Since 1958,NASA has overseen more than 1,000uncrewed missions into Earth orbit or beyond.[1] It has both launched its own missions and provided funding for private-sector missions. A number of NASA missions, including theExplorers Program,Voyager program, andNew Frontiers program, are ongoing.
The Explorer program has launched more than 90 missions since it began more than five decades ago. It has matured into one of NASA's lower-cost mission programs.[2]
The program started as a U.S. Army proposal to place a scientific satellite into orbit during theInternational Geophysical Year (1957–58). However, that proposal was rejected in favor of the U.S. Navy'sProject Vanguard. The Explorer program was later reestablished to catch up with the Soviet Union after the launch ofSputnik 1 in October 1957.Explorer 1 was launched January 31, 1958; at this time the project still belonged to theArmy Ballistic Missile Agency (ABMA) and theJet Propulsion Laboratory (JPL).[3] Besides being the first U.S. satellite, it is known for discovering theVan Allen radiation belt.[4]
The Explorer program was later transferred to NASA, which continued to use the name for an ongoing series of relatively small space missions, typically an artificial satellite with a science focus. Over the years, NASA has launched a series of Explorer spacecraft carrying a wide variety of scientific investigations.
The Pioneer program was a series of NASA uncrewed space missions designed for planetary exploration. There were a number of missions in the program, most notablyPioneer 10 andPioneer 11, which explored the outer planets and left theSolar System. Both carry agolden plaque, depicting a man and a woman and information about the origin and the creators of the probes, should anyextraterrestrials find them someday.[5]
Additionally, thePioneer mission to Venus consisted of two components, launched separately. Pioneer Venus 1 (Pioneer Venus Orbiter) was launched in May 1978 and remained in orbit until 1992. Pioneer Venus 2 (Pioneer Venus Multiprobe), launched in August 1978, sent four small probes into the Venusian atmosphere.[6]
Project Echo was the first passivecommunications satellite experiment. Each spacecraft was a metalizedballoon satellite to be inflated in space and acting as a passivereflector ofmicrowave signals. Communication signals were bounced off of them from one point on Earth to another.[7]NASA's Echo 1 satellite was built byGilmore Schjeldahl Company inNorthfield, Minnesota. Following the failure of theDelta rocket carrying Echo 1 on May 13, 1960, Echo 1A was put successfully into orbit by another Thor-Delta,[8][9] and the first microwave transmission was received on August 12, 1960.
Echo 2 was a 41.1-meter (135 ft) diametermetalized PET film balloon, which was the last balloon satellite launched by Project Echo.[10] It used an improved inflation system to improve the balloon's smoothness andsphericity.[11] It was launched January 25, 1964, on aThor Agena rocket.
The Ranger program was a series ofuncrewed space missions by the United States in the 1960s whose objective was to obtain the first close-up images of the surface of theMoon. The Ranger spacecraft were designed to take images of the lunar surface, returning those images until they were destroyed upon impact. A series of mishaps, however, led to the failure of the first five flights.[12] Congress launched an investigation into "problems of management" at NASA Headquarters and JPL.[13] After reorganizing the organization twice,Ranger 7 successfully returned images in July 1964, followed by two more successful missions.
Ranger was originally designed, beginning in 1959, in three distinct phases, called "blocks." Each block had different mission objectives and progressively more advanced system design. TheJPL mission designers planned multiple launches in each block, to maximize the engineering experience and scientific value of the mission and to assure at least one successful flight.[14] Total research, development, launch, and support costs for the Ranger series of spacecraft (Rangers 1 through 9) was approximately $170 million.[15]
Telstar was not a NASA program but rather a commercial communication satellite project. NASA's contributions to it were limited to launch services, as well as tracking and telemetry duties. The first two Telstar satellites were experimental and nearly identical. Telstar 1 was launched on top of aThor-Delta rocket on July 10, 1962. It successfully relayed through space the first television pictures, telephone calls, andfax images, as well as providing the first live transatlantic television feed. Telstar 2 was launched May 7, 1963.[11]
Bell Telephone Laboratories designed and built the Telstar satellites. They were prototypes intended to prove various concepts behind the large constellation of orbiting satellites. Bell Telephone Laboratories also developed much of the technology required for satellite communication, includingtransistors,solar cells, andtraveling wave tube amplifiers.AT&T built ground stations to handle Telstar communications.[11]
The Mariner program conducted by NASA launched a series ofroboticinterplanetary probes designed to investigateMars,Venus andMercury. The program included a number of firsts, including the firstplanetary flyby,[16] the first pictures from another planet, the first planetaryorbiter,[17] and the first interplanetarygravity assist maneuver,[18] which spent more than 13 years in orbit aroundSaturn.
