] The Ranger missions developed technology to build and deliver robotic probes into orbit and to the vicinity of the Moon. Ranger 7 successfully returned images of the Moon in July 1964, followed by two more successful missions.[135] NASA also played a role in the development and delivery of early communications satellite technology to orbit. Syncom 3 was the first geostationary satellite. It was an experimental geosynchronous communications satellite placed over the equator at 180 degrees longitude in the Pacific Ocean. The satellite provided live television coverage of the 1964 Olympic games in Tokyo, Japan and conducted various communications tests. Operations were turned over to the Department of Defense on January 1, 1965; Syncom 3 was to prove useful in the DoD's Vietnam communications.[136] Programs like Syncom, Telstar, and Applications Technology Satellites (ATS) demonstrated the utility of communications satellites and delivered early telephonic and video satellite transmission.[137] Planetary exploration William H. Pickering, (center) JPL Director, President John F. Kennedy, (right). NASA Administrator James E. Webb (background) discussing the Mariner program, with a model presented. Study of Mercury, Venus, or Mars has been the goal of more than ten uncrewed NASA programs. The first was Mariner in the 1960s and 1970s, which made multiple visits to Venus and Mars and one to Mercury. Probes launched under the Mariner program were also the first to make a planetary flyby (Mariner 2), to take the first pictures from another planet (Mariner 4), the first planetary orbiter (Mariner 9), and the first to make a gravity assist maneuver (Mariner 10). This is a technique where the satellite takes advantage of the gravity and velocity of planets to reach its destination.[138] Magellan orbited Venus for four years in the early 1990s capturing radar images of the planet's surface.[139] MESSENGER orbited Mercury between 2011 and 2015 after a 6.5-year journey involving a complicated series of flybys of Venus and Mercury to reduce velocity sufficiently enough to enter Mercury orbit. MESSENGER became the first spacecraft to orbit Mercury and used its science payload to study Mercury's surface composition, geological history, internal magnetic field, and verified its polar deposits were dominantly water-ice.[140] From 1966 to 1968, the Lunar Orbiter and Surveyor missions provided higher quality photographs and other measurements to pave the way for the crewed Apollo missions to the Moon.[141] Clementine spent a couple of months mapping the Moon in 1994 before moving on to other mission objectives.[142] Lunar Prospector spent 19 months from 1998 mapping the Moon's surface composition and looking for polar ice.[143] The first successful landing on Mars was made by Viking 1 in 1976. Viking 2 followed two months later. Twenty years later the Sojourner rover was landed on Mars by Mars Pathfinder.[144] After Mars, Jupiter was first visited by Pioneer 10 in 1973. More than 20 years later Galileo sent a probe into the planet's atmosphere and became the first spacecraft to orbit the planet.[145] Pioneer 11 became the first spacecraft to visit Saturn in 1979, with Voyager 2 making the first (and so far, only) visits to Uranus and Neptune in 1986 and 1989, respectively. The first spacecraft to leave the Solar System was Pioneer 10 in 1983. For a time, it was the most distant spacecraft, but it has since been surpassed by both Voyager 1 and Voyager 2.[146] Pioneers 10 and 11 and both Voyager probes carry messages from the Earth to extraterrestrial life.[147][148] Communication can be difficult with deep space travel. For instance, it took about three hours for a radio signal to reach the New Horizons spacecraft when it was more than halfway to Pluto.[149] Contact with Pioneer 10 was lost in 2003. Both Voyager probes continue to operate as they explore the outer boundary between the Solar System and interstellar space.[150] NASA continued to support in situ exploration beyond the asteroid belt, including Pioneer and Voyager traverses into the unexplored trans-Pluto region, and gas giant orbiters Galileo (1989–2003) and Cassini (1997–2017) exploring the Jovian and Saturnian systems respectively. Heliophysics The missions below represent the robotic spacecraft that have been delivered and operated by NASA to study the heliosphere. The Helios A and Helios B missions were launched in the 1970s to study the Sun and were the first spacecraft to orbit inside of Mercury's orbit.[151] The Fast Auroral Snapshot Explorer (FAST) mission was launched in August 1996 becoming the second SMEX mission placed in orbit. It studied the auroral zones near each pole during its transits in a highly elliptical orbit.[152] The International Earth-Sun Explorer-3 (ISEE-3) mission was launched in 1978 and is the first spacecraft designed to operate at the Earth-Sun L1 libration point. It studied solar-terrestrial relationships at the outermost boundaries of the Earth's magnetosphere and the structure of the solar wind. The spacecraft was subsequently maneuvered out of the halo orbit and conducted a flyby of the Giacobini-Zinner comet in 1985 as the rechristened International Cometary Explorer (ICE).[153] Ulysses was launched in 1990 and slingshotted around Jupiter to put it in an orbit to travel over the poles of the Sun. It was designed study the space environment above and below the poles and delivered scientific data for about 19 years.[154] Additional spacecraft launched for studies of the heliosphere include: Cluster II, IMAGE, POLAR, Reuven Ramaty High Energy Solar Spectroscopic Imager, and the Van Allen Probes. Earth Science The Earth Sciences Division of the NASA Science Mission Directorate leads efforts to study the planet Earth. Spacecraft have been used to study Earth since the mid-1960s. Efforts included the Television Infrared Observation Satellite (TIROS) and Nimbus satellite systems of which there were many carrying weather research and forecasting from space from 1960 into the 2020s. Artist rendering of ICESat in orbit, 2003 The Combined Release and Radiation Effects Satellite (CRRES) was launched in 1990 on a three-year mission to investigate fields, plasmas, and energetic particles inside the Earth's magnetosphere.[155] The Upper Atmosphere Research Satellite (UARS) was launched in 1991 by STS-48 to study the Earth's atmosphere especially the protective ozone layer.[156] TOPEX/Poseidon was launched in 1992 and was the first significant oceanographic research satellite.[157] The Ice, Cloud, and land Elevation Satellite (ICESat) was launched in 2003, operated for seven years, and measured ice sheet mass balance, cloud and aerosol heights, and well as topography and vegetation characteristics.[158] Over a dozen past robotic missions have focused on the study of the Earth and its environment. Some of these additional missions include Aquarius, Earth Observing-1 (EO-1), Jason-1, Ocean Surface Topography Mission/Jason-2, and Radarsat-1 missions. Active programs Human spaceflight International Space Station (1993–present) Further information: International Space Station ISS emblem.png The International Space Station as seen from Space Shuttle Endeavour during STS-134 The International Space Station (ISS) combines NASA's Space Station Freedom project with the Soviet/Russian Mir-2 station, the European Columbus station, and the Japanese Kibō laboratory module.[159] NASA originally planned in the 1980s to develop Freedom alone, but US budget constraints led to the merger of these projects into a single multi-national program in 1993, managed by NASA, the Russian Federal Space Agency (RKA), the Japan Aerospace Exploration Agency (JAXA), the European Space Agency (ESA), and the Canadian Space Agency (CSA).[160][161] The station consists of pressurized modules, external trusses, solar arrays and other components, which were manufactured in various factories around the world, and have been launched by Russian Proton and Soyuz rockets, and the US Space Shuttles.[159] The on-orbit assembly began in 1998, the completion of the US Orbital Segment occurred in 2009 and the completion of the Russian Orbital Segment occurred in 2010, though there are some debates of whether new modules should be added in the segment. The ownership and use of the space station is established in intergovernmental treaties and agreements[162] which divide the station into two areas and allow Russia to retain full ownership of the Russian Orbital Segment (with the exception of Zarya),[163][164] with the US Orbital Segment allocated between the other international partners.[162] Long-duration missions to the ISS are referred to as ISS Expeditions. Expedition crew members typically spend approximately six months on the ISS.[165] The initial expedition crew size was three, temporarily decreased to two following the Columbia disaster. Since May 2009, expedition crew size has been six crew members.[166] Crew size is expected to be increased to seven, the number the ISS was designed for, once the Commercial Crew Program becomes operational.[167] The ISS has been continuously occupied for the past 22 years and 173 days, having exceeded the previous record held by Mir; and has been visited by astronauts and cosmonauts from 15 different nations.[168][169] The station can be seen from the Earth with the naked eye and, as of 2023, is the largest artificial satellite in Earth orbit with a mass and volume greater than that of any previous space station.[170] The Russian Soyuz and American Dragon spacecraft are used to send astronauts to and from the ISS. Several uncrewed cargo spacecraft provide service to the ISS; they are the Russian Progress spacecraft which has done so since 2000, the European Automated Transfer Vehicle (ATV) since 2008, the Japanese H-II Transfer Vehicle (HTV) since 2009, the (uncrewed) Dragon since 2012, and the American Cygnus spacecraft since 2013.[171][172] The Space Shuttle, before its retirement, was also used for cargo transfer and would often switch out expedition crew members, although it did not have the capability to remain docked for the duration of their stay. Between the retirement of the Shuttle in 2011 and the commencement of crewed Dragon flights in 2020, American astronauts exclusively used the Soyuz for crew transport to and from the ISS[173] The highest number of people occupying the ISS has been thirteen; this occurred three times during the late Shuttle ISS assembly missions.[174] The ISS program is expected to continue to 2030,[175] after which the space station will be retired and destroyed in a controlled de-orbit.