NASA

The National Aeronautics and Space Administration (NASA /ˈnæsə/) is an independent agency of the United States Federal Government responsible for the civilian space program, as well as aeronautics and aerospace research.[note 1]

National Aeronautics and Space Administration (NASA)
Seal
Emblem

Flag
Agency overview
FormedJuly 29, 1958 (1958-07-29)
Preceding agency
  • NACA (1915–1958)[1]
JurisdictionUS Federal Government
HeadquartersTwo Independence Square, Washington, D.C.,
United States
38°52′59″N 77°0′59″W
MottoFor the Benefit of All[2]
Employees17,373 (2020)[3]
Annual budget US$22.629 billion (2020)[4]
Agency executives
WebsiteNASA.gov

NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA). The new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science.[7][8][9] Since its establishment, most US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, and later the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for uncrewed NASA launches.

NASA science is focused on better understanding Earth through the Earth Observing System;[10] advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program;[11] exploring bodies throughout the Solar System with advanced robotic spacecraft missions such as New Horizons;[12] and researching astrophysics topics, such as the Big Bang, through the Great Observatories and associated programs.[13]

Creation

Since 1946, the National Advisory Committee for Aeronautics (NACA) had been experimenting with rocket planes such as the supersonic Bell X-1.[14] In the early 1950s, there was a challenge to launch an artificial satellite for the International Geophysical Year (1957–58), resulting in the American Project Vanguard among others. After the Soviet 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 and his advisers counseled more deliberate measures. On January 12, 1958, NACA organized a "Special Committee on Space Technology", headed by Guyford Stever.[9] On January 14, 1958, NACA Director Hugh Dryden published "A National Research Program for Space Technology" stating:[15]

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.[15]

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.[16]

On July 29, 1958, Eisenhower signed the National Aeronautics and Space Act, establishing NASA. 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.[17] A NASA seal was approved by President Eisenhower in 1959.[18] 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.[19] Earlier research efforts within the US Air Force[17] and many of ARPA's early space programs were also transferred to NASA.[20] In December 1958, NASA gained control of the Jet Propulsion Laboratory, a contractor facility operated by the California Institute of Technology.[17]

Leadership

Jim Bridenstine official NASA portrait, April 26, 2018 at NASA Headquarters, Washington D.C.

The agency's leader, NASA's administrator, is nominated by the President of the United States subject to approval of the US Senate, and reports to him or her and serves as senior space science advisor. Though space exploration is ostensibly non-partisan, the appointee usually is associated with the President's political party (Democratic or Republican), and a new administrator is usually chosen when the Presidency changes parties. The only exceptions to this have been:

  • Democrat Thomas O. Paine, acting administrator under Democrat Lyndon B. Johnson, stayed on while Republican Richard Nixon tried but failed to get one of his own choices to accept the job. Paine was confirmed by the Senate in March 1969 and served through September 1970.[21]
  • Republican James C. Fletcher, appointed by Nixon and confirmed in April 1971, stayed through May 1977 into the term of Democrat Jimmy Carter.
  • Daniel Goldin was appointed by Republican George H. W. Bush and stayed through the entire administration of Democrat Bill Clinton.
  • Robert M. Lightfoot, Jr., associate administrator under Democrat Barack Obama, was kept on as acting administrator by Republican Donald Trump until Trump's own choice Jim Bridenstine, was confirmed in April 2018.[22]

The first administrator was Dr. T. Keith Glennan appointed by Republican President Dwight D. Eisenhower. During his term he brought together the disparate projects in American space development research.[23]

The second administrator, James E. Webb (1961–1968), appointed by President John F. Kennedy, was a Democrat who first publicly served under President Harry S. Truman. In order to implement the Apollo program to achieve Kennedy's Moon landing goal by the end of the 1960s, Webb directed major management restructuring and facility expansion, establishing the Houston Manned Spacecraft (Johnson) Center and the Florida Launch Operations (Kennedy) Center. Capitalizing on Kennedy's legacy, President Lyndon Johnson kept continuity with the Apollo program by keeping Webb on when he succeeded Kennedy in November 1963. But Webb resigned in October 1968 before Apollo achieved its goal, and Republican President Richard M. Nixon replaced Webb with Republican Thomas O. Paine.

Organizational structure of NASA (2015)

James Fletcher was responsible for early planning of the Space Shuttle program during his first term as administrator under President Nixon. He was appointed for a second term as administrator from May 1986 through April 1989 by President Ronald Reagan to help the agency recover from the Space Shuttle Challenger disaster.

Former astronaut Charles Bolden served as NASA's twelfth administrator from July 2009 to January 20, 2017.[24] Bolden is one of three former astronauts who became NASA administrators, along with Richard H. Truly (served 1989–1992) and Frederick D. Gregory (acting, 2005).

The agency's administration is located at NASA Headquarters in Washington, DC and provides overall guidance and direction.[25] Except under exceptional circumstances, NASA civil service employees are required to be citizens of the United States.[26]

Space flight programs

At launch control for the May 28, 1964, Saturn I SA-6 launch. Wernher von Braun is at center.
NASA is famous for the first human visits to the Moon,[27] (Apollo 8 image of Earth, 1968)

NASA has conducted many crewed and uncrewed spaceflight programs throughout its history. Uncrewed 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. Crewed programs sent the first Americans into low Earth orbit (LEO), won the Space Race with the Soviet Union by landing twelve men on the Moon from 1969 to 1972 in the Apollo program, developed a semi-reusable LEO Space Shuttle, and developed LEO space station capability by itself and with the cooperation of several other nations including post-Soviet Russia. Some missions include both crewed and uncrewed aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent uncrewed to Jupiter.

Crewed programs

The experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for crewed spaceflight. This was followed by a one-man space capsule program, and in turn by a two-man capsule program. Reacting to loss of national prestige and security fears caused by early leads in space exploration by the Soviet Union, in 1961 President John F. Kennedy proposed the ambitious goal "of landing a man on the Moon by the end of [the 1960s], and returning him safely to the Earth." This goal was met in 1969 by the Apollo program, and NASA planned even more ambitious activities leading to a human mission to Mars. However, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, and a semi-reusable Earth orbital shuttle. In the 1990s, funding was approved for NASA to develop a permanent Earth orbital space station in cooperation with the international community, which now included the former rival, post-Soviet Russia. To date, NASA has launched a total of 166 crewed space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude, 260,000 feet (80 km).[28]

X-15 rocket plane (1959–1968)

X-15 in powered flight

The North American X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force and Navy. The design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems.[29] Requests for proposal were issued on December 30, 1954, for the airframe, and February 4, 1955, for the rocket engine. The airframe contract was awarded to North American Aviation in November 1955, and the XLR30 engine contract was awarded to Reaction Motors in 1956, and three planes were built. 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).

Twelve pilots were selected for the program from the Air Force, Navy, and NACA (later NASA). A total of 199 flights were made between 1959 and 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).[30] The altitude record for X-15 was 354,200 feet (107.96 km).[31] 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.[31] The reentry and landing data collected were valuable to NASA for designing the Space Shuttle.[29]

Project Mercury (1958–1963)

John Glenn on Friendship 7: first US orbital flight, 1962

Shortly after the Space Race began, an early objective was to get a person into Earth orbit as soon as possible, therefore the simplest spacecraft that could be launched by existing rockets was favored. The US Air Force's Man in Space Soonest program considered many crewed spacecraft designs, ranging from rocket planes like the X-15, to small ballistic space capsules.[32] By 1958, the space plane concepts were eliminated in favor of the ballistic capsule.[33]

When NASA was created that same year, the Air Force program was transferred to it and renamed 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 Freedom 7, launched by a Redstone booster on a 15-minute ballistic (suborbital) flight.[34] John Glenn became the first American to be launched into orbit, by an Atlas launch vehicle on February 20, 1962, aboard Friendship 7.[35] 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.[36] Katherine Johnson, Mary Jackson, and Dorothy Vaughan were three of the human computers doing calculations on trajectories during the Space Race.[37][38][39] 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.[37]

The Soviet Union (USSR) competed with its own single-pilot spacecraft, Vostok. They sent the first man in space, by launching cosmonaut Yuri Gagarin into a single Earth orbit aboard Vostok 1 in April 1961, one month before Shepard's flight.[40] 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.

Project Gemini (1961–1966)

Ed White on Gemini 4: first US spacewalk, 1965

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 1962 to overcome the Soviets' lead and to support the 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.[41] 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.[42][43]

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. After this, the program was canceled, and Gemini caught up while spacecraft designer Sergei Korolev developed the Soyuz spacecraft, their answer to Apollo.

Apollo program (1961–1972)

Apollo 11: Buzz Aldrin on the Moon, 1969

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 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.[44]

Apollo was one of the most expensive American scientific programs ever. It cost more than $20 billion in 1960s dollars[45] or an estimated $223 billion in present-day US dollars.[46] (In comparison, the Manhattan Project cost roughly $28.4 billion, accounting for inflation.)[46][47] It used the Saturn rockets as launch vehicles, which were far bigger than the rockets built for previous projects.[48] The spacecraft was also bigger; it had two main parts, the combined command and service module (CSM) and the Apollo Lunar Module (LM). The LM was to be left on the Moon and only the command module (CM) containing the three astronauts would eventually return to Earth.[note 2]

The second crewed mission, Apollo 8, brought astronauts for the first time in a flight around the Moon in December 1968.[49] Shortly before, the Soviets had sent an uncrewed spacecraft around the Moon.[50] On the next two missions docking maneuvers that were needed for the Moon landing were practiced[51][52] and then finally the Moon landing was made on the Apollo 11 mission in July 1969.[53]

Apollo 17: Lunar Roving Vehicle-003, 1972

The first person to walk on the Moon was Neil Armstrong, who was followed 19 minutes later by Buzz Aldrin, while Michael Collins orbited above. Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972. Throughout these six 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.[54] The Moon landing marked the end of the space race; and as a gesture, Armstrong mentioned mankind when he stepped down on the Moon.[55]

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.[56] 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)

Skylab in 1974, seen from the departing Skylab 4 CSM.
Days in Space
Mission
    Skylab 2
    28
    Skylab 3
    60
    Skylab 4
    84
    Owen Garriott performing an EVA in 1973

    Skylab was the United States' first and only independently built space station.[57] 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.[57] It included a laboratory for studying the effects of microgravity, and a solar observatory.[57] NASA planned to have a 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 on July 11, 1979.[58]

    To save cost, NASA used one of the Saturn V rockets originally earmarked for a canceled Apollo mission to launch the Skylab. Apollo spacecraft were used for transporting astronauts to and from the station. Three three-man crews 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.[58]

    Apollo–Soyuz Test Project (1972–1975)

    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.[59] This authorized the Apollo-Soyuz Test Project (ASTP), involving the rendezvous and docking in Earth orbit of a surplus Apollo Command/Service Module with a Soyuz spacecraft. The mission took place in July 1975. This was the last US crewed space flight until the first orbital flight of the Space Shuttle in April 1981.[60]

    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[61] and the International Space Station.