All Mariner spacecraft were based on a hexagonal or octagonal "bus", which housed all of the electronics, and to which all components were attached, such as antennae, cameras, propulsion, and power sources. All probes exceptMariner 1,Mariner 2 andMariner 5 had TV cameras. The first five Mariners were launched onAtlas-Agenarockets, while the last five used theAtlas-Centaur.
The Lunar Orbiter program was a series of fiveuncrewedlunar orbiter missions launched by theUnited States, starting in 1966. It was intended to help select landing sites for theApollo program by mapping the Moon's surface.[19] The program produced the first photographs ever taken from lunar orbit.
All five missions were successful, and 99% of the Moon was mapped from photographs taken with a resolution of 60 meters (200 ft) or better. The first three missions were dedicated to imaging 20 potential human lunar landing sites, selected based on Earth-based observations. These were flown at low inclination orbits. The fourth and fifth missions were devoted to broader scientific objectives and were flown in high-altitude polar orbits.[20] All Lunar Orbiter craft were launched by anAtlas-Agena D launch vehicle.
During the Lunar Orbiter missions, the first pictures of Earth as a whole were taken, beginning with Earth-rise over the lunar surface by Lunar Orbiter 1 in August 1966. The first full picture of the whole Earth was taken by Lunar Orbiter 5 on August 8, 1967.[21] A second photo of the whole Earth was taken by Lunar Orbiter 5 on November 10, 1967.
The Surveyor Program was a NASA program that, from 1966 through 1968, sent sevenrobotic spacecraft to the surface of theMoon. Its primary goal was to demonstrate the feasibility of softlandings on the Moon. The program was implemented by NASA'sJet Propulsion Laboratory (JPL) to prepare for theApollo program.[22] The total cost of the Surveyor program was officially $469 million.[23]
Five of the Surveyor craft successfully soft-landed on the Moon. Two failed: Surveyor 2 crashed at high velocity after a failed mid-course correction, and Surveyor 4 was lost for contact 2.5 minutes before its scheduled touch-down.[22]
All seven spacecraft are still on the Moon; none of the missions included returning them to Earth. Some parts ofSurveyor 3 were returned to Earth by the crew ofApollo 12, which landed near it in 1969.
Helios I and Helios II, also known as Helios-A and Helios-B, were a pair of space probes launched intoheliocentric orbit for the purpose of studyingsolar processes. A joint venture of theFederal Republic of Germany (West Germany) and NASA, the probes were launched fromCape Canaveral Air Force Station, Florida, on December 10, 1974, and January 15, 1976, respectively. Helios 2 set a maximum speed record among spacecraft at about 247,000 kilometers per hour (153,000 mph) relative to the Sun (68.6 kilometers per second (42.6 mi/s) or 0.000229c).[24] The Helios space probes completed their primary missions by the early 1980s, but they continued to send data up to 1985. The probes are no longer functional but still remain in their elliptical orbit around the Sun.
The Viking program consisted of a pair of American space probes sent to Mars—Viking 1 andViking 2. Each vehicle was composed of two main parts, an orbiter designed to photograph the surface of Mars fromorbit, and a lander designed to study the planet from the surface. The orbiters also served as communication relays for the landers once they touched down.Viking 1 waslaunched on August 20, 1975, and the second craft,Viking 2, was launched on September 9, 1975, both riding atopTitan III-E rockets withCentaur upper stages.[25][26] By discovering many geological forms that are typically formed from large amounts of water, the Viking program caused a revolution in scientific ideas aboutwater on Mars.