[176] Commercial Resupply Services (2008–present) Further information: Commercial Resupply Services Dragon Cygnus Commercial Resupply Services missions approaching International Space Station Commercial Resupply Services (CRS) are a contract solution to deliver cargo and supplies to the International Space Station (ISS) on a commmercial basis.[177] NASA signed its first CRS contracts in 2008 and awarded $1.6 billion to SpaceX for twelve cargo Dragon and $1.9 billion to Orbital Sciences[note 2] for eight Cygnus flights, covering deliveries to 2016. Both companies evolved or created their launch vehicle products to support the solution (SpaceX with The Falcon 9 and Orbital with the Antares). SpaceX flew its first operational resupply mission (SpaceX CRS-1) in 2012.[178] Orbital Sciences followed in 2014 (Cygnus CRS Orb-1).[179] In 2015, NASA extended CRS-1 to twenty flights for SpaceX and twelve flights for Orbital ATK.[note 2][180][181] A second phase of contracts (known as CRS-2) was solicited in 2014; contracts were awarded in January 2016 to Orbital ATK[note 2] Cygnus, Sierra Nevada Corporation Dream Chaser, and SpaceX Dragon 2, for cargo transport flights beginning in 2019 and expected to last through 2024. In March 2022, NASA awarded an additional six CRS-2 missions each to both SpaceX and Northrop Grumman (formerly Orbital).[182] Northrop Grumman successfully delivered Cygnus NG-17 to the ISS in February 2022.[183] In July 2022, SpaceX launched its 25th CRS flight (SpaceX CRS-25) and successfully delivered its cargo to the ISS.[184] In late 2022, Sierra Nevada continued to assemble their Dream Chaser CRS solution; current estimates put its first launch in early 2023.[185] Commercial Crew Program (2011–present) Further information: Commercial Crew Program NASA Commercial Crew Program logo (cropped).svg The Crew Dragon (left) and Starliner (right) approaching the ISS on their respective missions The Commercial Crew Program (CCP) provides commercially operated crew transportation service to and from the International Space Station (ISS) under contract to NASA, conducting crew rotations between the expeditions of the International Space Station program. American space manufacturer SpaceX began providing service in 2020, using the Crew Dragon spacecraft, and NASA plans to add Boeing when its Boeing Starliner spacecraft becomes operational some time after 2022[needs update].[186] NASA has contracted for six operational missions from Boeing and fourteen from SpaceX, ensuring sufficient support for ISS through 2030.[187] The spacecraft are owned and operated by the vendor, and crew transportation is provided to NASA as a commercial service. Each mission sends up to four astronauts to the ISS, with an option for a fifth passenger available. Operational flights occur approximately once every six months for missions that last for approximately six months. A spacecraft remains docked to the ISS during its mission, and missions usually overlap by at least a few days. Between the retirement of the Space Shuttle in 2011 and the first operational CCP mission in 2020, NASA relied on the Soyuz program to transport its astronauts to the ISS. A Crew Dragon spacecraft is launched to space atop a Falcon 9 Block 5 launch vehicle and the capsule returns to Earth via splashdown in the ocean near Florida. The program's first operational mission, SpaceX Crew-1, launched on 16 November 2020.[188] Boeing Starliner operational flights will now commence after its final test flight which was launched atop an Atlas V N22 launch vehicle. Instead of a splashdown, a Starliner capsule returns on land with airbags at one of four designated sites in the western United States.[189] Artemis (2017–present) Further information: Artemis program An arrowhead combined with a depiction of a trans-lunar injection trajectory forms an "A", with an "Artemis" wordmark printed underneath SLS with Orion rolling to Launch Complex 39B for tests, Mar 2022 Since 2017, NASA's crewed spaceflight program has been the Artemis program, which involves the help of US commercial spaceflight companies and international partners such as ESA, JAXA, and CSA.[190] The goal of this program is to land "the first woman and the next man" on the lunar south pole region by 2024. Artemis would be the first step towards the long-term goal of establishing a sustainable presence on the Moon, laying the foundation for companies to build a lunar economy, and eventually sending humans to Mars. The Orion Crew Exploration Vehicle was held over from the canceled Constellation program for Artemis. Artemis 1 was the uncrewed initial launch of Space Launch System (SLS) that would also send an Orion spacecraft on a Distant Retrograde Orbit.[191] NASA's next major space initiative is to be the construction of the Lunar Gateway, a small space station in lunar orbit.[192] This space station will be designed primarily for non-continuous human habitation. The first tentative steps of returning to crewed lunar missions will be Artemis 2, which is to include the Orion crew module, propelled by the SLS, and is to launch in 2024.[190] This mission is to be a 10-day mission planned to briefly place a crew of four into a Lunar flyby.[131] The construction of the Gateway would begin with the proposed Artemis 3, which is planned to deliver a crew of four to Lunar orbit along with the first modules of the Gateway. This mission would last for up to 30 days. NASA plans to build full scale deep space habitats such as the Lunar Gateway and the Nautilus-X as part of its Next Space Technologies for Exploration Partnerships (NextSTEP) program.[193] In 2017, NASA was directed by the congressional NASA Transition Authorization Act of 2017 to get humans to Mars-orbit (or to the Martian surface) by the 2030s.[194][195] In support of the Artemis missions, NASA has been funding private companies to land robotic probes on the lunar surface in a program known as the Commercial Lunar Payload Services. As of March 2022, NASA has awarded contracts for robotic lunar probes to companies such as Intuitive Machines, Firefly Space Systems, and Astrobotic.[196] On April 16, 2021, NASA announced they had selected the SpaceX Lunar Starship as its Human Landing System. The agency's Space Launch System rocket will launch four astronauts aboard the Orion spacecraft for their multi-day journey to lunar orbit where they will transfer to SpaceX's Starship for the final leg of their journey to the surface of the Moon.[197] In November 2021, it was announced that the goal of landing astronauts on the Moon by 2024 had slipped to no earlier than 2025 due to numerous factors. Artemis 1 launched on November 16, 2022 and returned to Earth safely on December 11, 2022. As of June 2022, NASA plans to launch Artemis 2 in May 2024 and Artemis 3 in December 2025.[198][199] Additional Artemis missions, Artemis 4 and Artemis 5, are planned to launch after 2025.[200] Commercial LEO Development (2021–present) The Commercial Low Earth Orbit Destinations program is an initiative by NASA to support work on commercial space stations that the agency hopes to have in place by the end of the current decade to replace the "International Space Station". The three selected companies are: Blue Origin (et al.) with their Orbital Reef station concept, Nanoracks (et al.) with their Starlab Space Station concept, and Northrop Grumman with a station concept based on the HALO-module for the Gateway station.[201] Robotic exploration Further information: List of NASA missions and List of uncrewed NASA missions Video of many of the uncrewed missions used to explore the outer reaches of space NASA has conducted many uncrewed and robotic spaceflight programs throughout its history. More than 1,000 uncrewed missions have been designed to explore the Earth and the Solar System.[133] Mission selection process NASA executes a mission development framework to plan, select, develop, and operate robotic missions. This framework defines cost, schedule and technical risk parameters to enable competitive selection of missions involving mission candidates that have been developed by principal investigators and their teams from across NASA, the broader U.S. Government research and development stakeholders, and industry. The mission development construct is defined by four umbrella programs. Explorer program Further information: Explorers Program The Explorer program derives its origin from the earliest days of the U.S. Space program. In current form, the program consists of three classes of systems - Small Explorers (SMEX), Medium Explorers (MIDEX), and University-Class Explorers (UNEX) missions. The NASA Explorer program office provides frequent flight opportunities for moderate cost innovative solutions from the heliophysics and astrophysics science areas. The Small Explorer missions are required to limit cost to NASA to below $150M (2022 dollars). Medium class explorer missions have typically involved NASA cost caps of $350M. The Explorer program office is based at NASA Goddard Space Flight Center.[202] Discovery program Further information: Discovery Program The NASA Discovery program develops and delivers robotic spacecraft solutions in the planetary science domain. Discovery enables scientists and engineers to assemble a team to deliver a solution against a defined set of objectives and competitively bid that solution against other candidate programs. Cost caps vary but recent mission selection processes were accomplished using a $500M cost cap to NASA. The Planetary Mission Program Office is based at the NASA Marshall Space Flight Center and manages both the Discovery and New Frontiers missions. The office is part of the Science Mission Directorate.[203] NASA Administrator Bill Nelson announced on June 2, 2021, that the DAVINCI+ and VERITAS missions were selected to launch to Venus in the late 2020s, having beat out competing proposals for missions to Jupiter's volcanic moon Io and Neptune's large moon Triton that were also selected as Discovery program finalists in early 2020. Each mission has an estimated cost of $500 million, with launches expected between 2028 and 2030. Launch contracts will be awarded later in each mission's development.[204] New Frontiers program Further information: New Frontiers program The New Frontiers program focuses on specific Solar System exploration goals identified as top priorities by the planetary science community. Primary objectives include Solar System exploration employing medium class spacecraft missions to conduct high-science-return investigations. New Frontiers builds on the development approach employed by the Discovery program but provides for higher cost caps and schedule durations than are available with Discovery. Cost caps vary by opportunity; recent missions have been awarded based on a defined cap of $1 Billion. The higher cost cap and projected longer mission durations result in a lower frequency of new opportunities for the program - typically one every several years. OSIRIS-REx and New Horizons are examples of New Frontiers missions.