The National Aeronautics and Space Administration (NASA ) is an independent agency of the U.S. federal government responsible for the United States' civil space program, as well as research in aeronautics and space. Headquartered in Washington, D.C., NASA operates ten field centers across the US and is organized into three mission directorates: Human Spaceflight, Research and Technology, and Science. Established in 1958 amid the Space Race, NASA succeeded the National Advisory Committee for Aeronautics (NACA) to give the US space program a distinct civilian orientation focused on peaceful applications. Since then, it has led most American spaceflight programs, including Project Mercury, Project Gemini, the Apollo program, Skylab, the Space Shuttle, the International Space Station (ISS), and the ongoing multi-national Artemis program. NASA maintains extensive ground and communications infrastructure, including the Deep Space Network and the Near Earth Network. Its science programs focus on Earth observation through the Earth Observing System, heliophysics research, Solar System exploration with robotic missions such as New Horizons and the Perseverance rover, and astrophysics investigations using space-based observatories including the James Webb Space Telescope and the Hubble Space Telescope. The Launch Services Program oversees operations for uncrewed launches. The agency supports the ISS through international partnerships and highly successful commercial initiatives, such as the Commercial Crew Program and Commercial Resupply Services. NASA also leads the development of the Orion spacecraft and the Space Launch System rocket for the Artemis program. NASA collaborates globally with organizations including the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA), the Canadian Space Agency (CSA), and Russia's Roscosmos (for ISS operations), as well as domestically with US agencies such as the National Oceanic and Atmospheric Administration, the United States Geological Survey, and the United States Space Force. NASA's missions and media initiatives, including the NASA+ streaming service, contribute significantly to its public visibility and outreach. The agency has also maintained a lasting influence on popular culture since the historic Apollo 11 Moon landing in 1969. For fiscal year 2026, NASA was authorized a budget of $24.4 billion and employs approximately 18,400 civil servants; since December 2025, its administrator has been Jared Isaacman.
History
Creation
NASA traces its roots to the National Advisory Committee for Aeronautics (NACA). Although Dayton, Ohio, is considered the birthplace of aviation, by 1914 the United States recognized that it lagged significantly behind Europe in aviation capability. Determined to regain American leadership in aviation, the US Congress created the Aviation Section of the US Army Signal Corps in 1914 and established NACA in 1915 to foster aeronautical research and development. Over the next forty years, NACA conducted aeronautical research in support of the US Air Force, US Army, US Navy, and the civil aviation sector. Following the end of World War II, NACA became interested in the possibilities of guided missiles and supersonic aircraft, developing and testing the Bell X-1 in a joint program with the US Air Force. NACA's interest in space grew out of its rocketry program at the Pilotless Aircraft Research Division.
The Soviet Union's launch of Sputnik 1 ushered in the Space Age and kicked off the Space Race. Despite NACA's early rocketry program, the responsibility for launching the first American satellite initially fell to the Naval Research Laboratory's Project Vanguard. Vanguard's operational issues led the Army Ballistic Missile Agency to successfully launch Explorer 1, America's first satellite, on February 1, 1958. The Eisenhower Administration decided to separate the nation's military and civil spaceflight programs, which had been previously organized together under the Department of Defense's Advanced Research Projects Agency. NASA was established on July 29, 1958, with the signing of the National Aeronautics and Space Act, and began operations on October 1, 1958. As America's premier aeronautics agency, NACA formed the core of NASA's new structure, reassigning 8,000 employees and three major research laboratories to the new entity. NASA also absorbed the Naval Research Laboratory's Project Vanguard, the Army's Jet Propulsion Laboratory (JPL), and the Army Ballistic Missile Agency under the leadership of Wernher von Braun. This established NASA firmly as the US's civil space leader, while the Air Force retained military space leadership.