    Space Shuttle program (1972–2011)

    NASA officials and politicians welcome the arrival of Spacelab in 1982

    The Space Shuttle became the major focus of NASA in the late 1970s and the 1980s. Planned as a frequently launchable and mostly reusable vehicle, four Space Shuttle orbiters were built by 1985. The first to launch, Columbia, did so on April 12, 1981,[62] the 20th anniversary of the first known human space flight.[63]

    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)[64] and carry a maximum payload (to low orbit) of 24,400 kg (54,000 lb).[65] Missions could last from 5 to 17 days and crews could be from 2 to 8 astronauts.[64]

    Mae Jemison working in Spacelab. Spacelab was a major NASA collaboration with space agencies in Europe, who constructed the space laboratory and many of its modular additions.

    On 20 missions (1983–98) 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.[66] On June 18, 1983 Sally Ride became the first American woman in space, on board the Space Shuttle Challenger STS-7 mission.[67] Another famous series of missions were the launch and later successful repair of the Hubble Space Telescope in 1990 and 1993, respectively.[68]

    Launch of a Space Shuttle in 2008

    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). 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.[69] 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.[69] 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 over 300 astronauts sent into space.[70]

    International Space Station (1993–present)

    Animation of assembly of the ISS

    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.[71] 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).[72][73] 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.[71] It is currently being assembled in Low Earth Orbit. The on-orbit assembly began in 1998, the completion of the US Orbital Segment occurred in 2019 and the completion of the Russian Orbital Segment is expected by 2020s.[74][75] The ownership and use of the space station is established in intergovernmental treaties and agreements[76] which divide the station into two areas and allow Russia to retain full ownership of the Russian Orbital Segment (with the exception of Zarya),[77][78] with the US Orbital Segment allocated between the other international partners.[76]

    Long-duration missions to the ISS are referred to as ISS Expeditions. Expedition crew members typically spend approximately six months on the ISS.[79] 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.[80] Crew size is expected to be increased to seven, the number the ISS was designed for, once the Commercial Crew Program becomes operational.[81] The ISS has been continuously occupied for the past 19 years and 175 days, having exceeded the previous record held by Mir; and has been visited by astronauts and cosmonauts from 15 different nations.[82][83]

    The International Space Station as seen by the final Space Shuttle mission

    The station can be seen from the Earth with the naked eye and, as of 2020, is the largest artificial satellite in Earth orbit with a mass and volume greater than that of any previous space station.[84] The Soyuz spacecraft delivers crew members, stays docked for their half-year-long missions and then returns them home. Several uncrewed cargo spacecraft service 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 American Dragon spacecraft since 2012, and the American Cygnus spacecraft since 2013. 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. Until another US crewed spacecraft is ready, crew members will travel to and from the International Space Station exclusively aboard the Soyuz.[85] The highest number of people occupying the ISS has been thirteen; this occurred three times during the late Shuttle ISS assembly missions.[86]

    The ISS program is expected to continue to 2030.[87] On March 29, 2019, the ISS had its first all-female spacewalk; Anne McClain and Christina Koch will take flight during Women's History Month.[88]

    Commercial programs (2006–present)
    Dragon being berthed to the ISS in May 2012
    Cygnus berthed to the ISS in September 2013

    The development of the Commercial Resupply Services (CRS) vehicles began in 2006 with the purpose of creating American commercially operated uncrewed cargo vehicles to service the ISS.[89] 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.[90] Companies were also required to raise an unspecified amount of private investment for their proposal.[91]

    On December 23, 2008, NASA awarded Commercial Resupply Services contracts to SpaceX and Orbital Sciences Corporation.[92] SpaceX uses its Falcon 9 rocket and Dragon spacecraft.[93] Orbital Sciences uses its Antares rocket and Cygnus spacecraft. The first Dragon resupply mission occurred in May 2012.[94] The first Cygnus resupply mission occurred in September 2013.[95] 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 European ATV and the Japanese HTV.[96]

    Dragon V2
    Rendering of CST-100

    The Commercial Crew Development (CCDev) program was started in 2010 with the purpose of creating American commercially operated crewed spacecraft capable of delivering at least four crew members to the ISS, staying docked for 180 days and then returning them back to Earth.[97] It is hoped that these vehicles could also transport non-NASA customers to private space stations such those planned by Bigelow Aerospace.[98] Like COTS, CCDev is a fixed-price, milestone-based developmental program that requires some private investment.[90]

    In 2010, when NASA announced the winners of the first phase of the program, a total of $50 million was divided among five American companies to foster research and development into human spaceflight concepts and technologies in the private sector. In 2011, the winners of the second phase of the program were announced, and $270 million was divided among four companies.[99] In 2012, the winners of the third phase of the program were announced; NASA provided $1.1 billion divided among three companies to further develop their crew transportation systems.[100] In 2014, the winners of the final round were announced.[101] SpaceX's Dragon V2 (planned to be launched on a Falcon 9 v1.1) received a contract valued up to $2.6 billion and Boeing's CST-100 (to be launched on an Atlas V) received a contract valued up to $4.2 billion.[102] NASA expects these vehicles to begin transporting humans to the ISS in 2019.[103]

    Constellation program (2005–2009) and Journey To Mars (2010–2017)

    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, return to 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.

    After the Augustine Committee found that the Constellation program could not meet its goals without substantially more funding, in February 2010, President Barack Obama's administration proposed eliminating public funds for it.[104] Obama's plan was to develop American private spaceflight capabilities to get astronauts to the International Space Station, replacing Russian Soyuz capsules, and to 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.[105] 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.[105] The NASA Authorization Act of 2010 was passed by Congress and signed into law on October 11, 2010.[106] The act officially canceled the Constellation program.[106]

    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.[107] The Orion spacecraft, which was being developed as part of the Constellation program, was chosen to fulfill this role.[108] The Space Launch System is planned to launch both Orion and other necessary hardware for missions beyond low Earth orbit.[109] 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).[108][110] 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.[110]

    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 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.

    Artemis program (2017–present)

    Artemis program logo

    Since 2017, NASA's crewed spaceflight program has been the Artemis program, which involves the help of U.S. commercial spaceflight companies and international partners such as ESA.[111] 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 private 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 is the uncrewed initial launch of SLS that would also send an Orion spacecraft on a Distant Retrograde Orbit, which is planned to launch no earlier than November 2020.[112]

    NASA's next major space initiative is to be the construction of the Lunar Gateway. This initiative is to involve the construction of a new space station, which will have many features in common with the current International Space Station, except that it will be in orbit about the Moon, instead of the Earth.[113] 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 2022.[111] This mission is to be a 10-day mission planned to briefly place a crew of four into a Lunar flyby.[110] 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.[114] 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 2030s.[115][116]

    On June 5, 2016, NASA and DARPA announced plans to also build a series of new X-planes over the next 10 years.[117] One of the planes will be the Quiet Supersonic Technology project, burning low-carbon biofuels and generating quiet sonic booms.[117]

    Uncrewed programs

    More than 1,000 uncrewed missions have been designed to explore the Earth and the solar system.[118] Besides exploration, communication satellites have also been launched by NASA.[119] The missions have been launched directly from Earth or from orbiting space shuttles, which could either deploy the satellite itself, or with a rocket stage to take it farther.

    Pioneer 3 and 4 launched in 1958 and 1959.

    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 to this day. Its missions have been focusing on the Earth and the Sun, measuring magnetic fields and the solar wind, among other aspects.[120] A more recent Earth mission, not related to the Explorer program, was the Hubble Space Telescope, which was brought into orbit in 1990.[121]

    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.

    The inner Solar System has been made the goal of at least four uncrewed 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.[122]

    The first successful landing on Mars was made by Viking 1 in 1976. Twenty years later a rover was landed on Mars by Mars Pathfinder.[123]

    Outside 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.[124] 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.[125]

    Pioneers 10 and 11 and both Voyager probes carry messages from the Earth to extraterrestrial life.[126][127] 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.[128] 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.[129]

    On November 26, 2011, NASA's Mars Science Laboratory mission was successfully launched for Mars. Curiosity successfully landed on Mars on August 6, 2012, and subsequently began its search for evidence of past or present life on Mars.[130][131][132]

    Activities (2005–2017)

    The EFT-1 test flight was conducted in 2014, uncrewed capsule shown

    NASA's ongoing investigations include in-depth surveys of Mars (Perseverance and InSight) and Saturn and studies of the Earth and the Sun. Other active spacecraft missions are Juno for Jupiter, New Horizons (for Jupiter, Pluto, and beyond), and Dawn for the asteroid belt. 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), Cassini (1997–2017), and Juno (2011–). In the early 2000s, NASA was put on course for the Moon, however in 2010 this program was cancelled (see Constellation program). As part of that plan the Shuttle was going to be replaced, however, although it was retired its replacement was also cancelled, leaving the US with no human spaceflight launcher for the first time in over three decades.