[205] NASA has determined that the next opportunity to propose for the fifth round of New Frontiers missions will occur no later than the fall of 2024. Missions in NASA's New Frontiers Program tackle specific Solar System exploration goals identified as top priorities by the planetary science community. Exploring the Solar System with medium-class spacecraft missions that conduct high-science-return investigations is NASA's strategy to further understand the Solar System.[206] Large strategic missions Further information: Large strategic science missions Large strategic missions (formerly called Flagship missions) are strategic missions that are typically developed and managed by large teams that may span several NASA centers. The individual missions become the program as opposed to being part of a larger effort (see Discovery, New Frontiers, etc.). The James Webb Space Telescope is a strategic mission that was developed over a period of more than 20 years. Strategic missions are developed on an ad-hoc basis as program objectives and priorities are established. Missions like Voyager, had they been developed today, would have been strategic missions. Three of the Great Observatories were strategic missions (the Chandra X-ray Observatory, Compton, and the Hubble Space Telescope). Europa Clipper is the next large strategic mission in development by NASA. Planetary science missions NASA continues to play a material in exploration of the Solar System as it has for decades. Ongoing missions have current science objectives with respect to more than five extraterrestrial bodies within the Solar System – Moon (Lunar Reconnaissance Orbiter), Mars (Perseverance rover), Jupiter (Juno), asteroid Bennu (OSIRIS-REx), and Kuiper Belt Objects (New Horizons). The Juno extended mission will make multiple flybys of the Jovian moon Io in 2023 and 2024 after flybys of Ganymede in 2021 and Europa in 2022. Voyager 1 and Voyager 2 continue to provide science data back to Earth while continuing on their outward journeys into interstellar space. On November 26, 2011, NASA's Mars Science Laboratory mission was successfully launched for Mars. The Curiosity rover successfully landed on Mars on August 6, 2012, and subsequently began its search for evidence of past or present life on Mars.[207][208][209] In September 2014, NASA's MAVEN spacecraft, which is part of the Mars Scout Program, successfully entered Mars orbit and, as of October 2022, continues its study of the atmosphere of Mars.[210][211] NASA's ongoing Mars investigations include in-depth surveys of Mars by the Perseverance rover and InSight). NASA's Europa Clipper, planned for launch in October 2024, will study the Galilean moon Europa through a series of flybys while in orbit around Jupiter. Dragonfly will send a mobile robotic rotorcraft to Saturn's biggest moon, Titan.[212] As of May 2021, Dragonfly is scheduled for launch in June 2027.[213][214] Astrophysics missions NASA astrophysics spacecraft fleet, credit NASA GSFC, 2022 The NASA Science Mission Directorate Astrophysics division manages the agency's astrophysics science portfolio. NASA has invested significant resources in the development, delivery, and operations of various forms of space telescopes. These telescopes have provided the means to study the cosmos over a large range of the electromagnetic spectrum.[215] The Great Observatories that were launched in the 1980s and 1990s have provided a wealth of observations for study by physicists across the planent. The first of them, the Hubble Space Telescope, was delivered to orbit in 1990 and continues to function, in part due to prior servicing missions performed by the Space Shuttle.[216][217] The other remaining active great observatory include the Chandra X-ray Observatory (CXO), launched by STS-93 in July 1999 and is now in a 64-hour elliptical orbit studying X-ray sources that are not readily viewable from terrestrial observatories.[218] Chandra X-ray Observatory (rendering), 2015 The Imaging X-ray Polarimetry Explorer (IXPE) is a space observatory designed to improve the understanding of X-ray production in objects such as neutron stars and pulsar wind nebulae, as well as stellar and supermassive black holes.[219] IXPE launched in December 2021 and is an international collaboration between NASA and the Italian Space Agency (ASI). It is part of the NASA Small Explorers program (SMEX) which designs low-cost spacecraft to study heliophysics and astrophysics.[220] The Neil Gehrels Swift Observatory was launched in November 2004 and is Gamma-ray burst observatory that also monitors the afterglow in X-ray, and UV/Visible light at the location of a burst.[221] The mission was developed in a joint partnership between Goddard Space Flight Center (GSFC) and an international consortium from the United States, United Kingdom, and Italy. Pennsylvania State University operates the mission as part of NASA's Medium Explorer program (MIDEX).[222] The Fermi Gamma-ray Space Telescope (FGST) is another gamma-ray focused space observatory that was launched to low Earth orbit in June 2008 and is being used to perform gamma-ray astronomy observations.[223] In addition to NASA, the mission involves the United States Department of Energy, and government agencies in France, Germany, Italy, Japan, and Sweden.[224] The James Webb Space Telescope (JWST), launched in December 2021 on an Ariane 5 rocket, operates in a halo orbit circling the Sun-Earth L2 point.[225][226][227] JWST's high sensitivity in the infrared spectrum and its imaging resolution will allow it to view more distant, faint, or older objects than its predecessors, including Hubble.[228] Earth Sciences Program missions (1965–present) Further information: NASA Earth Science Schematic of NASA Earth Science Division operating satellite missions as of February 2015 NASA Earth Science is a large, umbrella program comprising a range of terrestrial and space-based collection systems in order to better understand the Earth system and its response to natural and human-caused changes. Numerous systems have been developed and fielded over several decades to provide improved prediction for weather, climate, and other changes in the natural environment. Several of the current operating spacecraft programs include: Aqua,[229] Aura,[230] Orbiting Carbon Observatory 2 (OCO-2),[231] Gravity Recovery and Climate Experiment Follow-on (GRACE FO),[232] and Ice, Cloud, and land Elevation Satellite 2 (ICESat-2).[233] In addition to systems already in orbit, NASA is designing a new set of Earth Observing Systems to study, assess, and generate responses for climate change, natural hazards, forest fires, and real-time agricultural processes.[234] The GOES-T satellite (designated GOES-18 after launch) joined the fleet of U.S. geostationary weather monitoring satellites in March 2022.[235] NASA also maintains the Earth Science Data Systems (ESDS) program to oversee the life cycle of NASA's Earth science data — from acquisition through processing and distribution. The primary goal of ESDS is to maximize the scientific return from NASA's missions and experiments for research and applied scientists, decision makers, and society at large.[236] The Earth Science program is managed by the Earth Science Division of the NASA Science Mission Directorate. Space operations architecture NASA invests in various ground and space-based infrastructures to support its science and exploration mandate. The agency maintains access to suborbital and orbital space launch capabilities and sustains ground station solutions to support its evolving fleet of spacecraft and remote systems. Deep Space Network (1963–present) Further information: NASA Deep Space Network The NASA Deep Space Network (DSN) serves as the primary ground station solution for NASA's interplanetary spacecraft and select Earth-orbiting missions.[237] The system employs ground station complexes near Barstow California in the United States, in Spain near Madrid, and in Australia near Canberra. The placement of these ground stations approximately 120 degrees apart around the planet provides the ability for communications to spacecraft throughout the Solar System even as the Earth rotates about its axis on a daily basis. The system is controlled at a 24x7 operations center at JPL in Pasadena California which manages recurring communications linkages with up to 40 spacecraft.[238] The system is managed by the Jet Propulsion Laboratory (JPL).[237] Near Space Network (1983–present) Further information: Near Earth Network and Tracking and Data Relay Satellite System Near Earth Network Ground Stations, 2021 The Near Space Network (NSN) provides telemetry, commanding, ground-based tracking, data and communications services to a wide range of customers with satellites in low earth orbit (LEO), geosynchronous orbit (GEO), highly elliptical orbits (HEO), and lunar orbits. The NSN accumulates ground station and antenna assets from the Near-Earth Network and the Tracking and Data Relay Satellite System (TDRS) which operates in geosynchronous orbit providing continuous real-time coverage for launch vehicles and low earth orbit NASA missions.[239] The NSN consists of 19 ground stations worldwide operated by the US Government and by contractors including Kongsberg Satellite Services (KSAT), Swedish Space Corporation (SSC), and South African National Space Agency (SANSA).[240] The ground network averages between 120 and 150 spacecraft contacts a day with TDRS engaging with systems on a near-continuous basis as needed; the system is managed and operated by the Goddard Space Flight Center.[241] Sounding Rocket Program (1959–present) Further information: NASA Sounding Rocket Program NASA sounding rocket launch from the Wallops Flight Facility The NASA Sounding Rocket Program (NSRP) is located at the Wallops Flight Facility and provides launch capability, payload development and integration, and field operations support to execute suborbital missions.[242] The program has been in operation since 1959 and is managed by the Goddard Space Flight Center using a combined US Government and contractor team.[243] The NSRP team conducts approximately 20 missions per year from both Wallops and other launch locations worldwide to allow scientists to collect data "where it occurs". The program supports the strategic vision of the Science Mission Directorate collecting important scientific data for earth science, heliophysics, and astrophysics programs.[242] In June 2022, NASA conducted its first rocket launch from a commercial spaceport outside the US. It launched a Black Brant IX from the Arnhem Space Centre in Australia.