First orbital and hypersonic flights
Plans for human spaceflight began within the US Armed Forces prior to NASA's creation. The Air Force's Man in Space Soonest project formed in 1956, coupled with the Army's Project Adam, serving as the foundation for Project Mercury. NASA established the Space Task Group to manage the program, which conducted crewed suborbital flights with the Army's Redstone rockets and orbital flights with the Air Force's Atlas launch vehicles. While NASA originally intended for its first astronauts to be civilians, President Eisenhower directed that they be selected from the military. The Mercury 7 astronauts included three Air Force pilots, three Navy aviators, and one Marine Corps pilot.
On May 5, 1961, Alan Shepard became the first American to enter space, performing a suborbital spaceflight aboard Freedom 7. This flight occurred 23 days after the Soviet cosmonaut Yuri Gagarin became the first human in space, executing a full orbital flight. NASA's first orbital spaceflight was conducted by John Glenn on February 20, 1962, in the Friendship 7, completing three full orbits before reentering. Glenn had to fly parts of his final two orbits manually due to an autopilot malfunction. The sixth and final Mercury mission was flown by Gordon Cooper in May 1963, completing 22 orbits over 34 hours aboard Faith 7. The Mercury program was widely recognized as a resounding success, achieving its objectives to orbit a human in space, develop tracking and control systems, and identify other technical and physiological issues associated with human spaceflight. While much of NASA's attention turned to space, it continued its aeronautics mission. Early aeronautics research attempted to build upon the X-1's supersonic flight to develop an aircraft capable of hypersonic flight. The North American X-15 was a joint NASA–US Air Force program, with the hypersonic test aircraft becoming the first non-dedicated spacecraft to cross from the atmosphere into outer space. The X-15 also served as a critical testbed for Apollo program technologies, as well as ramjet and scramjet propulsion.
Moon landing
Escalations in the Cold War between the US and the Soviet Union prompted President John F. Kennedy to charge NASA with landing a man on the Moon and returning him safely to Earth by the end of the 1960s. Kennedy installed James E. Webb as NASA administrator to execute this ambitious objective. On May 25, 1961, Kennedy openly declared this goal in his "Urgent National Needs" speech to Congress, stating:
I believe this Nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to Earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish. Kennedy further galvanized the nation during his "We choose to go to the Moon" speech on September 12, 1962, at Rice University, hoping to reinforce public support for the Apollo program. Despite criticism of the Moon landing goal from former president Dwight D. Eisenhower and 1964 presidential candidate Barry Goldwater, President Kennedy was able to protect NASA's growing budget, half of which was dedicated directly to human spaceflight. It was later estimated that, at its peak, 5% of the American workforce contributed in some capacity to the Apollo program.
Mirroring the Department of Defense's management concept of using redundant systems to build the first intercontinental ballistic missiles, NASA requested that the Air Force assign Major General Samuel C. Phillips to the space agency, where he served as the director of the Apollo program. Development of the Saturn V rocket was led by Wernher von Braun and his team at the Marshall Space Flight Center, deriving it from the Army Ballistic Missile Agency's original Saturn I. The Apollo spacecraft was designed and built by North American Aviation, while the Apollo Lunar Module was designed and built by Grumman. To develop the spaceflight skills and equipment required for a lunar mission, NASA initiated Project Gemini. Using a modified Air Force Titan II launch vehicle, the Gemini capsule could hold two astronauts for flights lasting over two weeks. Gemini pioneered the use of fuel cells instead of batteries, and conducted the first American spacewalks and orbital rendezvous operations.