    The New Horizons mission to Pluto was launched in 2006 and successfully performed a flyby of Pluto on July 14, 2015. The probe received a gravity assist from Jupiter in February 2007, examining some of Jupiter's inner moons and testing on-board instruments during the flyby. On the horizon of NASA's plans is the MAVEN spacecraft as part of the Mars Scout Program to study the atmosphere of Mars.[133]

    On December 4, 2006, NASA announced it was planning a permanent Moon base.[134] 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."[135] In 2010, President Barack Obama halted existing plans, including the Moon base, and directed a generic focus on crewed missions to asteroids and Mars, as well as extending support for the International Space Station.[136]

    Since 2011, NASA's strategic goals have been[137]

    • Extend and sustain human activities across the solar system
    • Expand scientific understanding of the Earth and the universe
    • Create innovative new space technologies
    • Advance aeronautics research
    • Enable program and institutional capabilities to conduct NASA's aeronautics and space activities
    • Share NASA with the public, educators, and students to provide opportunities to participate

    In August 2011, NASA accepted the donation of two space telescopes from the National Reconnaissance Office. Despite being stored unused, the instruments are superior to the Hubble Space Telescope.[138]

    Curiosity on Mars

    In September 2011, NASA announced the start of the Space Launch System program to develop a human-rated heavy lift vehicle. The Space Launch System is intended to launch the Orion spacecraft and other elements towards the Moon and Mars.[139] The Orion spacecraft conducted an uncrewed test launch on a Delta IV Heavy rocket in December 2014.[140]

    The James Webb Space Telescope's main mirror assembled, November 2016

    On August 6, 2012, NASA landed the rover Curiosity on Mars. On August 27, 2012, Curiosity transmitted the first pre-recorded message from the surface of Mars back to Earth, made by Administrator Charlie Bolden:

    Hello. This is Charlie Bolden, NASA Administrator, speaking to you via the broadcast capabilities of the Curiosity rover, which is now on the surface of Mars.

    Since the beginning of time, humankind's curiosity has led us to constantly seek new life ... new possibilities just beyond the horizon. I want to congratulate the men and women of our NASA family as well as our commercial and government partners around the world, for taking us a step beyond to Mars.

    This is an extraordinary achievement. Landing a rover on Mars is not easy – others have tried – only America has fully succeeded. The investment we are making ... the knowledge we hope to gain from our observation and analysis of Gale Crater, will tell us much about the possibility of life on Mars as well as the past and future possibilities for our own planet. Curiosity will bring benefits to Earth and inspire a new generation of scientists and explorers, as it prepares the way for a human mission in the not too distant future. Thank you.[141]

    The James Webb Space Telescope (JWST) is currently scheduled to launch in March 2021.[142]

    NEO detection

    In 1994, there was a Congressional directive to find near-Earth objects (NEOs) larger than 1 kilometer, and 90% of 1 kilometer sized asteroids are estimated to have been found by 2010.[143]

    Plot of orbits of known Potentially Hazardous Asteroids (size over 460 feet (140 m) and passing within 4.7 million miles (7.6×10^6 km) of Earth's orbit)
    Large NEAs (at least 1 km in diameter) discovered each year
    NASA visited a near-Earth asteroid with a probe for the first time in 1998(flyby)/2000(orbit), asteroid 433 Eros
    Large Earth NEO collisions are seen as unlikely but possible.

    In 2005, the US Congress mandated NASA to achieve by the year 2020 specific levels of search completeness for discovering, cataloging, and characterizing dangerous asteroids larger than 140 meters (460 ft) (Act of 2005, H.R. 1022; 109th),[144][145] but no new funds were appropriated for this effort.[146] As of January 2019, it is estimated about 40% of the NEOs of this size have been found, although since by its nature the exact amount of NEOs are unknown the calculations are based on predictions of how many there could be.[147]

    (d) Near-Earth Object Survey.-- (1) Survey program.--The Administrator shall plan, develop, and implement a Near-Earth Object Survey program to detect, track, catalogue, and characterize the physical characteristics of near-Earth objects equal to or greater than 140 meters in diameter in order to assess the threat of such near-Earth objects to the Earth. <<NOTE: Deadline.>> It shall be the goal of the

    Page 119 STAT. 2923

    Survey program to achieve 90 percent completion of its near- Earth object catalogue (based on statistically predicted populations of near-Earth objects) within 15 years after the

    date of enactment of this Act.

    [148]

    NEOs were defined in this case by the term near-Earth object as an asteroid or comet with a perihelion distance of less than 1.3 Astronomical Units from the Sun.[149] In late 2019 the directive gained increased notoriety and NASA approved an additional space telescope in addition to the existing observatory programs.[150]

    One issue with NEO prediction is trying to estimate how many more are likely to be found In 2000, NASA reduced its estimate of the number of existing near-Earth asteroids over one kilometer in diameter from 1,000–2,000 to 500–1,000.[151][152] Shortly thereafter, the LINEAR survey provided an alternative estimate of 1,227+170
    −90
    .[153] In 2011, on the basis of NEOWISE observations, the estimated number of one-kilometer NEAs was narrowed to 981±19 (of which 93% had been discovered at the time), while the number of NEAs larger than 140 meters across was estimated at 13,200±1,900.[154][155] The NEOWISE estimate differed from other estimates in assuming a slightly lower average asteroid albedo, which produces larger estimated diameters for the same asteroid brightness. This resulted in 911 then known asteroids at least 1 km across, as opposed to the 830 then listed by CNEOS.[156] In 2017, using an improved statistical method, two studies reduced the estimated number of NEAs brighter than absolute magnitude 17.75 (approximately over one kilometer in diameter) to 921±20.[157][158] The estimated number of asteroids brighter than absolute magnitude of 22.0 (approximately over 140 m across) rose to 27,100±2,200, double the WISE estimate,[158] of which about a third are known as of 2018. A problem with estimating the number of NEOs is that detections are influenced by a number of factors.[159] Observational biases need to be taken into account when trying to calculate the number of bodies in a population.[159] What is easily detected will be more counted.[160]

    For example, it has been easier to spot objects on the night-side of Earth. There is less noise from twilight, and the searcher is looking at the sunlit side of the asteroids. In the daytime sky, a searcher looking towards the sun sees the backside of the object (e.g. comparing a Full Moon at night to a New Moon in daytime). In addition, opposition surge make them even brighter when the Earth is along the axis of sunlight. Finally, the day sky near the Sun is bright.[160] The light of sun hitting asteroids has been called "full asteroid" similar to a "full Moon" and the greater amount of light, creates a bias that makes them easier to detect in this case.[160]

    Over half (53%) of the discoveries of Near Earth objects were made in 3.8% of the sky, in a 22.5° cone facing directly away from the Sun, and the vast majority (87%) were made in 15% of the sky, in a 45° cone facing away from the Sun.[161]

    WISE infrared telescope

    NASA turned the infrared space survey telescope WISE back on in 2013 to look for NEOs, and it found some during the course of its operation. NEOcam competed in the highly competitive Discovery program, which became more so due to a low mission rate in the 2010s. Also the Mars Scout Program was terminated at that time, further increasing competition. From its start until 2010, ten missions where launched, only two more mission were launched by 2020 (to the Moon and Mars), additionally the Mars Scout program had launched two additional programs to the planet Mars, which competed with NEOcam as well as more obscure destinations like Venus, which has had no dedicated mission since the 1980s. Finally, NASA plans to turn off its existing Infrared Great Observatory, the Spitzer Space Telescope in 2021 due to technical problems (It is drifting away from the Earth in an Earth-trailing orbit which means it must rotate at extreme angle to communicate with Earth, but keep its battery charge).

    Background

    Two of the biggest Near-Earth objects, 433 Eros and 1036 Ganymed, were among the first Near Earth asteroids to be detected.[162] As bigger asteroids they reflected more light.[160] The eccentric 433 asteroid was discovered by German astronomer Carl Gustav Witt at the Berlin Urania Observatory on 13 August 1898.[163] 1036 Ganymed is about 20 miles (35 km) in diameter,[162] and it was discovered by German astronomer Walter Baade at the Bergedorf Observatory in Hamburg on 23 October 1924.[164][165] In 1999 NASA visited 433 Eros with the NEAR spacecraft which entered its orbit in 2000, closely imaging the asteroid with various instruments at that time.[166] 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.

    Due to the opposition effect over half (53%) of the discoveries of Near Earth objects were made in 3.8% of the sky, in a 22.5° cone facing directly away from the Sun, and the vast majority (87%) were made in 15% of the sky, in a 45° cone facing away from the Sun.[161]

    Recent and planned activities

    Saturn by the Cassini-Huygens mission
    Animation of a robotic arm moving on the OSIRIS-REx mission to retrieve a sample from an asteroid
    Published by NASA in March 2019, the "Jupiter Marble" by the Juno probe, in orbit around planet Jupiter
    The Kuiper belt object 486958 Arrokoth was imaged during a flyby on January 1, 2019 by the New Horizons probe.[167]

    NASA's ongoing investigations include in-depth surveys of Mars (Mars 2020 and InSight) and Saturn and studies of the Earth and the Sun. Other active spacecraft missions are Juno for Jupiter, New Horizons (for Jupiter, Pluto, and beyond), and Dawn for the asteroid belt. 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), Cassini (1997–2017), and Juno (2011–).

    The New Horizons mission to Pluto was launched in 2006 and successfully performed a flyby of Pluto on July 14, 2015. The probe received a gravity assist from Jupiter in February 2007, examining some of Jupiter's inner moons and testing on-board instruments during the flyby. On the horizon of NASA's plans is the MAVEN spacecraft as part of the Mars Scout Program to study the atmosphere of Mars.[133]

    In 2017, President Donald Trump directed NASA to send Humans to Mars by the year 2033.[115][168] Foci in general for NASA were noted as human space exploration, space science, and technology.[168] The Europa Clipper and Mars 2020 continue to be supported for their planned schedules.[169]

    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 1,500C and beyond. The final goal of this project is improving the safety of jet engines as well as increasing efficiency and reducing CO2 emissions.[170]

    The Northrop Grumman Antares rocket, with Cygnus resupply spacecraft on board, launches from Pad-0A, Wednesday, April 17, 2019 at NASA's Wallops Flight Facility in Virginia. Northrop Grumman's 11th contracted cargo resupply mission for NASA to the International Space Station will deliver about 7,600 pounds of science and research, crew supplies and vehicle hardware to the orbital laboratory and its crew.[171]

    Recent and planned activities include:

    • InSight, launched and landed on Mars in 2018
    • New Horizons, Kuiper belt object 486958 Arrokoth flyby on January 1, 2019[167]
    • OSIRIS-REx, en route for asteroid sample return on September 24, 2023[172]
    • Mars 2020 rover (planned)[173]
    • Europa Clipper (planned)
    • Misc. Discovery Missions
    • Misc. Explorer Missions
    • New Frontier mission including New Horizons, Juno, and OSIRIS-REx[174]
    • Earth Observation, Solar and Astronomical observatories
    • James Webb Space Telescope (planned)
    • Parker Solar Probe, launched August 2018
    • Transiting Exoplanet Survey Satellite (TESS), launched in April 2018
    • Wide Field Infrared Survey Telescope (WFIRST) (planned)[175]
    InSight Lander – panorama (December 2018)

    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 aerospace 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.[176] 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).[177]

    The National Aeronautics and Space Administration Authorization Act of 2014 reaffirmed the importance of ASAP.