[244] Launch Services Program (1990–present) Further information: NASA Launch Services Program Launch Services Program logo.svg The NASA Launch Services Program (LSP) is responsible for procurement of launch services for NASA uncrewed missions and oversight of launch integration and launch preparation activity, providing added quality and mission assurance to meet program objectives.[245] Since 1990, NASA has purchased expendable launch vehicle launch services directly from commercial providers, whenever possible, for its scientific and applications missions. Expendable launch vehicles can accommodate all types of orbit inclinations and altitudes and are ideal vehicles for launching Earth-orbit and interplanetary missions. LSP operates from Kennedy Space Center and falls under the NASA Space Operations Mission Directorate (SOMD).[246][247] Aeronautics Research Further information: NASA research and Aeronautics Research Mission Directorate The Aeronautics Research Mission Directorate (ARMD) is one of five mission directorates within NASA, the other four being the Exploration Systems Development Mission Directorate, the Space Operations Mission Directorate, the Science Mission Directorate, and the Space Technology Mission Directorate.[248] The ARMD is responsible for NASA's aeronautical research, which benefits the commercial, military, and general aviation sectors. ARMD performs its aeronautics research at four NASA facilities: Ames Research Center and Armstrong Flight Research Center in California, Glenn Research Center in Ohio, and Langley Research Center in Virginia.[249] NASA X-57 Maxwell aircraft (2016–present) Further information: NASA X-57 Maxwell The NASA X-57 Maxwell is an experimental aircraft being developed by NASA to demonstrate the technologies required to deliver a highly efficient all-electric aircraft.[250] The primary goal of the program is to develop and deliver all-electric technology solutions that can also achieve airworthiness certification with regulators. The program involves development of the system in several phases, or modifications, to incrementally grow the capability and operability of the system. The initial configuration of the aircraft has now completed ground testing as it approaches its first flights. In mid-2022, the X-57 was scheduled to fly before the end of the year.[251] The development team includes staff from the NASA Armstrong, Glenn, and Langley centers along with number of industry partners from the United States and Italy.[252] Next Generation Air Transportation System (2007–present) Further information: Next Generation Air Transportation System NASA is collaborating with the Federal Aviation Administration and industry stakeholders to modernize the United States National Airspace System (NAS). Efforts began in 2007 with a goal to deliver major modernization components by 2025.[253] The modernization effort intends to increase the safety, efficiency, capacity, access, flexibility, predictability, and resilience of the NAS while reducing the environmental impact of aviation.[254] The Aviation Systems Division of NASA Ames operates the joint NASA/FAA North Texas Research Station. The station supports all phases of NextGen research, from concept development to prototype system field evaluation. This facility has already transitioned advanced NextGen concepts and technologies to use through technology transfers to the FAA.[253] NASA contributions also include development of advanced automation concepts and tools that provide air traffic controllers, pilots, and other airspace users with more accurate real-time information about the nation's traffic flow, weather, and routing. Ames' advanced airspace modeling and simulation tools have been used extensively to model the flow of air traffic flow across the U.S., and to evaluate new concepts in airspace design, traffic flow management, and optimization.[255] Technology research For technologies funded or otherwise supported by NASA, see NASA spinoff technologies. Nuclear in-space power and propulsion (ongoing) NASA has made use of technologies such as the multi-mission radioisotope thermoelectric generator (MMRTG), which is a type of radioisotope thermoelectric generator used to power spacecraft.[256] Shortages of the required plutonium-238 have curtailed deep space missions since the turn of the millennium.[257] An example of a spacecraft that was not developed because of a shortage of this material was New Horizons 2.[257] In July 2021, NASA announced contract awards for development of nuclear thermal propulsion reactors. Three contractors will develop individual designs over 12 months for later evaluation by NASA and the U.S. Department of Energy.[258] NASA's space nuclear technologies portfolio are led and funded by its Space Technology Mission Directorate. Other initiatives Free Space Optics. NASA contracted a third party to study the probability of using Free Space Optics (FSO) to communicate with Optical (laser) Stations on the Ground (OGS) called laser-com RF networks for satellite communications.[259] Water Extraction from Lunar Soil. On July 29, 2020, NASA requested American universities to propose new technologies for extracting water from the lunar soil and developing power systems. The idea will help the space agency conduct sustainable exploration of the Moon.[260] Human Spaceflight Research (2005–present) Human Research Program logo.png SpaceX Crew-4 astronaut Samantha Cristoforetti operating the rHEALTH ONE on the ISS to address key health risks for space travel NASA's Human Research Program (HRP) is designed to study the effects of space on human health and also to provide countermeasures and technologies for human space exploration. The medical effects of space exploration are reasonably limited in low Earth orbit or in travel to the Moon. Travel to Mars, however, is significantly longer and deeper into space and significant medical issues can result. This includes bone loss, radiation exposure, vision changes, circadian rhythm disturbances, heart remodeling, and immune alterations. In order to study and diagnose these ill-effects, HRP has been tasked with identifying or developing small portable instrumentation with low mass, volume, and power to monitor the health of astronauts.[261] To achieve this aim, on May 13, 2022, NASA and SpaceX Crew-4 astronauts successfully tested its rHEALTH ONE universal biomedical analyzer for its ability to identify and analyzer biomarkers, cells, microorganisms, and proteins in a spaceflight environment.[262] Planetary Defense (2016–present) Further information: Planetary Defense Coordination Office and Near Earth Objects Planetary Defense Coordination Office seal.png NASA established the Planetary Defense Coordination Office (PDCO) in 2016 to catalog and track potentially hazardous near-Earth objects (NEO), such as asteroids and comets and develop potential responses and defenses against these threats.[263] The PDCO is chartered to provide timely and accurate information to the government and the public on close approaches by Potentially hazardous objects (PHOs) and any potential for impact. The office functions within the Science Mission Directorate Planetary Science division.[264] The PDCO augmented prior cooperative actions between the United States, the European Union, and other nations which had been scanning the sky for NEOs since 1998 in an effort called Spaceguard.[265] Near Earth object detection (1998–present) From the 1990s NASA has run many NEO detection programs from Earth bases observatories, greatly increasing the number of objects that have been detected. However, many asteroids are very dark and the ones that are near the Sun are much harder to detect from Earth-based telescopes which observe at night, and thus face away from the Sun. NEOs inside Earth orbit only reflect a part of light also rather than potentially a "full Moon" when they are behind the Earth and fully lit by the Sun. In 1998, the United States Congress gave NASA a mandate to detect 90% of near-Earth asteroids over 1 km (0.62 mi) diameter (that threaten global devastation) by 2008.[266] This initial mandate was met by 2011.[267] In 2005, the original USA Spaceguard mandate was extended by the George E. Brown, Jr. Near-Earth Object Survey Act, which calls for NASA to detect 90% of NEOs with diameters of 140 m (460 ft) or greater, by 2020 (compare to the 20-meter Chelyabinsk meteor that hit Russia in 2013).[268] As of January 2020, it is estimated that less than half of these have been found, but objects of this size hit the Earth only about once in 2,000 years.[269] In January 2020, NASA officials estimated it would take 30 years to find all objects meeting the 140 m (460 ft) size criteria, more than twice the timeframe that was built into the 2005 mandate.[270] In June 2021, NASA authorized the development of the NEO Surveyor spacecraft to reduce that projected duration to achieve the mandate down to 10 years.[271][272] Involvement in current robotic missions NASA has incorporated planetary defense objectives into several ongoing missions. In 1999, NASA visited 433 Eros with the NEAR Shoemaker spacecraft which entered its orbit in 2000, closely imaging the asteroid with various instruments at that time.[273] NEAR Shoemaker became the first spacecraft to successfully orbit and land on an asteroid, improving our understanding of these bodies and demonstrating our capacity to study them in greater detail.[274] OSIRIS-REx used its suite of instruments to transmit radio tracking signals and capture optical images of Bennu during its study of the asteroid that will help NASA scientists determine its precise position in the solar system and its exact orbital path. As Bennu has the potential for recurring approaches to the Earth-Moon system in the next 100–200 years, the precision gained from OSIRIS-REx will enable scientists to better predict the future gravitational interactions between Bennu and our planet and resultant changes in Bennu's onward flight path.[275][276] The WISE/NEOWISE mission was launched by NASA JPL in 2009 as an infrared-wavelength astronomical space telescope. In 2013, NASA repurposed it as the NEOWISE mission to find potentially hazardous near-Earth asteroids and comets; its mission has been extended into 2023.[277][278] NASA and Johns Hopkins Applied Physics Laboratory (JHAPL) jointly developed the first planetary defense purpose-built satellite, the Double Asteroid Redirection Test (DART) to test possible planetary defense concepts.[279] DART was launched in November 2021 by a SpaceX Falcon 9 from California on a trajectory designed to impact the Dimorphos asteroid. Scientists were seeking to determine whether an impact could alter the subsequent path of the asteroid; a concept that could be applied to future planetary defense.