The Ranger Program started in the 1950s as a response to Soviet lunar exploration; however, most early missions ended in failure. The Lunar Orbiter program achieved greater success, mapping the surface in preparation for Apollo landings, conducting meteoroid detection, and measuring radiation levels. The Surveyor program conducted uncrewed lunar landings and takeoffs, capturing surface and regolith observations. Despite the tragic setback caused by the Apollo 1 fire, which killed three astronauts, the lunar program proceeded. Apollo 8 was the first crewed spacecraft to leave low Earth orbit and the first human spaceflight to reach the Moon. The crew orbited the Moon ten times on December 24 and 25, 1968, before returning safely to Earth. The three Apollo 8 astronauts—Frank Borman, James Lovell, and William Anders—were the first humans to see the Earth as a globe in space, the first to witness an Earthrise, and the first to manually photograph the far side of the Moon. The first lunar landing was achieved by Apollo 11. Commanded by Neil Armstrong alongside astronauts Buzz Aldrin and Michael Collins, Apollo 11 was one of the most historically significant missions in NASA's history, effectively ending the Space Race as the Soviet Union subsequently scaled back its lunar ambitions. Becoming the first human to step on the surface of the Moon, Neil Armstrong uttered his now famous words:
That's one small step for [a] man, one giant leap for mankind. NASA conducted a total of six lunar landings as part of the Apollo program, with Apollo 17 concluding the program in 1972.
End of Apollo
Wernher von Braun had advocated for NASA to develop a space station since the agency's creation. In 1973, following the end of the Apollo lunar missions, NASA launched its first space station, Skylab, aboard the final flight of the Saturn V rocket. Skylab heavily reused Apollo and Saturn hardware, with a repurposed Saturn V third stage serving as the primary orbital module. Damage sustained during its launch required the first crew to perform critical spacewalks to render the station habitable and operational. Skylab hosted nine missions and was decommissioned in 1974. It ultimately deorbited in 1979, two years prior to the inaugural flight of the Space Shuttle, making any attempt to boost its orbit impossible. In 1975, the Apollo–Soyuz test project represented the first international spaceflight and a major diplomatic accomplishment between the Cold War rivals, simultaneously marking the last flight of the Apollo capsule. During this mission, an American Apollo spacecraft docked in orbit with a Soviet Soyuz capsule.
Interplanetary exploration and space science
During the 1960s, NASA expanded its space science and interplanetary probe program. The Mariner program served as its flagship, launching probes to Venus, Mars, and Mercury throughout the decade. The Jet Propulsion Laboratory became the lead NASA center for robotic interplanetary exploration, facilitating significant discoveries about the inner planets. Despite these early successes, Congress became hesitant to fund further interplanetary missions, and NASA Administrator James Webb suspended all future interplanetary probes to focus the agency's resources on the Apollo program. Following the conclusion of Apollo, NASA resumed launching interplanetary probes and expanded its space science programs. The first planet targeted for intensive exploration was Venus, which shares several similarities to Earth. First visited by the American Mariner 2 spacecraft, Venus was revealed to be a hot and inhospitable planet. Follow-on missions included the Pioneer Venus project in the 1970s and Magellan, which performed extensive radar mapping of Venus's surface in the 1980s and 1990s. Later missions primarily utilized Venus flybys for gravity assists on their way to other destinations in the Solar System. Mars has long been a planet of intense fascination for NASA, being suspected of having potentially harbored life in its past. Mariner 5 was the first NASA spacecraft to fly by Mars, followed by Mariner 6 and Mariner 7. Mariner 9 was the first orbital mission to Mars. Launched in 1975, the Viking program culminated in two successful surface landings on Mars in 1976. Surface exploration would not resume until 1996, with the Mars Global Surveyor orbiter and Mars Pathfinder, the latter deploying the first Mars rover, Sojourner. During the early 2000s, the 2001 Mars Odyssey orbiter reached the planet, and in 2004 the twin Spirit and Opportunity rovers landed on the Red Planet. They were followed in 2005 by the Mars Reconnaissance Orbiter and the 2007 Phoenix Mars lander. The 2012 landing of Curiosity revealed that the radiation levels on Mars were comparable to those on the International Space Station (ISS)—increasing the plausibility of future human exploration—and detected key chemical ingredients necessary for life. In 2013, the Mars Atmosphere and Volatile Evolution (MAVEN) mission observed the Martian upper atmosphere and space