    Directives

    Artistic rendition of Space Station Freedom with the Space Shuttle Orbiter Vehicle

    Some of NASA's main directives have been the landing of a manned spacecraft on the Moon, the designing and construction of the Space Shuttle, and efforts to construct a large, crewed space station. Typically, the major directives originated from the intersection of scienctific interest and advice, political interests, federal funding concerns, and the public interest, that all together brought varying waves of effort, often heavily swayed by technical developments, funding changes, and world events. For example, in the 1980's, the Reagan administration announced a directive with a major push to build a crewed space station, given the name Space Station Freedom [178] . But, when the Cold War ended, Russia, the United States, and other international partners came together to design and build the International Space Station.

    In the 2010s, major shifts in directives include retirement of the Space Shuttle, and the later development of a new crewed heavy lift rocket, the Space Launch System. Missions for the new Space Launch System have varied, but overall, NASA's directives are similar to the Space Shuttle program as the primary goal and desire is human spaceflight. Additionally, NASA's Space Exploration Initiative of the 1980s opened new avenues of exploration focused on other galaxies.

    For the coming decades, NASA's focus has gradually shifting towards eventual exploration of Mars [179]. One of the technological options focused on was the Asteroid Redirect Mission (ARM).[179] ARM had largely been defunded in 2017, but the key technologies developed for ARM would be utilized for future exploration, notably on a solar electric propulsion system.[180][179]

    Longer project execution timelines leaves future executive administration officials to execute on a directive, which can lead to directional mismanagement.

    Previously, in the early 2000s, NASA worked towards a strategic plan called the Constellation Program, but the program was defunded in the early 2010s.[181][182][183][184] In the 1990s, the NASA administration adopted an approach to planning coined "Faster, Better, Cheaper"[185].

    NASA Authorization Act of 2017

    Orion at ISS artwork

    The NASA Authorization Act of 2017, which included $19.5 billion in funding for that fiscal year, directed NASA to get humans near or on the surface of Mars by the early 2030s.[186]

    Though the agency is independent, the survival or discontinuation of projects can depend directly on the will of the President.[187]

    Space Policy Directive 1

    In December 2017, on the 45th anniversary of the last crewed mission to the Lunar surface, President Donald Trump approved a directive that includes a lunar mission on the pathway to Mars and beyond.[179]

    We'll learn. The directive I'm signing today will refocus America's space program on human exploration and discovery. It marks an important step in returning American astronauts to the Moon for the first time since 1972 for long-term exploration and use. This time, we will not only plant our flag and leave our footprint, we will establish a foundation for an eventual mission to Mars. And perhaps, someday, to many worlds beyond.

    President Donald Trump, 2017[188]

    New NASA administrator Jim Bridenstine addressed this directive in an August 2018 speech where he focused on the sustainability aspects—going to the Moon to stay—that are explicit in the directive, including taking advantage of US commercial space capability that did not exist even five years ago, which have driven down costs and increased access to space.[189]

    Research

    NASA developed this hard-suit in the 1980s at the Ames Research Center

    NASA's Aeronautics Research Mission Directorate conducts aeronautics research.

    NASA has made use of technologies such as the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), which is a type of Radioisotope thermoelectric generator used on space missions.[190] Shortages of the required plutonium-238 have curtailed deep space missions since the turn of the millennium.[191] An example of a spacecraft that was not developed because of a shortage of this material was New Horizons 2.[191]

    The Earth science research program was created and first funded in the 1980s under the administrations of Ronald Reagan and George H.W. Bush.[192][193]

    NASA started an annual competition in 2014 named Cubes in Space.[194] 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, Kalam SAT, built by an Indian team, was launched.[195]

    Climate and other research

    NASA also researches and publishes on climate change.[196] Its statements concur with the global scientific consensus that the global climate is warming.[197] 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.[198]

    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.[199]

    Use of the International System of units

    US law requires the International System of Units to be used in all U.S. Government programs, "except where impractical".[200] Today NASA is predominantly working with SI units, but some projects still use a mix of US and SI units.

    Timeline of notable unit usage
    • In 1969, the 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 full metrication, and was predominantly metric by the 1990s.[201]
    • On September 23, 1999, a unit mixup between US and SI units resulted in a loss of the Mars Climate Orbiter.[202]
    • In 2007, NASA decided to exclusively use metric units for all future operations on the Moon.[203]

    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. The ten field centers are:

    A Ball Aerospace engineer performs final checks before the spacecraft shipped to NASA's Kennedy Space Center in Florida for launch processing.
    Vehicle Assembly Building and Launch Control Center at Kennedy Space Center
    • John F. Kennedy Space Center (KSC) is one of the best-known NASA facilities. It has been the launch site for every U.S. human space flight from 1968 through 2011. Although human flights are currently on pause, KSC continues to manage and operate uncrewed rocket launch facilities for America's civilian space program from three pads at the adjoining Cape Canaveral Air Force Station. NASA also operates a short-line railroad at KSC and uses special aircraft.
    FCR 1 in 2009 during the STS-128 mission, JSC in Houston
    • Lyndon B. Johnson Space Center (JSC) in Houston, Texas contains the Christopher C. Kraft Jr. Mission Control Center, where all flight control is managed for crewed space missions. JSC is the lead NASA center for activities regarding the International Space Station and also houses the NASA Astronaut Corps that selects, trains, and provides astronauts as crew members for US and international space missions.
    • George C. Marshall Space Flight Center in Huntsville, Alabama is the rocket development center, at which the Saturn V rocket and Skylab were developed.[204]
    • Ames Research Center (ARC) at Moffett Field, in California's Silicon Valley, was founded on December 20, 1939. The center was named after Joseph Sweetman Ames, a founding member of the National Advisory Committee for Aeronautics (NACA).
    • Armstrong Flight Research Center (formerly Hugh L. Dryden Flight Research Facility), Edwards, California
    • Goddard Space Flight Center, Greenbelt, Maryland
    Jet Propulsion Laboratory complex in Pasadena, California
    • Jet Propulsion Laboratory (JPL) worked together with the Army Ballistic Missile Agency (ABMA), one of the agencies behind Explorer 1, the first American space mission. It is located near Pasadena, California
    • Langley Research Center (LaRC), founded in 1917, is the oldest of NASA's field centers, located in Hampton, Virginia. LaRC focuses primarily on aeronautical research, though the Apollo lunar lander was flight-tested at the facility and a number of high-profile space missions have been planned and designed on-site. Langley currently devotes two-thirds of its programs to aeronautics, and the rest to space.
    • John H. Glenn Research Center (GRC), formerly the Lewis Flight Propulsion Laboratory, located in Brook Park, Ohio, was established in 1942 as a laboratory for aircraft engine research. John H. Glenn Research Center, Cleveland, Ohio
    • John C. Stennis Space Center, Bay St. Louis, Mississippi

    Subordinate facilities include the Wallops Flight Facility in Wallops Island, Virginia; the Michoud Assembly Facility in New Orleans, Louisiana; the White Sands Test Facility in Las Cruces, New Mexico; and Deep Space Network stations in Barstow, California; Madrid, Spain; and Canberra, Australia.

    Budget

    NASA's budget from 1958 to 2012 as a percentage of federal budget
    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.

    NASA's share of the total federal budget peaked at approximately 4.41% in 1966 during the Apollo program, then rapidly declined to approximately 1% in 1975, and stayed around that level through 1998.[187][205] The percentage then gradually dropped, until leveling off again at around half a percent in 2006 (estimated in 2012 at 0.48% of the federal budget).[206] In a March 2012 hearing of the United States Senate Science Committee, science communicator Neil deGrasse Tyson testified that "Right now, NASA's annual budget is half a penny on your tax dollar. For twice that—a penny on a dollar—we can transform the country from a sullen, dispirited nation, weary of economic struggle, to one where it has reclaimed its 20th century birthright to dream of tomorrow."[207][208]

    Despite this, public perception of NASA's budget differs significantly: a 1997 poll indicated that most Americans believed that 20% of the federal budget went to NASA.[209]

    For Fiscal Year 2015, NASA received an appropriation of US$18.01 billion from Congress—$549 million more than requested and approximately $350 million more than the 2014 NASA budget passed by Congress.[210]

    In Fiscal Year 2016, NASA received $19.3 billion.[168]

    President Donald Trump signed the NASA Transition Authorization Act of 2017 in March, which set the 2017 budget at around $19.5 billion.[168] The budget is also reported as $19.3 billion for 2017, with $20.7 billion proposed for FY2018.[211][212]

    Examples of some proposed FY2018 budgets:[212]

    • Exploration: $4.79 billion
    • Planetary science: $2.23 billion
    • Earth science: $1.92 billion
    • Aeronautics: $0.685 billion

    Environmental impact

    NASA vision for the first Humans On Mars
    (Artist Concept; 12 June 2019)
    By expanding to a new planet, additional knowledge about environment can be acquired, such as eating insects for food.[213]

    The exhaust gases produced by rocket propulsion systems, both in Earth's atmosphere and in space, can adversely effect 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.[214] However, carbon dioxide emissions are insignificant compared to those from other sources; on average, the United States consumed 802,620,000 US gallons (3.0382×109 L) of liquid fuels per day in 2014, while a single Falcon 9 rocket first stage burns around 25,000 US gallons (95,000 L) of kerosene fuel per launch.[215][216] 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.[217] NASA addressed environmental concerns with its canceled Constellation program in accordance with the National Environmental Policy Act in 2011.[218] In contrast, ion engines use harmless noble gases like xenon for propulsion.[219][220]

    On May 8, 2003, 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.[221]

    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.[222]

    Observations

    Spacecraft

    Planned spacecraft

    Concepts

    NASA has developed oftentimes elaborate plans and technology concepts, some of which become worked into real plans.

    Examples of missions by target

    Here are some selected examples of missions to planetary-sized objects. Other major targets of study are the Earth itself, the Sun, and smaller Solar System bodies like asteroids and comets. In addition, the moons of the planets or body are also studied.