The primary objectives of the Viking orbiters were to transport the landers to Mars, perform reconnaissance to locate and certify landing sites, act as communications relays for the landers, and to perform their own scientific investigations. The orbiter, based on the earlierMariner 9 spacecraft, was anoctagon approximately 2.5 m (8.2 ft) across. The total launch mass was 2,328 kilograms (5,132 lb), of which 1,445 kilograms (3,186 lb) were propellant and attitude control gas.[25]
The Voyager program consists of a pair of uncrewed scientificprobes,Voyager 1 andVoyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s. Although they were originally designated to study justJupiter andSaturn,Voyager 2 was able to continue to Uranus and Neptune. Both missions have gathered large amounts of data about thegas giants of theSolar System, of which little was previously known.[27] Both probes have achieved escape velocity from the Solar System and will never return.Voyager 1 enteredinterstellar space in 2012.[28]
As of January 19, 2019[update],Voyager 1 was at a distance of 145.148 AU (13.492 billion miles (21.713×10^9 km)) from Earth, traveling away from theSun at a speed of about 10.6 mi/s (17.1 km/s), which corresponds to a greaterspecific orbital energy than any other probe.[29]
The first ofNASA's three High Energy Astronomy Observatories, HEAO 1, launched August 12, 1977, aboard anAtlas rocket with aCentaur upper stage, operated until January 9, 1979. During that time, it scanned theX-ray sky almost three times over 0.2 keV – 10 MeV, provided nearly constant monitoring of X-ray sources near the ecliptic poles, as well as more detailed studies of a number of objects through pointed observations.[30]
HEAO included four large X-ray and gamma-ray astronomy instruments, known as A1, A2, A3, and A4, respectively (before launch, HEAO 1 was known as HEAO A). The orbital inclination was about 22.7 degrees.[31] HEAO 1re-entered the Earth's atmosphere on March 15, 1979.
The Solar Maximum Missionsatellite (or SolarMax) was designed to investigate solar phenomena, particularlysolar flares. It was launched on February 14, 1980.
Although not unique in this endeavor, the SMM was notable in that its useful life compared with similarspacecraft was significantly increased by the direct intervention of a human space mission. DuringSTS-41-C in 1984, theSpace ShuttleChallenger intercepted the SMM, maneuvering it into the shuttle's payload bay for maintenance and repairs. SMM had been fitted with a shuttle "grapple fixture" so that the shuttle'srobot arm could grab it for repair.[32]
The Solar Maximum Mission ended on December 2, 1989, when the spacecraft re-entered the atmosphere and burned up.[33]
The Infrared Astronomical Satellite (IRAS) was the first-ever space-basedobservatory to perform asurvey of the entiresky atinfraredwavelengths.[34] It discovered about 350,000 sources, many of which are still awaiting identification. New discoveries included a dust disk aroundVega and the first images of theMilky Way Galaxy's core.
IRAS's life, like those of most infrared satellites that followed it, was limited by its cooling system. To effectively work in the infrared domain, the telescope must be cooled to cryogenic temperatures.Superfluidhelium kept IRAS at a temperature of 2kelvins (about −271 °C) byevaporation.[35] The supply of liquid helium was depleted on November 21, 1983, preventing further observations.[36] The spacecraft continues to orbit close to the Earth.
The telescope was a joint project of the United States (NASA), theNetherlands (NIVR), and the United Kingdom (SERC). Over 250,000 infrared sources were observed at 12, 25, 60, and 100 micrometer wavelengths.[37]
The Magellan spacecraft was a space probe sent to the planet Venus, the first uncrewed interplanetary spacecraft to be launched by NASA since its successfulPioneer Orbiter, also to Venus, in 1978. It was also the first deep-space probe to be launched on the Space Shuttle.[38] In 1993, it employedaerobraking techniques to lower its orbit. This was the first prolonged use of the technique, which had been tested byHiten in 1991.[39]
Magellan created the first (and currently the best) high-resolution mapping of the planet's surface features. Prior Venus missions had created low-resolution radar globes of general, continent-sized formations. Magellan, performed detailed imaging and analysis of craters, hills, ridges, and other geologic formations, to a degree comparable to the visible-light photographic mapping of other planets.