[280] On September 26, 2022, DART hit its target. In the weeks following impact, NASA declared DART a success, confirming it had shortened Dimorphos' orbital period around Didymos by about 32 minutes, surpassing the pre-defined success threshold of 73 seconds.[281][282] NEO Surveyor, formerly called the Near-Earth Object Camera (NEOCam) mission, is a space-based infrared telescope under development to survey the Solar System for potentially hazardous asteroids.[283] The spacecraft is scheduled to launch in 2026. Study of Unidentified Aerial Phenomena (2022–present) In June 2022, the head of the NASA Science Mission Directorate, Thomas Zurbuchen, confirmed that NASA would join the hunt for Unidentified Flying Objects (UFOs)/Unidentified Aerial Phenomena (UAPs).[284] At a speech before the National Academies of Science, Engineering and Medicine, Zurbuchen said the space agency would bring a scientific perspective to efforts already underway by the Pentagon and intelligence agencies to make sense of dozens of such sightings. He said it was "high-risk, high-impact" research that the space agency should not shy away from, even if it is a controversial field of study.[285] Collaboration NASA Advisory Council In response to the Apollo 1 accident, which killed three astronauts in 1967, Congress directed NASA to form an Aerospace Safety Advisory Panel (ASAP) to advise the NASA Administrator on safety issues and hazards in NASA's air and space programs. In the aftermath of the Shuttle Columbia disaster, Congress required that the ASAP submit an annual report to the NASA Administrator and to Congress.[286] By 1971, NASA had also established the Space Program Advisory Council and the Research and Technology Advisory Council to provide the administrator with advisory committee support. In 1977, the latter two were combined to form the NASA Advisory Council (NAC).[287] The NASA Authorization Act of 2014 reaffirmed the importance of ASAP. National Oceanic and Atmospheric Administration (NOAA) Further information: National Oceanic and Atmospheric Administration NOAA logo mobile.svg NASA and NOAA have cooperated for decades on the development, delivery and operation of polar and geosynchronous weather satellites.[288] The relationship typically involves NASA developing the space systems, launch solutions, and ground control technology for the satellites and NOAA operating the systems and delivering weather forecasting products to users. Multiple generations of NOAA Polar orbiting platforms have operated to provide detailed imaging of weather from low altitude.[289] Geostationary Operational Environmental Satellites (GOES) provide near-real-time coverage of the western hemisphere to ensure accurate and timely understanding of developing weather phenomenon.[290] United States Space Force Further information: United States Space Force United States Space Force logo.svg The United States Space Force (USSF) is the space service branch of the United States Armed Forces, while the National Aeronautics and Space Administration (NASA) is an independent agency of the United States government responsible for civil spaceflight. NASA and the Space Force's predecessors in the Air Force have a long-standing cooperative relationship, with the Space Force supporting NASA launches out of Kennedy Space Center, Cape Canaveral Space Force Station, and Vandenberg Space Force Base, to include range support and rescue operations from Task Force 45.[291] NASA and the Space Force also partner on matters such as defending Earth from asteroids.[292] Space Force members can be NASA astronauts, with Colonel Michael S. Hopkins, the commander of SpaceX Crew-1, commissioned into the Space Force from the International Space Station on December 18, 2020.[293][294][295] In September 2020, the Space Force and NASA signed a memorandum of understanding formally acknowledging the joint role of both agencies. This new memorandum replaced a similar document signed in 2006 between NASA and Air Force Space Command.[296][297] U.S. Geological Survey Further information: United States Geological Survey and Landsat 9 USGS logo green.svg The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program.[298] On July 23, 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to Landsat 1 in 1975.[299] The most recent satellite in the series, Landsat 9, was launched on September 27, 2021.[300] The instruments on the Landsat satellites have acquired millions of images. The images, archived in the United States and at Landsat receiving stations around the world, are a unique resource for global change research and applications in agriculture, cartography, geology, forestry, regional planning, surveillance and education, and can be viewed through the U.S. Geological Survey (USGS) "EarthExplorer" website. The collaboration between NASA and USGS involves NASA designing and delivering the space system (satellite) solution, launching the satellite into orbit with the USGS operating the system once in orbit.[298] As of October 2022, nine satellites have been built with eight of them successfully operating in orbit. European Space Agency (ESA) Further information: European Space Agency European Space Agency logo.svg NASA collaborates with the European Space Agency on a wide range of scientific and exploration requirements.[301] From participation with the Space Shuttle (the Spacelab missions) to major roles on the Artemis program (the Orion Service Module), ESA and NASA have supported the science and exploration missions of each agency. There are NASA payloads on ESA spacecraft and ESA payloads on NASA spacecraft. The agencies have developed joint missions in areas including heliophysics (e.g. Solar Orbiter)[302] and astronomy (Hubble Space Telescope, James Webb Space Telescope).[303] Under the Artemis Gateway partnership, ESA will contribute habitation and refueling modules, along with enhanced lunar communications, to the Gateway.[304][305] NASA and ESA continue to advance cooperation in relation to Earth Science including climate change with agreements to cooperate on various missions including the Sentinel-6 series of spacecraft[306] Japan Aerospace Exploration Agency (JAXA) Further information: Japan Aerospace Exploration Agency Jaxa logo.svg NASA and the Japan Aerospace Exploration Agency (JAXA) cooperate on a range of space projects. JAXA is a direct participant in the Artemis program, including the Lunar Gateway effort. JAXA's planned contributions to Gateway include I-Hab's environmental control and life support system, batteries, thermal control, and imagery components, which will be integrated into the module by the European Space Agency (ESA) prior to launch. These capabilities are critical for sustained Gateway operations during crewed and uncrewed time periods.[307][308] JAXA and NASA have collaborated on numerous satellite programs, especially in areas of Earth science. NASA has contributed to JAXA satellites and vice versa. Japanese instruments are flying on NASA's Terra and Aqua satellites, and NASA sensors have flown on previous Japanese Earth-observation missions. The NASA-JAXA Global Precipitation Measurement mission was launched in 2014 and includes both NASA- and JAXA-supplied sensors on a NASA satellite launched on a JAXA rocket. The mission provides the frequent, accurate measurements of rainfall over the entire globe for use by scientists and weather forecasters.[309] Roscosmos Further information: Roscosmos Roscosmos logo ru.svg NASA and Roscosmos have cooperated on the development and operation of the International Space Station since September 1993.[310] The agencies have used launch systems from both countries to deliver station elements to orbit. Astronauts and Cosmonauts jointly maintain various elements of the station. Both countries provide access to the station via launch systems noting Russia's unique role as the sole provider of delivery of crew and cargo upon retirement of the space shuttle in 2011 and prior to commencement of NASA COTS and crew flights. In July 2022, NASA and Roscosmos signed a deal to share space station flights enabling crew from each country to ride on the systems provided by the other.[311] Current geopolitical conditions in late 2022 make it unlikely that cooperation will be extended to other programs such as Artemis or lunar exploration.[312] Indian Space Research Organisation Further information: Indian Space Research Organisation Indian Space Research Organisation Logo.svg In September 2014, NASA and Indian Space Research Organisation (ISRO) signed a partnership to collaborate on and launch a joint radar mission, the NASA-ISO Synthetic Aperature Radar (NISAR) mission. The mission is targeted to launch in 2024. NASA will provide the mission's L-band synthetic aperture radar, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder and payload data subsystem. ISRO provides the spacecraft bus, the S-band radar, the launch vehicle and associated launch services.[313][314] Artemis Accords Further information: Artemis Accords The Artemis Accords have been established to define a framework for cooperating in the peaceful exploration and exploitation of the Moon, Mars, asteroids, and comets. The Accords were drafted by NASA and the U.S. State Department and are executed as a series of bilateral agreements between the United States and the participating countries.[315][316] As of September 2022, 21 countries have signed the accords. They are Australia, Bahrain, Brazil, Canada, Colombia, France, Israel, Italy, Japan, the Republic of Korea, Luxembourg, Mexico, New Zealand, Poland, Romania, the Kingdom of Saudi Arabia, Singapore, Ukraine, the United Arab Emirates, the United Kingdom, and the United States.[317][318] China National Space Administration Further information: Wolf Amendment and China National Space Administration The Wolf Amendment was passed by the U.S. Congress into law in 2011 and prevents NASA from engaging in direct, bilateral cooperation with the Chinese government and China-affiliated organizations such as the China National Space Administration without the explicit authorization from Congress and the Federal Bureau of Investigation. The law has been renewed annually since by inclusion in annual appropriations bills.[319] Sustainability Environmental impact The exhaust gases produced by rocket propulsion systems, both in Earth's atmosphere and in space, can adversely affect the Earth's environment. Some hypergolic rocket propellants, such as hydrazine, are highly toxic prior to combustion, but decompose into less toxic compounds after burning. Rockets using hydrocarbon fuels, such as kerosene, release carbon dioxide and soot in their exhaust.