    Examples of robotic missions
    Spacecraft Launch
    year
    Mercury Venus Mars Ceres Jupiter Saturn Uranus Neptune Pluto Mission
    end
    Mariner 2 1962 Flyby 1963
    Mariner 4 1964 Flyby 1967
    Mariner 5 1967 Flyby 1968
    Mariner 6 and 7 1969 Flyby 1971
    Mariner 9 1971 Orbiter 1972
    Pioneer 10 1972 Flyby 2003
    Pioneer 11 1973 Flyby Flyby 1995
    Mariner 10 1973 Flyby Flyby 1975
    Viking 1 and Viking 2 1975 Orbiters
    Landers
    1982 & 1980
    Voyager 1 1977 Flyby Flyby Active
    Voyager 2 1977 Flyby Flyby Flyby Flyby Active
    Galileo 1989 Flyby Orbiter 2003
    Magellan 1989 Orbiter 1994
    Mars Global Surveyor 1996 Orbiter 2007
    Cassini 1997 Flyby Flyby Orbiter 2017
    Mars Odyssey 2001 Orbiter Active
    Spirit and Opportunity 2003 Rovers 2010 & 2019
    MESSENGER 2004 Orbiter Flyby 2015
    Mars Reconnaissance Orbiter 2005 Orbiter Active
    New Horizons 2006 Flyby Flyby Active
    Dawn 2007 Flyby Orbiter 2019
    Phoenix 2007 Lander 2010
    Juno 2011 Orbiter Active
    Curiosity (Mars Science Laboratory) 2011 Rover Active
    MAVEN 2013 Orbiter Active
    InSight 2018 Lander Active
    Spacecraft Launch
    year
    Mercury Venus Mars Ceres Jupiter Saturn Uranus Neptune Pluto Mission
    end

    Examples of missions to the Sun:

    • Interface Region Imaging Spectrograph
    • Solar Dynamics Observatory
    • STEREO
    • Ulysses
    • Parker Solar Probe

    Examples of missions to the Moon:

    Examples of missions to small Solar System bodies (e.g. comets and asteroids):

    Juno (spacecraft)New HorizonsInSightLunar Reconnaissance OrbiterKepler (spacecraft)Dawn (spacecraft)Deep Impact (spacecraft)MESSENGERMars Pathfinder

    See also

    • Astronomy Picture of the Day
    • Department of Defense Manned Space Flight Support Office
    • List of government space agencies
    • List of NASA aircraft
    • List of United States rockets
    • NASA Advanced Space Transportation Program
    • NASA Art Program
    • NASA insignia
    • NASA Research Park
    • NASA TV
    • NASAcast
    • Small Explorer program
    • Space policy of the Barack Obama administration
    • TechPort (NASA)
    • Chinese space program
    • Indian Space Research Organisation
    • Roscosmos
    • United States Space Force

    Notes

    1. NASA is an independent agency that is not a part of any executive department, but reports directly to the President.[5][6]
    2. The descend stage of the LM stayed on the Moon after landing while the ascend stage brought the two astronauts back to the CSM and then fell back to the Moon.
    3. From left to right: Launch vehicle of Apollo (Saturn 5), Gemini (Titan 2) and Mercury (Atlas). Left, top-down: Spacecraft of Apollo, Gemini and Mercury. The Saturn IB and Mercury-Redstone launch vehicles are left out.