Galileo was an uncrewed spacecraft sent by NASA to study the planetJupiter and itsmoons. It was launched on October 18, 1989, by theSpace ShuttleAtlantis on theSTS-34 mission. It arrived at Jupiter on December 7, 1995, viagravitational assist flybys of Venus and Earth.[40]
Despite antenna problems,Galileo conducted the firstasteroid flyby, discovered the firstasteroid moon, was the first spacecraft to orbit Jupiter, and launched the first probe into Jupiter'satmosphere. Galileo's prime mission was a two-year study of the Jovian system. The spacecraft traveled around Jupiter in elongatedellipses, each orbit lasting about two months. The differing distances from Jupiter afforded by these orbits allowedGalileo to sample different parts of the planet's extensivemagnetosphere. The orbits were designed for close up flybys of Jupiter's largest moons. OnceGalileo's prime mission was concluded, an extended mission followed starting on December 7, 1997; the spacecraft made a number of close flybys of Jupiter's moonsEuropa andIo.[40]
On September 21, 2003,Galileo's mission was terminated by sending the orbiter into Jupiter's atmosphere at a speed of nearly 50 kilometers per second. The spacecraft was low on propellant; another reason for its destruction was to avoid contamination of local moons, such as Europa, with bacteria from Earth.[41]
The Hubble Space Telescope (HST) is aspace telescope that was carried intoorbit by a Space Shuttle in April 1990. It is named after AmericanastronomerEdwin Hubble. Although not the first space telescope, Hubble is one of the largest and most versatile, and is well known as both a vital research tool and a public relations boon forastronomy. The HST is a collaboration between NASA and theEuropean Space Agency, and is one of NASA'sGreat Observatories, along with theCompton Gamma Ray Observatory, theChandra X-ray Observatory, and theSpitzer Space Telescope.[42] The HST's success has paved the way for greater collaboration between the agencies.
The HST was created with a budget of $2 billion[43] and has continued operation since 1990, delighting both scientists and the public. Some of its images, such as theHubble Deep Field, have become famous.
Ulysses is a decommissionedroboticspace probe that was designed to study theSun as a joint venture of NASA and theEuropean Space Agency (ESA).Ulysses was launched on October 6, 1990, aboardDiscovery (missionSTS-41). The spacecraft's mission was to study the Sun at all latitudes. This required a major orbital plane shift, which was accomplished by using an encounter with Jupiter. The need for a Jupiter encounter meant thatUlysses could not be powered by solar cells and was powered by aradioisotope thermoelectric generator (RTG) instead.[44]
By February 2008, the power output from theRTG, which is generated by heat from radioactive decay, had decreased enough to leave insufficient power to keep the spacecraft'sattitude control hydrazine fuel from freezing. Mission scientists kept the fuel liquid by conducting short thruster burns, allowing the mission to continue.[45][46][47] The cessation of mission operations and deactivation of the spacecraft was determined by the inability to prevent attitude control fuel from freezing.[45][48] The last day for mission operations onUlysses was June 30, 2009.[49][50]
The Upper Atmosphere Research Satellite (UARS) was a science satellite used from 1991 to 2005 to study Earth's atmosphere, including theozone layer. Planned for a three-year mission, it proved much more durable, allowing extended observation from its instrument suite. It was launched aboardSpace ShuttleDiscovery and deployed into space from the payload bay with its robotic arm, under guidance from the crew. The satellite underwent atmospheric re-entry at about 04:00 24 September 2011UTC.[51] At about 6 tonnes, it was the heaviest NASA satellite to undergo uncontrolled atmospheric entry sinceSkylab in the summer of 1979.[52]
NASA's Discovery Program (as compared toNew Frontiers orFlagship Programs) is a series of lower-cost, highly focused scientific space missions that are exploring the Solar System. It was founded in 1992 to implement then-NASA AdministratorDaniel S. Goldin's vision of "faster, better, cheaper" planetary missions. Discovery missions differ from traditional NASA missions where targets and objectives are pre-specified. Instead, these cost-capped missions are proposed and led by a scientist called thePrincipal investigator (PI). Proposing teams may include people from industry, small businesses, government laboratories, and universities. Proposals are selected through a competitive peer review process. The Discovery missions are adding significantly to the body of knowledge about the Solar System.