[320] However, carbon dioxide emissions are insignificant compared to those from other sources; on average, the United States consumed 803 million US gal (3.0 million m3) of liquid fuels per day in 2014, while a single Falcon 9 rocket first stage burns around 25,000 US gallons (95 m3) of kerosene fuel per launch.[321][322] Even if a Falcon 9 were launched every single day, it would only represent 0.006% of liquid fuel consumption (and carbon dioxide emissions) for that day. Additionally, the exhaust from LOx- and LH2- fueled engines, like the SSME, is almost entirely water vapor.[323] NASA addressed environmental concerns with its canceled Constellation program in accordance with the National Environmental Policy Act in 2011.[324] In contrast, ion engines use harmless noble gases like xenon for propulsion.[325][326] An example of NASA's environmental efforts is the NASA Sustainability Base. Additionally, the Exploration Sciences Building was awarded the LEED Gold rating in 2010.[327] On May 8, 2003, the Environmental Protection Agency recognized NASA as the first federal agency to directly use landfill gas to produce energy at one of its facilities—the Goddard Space Flight Center, Greenbelt, Maryland.[328] In 2018, NASA along with other companies including Sensor Coating Systems, Pratt & Whitney, Monitor Coating and UTRC launched the project CAUTION (CoAtings for Ultra High Temperature detectION). This project aims to enhance the temperature range of the Thermal History Coating up to 1,500 °C (2,730 °F) and beyond. The final goal of this project is improving the safety of jet engines as well as increasing efficiency and reducing CO2 emissions.[329] Climate change NASA also researches and publishes on climate change.[330] Its statements concur with the global scientific consensus that the global climate is warming.[331] Bob Walker, who has advised US President Donald Trump on space issues, has advocated that NASA should focus on space exploration and that its climate study operations should be transferred to other agencies such as NOAA. Former NASA atmospheric scientist J. Marshall Shepherd countered that Earth science study was built into NASA's mission at its creation in the 1958 National Aeronautics and Space Act.[332] NASA won the 2020 Webby People's Voice Award for Green in the category Web.[333] STEM Initiatives Further information: STEM Educational Launch of Nanosatellites (ELaNa). Since 2011, the ELaNa program has provided opportunities for NASA to work with university teams to test emerging technologies and commercial-off-the-shelf solutions by providing launch opportunities for developed CubeSats using NASA procured launch opportunities.[334] By example, two NASA-sponsored CubeSats launched in June 2022 on a Virgin Orbit LauncherOne vehicle as the ELaNa 39 mission.[335] Cubes in Space. NASA started an annual competition in 2014 named "Cubes in Space".[336] It is jointly organized by NASA and the global education company I Doodle Learning, with the objective of teaching school students aged 11–18 to design and build scientific experiments to be launched into space on a NASA rocket or balloon. On June 21, 2017, the world's smallest satellite, KalamSAT, was launched.[337] Use of the metric system US law requires the International System of Units to be used in all US Government programs, "except where impractical".[338] In 1969, Apollo 11 landed on the Moon using a mix of United States customary units and metric units. In the 1980s, NASA started the transition towards the metric system, but was still using both systems in the 1990s.[339][340] On September 23, 1999, a mixup between NASA's use of SI units and Lockheed Martin Space's use of US units resulted in the loss of the Mars Climate Orbiter.[341] In August 2007, NASA stated that all future missions and explorations of the Moon would be done entirely using the SI system. This was done to improve cooperation with space agencies of other countries that already use the metric system.[342] As of 2007, NASA is predominantly working with SI units, but some projects still use US units, and some, including the International Space Station, use a mix of both.[343] Media presence NASA TV Further information: NASA TV Approaching 40 years of service, the NASA TV channel airs content ranging from live coverage of crewed missions to video coverage of significant milestones for operating robotic spacecraft (e.g., rover landings on Mars for example) and domestic and international launches.[344] The channel is delivered by NASA and is broadcast by satellite and over the Internet. The system initially started to capture archival footage of important space events for NASA managers and engineers and expanded as public interest grew. The Apollo 8 Christmas Eve broadcast while in orbit around the Moon was received by more than a billion people.[345] NASA's video transmission of the Apollo 11 Moon landing was awarded a primetime Emmy in commemoration of the 40th anniversary of the landing.[346] The channel is a product of the U.S. Government and is widely available across many television and Internet platforms.[347] NASAcast NASAcast is the official audio and video podcast of the NASA website. Created in late 2005, the podcast service contains the latest audio and video features from the NASA web site, including NASA TV's This Week at NASA and educational materials produced by NASA. Additional NASA podcasts, such as Science@NASA, are also featured and give subscribers an in-depth look at content by subject matter.[348] NASA EDGE NASA EDGE broadcasting live from White Sands Missile Range in 2010 NASA EDGE is a video podcast which explores different missions, technologies and projects developed by NASA. The program was released by NASA on March 18, 2007, and, as of August 2020, there have been 200 vodcasts produced. It is a public outreach vodcast sponsored by NASA's Exploration Systems Mission Directorate and based out of the Exploration and Space Operations Directorate at Langley Research Center in Hampton, Virginia. The NASA EDGE team takes an insiders look at current projects and technologies from NASA facilities around the United States, and it is depicted through personal interviews, on-scene broadcasts, computer animations, and personal interviews with top scientists and engineers at NASA.[note 3] The show explores the contributions NASA has made to society as well as the progress of current projects in materials and space exploration. NASA EDGE vodcasts can be downloaded from the NASA website and from iTunes. In its first year of production, the show was downloaded over 450,000 times. As of February 2010, the average download rate is more than 420,000 per month, with over one million downloads in December 2009 and January 2010.[350] NASA and the NASA EDGE have also developed interactive programs designed to complement the vodcast. The Lunar Electric Rover App allows users to drive a simulated Lunar Electric Rover between objectives, and it provides information about and images of the vehicle.[351] The NASA EDGE Widget provides a graphical user interface for accessing NASA EDGE vodcasts, image galleries, and the program's Twitter feed, as well as a live NASA news feed.[352] Astronomy Picture of the Day This section is an excerpt from Astronomy Picture of the Day.[edit] Astronomy Picture of the Day (APOD) is a website provided by NASA and Michigan Technological University (MTU). According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."[353] The photograph does not necessarily correspond to a celestial event on the exact day that it is displayed, and images are sometimes repeated.[354] However, the pictures and descriptions often relate to current events in astronomy and space exploration. The text has several hyperlinks to more pictures and websites for more information. The images are either visible spectrum photographs, images taken at non-visible wavelengths and displayed in false color, video footage, animations, artist's conceptions, or micrographs that relate to space or cosmology. Past images are stored in the APOD Archive, with the first image appearing on June 16, 1995.[355] This initiative has received support from NASA, the National Science Foundation, and MTU. The images are sometimes authored by people or organizations outside NASA, and therefore APOD images are often copyrighted, unlike many other NASA image galleries.[356] When the APOD website was created, it received a total of 14 page views on its first day. As of 2012, the APOD website has received over a billion image views throughout its lifetime.[357] APOD is also translated into 21 languages daily." (wikipedia.org) "A puzzle is a game, problem, or toy that tests a person's ingenuity or knowledge. In a puzzle, the solver is expected to put pieces together (or take them apart) in a logical way, in order to arrive at the correct or fun solution of the puzzle. There are different genres of puzzles, such as crossword puzzles, word-search puzzles, number puzzles, relational puzzles, and logic puzzles. The academic study of puzzles is called enigmatology. Puzzles are often created to be a form of entertainment but they can also arise from serious mathematical or logical problems. In such cases, their solution may be a significant contribution to mathematical research.[1] Etymology The Oxford English Dictionary dates the word puzzle (as a verb) to the end of the 16th century. Its earliest use documented in the OED was in a book titled The Voyage of Robert Dudley...to the West Indies, 1594–95, narrated by Capt. Wyatt, by himself, and by Abram Kendall, master (published circa 1595). The word later came to be used as a noun, first as an abstract noun meaning 'the state or condition of being puzzled', and later developing the meaning of 'a perplexing problem'. The OED's earliest clear citation in the sense of 'a toy that tests the player's ingenuity' is from Sir Walter Scott's 1814 novel Waverley, referring to a toy known as a "reel in a bottle".[2] The etymology of the verb puzzle is described by OED as "unknown"; unproven hypotheses regarding its origin include an Old English verb puslian meaning 'pick out', and a derivation of the verb pose.[3] Genres Various puzzles Simple puzzle made of three pieces Puzzles can be categorized as:     Lateral thinking puzzles, also called "situation puzzles"     Mathematical puzzles include the missing square puzzle and many impossible puzzles — puzzles which have no solution, such as the Seven Bridges of Königsberg, the three cups problem, and three utilities problem         Sangaku (Japanese temple tablets with geometry puzzles)     A chess problem is a puzzle that uses chess pieces on a chess board. Examples are the knight's tour and the eight queens puzzle.     Mechanical puzzles or dexterity puzzles such as the Rubik's Cube and Soma cube can be stimulating toys for children or recreational activities for adults.         