    References

    1. US Centennial of Flight Commission, NACA Archived February 20, 2014, at the Wayback Machine. centennialofflight.net. Retrieved on November 3, 2011.
    2. Lale Tayla & Figen Bingul (2007). "NASA stands 'for the benefit of all.'—Interview with NASA's Dr. Süleyman Gokoglu". The Light Millennium. Archived from the original on October 12, 2007. Retrieved September 17, 2018.
    3. "Workforce Profile". NASA. Retrieved April 23, 2020.
    4. Casey Dreier (December 30, 2019). "NASA's FY 2020 Budget". The Planetary Society. Retrieved December 31, 2019.
    5. "Official US Executive Branch Web Sites – Newspaper and Current Periodical Reading Room (Serial and Government Publications Division, Library of Congress)". loc.gov. Archived from the original on May 16, 2016. Retrieved May 24, 2016.
    6. "Frequently Asked Questions". hq.nasa.gov. Archived from the original on May 4, 2016. Retrieved May 24, 2016.
    7. "Ike in History: Eisenhower Creates NASA". Eisenhower Memorial. 2013. Archived from the original on November 19, 2013. Retrieved November 27, 2013.
    8. "The National Aeronautics and Space Act". NASA. 2005. Archived from the original on August 16, 2007. Retrieved August 29, 2007.
    9. Bilstein, Roger E. (1996). "From NACA to NASA". NASA SP-4206, Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles. NASA. pp. 32–33. ISBN 978-0-16-004259-1. Retrieved May 6, 2013.
    10. Netting, Ruth (June 30, 2009). "Earth—NASA Science". Archived from the original on July 16, 2009. Retrieved July 15, 2009.
    11. Netting, Ruth (January 8, 2009). "Heliophysics—NASA Science". Archived from the original on July 16, 2009. Retrieved July 15, 2009.
    12. Roston, Michael (August 28, 2015). "NASA's Next Horizon in Space". New York Times. Archived from the original on August 29, 2015. Retrieved August 28, 2015.
    13. Netting, Ruth (July 13, 2009). "Astrophysics—NASA Science". Archived from the original on July 16, 2009. Retrieved July 15, 2009.
    14. "The NACA, NASA, and the Supersonic-Hypersonic Frontier" (PDF). NASA. Archived (PDF) from the original on November 2, 2013. Retrieved September 30, 2011.
    15. Erickson, Mark (2005). Into the Unknown Together—The DOD, NASA, and Early Spaceflight (PDF). ISBN 978-1-58566-140-4. Archived from the original (PDF) on September 20, 2009.
    16. Subcommittee On Military Construction, United States. Congress. Senate. Committee on Armed Services (January 21–24, 1958). Supplemental military construction authorization (Air Force).: Hearings, Eighty-fifth Congress, second session, on H.R. 9739. Archived from the original on September 5, 2015. Retrieved June 27, 2015.
    17. "T. Keith Glennan". NASA. August 4, 2006. Archived from the original on February 14, 2017. Retrieved July 15, 2009.
    18. Executive Order 10849 (Wikisource)
    19. von Braun, Werner (1963). "Recollections of Childhood: Early Experiences in Rocketry as Told by Werner Von Braun 1963". MSFC History Office. NASA Marshall Space Flight Center. Archived from the original on July 9, 2009. Retrieved July 15, 2009.
    20. Van Atta, Richard (April 10, 2008). "50 years of Bridging the Gap" (PDF). Archived from the original (PDF) on February 24, 2009. Retrieved July 15, 2009.
    21. Heppenheimer, T. A. (1999). "3. Mars and Other Dream Worlds". SP-4221 The Space Shuttle Decision. Washington DC: NASA. p. 115. Retrieved August 22, 2018.
    22. Administrator, NASA Content (January 30, 2017). "Robert M. Lightfoot Jr., Acting Administrator". Archived from the original on February 1, 2017. Retrieved February 1, 2017.
    23. "T. Keith Glennan biography". NASA. August 4, 2006. Archived from the original on February 14, 2017. Retrieved July 5, 2008.
    24. Cabbage, Michael (July 15, 2009). "Bolden and Garver Confirmed by U.S. Senate" (Press release). NASA. Archived from the original on October 28, 2009. Retrieved July 16, 2009.
    25. Shouse, Mary (July 9, 2009). "Welcome to NASA Headquarters". Archived from the original on July 13, 2009. Retrieved July 15, 2009.
    26. Information for Non U.S. Citizens Archived October 7, 2018, at the Wayback Machine, NASA (downloaded September 16, 2013)
    27. "Apollo 11 Put the First Men on the Moon. What About Missions 12-17?". August 30, 2019. Archived from the original on September 20, 2019. Retrieved September 20, 2019.
    28. The Air Force definition of outer space differs from that of the International Aeronautical Federation, which is 100 kilometers (330,000 ft).
    29. Aerospaceweb, North American X-15 Archived September 21, 2011, at the Wayback Machine. Aerospaceweb.org. Retrieved on November 3, 2011.
    30. Aircraft Museum X-15." Archived September 21, 2011, at the Wayback Machine Aerospaceweb.org, November 24, 2008.
    31. NASA, X-15 Hypersonic Research Program Archived October 7, 2018, at the Wayback Machine, retrieved October 17, 2011
    32. Encyclopedia Astronautica, Project 7969 Archived October 11, 2011, at the Wayback Machine, retrieved October 17, 2011
    33. NASA, Project Mercury Overview Archived June 3, 2013, at the Wayback Machine, retrieved October 17, 2011
    34. Swenson Jr., Loyd S.; Grimwood, James M.; Alexander, Charles C. (1989). "11-4 Shepard's Ride". In Woods, David; Gamble, Chris (eds.). This New Ocean: A History of Project Mercury (url). Published as NASA Special Publication-4201 in the NASA History Series. NASA. Archived from the original on July 13, 2009. Retrieved July 14, 2009.
    35. Swenson Jr., Loyd S.; Grimwood, James M.; Alexander, Charles C. (1989). "13-4 An American in Orbit". In Woods, David; Gamble, Chris (eds.). This New Ocean: A History of Project Mercury (url). Published as NASA Special Publication-4201 in the NASA History Series. NASA. Archived from the original on July 13, 2009. Retrieved July 14, 2009.
    36. "Mercury Manned Flights Summary". NASA. Archived from the original on September 16, 2011. Retrieved October 9, 2011.
    37. Loff, Sarah (November 22, 2016). "Katherine Johnson Biography". NASA. Archived from the original on March 31, 2019. Retrieved March 8, 2019.
    38. Loff, Sarah (November 22, 2016). "Mary Jackson Biography". NASA. Archived from the original on January 20, 2019. Retrieved March 8, 2019.
    39. Loff, Sarah (November 22, 2016). "Dorothy Vaughan Biography". NASA. Archived from the original on November 30, 2018. Retrieved March 8, 2019.
    40. "NASA history, Gagarin". NASA. Archived from the original on October 25, 2011. Retrieved October 9, 2011.
    41. Barton C. Hacker; James M. Grimwood (December 31, 2002). "10-1 The Last Hurdle". On the Shoulders of Titans: A History of Project Gemini (url). NASA. ISBN 978-0-16-067157-9. Archived from the original on February 1, 2010. Retrieved July 14, 2009.
    42. Barton C. Hacker; James M. Grimwood (December 31, 2002). "12-5 Two Weeks in a Spacecraft". On the Shoulders of Titans: A History of Project Gemini. NASA. ISBN 978-0-16-067157-9. Archived from the original on February 1, 2010. Retrieved July 14, 2009.
    43. Barton C. Hacker; James M. Grimwood (December 31, 2002). "13-3 An Alternative Target". On the Shoulders of Titans: A History of Project Gemini. NASA. ISBN 978-0-16-067157-9. Archived from the original on February 1, 2010. Retrieved July 14, 2009.
    44. John F. Kennedy "Landing a man on the Moon" Address to Congress on YouTube, speech
    45. Butts, Glenn; Linton, Kent (April 28, 2009). "The Joint Confidence Level Paradox: A History of Denial, 2009 NASA Cost Symposium" (PDF). pp. 25–26. Archived from the original (PDF) on October 26, 2011.
    46. Federal Reserve Bank of Minneapolis. "Consumer Price Index (estimate) 1800–". Retrieved January 1, 2020.
    47. Nichols, Kenneth David (1987). The Road to Trinity: A Personal Account of How America's Nuclear Policies Were Made, pp 34–35. New York: William Morrow and Company. ISBN 978-0-688-06910-0. OCLC 15223648.CS1 maint: ref=harv (link)
    48. "Saturn V". Encyclopedia Astronautica. Archived from the original on October 7, 2011. Retrieved October 13, 2011.
    49. "Apollo 8: The First Lunar Voyage". NASA. Archived from the original on October 27, 2011. Retrieved October 13, 2011.
    50. Siddiqi, Asif A. (2003). The Soviet Space Race with Apollo. Gainesville: University Press of Florida. pp. 654–656. ISBN 978-0-8130-2628-2.
    51. "Apollo 9: Earth Orbital trials". NASA. Archived from the original on October 27, 2011. Retrieved October 13, 2011.
    52. "Apollo 10: The Dress Rehearsal". NASA. Archived from the original on October 27, 2011. Retrieved October 13, 2011.
    53. "The First Landing". NASA. Archived from the original on October 27, 2011. Retrieved October 13, 2011.
    54. Chaikin, Andrew (March 16, 1998). A Man on the Moon. New York: Penguin Books. ISBN 978-0-14-027201-7.
    55. The Phrase Finder: Archived September 24, 2011, at the Wayback Machine ... a giant leap for mankind, retrieved October 1, 2011
    56. 30th Anniversary of Apollo 11, Manned Apollo Missions Archived February 20, 2011, at the Wayback Machine. NASA, 1999.
    57. Belew, Leland F., ed. (1977). Skylab Our First Space Station—NASA report (PDF). NASA. NASA-SP-400. Archived (PDF) from the original on March 17, 2010. Retrieved July 15, 2009.
    58. Benson, Charles Dunlap and William David Compton. Living and Working in Space: A History of Skylab Archived November 5, 2015, at the Wayback Machine. NASA publication SP-4208.
    59. Gatland, Kenneth (1976). Manned Spacecraft, Second Revision. New York: Macmillan Publishing Co., Inc. p. 247. ISBN 978-0-02-542820-1.
    60. Grinter, Kay (April 23, 2003). "The Apollo Soyuz Test Project". Archived from the original on July 25, 2009. Retrieved July 15, 2009.
    61. NASA, Shuttle-MIR history Archived October 7, 2018, at the Wayback Machine, retrieved October 15, 2011
    62. Bernier, Serge (May 27, 2002). Space Odyssey: The First Forty Years of Space Exploration. Cambridge University Press. ISBN 978-0-521-81356-3.
    63. Encyclopedia Astronautica, Vostok 1 Archived October 28, 2011, at the Wayback Machine, retrieved October 18, 2011
    64. NASA, Shuttle Basics Archived October 7, 2018, at the Wayback Machine, retrieved October 18, 2011
    65. Encyclopedia Astronautica, Shuttle Archived April 7, 2004, at the Wayback Machine, retrieved October 18, 2011
    66. Encyclopedia Astronautica, Spacelab Archived October 11, 2011, at the Wayback Machine. Retrieved October 20, 2011
    67. Spaceflight, Kim Ann Zimmermann 2018-01-19T02:02:00Z. "Sally Ride: First American Woman in Space". Space.com. Archived from the original on March 8, 2019. Retrieved March 8, 2019.
    68. Encyclopedia Astronautica, HST Archived August 18, 2011, at WebCite. Retrieved October 20, 2011
    69. Watson, Traci (January 8, 2008). "Shuttle delays endanger space station". USA Today. Archived from the original on March 26, 2009. Retrieved July 15, 2009.
    70. "NASA's Last Space Shuttle Flight Lifts Off From Cape Canaveral". KHITS Chicago. July 8, 2011. Archived from the original on July 14, 2011.
    71. John E. Catchpole (June 17, 2008). The International Space Station: Building for the Future. Springer-Praxis. ISBN 978-0-387-78144-0.
    72. "Human Spaceflight and Exploration—European Participating States". European Space Agency (ESA). 2009. Archived from the original on August 8, 2012. Retrieved January 17, 2009.
    73. Gary Kitmacher (2006). Reference Guide to the International Space Station. Canada: Apogee Books. pp. 71–80. ISBN 978-1-894959-34-6. ISSN 1496-6921.
    74. Gerstenmaier, William (October 12, 2011). "Statement of William H. Gerstenmaier Associate Administrator for HEO NASA before the Subcommittee on Space and Aeronautics Committee on Science, Space and Technology U. S. House of Representatives" (PDF). United States House of Representatives. Archived from the original (PDF) on September 21, 2012. Retrieved August 31, 2012.