NASA also accepts proposals for competitively selected Discovery Program Missions of Opportunity. This provides opportunities to participate in non-NASA missions by providing funding for a science instrument or hardware components of a science instrument or to re-purpose an existing NASA spacecraft.
Missions funded by NASA through this program includeMars Pathfinder,Kepler,Stardust,Genesis andDeep Impact.
TheMars Pathfinder (MESUR Pathfinder[53]) was launched on December 4, 1996, just a month after the Mars Global Surveyor was launched. On board thelander, later renamed the Carl Sagan Memorial Station, was a smallrover calledSojourner that executed many experiments on the Martian surface.[54] It was the second project from NASA'sDiscovery Program. The mission was directed by the Jet Propulsion Laboratory, a division of theCalifornia Institute of Technology, responsible for NASA'sMars Exploration Program.
Stardust was a 300-kilogramroboticspace probe launched by NASA on February 7, 1999, to study theasteroid5535 Annefrank and collect samples from thecoma ofcometWild 2. The primary mission was completed January 15, 2006, when thesample return capsule returned to Earth.[55] Stardust intercepted cometTempel 1 on February 15, 2011, asmall Solar System body previously visited byDeep Impact on July 4, 2005. Stardust was decommissioned on March 25, 2011.[56] It is the firstsample return mission to collectcosmic dust.
TheGenesis spacecraft was a NASAsample return probe which collected a sample ofsolar wind and returned it toEarth for analysis. It was the first NASA sample return mission to return material since theApollo Program, and the first to return material from beyond the orbit of theMoon.[57] Genesis was launched on August 8, 2001, and crash-landed inUtah on September 8, 2004, after a design flaw prevented the deployment of itsdrogue parachute.[58] The crash contaminated and damaged many of the sample collectors, but many of them were successfully recovered.[59]
Deep Impact is a NASAspace probe launched on January 12, 2005. It was designed to study the composition of the interior of comet9P/Tempel, by releasing an impactor into the comet. On July 4, 2005, the impactor successfully collided with the comet'snucleus, excavating debris from the interior of the nucleus. Photographs of the debris and impact crater showed that the comet was very porous and its outgassing was chemically diverse.[60]
Kepler is aspace observatory launched by NASA to discoverEarth-like planets orbiting other stars. The spacecraft, named in honor of the 17th-century German astronomerJohannes Kepler,[61] was launched in March 2009.[62] Kepler's primary mission ended in May 2013 when it lost a secondreaction wheel. The telescope's second mission, K2, began in May 2014.[63] As of February 2018, Kepler has discovered more than 2000 exoplanets.[64]
Clementine (officially called the Deep Space Program Science Experiment (DSPSE)) was a joint space project between theBallistic Missile Defense Organization (BMDO, previously theStrategic Defense Initiative Organization, or SDIO) and NASA. Launched on January 25, 1994, the objective of the mission was to test sensors and spacecraft components under extended exposure to the space environment and to make scientific observations of theMoon and thenear-Earth asteroid1620 Geographos. The Geographos observations were not made due to a malfunction in the spacecraft.[65]
TheMars Global Surveyor (MGS) was developed by NASA's Jet Propulsion Laboratory and launched November 1996. It began the United States' return to Mars after a 10-year absence. It completed its primary mission in January 2001 and was in its third extended mission phase when, on November 2, 2006, the spacecraft failed to respond to commands. In January 2007 NASA officially ended the mission.[66]
TheSurveyor spacecraft used a series of high-resolution cameras to explore the surface of Mars, returning more than 240,000 images from September 1997 to November 2006.[67] The surveyor had three cameras; a high-resolution camera took black-and-white images (usually 1.5 to 12 m per pixel), and red and blue wide-angle cameras took images for context (240 m per pixel) and daily global images (7.5 kilometers (4.7 mi) per pixel).[68]
Cassini–Huygens was a joint NASA/ESA/ASI spacecraft mission studying the planetSaturn and its manynatural satellites. It included a Saturn orbiter and an atmospheric probe/lander for the moonTitan, although it also returned data on a wide variety of other things including theHeliosphere,Jupiter, andrelativity tests. The Titan probe,Huygens, entered and landed on Titan in 2005.Cassini was the fourth space probe to visit Saturn and the first to enter orbit.