combination puzzles like Peg solitaire         construction puzzles such as stick puzzles         disentanglement puzzles,         folding puzzles         jigsaw puzzles. Puzz 3D is a three-dimensional variant of this type.         lock puzzles         A puzzle box can be used to hide something — jewelry, for instance.         sliding puzzles (also called sliding tile puzzles) such as the 15 Puzzle and Sokoban         tiling puzzles like Tangram         Tower of Hanoi     Metapuzzles are puzzles which unite elements of other puzzles.     Paper-and-pencil puzzles such as Uncle Art's Funland, connect the dots, and nonograms         Also the logic puzzles published by Nikoli: Sudoku, Slitherlink, Kakuro, Fillomino, Hashiwokakero, Heyawake, Hitori, Light Up, Masyu, Number Link, Nurikabe, Ripple Effect, Shikaku, and Kuromasu.     Spot the difference     Tour puzzles like a maze     Word puzzles, including anagrams, ciphers, crossword puzzles, Hangman (game), and word search puzzles. Tabletop and digital word puzzles include Bananagrams, Boggle, Bonza, Dabble, Letterpress (video game), Perquackey, Puzzlage, Quiddler, Ruzzle, Scrabble, Upwords, WordSpot, and Words with Friends. Wheel of Fortune (U.S. game show) is a game show centered on a word puzzle.     Puzzle video games         Tile-matching video game         Puzzle-platformer         Adventure game         Hidden object game         Minesweeper Puzzle solving     This section possibly contains original research. Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. (November 2018) (Learn how and when to remove this template message) Solutions of puzzles often require the recognition of patterns and the adherence to a particular kind of ordering. People with a high level of inductive reasoning aptitude may be better at solving such puzzles than others. But puzzles based upon inquiry and discovery may be solved more easily by those with good deduction skills. Deductive reasoning improves with practice. Mathematical puzzles often involve BODMAS. BODMAS is an acronym and it stands for Bracket, Of, Division, Multiplication, Addition and Subtraction. In certain regions, PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition and Subtraction) is the synonym of BODMAS. It explains the order of operations to solve an expression. Some mathematical puzzles require Top to Bottom convention to avoid the ambiguity in the order of operations. It is an elegantly simple idea that relies, as sudoku does, on the requirement that numbers appear only once starting from top to bottom as coming along.[4] Puzzle makers Puzzle makers are people who make puzzles. In general terms of occupation, a puzzler is someone who composes and/or solves puzzles. Some notable creators of puzzles are:     Ernő Rubik     Sam Loyd     Henry Dudeney     Boris Kordemsky     David J. Bodycombe     Will Shortz     Oskar van Deventer     Lloyd King     Martin Gardner     Raymond Smullyan History of jigsaw and other puzzles Main article: Jigsaw puzzle Jigsaw puzzles are perhaps the most popular form of puzzle. Jigsaw puzzles were invented around 1760, when John Spilsbury, a British engraver and cartographer, mounted a map on a sheet of wood, which he then sawed around the outline of each individual country on the map. He then used the resulting pieces as an aid for the teaching of geography.[5] After becoming popular among the public, this kind of teaching aid remained the primary use of jigsaw puzzles until about 1820.[6] The largest puzzle (40,320 pieces) is made by German game company Ravensburger.[7] The smallest puzzle ever made was created at LaserZentrum Hannover. It is only five square millimeters, the size of a sand grain. The puzzles that were first documented are riddles. In Europe, Greek mythology produced riddles like the riddle of the Sphinx. Many riddles were produced during the Middle Ages, as well.[8] By the early 20th century, magazines and newspapers found that they could increase their readership by publishing puzzle contests, beginning with crosswords and in modern days sudoku. Organizations and events There are organizations and events that cater to puzzle enthusiasts, such as:     Nob Yoshigahara Puzzle Design Competition     World Puzzle Championship     National Puzzlers' League     Puzzlehunts such as the Maze of Games     World Cube Association" (wikipedia.org) "A jigsaw puzzle is a tiling puzzle that requires the assembly of often irregularly shaped interlocking and mosaiced pieces, each of which typically has a portion of a picture. When assembled, the puzzle pieces produce a complete picture. In the 18th century, jigsaw puzzles were created by painting a picture on a flat, rectangular piece of wood, then cutting it into small pieces. Despite the name, a jigsaw was never used. John Spilsbury, a London cartographer and engraver, is credited with commercialising jigsaw puzzles around 1760. His design took world maps, and cut out the individual nations in order for them to be reassembled by students as a geographical teaching aid.[1] They have since come to be made primarily of interlocking cardboard pieces, incorporating a variety of images & designs. Typical images on jigsaw puzzles include scenes from nature, buildings, and repetitive designs—castles and mountains are common, as well as other traditional subjects. However, any picture can be used. Artisan puzzle-makers and companies using technologies for one-off and small print-run puzzles utilize a wide range of subject matter, including optical illusions, unusual art, and personal photographs. In addition to traditional flat, two-dimensional puzzles, three-dimensional puzzles have entered large-scale production, including spherical puzzles and architectural recreations. A range of jigsaw puzzle accessories, including boards, cases, frames, and roll-up mats, have become available to assist jigsaw puzzle enthusiasts. While most assembled puzzles are disassembled for reuse, they can also be attached to a backing with adhesive and displayed as art. History John Spilsbury's "Europe divided into its kingdoms, etc." (1766). He created the jigsaw puzzle for educational purposes, and called them "Dissected Maps".[2][3] John Spilsbury is believed to have produced the first jigsaw puzzle around 1760, using a marquetry saw.[1] Early puzzles, known as dissections, were produced by mounting maps on sheets of hardwood and cutting along national boundaries, creating a puzzle useful for teaching geography.[1] Royal governess Lady Charlotte Finch used such "dissected maps" to teach the children of King George III and Queen Charlotte[4][5] Cardboard jigsaw puzzles appeared in the late 1800s, but were slow to replace wooden ones because manufacturers felt that cardboard puzzles would be perceived as low-quality, and because profit margins on wooden jigsaws were larger.[1] British printed puzzle from 1874. The name "jigsaw" came to be associated with the puzzle around 1880 when fretsaws became the tool of choice for cutting the shapes. Since fretsaws are distinct from jigsaws, the name appears to be a misnomer.[1] Wooden jigsaw pieces, cut by hand Jigsaw puzzles soared in popularity during the Great Depression, as they provided a cheap, long-lasting, recyclable form of entertainment.[1][6] It was around this time that jigsaws evolved to become more complex and appealing to adults.[1] They were also given away in product promotions and used in advertising, with customers completing an image of the promoted product.[1][6] Sales of wooden puzzles fell after World War II as improved wages led to price increases, while improvements in manufacturing processes made paperboard jigsaws more attractive.[6] Demand for jigsaw puzzles saw a surge, comparable to that of the Great Depression, during the COVID-19 pandemic's stay-at-home orders.[7][8] Modern construction Paperboard jigsaw pieces Most modern jigsaw puzzles are made of paperboard as they are easier and cheaper to mass-produce. An enlarged photograph or printed reproduction of a painting or other two-dimensional artwork is glued to cardboard, which is then fed into a press. The press forces a set of hardened steel blades of the desired pattern, called a puzzle die, through the board until fully cut. The puzzle die is a flat board, often made from plywood, with slots cut or burned in the same shape as the knives that are used. The knives are set into the slots and covered in a compressible material, typically foam rubber, which ejects the cut puzzle pieces. The cutting process is similar to making shaped cookies with a cookie cutter. However, the forces involved are tremendously greater: A typical 1000-piece puzzle requires upwards of 700 tons of force to push the die through the board. Beginning in the 1930s, jigsaw puzzles were cut using large hydraulic presses that now cost hundreds of thousands of dollars. The precise cuts gave a snug fit, but the cost limited jigsaw puzzle production to large corporations. Recent roller-press methods achieve the same results at a lower cost.[citation needed] New technology has also enabled laser-cutting of wooden or acrylic jigsaw puzzles. The advantage is that the puzzle can be custom-cut to any size or shape, with any number or average size of pieces. Many museums have laser-cut acrylic puzzles made of some of their art so visiting children can assemble puzzles of the images on display. Acrylic pieces are very durable, waterproof, and can withstand continued use without the image degrading. Also, because the print and cut patterns are computer-based, missing pieces can easily be remade. By the early 1960s, Tower Press was the world's largest jigsaw puzzle maker; it was acquired by Waddingtons in 1969.[9] Numerous smaller-scale puzzle makers work in artisanal styles, handcrafting and handcutting their creations.