    75. Afanasev, Igor; Vorontsov, Dmitrii (January 11, 2012). "The Russian ISS segment is to be completed by 2016". Air Transport Observer. Archived from the original on February 28, 2012. Retrieved October 14, 2012.
    76. "ISS Intergovernmental Agreement". European Space Agency (ESA). April 19, 2009. Archived from the original on June 10, 2009. Retrieved April 19, 2009.
    77. "Memorandum of Understanding Between the National Aeronautics and Space Administration of the United States of America and the Russian Space Agency Concerning Cooperation on the Civil International Space Station". NASA. January 29, 1998. Archived from the original on June 10, 2009. Retrieved April 19, 2009.
    78. Zak, Anatoly (October 15, 2008). "Russian Segment: Enterprise". RussianSpaceWeb. Archived from the original on September 20, 2012. Retrieved August 4, 2012.
    79. "ISS Fact sheet: FS-2011-06-009-JSC" (PDF). NASA. 2011. Archived (PDF) from the original on May 10, 2013. Retrieved September 2, 2012.
    80. "MCB Joint Statement Representing Common Views on the Future of the ISS" (PDF). International Space Station Multilateral Coordination Board. February 3, 2010. Archived (PDF) from the original on November 16, 2012. Retrieved August 16, 2012.
    81. Leone, Dan (June 20, 2012). "Wed, 20 June, 2012 NASA Banking on Commercial Crew To Grow ISS Population". Space News. Retrieved September 1, 2012.
    82. "Nations Around the World Mark 10th Anniversary of International Space Station". NASA. November 17, 2008. Archived from the original on February 13, 2009. Retrieved March 6, 2009.
    83. Boyle, Rebecca (November 11, 2010). "The International Space Station Has Been Continuously Inhabited for Ten Years Today". Popular Science. Archived from the original on March 18, 2013. Retrieved September 1, 2012.
    84. International Space Station Archived February 24, 2009, at the Wayback Machine, Retrieved October 20, 2011
    85. Chow, Denise (November 17, 2011). "U.S. Human Spaceflight Program Still Strong, NASA Chief Says". Space.com. Archived from the original on June 25, 2012. Retrieved July 2, 2012.
    86. Potter, Ned (July 17, 2009). "Space Shuttle, Station Dock: 13 Astronauts Together". ABC News. Archived from the original on June 30, 2017. Retrieved September 7, 2012.
    87. Nelson, Bill [@SenBillNelson] (December 20, 2018). "Commercial Space Company Bill Announcement" (Tweet) via Twitter.
    88. Epstein, Kayla (March 7, 2019). "Washington Post". Archived from the original on March 7, 2019. Retrieved March 8, 2019.
    89. "NASA Selects Crew and Cargo Transportation to Orbit Partners" (Press release). NASA. August 18, 2006. Archived from the original on October 12, 2006. Retrieved November 21, 2006.
    90. "Moving Forward: Commercial Crew Development Building the Next Era in Spaceflight" (PDF). Rendezvous. NASA. 2010. pp. 10–17. Archived (PDF) from the original on November 24, 2010. Retrieved February 14, 2011. 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.
    91. McAlister, Phil (October 2010). "The Case for Commercial Crew" (PDF). NASA. Archived (PDF) from the original on April 4, 2012. Retrieved July 2, 2012.
    92. "NASA Awards Space Station Commercial Resupply Services Contracts". NASA. December 23, 2008. Archived from the original on December 2, 2017.
    93. "Space Exploration Technologies Corporation – Press". Spacex.com. Archived from the original on July 21, 2009. Retrieved July 17, 2009.
    94. Clark, Stephen (June 2, 2012). "NASA expects quick start to SpaceX cargo contract". SpaceFlightNow. Archived from the original on June 30, 2012. Retrieved June 30, 2012.
    95. Bergin, Chris (September 28, 2013). "Orbital's Cygnus successfully berthed on the ISS". NASASpaceFlight.com (not affiliated with NASA). Archived from the original on October 13, 2013. Retrieved October 17, 2013.
    96. "SpaceX/NASA Discuss launch of Falcon 9 rocket and Dragon capsule". NASA. May 22, 2012. Archived from the original on July 21, 2013. Retrieved June 23, 2012.
    97. Berger, Brian (February 1, 2011). "Biggest CCDev Award Goes to Sierra Nevada". Imaginova Corp. Retrieved December 13, 2011.
    98. Morring, Frank (October 10, 2012). "Boeing Gets Most Money With Smallest Investment". Aviation Week. Archived from the original on May 10, 2013. Retrieved October 5, 2012.
    99. Dean, James (April 18, 2011). "NASA awards $270 million for commercial crew efforts". space.com. Archived from the original on April 19, 2011. Retrieved May 11, 2011.
    100. "NASA Announces Next Steps in Effort to Launch Americans from U.S. Soil". NASA. August 3, 2012. Archived from the original on March 19, 2017. Retrieved August 3, 2012.
    101. Bolden, Charlie. "American Companies Selected to Return Astronaut Launches to American Soil". NASA.gov. Archived from the original on September 16, 2014. Retrieved September 16, 2014.
    102. Foust, Jeff (September 19, 2014). "NASA Commercial Crew Awards Leave Unanswered Questions". Space News. Retrieved September 21, 2014. We basically awarded based on the proposals that we were given," Kathy Lueders, NASA commercial crew program manager, said in a teleconference with reporters after the announcement. "Both contracts have the same requirements. The companies proposed the value within which they were able to do the work, and the government accepted that.
    103. Lewis, Marie (November 21, 2018). "NASA's Commercial Crew Program Target Test Flight Dates". NASA.gov. NASA. Archived from the original on November 25, 2018. Retrieved November 29, 2018.
    104. Achenbach, Joel (February 1, 2010). "NASA budget for 2011 eliminates funds for manned lunar missions". Washington Post. Archived from the original on March 21, 2010. Retrieved February 1, 2010.
    105. "President Barack Obama on Space Exploration in the 21st Century". Office of the Press Secretary. April 15, 2010. Archived from the original on July 19, 2012. Retrieved July 4, 2012.
    106. "Today – President Signs NASA 2010 Authorization Act". Universetoday.com. Retrieved November 20, 2010.
    107. Svitak, Amy (March 31, 2011). "Holdren: NASA Law Doesn't Square with Budgetary Reality". Space News. Retrieved July 4, 2012.
    108. "National Aeronautics and Space Administration Authorization Act of 2010" (PDF). p. 11. Retrieved November 23, 2019.
    109. "NASA Announces Design for New Deep Space Exploration System". NASA. September 14, 2011. Archived from the original on April 13, 2012. Retrieved April 28, 2012.
    110. Bergin, Chris (February 23, 2012). "Acronyms to Ascent – SLS managers create development milestone roadmap". NASA. Archived from the original on April 30, 2012. Retrieved April 29, 2012.
    111. "NASA: Moon to Mars". NASA. Archived from the original on August 5, 2019. Retrieved May 19, 2019.
    112. "John Honeycutt, NASA SLS program manager, says at the ASEB meeting that while a new associate administrator for human exploration and operations will set a formal launch date for Artemis 1, his team is still working "aggressively" towards a November 2020 launch date". September 26, 2019.
    113. NASA Sets New Roadmap for Moon Base, Crewed Missions to Mars Archived November 27, 2018, at the Wayback Machine Extreme Tech. By Ryan Whitwam. September 27, 2018. Downloaded November 26, 2018.
    114. "NASA builds deep space habitats on Earth". Archived from the original on February 24, 2017. Retrieved December 30, 2016.
    115. "US Government Issues NASA Demand, 'Get Humans to Mars By 2033'". March 9, 2017. Archived from the original on February 17, 2018. Retrieved February 16, 2018.
    116. "Trump Signs NASA Authorization act of 2017". Spaceflight Insider. March 21, 2017. Archived from the original on December 3, 2018. Retrieved December 2, 2018.
    117. Grady, Mary (June 5, 2016). "NASA and DARPA plan to release new X-Planes". Yahoo Tech. Archived from the original on June 11, 2016. Retrieved June 8, 2016.
    118. "Launch History (Cumulative)" (PDF). NASA. Archived (PDF) from the original on October 19, 2011. Retrieved September 30, 2011.
    119. "NASA Experimental Communications Satellites, 1958–1995". NASA. Archived from the original on August 4, 2011. Retrieved September 30, 2011.
    120. "NASA, Explorers program". NASA. Archived from the original on September 27, 2011. Retrieved September 20, 2011.
    121. NASA mission STS-31 (35) Archived August 18, 2011, at WebCite
    122. "JPL, Chapter 4. Interplanetary Trajectories". NASA. Archived from the original on September 3, 2011. Retrieved September 30, 2011.
    123. "Missions to Mars". The Planet Society. Archived from the original on January 18, 2012. Retrieved September 30, 2011.
    124. "Missions to Jupiter". The Planet Society. Archived from the original on October 6, 2011. Retrieved September 30, 2011.
    125. "JPL Voyager". JPL. Archived from the original on October 8, 2011. Retrieved September 30, 2011.
    126. "Pioneer 10 spacecraft send last signal". NASA. Archived from the original on November 9, 2016. Retrieved September 30, 2011.
    127. "The golden record". JPL. Archived from the original on September 27, 2011. Retrieved September 30, 2011.
    128. "New Horizon". JHU/APL. Archived from the original on May 9, 2010. Retrieved September 30, 2011.
    129. "Voyages Beyond the Solar System: The Voyager Interstellar Mission". NASA. Archived from the original on September 27, 2011. Retrieved September 30, 2011.
    130. NASA Staff (November 26, 2011). "Mars Science Laboratory". NASA. Archived from the original on November 27, 2011. Retrieved November 26, 2011.
    131. "NASA Launches Super-Size Rover to Mars: 'Go, Go!'". New York Times. Associated Press. November 26, 2011. Retrieved November 26, 2011.
    132. Kenneth Chang (August 6, 2012). "Curiosity Rover Lands Safely on Mars". The New York Times. Archived from the original on August 6, 2012. Retrieved August 6, 2012.
    133. Wilson, Jim (September 15, 2008). "NASA Selects 'MAVEN' Mission to Study Mars Atmosphere". NASA. Archived from the original on June 19, 2009. Retrieved July 15, 2009.
    134. NASA Office of Public Affairs (December 4, 2006). "Global Exploration Strategy and Lunar Architecture" (PDF). NASA. Archived (PDF) from the original on June 24, 2009. Retrieved July 15, 2009.
    135. "Review of United States Human Space Flight Plans Committee" (PDF). Office of Science and Technology Policy. October 22, 2009. Archived (PDF) from the original on December 13, 2011. Retrieved December 13, 2011.
    136. Goddard, Jacqui (February 2, 2010). "Nasa reduced to pipe dreams as Obama cancels Moon flights". The Times. London. Archived from the original on May 29, 2010. Retrieved May 19, 2010.
    137. "NASA Strategic Plan, 2011" (PDF). NASA Headquarters. Archived (PDF) from the original on October 7, 2018. Retrieved April 12, 2018.
    138. Boyle, Rebecca (June 5, 2012). "NASA Adopts Two Spare Spy Telescopes, Each Maybe More Powerful than Hubble". Popular Science. Popular Science Technology Group. Archived from the original on June 7, 2012. Retrieved June 5, 2012.
    139. "NASA Announces Design for New Deep Space Exploration System". NASA. September 14, 2011. Archived from the original on April 13, 2012. Retrieved December 13, 2011.
    140. "NASA's Orion Flight Test Yields Critical Data". NASA. Archived from the original on May 5, 2019. Retrieved April 12, 2018.
    141. JPL, NASA. "First Recorded Voice from Mars". nasa.gov. Archived from the original on October 7, 2018. Retrieved April 12, 2018.
    142. "NASA Completes Webb Telescope Review, Commits to Launch in Early 2021". NASA. June 27, 2018. Retrieved June 27, 2018.
    143. Loff, Sarah (April 22, 2014). "NASA's Search for Asteroids to Help Protect Earth and Understand Our History". NASA. Retrieved September 30, 2019.
    144. H.R. 1022 (109th): George E. Brown, Jr. Near-Earth Object Survey Act - Original text. Tracking the United States Congress. Accessed: 31 October 2018.
    145. 290 Asteroid News: Time Is Running Out. Kevin Anderton, Forbes. 31 October 2018.