It launched on October 15, 1997, on aTitan IVB/Centaur and entered into orbit around Saturn on July 1, 2004, after an interplanetary voyage which included flybys of Earth, Venus, and Jupiter. On December 25, 2004,Huygens separated from the orbiter at approximately 02:00UTC. It reached Saturn's moonTitan on January 14, 2005, when it entered Titan's atmosphere and descended down to the surface. It successfully returned data to Earth, using the orbiter as a relay.[69] This was the firstlanding ever accomplished in theouter Solar System.
Sixteen European countries and the United States made up the team responsible for designing, building, flying and collecting data from theCassini orbiter and Huygens probe. The mission was managed by NASA'sJet Propulsion Laboratory in the United States, where the orbiter was assembled.Huygens was developed by theEuropean Space Research and Technology Centre.[70]
After several mission extensions,Cassini was deliberately plunged into Saturn's atmosphere on September 15, 2017, to prevent contamination of habitable moons.[71]
The Earth Observing System (EOS) is a program ofNASA comprising a series ofartificial satellite missions and scientific instruments inEarthorbit designed for long-term global observations of the land surface,biosphere,atmosphere, and oceans of the Earth. The satellite component of the program was launched in 1997. The program is the centerpiece of NASA'sEarth Science Enterprise (ESE). Missions carried out through this program includeSeaWiFS (1997),Landsat 7 (1999),QuikSCAT (1999),Jason 1 (2001),GRACE (2002),Aqua (2002),Aura (2004) andAquarius (2011).
New Millennium Program (NMP) is a NASA project with a focus on engineering validation of new technologies for space applications. Funding for the program was eliminated from the FY2009 budget by the110th United States Congress, effectively leading to its cancellation.[72] The spacecraft in the New Millennium Program were originally named "Deep Space" (for missions demonstrating technology for planetary missions) and "Earth Observing" (for missions demonstrating technology for Earth-orbiting missions). With a refocusing of the program in 2000, the Deep Space series was renamed "Space Technology."
Deep Space 1 (DS1) is aspacecraft dedicated to testing a payload of advanced, high-risk technologies. Launched on October 24, 1998, the Deep Space 1 mission carried out a flyby ofasteroid9969 Braille, the mission's science target. Its mission was extended twice to include an encounter withComet Borrelly and further engineering testing. Problems during its initial stages and with its star tracker led to repeated changes in mission configuration.[73] Deep Space 1 tested twelve technologies.[74] It was the first spacecraft to useion thrusters, in contrast to the traditional chemical powered rockets.[75]
The Deep Space series was continued by theDeep Space 2 probes, which were launched in January 1999 onMars Polar Lander and were intended to strike the surface of Mars.
The Gravity Recovery and Climate Experiment (GRACE), a joint mission of NASA and theGerman Aerospace Center, made detailed measurements ofEarth's gravity field from its launch in March 2002 until October 2017.[76] The satellites were launched fromPlesetsk Cosmodrome, Russia on aRockot launch vehicle. By measuring gravity, GRACE showed how mass is distributed around the planet and how it varies over time. Data from the GRACE satellites is an important tool for studying Earth's ocean, geology, andclimate.[77]
GRACE was a collaborative endeavor involving the Center for Space Research at theUniversity of Texas, Austin; NASA'sJet Propulsion Laboratory, Pasadena, Calif.; the German Space Agency and Germany's National Research Center for Geosciences, Potsdam.[78] The Jet Propulsion Laboratory was responsible for the overall mission management under the NASA ESSP program.[79]
NASA's Mars Exploration Rover Mission (MER), was a robotic space mission involving two rovers exploring the planet Mars. The mission is managed for NASA by the Jet Propulsion Laboratory, which designed, built and is operating the rovers.
The mission began in 2003 with the sending of the tworovers—MER-ASpirit and MER-BOpportunity—to explore the Martian surface and geology. The mission's scientific objective is to search for and studyrocks andsoils that indicate past water activity. The mission is part of NASA's Mars Exploration Program which includes three previous successful landers: the twoViking program landers in 1976 andMars Pathfinder probe in 1997.[80]
The total cost of building, launching, landing and operating the rovers on the surface for the initial 90-Martian-day (sol) primary mission was US$820 million.[81] However, both rovers were able to continue functioning beyond the initial 90-day mission, and received multiple mission extensions. TheSpirit rover remained operational until 2009, while theOpportunity rover remained operational until 2018.