[10][11][12][13] Variations Jigsaw puzzle software allowing rotation of pieces A three-dimensional puzzle composed of several two-dimensional puzzles stacked on top of one another A puzzle without a picture Jigsaw puzzles come in a variety of sizes. Among those marketed to adults, 300-, 500- and 750-piece puzzles are considered "smaller". More sophisticated, but still common, puzzles come in sizes of 1,000, 1,500, 2,000, 3,000, 4,000, 5,000, 6,000, 7,500, 8,000, 9,000, 13,200, 18,000, 24,000, 32,000 and 40,000 pieces. Jigsaw puzzles geared towards children typically have many fewer pieces and are typically much larger. For very young children, puzzles with as few as 4 to 9 large pieces (so as not to be a choking hazard) are standard. They are usually made of wood or plastic for durability and can be cleaned without damage. The most common layout for a thousand-piece puzzle is 38 pieces by 27 pieces, for an actual total of 1,026 pieces. Most 500-piece puzzles are 27 pieces by 19 pieces. A few puzzles are double-sided so they can be solved from either side—adding complexity, as the enthusiast must determine if they are looking at the right side of each piece. "Family puzzles" of 100–550 pieces use an assortment of small, medium and large pieces, with each size going in one direction or towards the middle of the puzzle. This allows a family of different skill levels and hand sizes to work on the puzzle together. Companies like Springbok, Cobble Hill, Ceaco, Buffalo Games and Suns Out make this type of specialty puzzle. Ravensburger, on the other hand, formerly made this type of puzzle from 2000 until 2008. There are also three-dimensional jigsaw puzzles. Many are made of wood or styrofoam and require the puzzle to be solved in a particular order, as some pieces will not fit if others are already in place. One type of 3-D jigsaw puzzle is a puzzle globe, often made of plastic. Like 2-D puzzles, the assembled pieces form a single layer, but the final form is three-dimensional. Most globe puzzles have designs representing spherical shapes such as the Earth, the Moon, and historical globes of the Earth. Also common are puzzle boxes, simple three-dimensional puzzles with a small drawer or box in the center for storage. Jigsaw puzzles can vary significantly in price depending on their complexity, number of pieces, and brand. In the US, children's puzzles can start around $5, while larger ones can be closer to $50. The most expensive puzzle to date was sold for $US27,000 in 2005 at a charity auction for The Golden Retriever Foundation.[14] Several word-puzzle games use pieces similar to those in jigsaw puzzles. Examples include Alfa-Lek, Jigsaw Words, Nab-It!, Puzzlage, Typ-Dom, Word Jigsaw, and Yottsugo.[15][citation needed] Puzzle pieces A "whimsy" piece in a wooden jigsaw puzzle A 3D jigsaw puzzle Many puzzles are termed "fully interlocking", which means that adjacent pieces are connected so that they stay attached when one is turned. Sometimes the connection is tight enough to pick up a solved part by holding one piece. Some fully interlocking puzzles have pieces of a similar shape, with rounded tabs (interjambs) on opposite ends and corresponding indentations—called blanks—on the other two sides to receive the tabs. Other fully interlocking puzzles may have tabs and blanks variously arranged on each piece; but they usually have four sides, and the numbers of tabs and blanks thus add up to four. Uniformly shaped fully interlocking puzzles, sometimes called "Japanese Style", are the most difficult because the differences in the pieces' shapes are most subtle.[citation needed] Most jigsaw puzzles are square, rectangular or round, with edge pieces with one straight or smoothly curved side, plus four corner pieces (if the puzzle is square or rectangular). However, some puzzles have edge, and corner pieces cut like the rest, with no straight sides, making it more challenging to identify them. Other puzzles utilize more complex edge pieces to form unique shapes when assembled, such as profiles of animals. The pieces of spherical jigsaw, like immersive panorama jigsaw, can be triangular-shaped, according to the rules of tessellation of the geoid primitive. Designer Yuu Asaka created "Jigsaw Puzzle 29". Instead of four corner pieces, it has five. The puzzle is made from pale blue acrylic without a picture.[16] It was awarded the Jury Honorable Mention of 2018 Puzzle Design Competition.[17] Because many puzzlers had solved it easily, he created "Jigsaw Puzzle 19" which composed only with corner pieces as revenge.[18] It was made with transparent green acrylic pieces without a picture.[19] Calculating the number of edge pieces Jigsaw puzzlers often want to know in advance how many border pieces they are looking for to verify they have found all of them. Puzzle sizes are typically listed on commercially distributed puzzles but usually include the total number of pieces in the puzzle and do not list the count of edge or interior pieces. Puzzlers, therefore, calculate the number of border pieces. To calculate B (border pieces) from P (the total piece count), follow this method:     List the prime factors of P.         For a 513-piece jigsaw, the prime factorization tree is 3×3×3×19=513     Take the square root of P and round off.         √513 ≈ 22.6         round to 23     Look for numbers in the prime factor list within ±20% of the square root of P.         Calculate 20% of the rounded square root of P.             1⁄5 × 23 = 4.6         Develop the range, ±20%, from the rounded square root of P.             23 ±4.6 = 18.4 to 27.6         Compare the range with the factor list. Define this as E1.             The factor list shows 19 in the range.     Determine the horizontal / vertical dimensions.         Divide P (the total number of pieces) by E1 to determine the horizontal / vertical dimensions, E1xE2.             513 / 19 = 27             This is probably a 19×27 puzzle.         Alternative method: take the remaining numbers from the prime factorization tree.             3x3x3 = 27     Add the four sides and subtract 4 to correct for the corner pieces, which would otherwise be counted in both the horizontal and vertical.         (27 × 2)+(19 × 2)-4 = 88 These 88 border pieces include 4 corners, 17 pieces between corners on the short sides, and 25 between corners on the long sides. Common puzzle dimensions:     1000 piece puzzle: 1026 pieces, 126 border pieces (38x27)[20] World records Largest commercially available jigsaw puzzles Pieces     Name of puzzle     Company     Year     Size [cm]     Area [m2] 60,000     What A Wonderful World     Dowdle Folk Art     2022     883 × 243     21.46 54,000     Travel around Art     Grafika     2020     864 × 204     17.63 52,110     (No title: collage of animals)     MartinPuzzle     2018     696 × 202     14.06 51,300     27 Wonders from Around the World     Kodak     2019     869 × 191     16.60 48,000     Around the World     Grafika     2017     768 × 204     15.67 42,000     La vuelta al Mundo     Educa Borras     2017     749 × 157     11.76 40,320     Making Mickey's Magic     Ravensburger     2018     680 × 192     13.06 40,320     Memorable Disney Moments     Ravensburger     2016     680 × 192     13.06 33,600     Wild Life     Educa Borras     2014     570 × 157     8.95 32,000     New York City Window     Ravensburger     2014     544 × 192     10.45 32,000     Double Retrospect     Ravensburger     2010     544 × 192     10.45 24,000     Life, The greatest puzzle     Educa Borras     2007     428 × 157     6.72 Largest-sized jigsaw puzzles The world's largest-sized jigsaw puzzle measured 5,428.8 m2 (58,435 sq ft) with 21,600 pieces, each measuring a Guinness World Records maximum size of 50 cm by 50 cm. It was assembled on 3 November 2002 by 777 people at the former Kai Tak Airport in Hong Kong.[21] Largest jigsaw puzzle – most pieces The Guinness record of CYM Group in 2011 with 551,232 pieces The jigsaw with the greatest number of pieces had 551,232 pieces and measured 14.85 × 23.20 m (48 ft 8.64 in × 76 ft 1.38 in). It was assembled on 25 September 2011 at Phú Thọ Indoor Stadium in Ho Chi Minh City, Vietnam, by students of the University of Economics, Ho Chi Minh City. It is listed by the Guinness World Records for the "Largest Jigsaw Puzzle – most pieces", but as the intact jigsaw had been divided into 3,132 sections, each containing 176 pieces, which were reassembled and then connected, the claim is controversial.[22][23] Society The logo of Wikipedia is a globe made out of jigsaw pieces. The incomplete sphere symbolizes the room to add new knowledge.[citation needed] In the logo of the Colombian Office of the Attorney General appears a jigsaw puzzle piece in the foreground. They named it "The Key Piece": "The piece of a puzzle is the proper symbol to visually represent the Office of the Attorney General because it includes the concepts of search, solution and answers that the entity pursues through the investigative activity."[24] Art and entertainment The central antagonist in the Saw film franchise is nicknamed Jigsaw,[25] due to his practice of cutting the shape of a puzzle piece from the remains of his victims. In the 1933 Laurel and Hardy short Me and My Pal, several characters attempt to complete a large jigsaw puzzle.[26] Lost in Translation is a poem about a child putting together a jigsaw puzzle, as well as an interpretive puzzle itself. Life: A User's Manual, Georges Perec's most famous novel, tells as pieces of a puzzle a story about a jigsaw puzzle maker. Jigsaw Puzzle (song), sometimes spelled "Jig-Saw Puzzle" is a song by the rock and roll band The Rolling Stones, featured on their 1968 album Beggars Banquet. In ‘‘Citizen Kane‘’ Susan Alexander Kane (Dorothy Comingore) is reduced to spending her days completing jigsaws after the failure of her operatic career. After Kane’s death when ‘’Xanadu’’ is emptied, hundreds of jigsaw puzzles are discovered in the cellar. Rhett And Link Do A Rainy Day Jigsaw Puzzle is a short video by self-described “internetainers” (portmanteau of “Internet” and “entertainers”) Rhett & Link which portrays the frustration of discovering a puzzle piece is missing. Mental health According to the Alzheimer Society of Canada, doing jigsaw puzzles is one of many activities that can help keep the brain active and may reduce the risk of Alzheimer's disease.[27] An "autism awareness" ribbon, featuring red, blue, and yellow jigsaw pieces Jigsaw puzzle pieces were first used as a symbol for autism in 1963 by the United Kingdom's National Autistic Society.[28] The organization chose jigsaw pieces for their logo to represent the "puzzling" nature of autism and the inability to "fit in" due to social differences, and also because jigsaw pieces were recognizable and otherwise unused.[29] Puzzle pieces have since been incorporated into the logos and promotional materials of many organizations, including the Autism Society of America and Autism Speaks. Proponents of the autism rights movement oppose the jigsaw puzzle iconography, stating that metaphors such as "puzzling" and "incomplete" are harmful to autistic people. Critics of the puzzle piece symbol instead advocate for a gold-colored or red infinity symbol representing diversity.[30] In 2017, the journal Autism concluded that the use of the jigsaw puzzle evoked negative public perception towards autistic individuals. They removed the puzzle piece from their cover in February 2018." (wikipedia.org)
  • Condition: New
  • Brand: Discovery
  • Year: 2020
  • Number of Pieces: 26 - 99 Pieces
  • Color: Multi-Color
  • Theme: Space
  • Features: Complete, Never Worked, Lenticular, STEM Activity
  • Material: Cardboard
  • Country/Region of Manufacture: China

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