environment, while the 2018 Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander studied the Martian interior. The 2021 landing of the Perseverance rover included the deployment of the first extraplanetary aircraft, a robotic helicopter named Ingenuity. NASA also returned to Mercury in 2004, with the MESSENGER probe demonstrating the first use of solar sailing techniques for trajectory control. NASA had been launching probes to the outer Solar System since the 1970s. Pioneer 10 became the first probe to visit the outer planets, flying by Jupiter, while Pioneer 11 provided the first close-up view of the system. Both probes eventually became the first artificial objects to leave the Solar System. The Voyager program launched in 1977, executing historic flybys of Jupiter, Saturn, Neptune, and Uranus on a trajectory extending into interstellar space. The Galileo spacecraft, deployed from Space Shuttle flight STS-34, became the first spacecraft to orbit Jupiter, discovering strong evidence of a subsurface ocean on the moon Europa. A joint NASA–ESA–ASI mission, Cassini–Huygens, explored Saturn's moon Titan—which, along with Mars and Europa, is considered one of the few celestial bodies in the Solar System capable of harboring life. Cassini discovered three new moons around Saturn, and the Huygens probe successfully entered Titan's atmosphere. The mission found evidence of liquid hydrocarbon lakes on Titan and a subsurface water ocean on the moon Enceladus, offering further astrobiological potential. Finally, the New Horizons mission, launched in 2006, became the first spacecraft to visit Pluto and the deeper Kuiper belt. Beyond interplanetary probes, NASA has deployed an array of sophisticated space telescopes. Initiated in the 1960s, the Orbiting Astronomical Observatory program comprised NASA's first orbital telescopes, delivering groundbreaking ultraviolet, gamma-ray, X-ray, and infrared observations. In the 1960s and 1970s, NASA launched the Orbiting Geophysical Observatory satellites to observe Earth and its interactions with the Sun. The Uhuru satellite became the first dedicated X-ray telescope, mapping 85% of the sky and discovering a large number of black holes.
Launched primarily in the 1990s and early 2000s, the Great Observatories program comprises some of NASA's most powerful astrophysical tools. The Hubble Space Telescope was launched in 1990 via Discovery on STS-31 and proved capable of viewing galaxies 15 billion light-years away. Although a major manufacturing defect in the telescope's primary mirror threatened to cripple the mission, NASA initially compensated using computer enhancement and later flew five Space Shuttle servicing missions to install corrective optics and upgrade components. The Compton Gamma Ray Observatory was launched by Atlantis on STS-37 in 1991, identifying a possible source of antimatter at the center of the Milky Way and confirming that the majority of gamma-ray bursts occur outside our galaxy. The Chandra X-ray Observatory was deployed from Columbia on STS-93 in 1999, studying black holes, quasars, supernovae, and dark matter. It provided critical observations of the Sagittarius A* black hole at the center of the Milky Way and observed the separation of dark and regular matter during galactic collisions. Finally, the Spitzer Space Telescope, an infrared observatory, launched in 2003 on a Delta II rocket. Placed in an Earth-trailing orbit around the Sun, it contributed to the discovery and study of brown dwarfs and exoplanets. Other telescopes, such as the Cosmic Background Explorer and the Wilkinson Microwave Anisotropy Probe, gathered robust evidence supporting the Big Bang theory. The James Webb Space Telescope, named after the NASA administrator who led the Apollo program, is a sophisticated infrared observatory launched in 2021. Designed as a direct successor to Hubble, it is optimized to observe the formation of the first galaxies in the universe. Further initiatives include the Kepler space telescope, launched in 2009 to identify exoplanets that may be potentially habitable. Kepler notably confirmed Kepler-22b, its first discovery orbiting within the habitable zone of its host star. NASA has also launched numerous satellites dedicated to studying Earth, including the Television Infrared Observation Satellite (TIROS) in 1960, which operated as the first weather satellite. NASA collaborated closely with the US Weather Bureau on subsequent TIROS missions and the second-generation Nimbus program. It expanded its Earth science portfolio through partnerships with the Environmental Science Services Administration and by fielding experimental Applications Technology Satellites in geosynchronous orbit. NASA's first dedicated Earth observation satellite, Landsat, launched in 1972. This long-standing focus ultimately led to NASA and the National Oceanic and Atmospheric Administration jointly developing the Geostationary Operational Environmental Satellite network and contributing to the global discovery of ozone depletion.