    146. "How NASA's Planetary Defense Budget Grew By More Than 4000% in 10 years". www.planetary.org. Retrieved September 30, 2019.
    147. Hutchison, Kay Bailey (December 30, 2005). "Text - S.1281 - 109th Congress (2005-2006): National Aeronautics and Space Administration Authorization Act of 2005". www.congress.gov. Retrieved September 30, 2019.
    148. "NASA to Build New Asteroid-Hunting Space Telescope". www.planetary.org. Retrieved September 30, 2019.
    149. Jane Platt (January 12, 2000). "Asteroid Population Count Slashed". Press Releases. NASA/JPL. Archived from the original on May 9, 2017. Retrieved November 10, 2017.
    150. David Rabinowitz; Eleanor Helin; Kenneth Lawrence & Steven Pravdo (January 13, 2000). "A reduced estimate of the number of kilometer-sized near-Earth asteroids". Nature. 403 (6766): 165–166. Bibcode:2000Natur.403..165R. doi:10.1038/35003128. PMID 10646594.
    151. J. S. Stuart (November 23, 2001). "A Near-Earth Asteroid Population Estimate from the LINEAR Survey". Science. 294 (5547): 1691–1693. Bibcode:2001Sci...294.1691S. doi:10.1126/science.1065318. PMID 11721048.
    152. "WISE Revises Numbers of Asteroids Near Earth". NASA/JPL. September 29, 2011. Archived from the original on December 5, 2017. Retrieved November 9, 2017.
    153. A. Mainzer; T. Grav; J. Bauer; et al. (December 20, 2011). "NEOWISE Observations of Near-Earth Objects: Preliminary Results". The Astrophysical Journal. 743 (2): 156. arXiv:1109.6400. Bibcode:2011ApJ...743..156M. doi:10.1088/0004-637X/743/2/156.
    154. Kelly Beatty (September 30, 2011). "WISE's Survey of Near-Earth Asteroids". Sky & Telescope. Retrieved February 8, 2018.
    155. Matt Williams (October 20, 2017). "Good News Everyone! There are Fewer Deadly Undiscovered Asteroids than we Thought". Universe Today. Archived from the original on November 4, 2017. Retrieved November 14, 2017.
    156. Tricarico, Pasquale (March 1, 2017). "The near-Earth asteroid population from two decades of observations" (PDF). Icarus. 284: 416–423. arXiv:1604.06328. Bibcode:2017Icar..284..416T. doi:10.1016/j.icarus.2016.12.008. Retrieved March 9, 2018.
    157. Bottke Jr, W. F. (2000). "Understanding the Distribution of Near-Earth Asteroids". Science. 288 (5474): 2190–2194. Bibcode:2000Sci...288.2190B. doi:10.1126/science.288.5474.2190. PMID 10864864.
    158. "Discovering Asteroids and NEOs by Telescopes". permanent.com. Retrieved November 16, 2018.
    159. "NEO Earth Close Approach data". NASA JPL. NASA. Retrieved July 7, 2018.
    160. Browne, Malcolm W. "Mathematicians Say Asteroid May Hit Earth in a Million Years". Retrieved November 16, 2018.
    161. Schmadel, Lutz D. (2007). "(433) Eros". Dictionary of Minor Planet Names – (433) Eros. Springer Berlin Heidelberg. p. 50. doi:10.1007/978-3-540-29925-7_434. ISBN 978-3-540-00238-3.
    162. "1036 Ganymed (1924 TD)". Minor Planet Center. Retrieved August 29, 2018.
    163. Schmadel, Lutz D. (2007). "(1036) Ganymed". Dictionary of Minor Planet Names – (1036) Ganymed. Springer Berlin Heidelberg. p. 89. doi:10.1007/978-3-540-29925-7_1037. ISBN 978-3-540-00238-3.
    164. Chang, Kenneth (December 31, 2018). "New Horizons Spacecraft Completes Flyby of Ultima Thule, the Most Distant Object Ever Visited". The New York Times. Archived from the original on January 1, 2019. Retrieved January 1, 2019.
    165. "Trump just signed a law that maps out NASA's long-term future — but a critical element is missing". Archived from the original on February 17, 2018. Retrieved February 16, 2018.
    166. Ledyard King (March 16, 2017). "Trump's NASA budget preserves Mars mission, cuts Earth science, asteroid trip, education". USA Today. Archived from the original on February 7, 2018. Retrieved February 16, 2018.
    167. SCS (August 23, 2018). "Sensor Coating Systems launches new national aerospace project with NATEP and some leading international players". Archived from the original on October 27, 2018. Retrieved October 12, 2018.
    168. SCS (April 18, 2019). "Northrop Grumman Heads to Space Station with New NASA Science, Cargo". Archived from the original on April 18, 2019. Retrieved April 18, 2019.
    169. "OSIRIS-REx Factsheet" (PDF). NASA/Explorers and Heliophysics Projects Division. August 2011. Archived (PDF) from the original on November 8, 2018. Retrieved October 30, 2018.
    170. mars.nasa.gov. "Overview – Mars 2020 Rover". mars.jpl.nasa.gov. Archived from the original on December 15, 2018. Retrieved October 30, 2018.
    171. "New Frontiers | Science Mission Directorate". science.nasa.gov. Archived from the original on July 2, 2019. Retrieved June 18, 2019.
    172. Faust, Jeff (March 28, 2018). "WFIRST work continues despite budget and schedule uncertainty". Retrieved September 17, 2018.
    173. "NASA Aerospace Safety Advisory Panel (ASAP)". oiir.hq.nasa.gov. Archived from the original on March 8, 2017. Retrieved April 13, 2017.
    174. Mochinski, Ron (April 8, 2015). "About Us – Background and Charter". Archived from the original on December 28, 2015. Retrieved April 13, 2017.
    175. "President Reagan's Statement on the International Space Station". Retrieved April 24, 2020.
    176. "President Trump Directs NASA to Return to the Moon, Then Aim for Mars". Archived from the original on January 9, 2018. Retrieved May 11, 2018.
    177. Jeff Foust (June 14, 2017). "NASA closing out Asteroid Redirect Mission". Space News. Retrieved September 9, 2017.
    178. Amos, Jonathan (February 1, 2010). "Obama cancels Moon return project". BBC News. Archived from the original on August 21, 2017. Retrieved March 7, 2010.
    179. "Terminations, Reductions, and Savings" (PDF). Archived from the original (PDF) on August 11, 2010. Retrieved March 7, 2010.
    180. Achenbach, Joel (February 1, 2010). "NASA budget for 2011 eliminates funds for manned lunar missions". Washington Post. Archived from the original on March 21, 2010. Retrieved February 1, 2010.
    181. "Fiscal Year 2011 Budget Estimates" (PDF). Archived from the original (PDF) on February 1, 2010. Retrieved March 7, 2010.
    182. "Archived copy" (PDF). Archived (PDF) from the original on January 20, 2017. Retrieved May 11, 2018.CS1 maint: archived copy as title (link)
    183. "US Government Issues NASA Demand, 'Get Humans to Mars By 2033'". Futurism. March 9, 2017. Archived from the original on February 17, 2018. Retrieved February 16, 2018.
    184. Fouriezos, Nick (May 30, 2016). "Your Presidential Candidates ... For the Milky Way". OZY. Archived from the original on May 30, 2016. Retrieved May 30, 2016.
    185. "Text of Remarks at Signing of Trump Space Policy Directive 1 and List of Attendees" Archived May 12, 2018, at the Wayback Machine, Marcia Smith, Space Policy Online, 11 December 2017, accessed 21 August 2018.
    186. Bridenstine Speaks at NASA Advisory Council Meeting, at 4:40, NASA TV, August 29, 2018, accessed September 1, 2018.
    187. "Radioisotope Power Systems for Space Exploration" (PDF). March 2011. Archived (PDF) from the original on March 4, 2016. Retrieved March 13, 2015.
    188. "New Horizons II Final Report – March 2005" (PDF). Archived (PDF) from the original on November 12, 2013. Retrieved November 14, 2016.
    189. Eric Berger (April 29, 2015). "A history primer: NASA's robust Earth Science program now under attack originated in the Reagan and Bush administrations". Houston Chronicle. Archived from the original on December 20, 2016.
    190. Eric Berger (October 29, 2015). "Republicans outraged over NASA earth science programs ... that Reagan began". Ars Tecnica. Archived from the original on May 11, 2017.
    191. "Cubes in Space". cubesinspace.com. Archived from the original on June 19, 2017. Retrieved July 1, 2017.
    192. "A Teen Created the World's Lightest Satellite & NASA Is Going to Launch It". Futurism. Archived from the original on May 18, 2019. Retrieved May 18, 2019.
    193. "Global Climate Change". NASA.
    194. ""2016 Climate Trends Continue to Break Records". NASA, July 19, 2016". Archived from the original on December 9, 2016. Retrieved December 14, 2016.
    195. Jason Samenow (July 23, 2016). "Trump adviser proposes dismantling NASA climate research". Washington Post. Archived from the original on November 24, 2016.
    196. Nyirady, Annamarie (April 25, 2019). "NASA Awards PathFinder Digital Free Space Optics Contract". Via Satellite. Archived from the original on April 30, 2019. Retrieved April 30, 2019.
    197. International System of Units - The Metric Measurement System | NASA
    198. CNN - Metric mishap caused loss of NASA orbiter - September 30, 1999
    199. Mars Climate Orbiter Failure Board Releases Report
    200. Metric Moon | Science Mission Directorate
    201. "MSFC_Fact_sheet" (PDF). NASA. Archived (PDF) from the original on October 25, 2011. Retrieved October 1, 2011.
    202. Rogers, Simon. (February 1, 2010) Nasa budgets: US spending on space travel since 1958 |Society Archived January 31, 2017, at the Wayback Machine. theguardian.com. Retrieved on August 26, 2013.
    203. "Fiscal Year 2013 Budget Estimates" (PDF). NASA. Archived (PDF) from the original on October 23, 2012. Retrieved February 13, 2013.
    204. "Past, Present, and Future of NASA — U.S. Senate Testimony". Hayden Planetarium. March 7, 2012. Archived from the original on October 29, 2012. Retrieved December 4, 2012.
    205. "Past, Present, and Future of NASA — U.S. Senate Testimony (Video)". Hayden Planetarium. March 7, 2012. Archived from the original on January 15, 2013. Retrieved December 4, 2012.
    206. Launius, Roger D. "Public opinion polls and perceptions of US human spaceflight". Division of Space History, National Air and Space Museum, Smithsonian Institution.
    207. Clark, Stephen (December 14, 2014). "NASA gets budget hike in spending bill passed by Congress". Spaceflight Now. Archived from the original on December 15, 2014. Retrieved December 15, 2014.
    208. Staff, Science News. "Updated: Congress approves largest U.S. research spending increase in a decade". Science. American Association for the Advancement of Science. Archived from the original on March 23, 2018. Retrieved March 23, 2018.
    209. Foust, Jeff. "NASA receives $20.7 billion in omnibus appropriations bill". Space News. Retrieved March 23, 2018.
    210. "Rocket Soot Emissions and Climate Change". The Aerospace Corporation. July 31, 2013. Archived from the original on July 7, 2014. Retrieved January 7, 2014.
    211. "Short-Term Energy Outlook" (PDF). U.S. Energy Information Administration. February 9, 2016. Archived (PDF) from the original on March 18, 2016. Retrieved February 24, 2016. U.S. Petroleum and Other Liquids
    212. "Spaceflight Now – Dragon Mission Report – Mission Status Center". Archived from the original on September 24, 2015. Retrieved July 4, 2015.
    213. "Space Shuttle Main Engines". NASA. July 16, 2009. Archived from the original on January 24, 2015. Retrieved January 20, 2015.
    214. "Constellation Programmatic Environmental Impact Statement". NASA. August 1, 2011. Archived from the original on August 8, 2014. Retrieved June 19, 2014.
    215. Shiga, David (September 28, 2007). "Next-generation ion engine sets new thrust record". New Scientist. Archived from the original on June 4, 2011. Retrieved February 2, 2011.
    216. Goto, T; Nakata Y; Morita S (2003). "Will xenon be a stranger or a friend?: the cost, benefit, and future of xenon anesthesia". Anesthesiology. 98 (1): 1–2. doi:10.1097/00000542-200301000-00002. PMID 12502969.
    217. Michael K. Ewert (2006). "Johnson Space Center's Role in a Sustainable Future" (PDF). NASA. Archived from the original (PDF) on May 27, 2008. Retrieved April 28, 2008.
    218. "NASA – NASA's New Building Awarded the U.S. Green Building Council LEED Gold Rating". nasa.gov. Archived from the original on October 7, 2018. Retrieved April 12, 2018.

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