MESSENGER (an acronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging) was a robotic spacecraft that orbited the planetMercury, the first spacecraft to do so.[82] The 485-kilogram (1,069 lb) spacecraft was launched aboard aDelta II rocket in August 2004 to study Mercury's chemical composition,geology, andmagnetic field.
MESSENGER used its instruments on a complex series offlybys that allowed it to decelerate relative to Mercury using minimal fuel. The spacecraft flew by Earth once andVenus twice. Then it flew by Mercury three times, in January 2008, October 2008,[83] and September 2009,[84][85] becoming the second mission to reach Mercury, afterMariner 10.MESSENGER entered orbit around Mercury on March 18, 2011, and it reactivated its science instruments on March 24, returning the first photo from Mercury orbit on March 29.
MESSENGER crashed into Mercury on April 30, 2015, after running out of propellant.[86]
The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of researching several of theSun's planets includingJupiter,Venus, and thedwarf planetPluto. NASA is encouraging both domestic and international scientists to submit mission proposals for the project.
New Frontiers was built on the approach used by theDiscovery andExplorer Programs ofprincipal investigator-led missions. It is designed for medium-class missions that could not be accomplished within the cost and time constraints of the Discovery Program, but are not as large as Flagship-class missions. There are currently three New Frontiers missions in progress.New Horizons was launched on January 19, 2006, and flew by Pluto in July 2015. A flyby of486958 Arrokoth took place in 2019.[87]Juno was launched on August 5, 2011, and entered orbit around Jupiter on July 4, 2016.[88]OSIRIS-REx, launched on September 8, 2016, plans on returning a sample to Earth on September 24, 2023,[89] and if successful, would be the first U.S. spacecraft to do so.
The development of theCommercial Resupply Services (CRS) vehicles began in 2006 with the purpose of creating American commercially operated uncrewed cargo vehicles to service the ISS.[90] The development of these vehicles was under a fixed-price, milestone-based program, meaning that each company that received a funded award had a list of milestones with a dollar value attached to them that they did not receive until after they had successfully completed the milestone.[91] Companies were also required to raise an unspecified amount of private investment for their proposal.[92]
On December 23, 2008, NASA awarded Commercial Resupply Services contracts toSpaceX andOrbital Sciences Corporation.[93] SpaceX uses itsFalcon 9 rocket andDragon spacecraft.[94] Orbital Sciences uses itsAntares rocket andCygnus spacecraft. Thefirst Dragon resupply mission occurred in May 2012.[95] Thefirst Cygnus resupply mission occurred in September 2013.[96] The CRS program now provides for all America's ISS cargo needs, with the exception of a few vehicle-specific payloads that are delivered on the EuropeanATV and the JapaneseHTV.[97]
The Mars Scout Program was aNASA initiative to send a series of small, low-cost robotic missions toMars, competitively selected from proposals by the scientific community. Each Scout project was to cost less than US$485 million. ThePhoenix lander andMAVEN orbiter were selected and developed before the program was retired in 2010.[98]
Phoenix was alander adapted from the canceledMars Surveyor mission.Phoenix was launched on August 4, 2007, and landed in the icy northern polar region of the planet on May 25, 2008. Phoenix was designed to search for environments suitable formicrobiallife on Mars and to research the history ofwater there.[99] The 90-day primary mission was successful, and the overall mission was concluded on November 10, 2008, after engineers were unable to contact the craft. The lander last made a brief communication with Earth on November 2, 2008.[100]
Dawn is a NASA spacecraft tasked with the exploration and study of theasteroidVesta and thedwarf planetCeres, the two largest members of theasteroid belt. The spacecraft was constructed with some European cooperation, with components contributed by partners in Germany, Italy, and theNetherlands. TheDawn mission is managed by NASA'sJet Propulsion Laboratory.[101]
Dawn is the first spacecraft to visit either Vesta or Ceres. It is also the first spacecraft to orbit two separate extraterrestrial bodies, usingion thrusters to travel between its targets. Previous multi-target missions using conventional drives, such as theVoyager program, were restricted toflybys.[102]