Space Shuttle
NASA had pursued spaceplane development since the 1960s, seeking to blend its dual aeronautics and spaceflight mandates. NASA viewed a spaceplane as part of a broader architectural program designed to provide routine and economical logistical support to a future space station in Earth orbit, which would, in turn, serve as a hub for lunar and Mars missions. An operational, reusable launch vehicle was expected to end reliance on expensive, expendable boosters like the Saturn V. In 1969, NASA designated the Johnson Space Center as the lead facility for the design, development, and manufacturing of the Space Shuttle orbiter, while the Marshall Space Flight Center led the development of the launch system. Insights gained from NASA's series of lifting body aircraft, culminating in the joint NASA–Air Force Martin Marietta X-24, directly informed the Space Shuttle's aerodynamic design. Official development began in 1972, with Rockwell International contracted to design the orbiter and engines, Martin Marietta producing the external fuel tank, and Morton Thiokol creating the solid rocket boosters. NASA eventually acquired six orbiters: Enterprise (for atmospheric testing), Columbia, Challenger, Discovery, Atlantis, and Endeavour. The Space Shuttle program allowed NASA to significantly evolve its Astronaut Corps. While nearly all early astronauts were military test pilots, the Shuttle's diverse operational needs led NASA to recruit civilian scientific and technical experts. Notably, Sally Ride became the first American woman in space aboard STS-7. The revised astronaut selection framework also allowed NASA to include exchange astronauts from US allies and international partners for the first time. The first orbital Space Shuttle flight occurred in 1981 when Columbia launched on the STS-1 mission, serving as a critical flight test for the new system. NASA initially intended for the Space Shuttle to fully replace expendable launch vehicles such as the Air Force's Atlas, Delta, and Titan, as well as the European Space Agency's Ariane rockets. The Shuttle's Spacelab payload module, developed by the ESA, drastically increased NASA's on-orbit scientific capabilities compared to prior eras.
NASA successfully launched commercial satellites on STS-5, and in 1984, the STS-41-C mission conducted the world's first on-orbit satellite servicing operation when Challenger captured and repaired the malfunctioning Solar Maximum Mission satellite. The Space Shuttle could also retrieve malfunctioning satellites—like Palapa B2 and Westar 6—and return them to Earth, where they were repaired and eventually relaunched. Despite ushering in an era where NASA could frequently contract launch services for commercial companies, the Space Shuttle drew significant criticism for failing to be as cost-effective or rapidly reusable as initially advertised. In 1986, the Challenger disaster during the STS-51L mission resulted in the tragic loss of the orbiter and all seven astronauts, grounding the entire fleet for 36 months. This forced the 44 commercial companies that had contracted with NASA to revert to using expendable launch vehicles. When the Space Shuttle resumed flights with the STS-26 mission, the program had undergone stringent modifications to enhance safety and reliability.
Following the collapse of the Soviet Union, the Russian Federation and the United States initiated the Shuttle–Mir program. The first Russian cosmonaut to fly on a Shuttle participated in the STS-60 mission in 1994, and Discovery performed a historic rendezvous—but did not dock—with the Russian space station Mir during STS-63. This was followed by Atlantis's STS-71 mission, achieving the Space Shuttle's long-intended goal of docking with a space station to transfer supplies and personnel. The Shuttle–Mir program continued until 1998, when an aging infrastructure and a series of orbital accidents aboard the Russian station brought it to an end. In 2003, a second orbiter was lost when Columbia disintegrated upon reentry during the STS-107 mission, resulting in the deaths of all seven astronauts. This tragedy marked the beginning of the end for the program, with President George W. Bush directing that the Space Shuttle be retired upon the completion of the ISS. The fleet returned to flight in 2006, executing critical missions to assemble the ISS and perform a final servicing of the Hubble Space Telescope. The Space Shuttle program concluded entirely after the STS-135 resupply mission in 2011.
Space stations
NASA never abandoned the concept of a permanent orbital laboratory following Skylab's reentry in 1979. As soon as the Space Shuttle became operational, the agency began lobbying for political support to build a larger space station, framing it as an orbital research hub, repair depot, and staging point for deep-space missions. NASA found a strong proponent in President Ronald Reagan, who stated in a 1984 speech:
America has always been greatest when we dared to be great. We can reach for greatness again. We can follow our dreams to distant stars, living and working in space for peaceful, economic, and scientific gain. Tonight I am directing NASA to develop a permanently manned space station and to do it within a decade. In 1985, NASA proposed Space Station Freedom, which both the agency and President Reagan intended to be an international effort. While international collaboration offered political legitimacy, elements within NASA hesitated to work with domestic or foreign partners as true equals, and there were significant concerns over sharing sensitive space technologies with Europe. Nevertheless, an international agreement to develop Freedom was signed in 1985 with thirteen nations, including European Space Agency (ESA) member states, Canada, and Japan. Despite its landmark status as the first truly international space endeavor, Space Station Freedom proved highly controversial, primarily due to escalating costs. Several sweeping redesigns in the early 1990s stripped the proposed station of many intended functions. Despite congressional pressure to cancel the program, it survived largely because, by 1992, it supported 75,000 aerospace jobs across 39 states. In 1993, the administration of President Bill Clinton sought to heavily reduce NASA's budget while protecting those jobs by directing that the station integrate the Russian Federation into the design.
Consequently, the Clinton Administration announced in 1993 that Space Station Freedom would be absorbed into what became the ISS program via a bilateral agreement with Russia. This infusion of American currency allowed Russia to preserve its faltering space sector post-Cold War and maintain its status as a premier spaceflight power. While the US financed and constructed the majority of the ISS, Russia, Canada, Japan, and the ESA provided critical hardware and modules. Though NASA initially projected costs to remain at $17.4 billion, budget overruns continually forced the agency to transfer funds from other programs. Ultimately, the total developmental and construction cost of the station approached $150 billion, with the US funding roughly two-thirds. Following the Columbia disaster in 2003, NASA grew reliant on Russian Soyuz spacecraft for astronaut transport, and the retirement of the Space Shuttle in 2011 punctuated the transition to operational dependency until American commercial solutions matured. Concurrently in the 1980s, NASA partnered with the Department of Defense to develop the Rockwell X-30 National Aerospace Plane. Recognizing that the Space Shuttle could not fulfill all of its economic and rapid-turnaround promises, NASA intended the X-30 to operate as a true single-stage-to-orbit spaceplane with both civil and military utility. With the end of the Cold War reducing defense spending, the X-30 was canceled in 1992 before achieving flight status.
Unleashing commercial space and returning to the Moon
In the aftermath of the 2003 Columbia disaster, President Bush introduced the Constellation program, designed to serve as a successor to the Space Shuttle and extend human spaceflight beyond low Earth orbit. Constellation sought to heavily leverage existing Shuttle technology and successfully return astronauts to the Moon. However, this program was later canceled under the Obama Administration. Prominent former astronauts, including Neil Armstrong, Gene Cernan, and Jim Lovell, strongly cautioned President Obama that failing to maintain strong human spaceflight capabilities risked relegating the United States to a second-tier space power. To adapt, NASA increasingly looked to the private sector. Calls to involve commercial enterprises in orbital space operations had surfaced as early as the Reagan Administration. In the 1990s, NASA and Lockheed Martin partnered on the X-33 demonstrator for the VentureStar concept—a commercial spaceplane intended to replace the Shuttle. Though the project was canceled in 2001 due to severe technical difficulties, it marked the first instance of a commercial entity directly expending significant internal resources on an orbital launch system. Around this time, the reality of space tourism challenged NASA's assumption that orbital travel would remain an exclusively governmental domain. Notably, Dennis Tito, an American investment manager, contracted with Russia to spend four days on the ISS in 2001, overriding intense initial opposition from NASA. Prominent figures like former astronaut Buzz Aldrin advocated strongly for expanding NASA's use of commercial partners, arguing it would free the agency to refocus on deep-space exploration and its historical roots in research and development. Embracing this highly efficient commercial approach, NASA introduced the Commercial Resupply Services program to manage ISS logistics, and later the Commercial Crew Program. SpaceX emerged as a vital partner in this shift; with the launch of the SpaceX Crew-1 mission in 2020, SpaceX successfully restored America's human spaceflight capability, ending nearly a decade of domestic reliance on Russian vehicles. Looking beyond low Earth orbit, NASA formally announced the Artemis program in 2019, targeting a return of humans to the Moon and the establishment of a sustainable lunar presence. The technological effort was paired diplomatically with the Artemis Accords, which seek to build a coalition of partner nations adhering to established norms for the commercial and peaceful use of lunar space. To organize this multifaceted deep-space strategy, NASA established the Moon to Mars Program Office in 2023. The office actively oversees hardware architectures, international mission planning, and science objectives associated with establishing long-term operations on the Moon and subsequently exploring Mars.