Launched on September 27, 2007,Dawn entered orbit around Vesta on July 16, 2011, and explored it until September 5, 2012.[103] Thereafter, the spacecraft headed to Ceres and started to orbit the dwarf planet on March 6, 2015.[104] In November 2018, NASA reported thatDawn had run out of fuel, effectively ending its mission; it will remain in orbit around Ceres, but can no longer communicate with Earth.[105]
The Lunar Reconnaissance Orbiter (LRO) is a NASArobotic spacecraft currently orbiting theMoon on a low50 km polar mapping orbit.[106]The LRO mission is a precursor to future human missions to the Moon by NASA. To this end, a detailed mapping program identifies safe landing sites, locates potential resources on the Moon, characterizes the radiation environment, and demonstrates new technology.[107][108]The probe has made a 3-D map of the Moon's surface and has provided some of the first images of Apollo equipmentleft on the Moon.[109][110]The first images from LRO were published on July 2, 2009, showing a region in the lunar highlands south ofMare Nubium (Sea of Clouds).[111]
Launched on June 18, 2009,[112] in conjunction with theLunar Crater Observation and Sensing Satellite (LCROSS), as the vanguard of NASA'sLunar Precursor Robotic Program,[113] this is the first United States mission to the Moon in over ten years.[114]LRO and LCROSS are the first missions launched as part of the United States'sVision for Space Exploration program.
In April 2022, NASA extended the LRO mission for it to continue to study the Moon's surface and geologic features and also investigate new regions enabled with the evolution of LRO's orbit[115]
Mars Science Laboratory (MSL) is a NASA mission to land and operate arover namedCuriosity on the surface ofMars.[116] It was launched by anAtlas V rocket on November 26, 2011,[117][118] and landed successfully on August 6, 2012, on the plains ofAeolis Palus inGale Crater nearAeolis Mons (formerlyMount Sharp).[119][120][121][122] On Mars, it is helping to assess Mars'habitability. It can chemically analyze samples by scooping up soil and drillingrocks using a laser and sensor system.[123]
TheCuriosity rover is about two times longer and fives times more massive than theSpirit orOpportunity Mars Exploration Rovers[123] and carries more than ten times the mass of scientific instruments.[118]
.png)
Mars 2020 is aMars rover mission byNASA'sMars Exploration Program that includes thePerseverance rover which launched on 30 July 2020 at 11:50 UTC, and has touched down inJezero crater on Mars on 18 February 2021 and deployed theIngenuity helicopter on 4 April 2021.[124][125] It will investigate anastrobiologically relevant ancient environment on Mars and investigate its surfacegeological processes and history, including the assessment of its pasthabitability, the possibility of pastlife on Mars, and the potential for preservation ofbiosignatures within accessible geological materials.[126][127] It will cache sample containers along its route for a potential futureMars sample-return mission.[127][128][129] The Mars 2020 mission was announced by NASA on 4 December 2012 at the fall meeting of theAmerican Geophysical Union in San Francisco.[130] ThePerseverance rover's design is derived from theCuriosity rover, and will use many components already fabricated and tested, new scientific instruments and acore drill.[131]
Commercial Lunar Payload Services (CLPS) is aNASA program to hire companies to send small robotic landers and rovers to theMoon'ssouth polar region, mostly[132][133] with the goals of scouting forlunar resources, testingin situ resource utilization (ISRU) concepts, and performing lunar science to support theArtemis lunar program. CLPS is intended to buy end-to-end payload services between Earth and the lunar surface usingfixed-price contracts.[134] The program was extended to add support for large payloads starting after 2025.
Clearly visible on the left side of the globe is the eastern half of Africa and the entire Arabian peninsula.
Just as in the COTS projects, in the CCDev project we have fixed-price, pay-for-performance milestones" Thorn said. "There's no extra money invested by NASA if the projects cost more than projected.
Using spare parts and mission plans developed for NASA's Curiosity Mars rover, the space agency says it can build and launch the rover in 2020 and stay within current budget guidelines.