Active programs
Human spaceflight
International Space Station (1993–present)
The International Space Station (ISS) represents a fusion of NASA's initial Space Station Freedom project with the Russian Mir-2 program, the European Columbus initiative, and the Japanese Kibō laboratory. Though NASA planned in the 1980s to develop Freedom unilaterally, domestic budget constraints forced a merger of these concepts into a single multi-national effort in 1993. The program is managed jointly by NASA, the Russian Federal Space Agency (Roscosmos), the Japan Aerospace Exploration Agency (JAXA), the European Space Agency (ESA), and the Canadian Space Agency (CSA). The station is constructed of multiple pressurized modules, large external trusses, solar arrays, and diverse scientific components manufactured globally and delivered to orbit by Russian Proton and Soyuz rockets alongside the American Space Shuttle. Orbital assembly began in 1998; the core US Orbital Segment was completed by 2009, with the Russian Orbital Segment achieving its primary assembly phase by 2010. Operations and habitation are governed by international treaties, granting Russia full ownership over its segment (excluding the early, US-funded Zarya module), while allocating the US Orbital Segment collaboratively among NASA and the other partners. Long-duration assignments aboard the station are classified as ISS Expeditions. Expedition crews historically spend roughly six months in orbit. Originally set at three, crew numbers temporarily decreased to two following the Columbia disaster before returning to and expanding to six residents by 2009. Following the successful introduction of the robust Commercial Crew capsules—which comfortably transport four crewmembers each—long-duration expeditions frequently support larger staffing contingents. The ISS has been continuously inhabited since November 2000, eclipsing the previous occupancy record set by Mir, and has hosted travelers from over 15 nations. The station can be seen from the Earth with the naked eye and, as of 2026, is the largest artificial satellite in Earth orbit with a mass and volume greater than that of any previous space station. The Russian Soyuz and American Dragon and Starliner spacecraft are used to send astronauts to and from the ISS. Several uncrewed cargo spacecraft provide service to the ISS; they are the Russian Progress spacecraft which has done so since 2000, the European Automated Transfer Vehicle (ATV) since 2008, the Japanese H-II Transfer Vehicle (HTV) since 2009, the (uncrewed) Dragon since 2012, and the American Cygnus spacecraft since 2013. The Space Shuttle, before its retirement, was also used for cargo transfer and would often switch out expedition crew members, although it did not have the capability to remain docked for the duration of their stay. Between the retirement of the Shuttle in 2011 and the commencement of crewed Dragon flights in 2020, American astronauts exclusively used the Soyuz for crew transport to and from the ISS. The highest number of people occupying the ISS has been thirteen; this occurred three times during the late Shuttle ISS assembly missions. The ISS program is expected to continue until 2030, after which the space station will be retired and destroyed in a controlled de-orbit.
Commercial Resupply Services (2008–present)
Commercial Resupply Services (CRS) are a contract solution to deliver cargo and supplies to the International Space Station on a commercial basis by private companies. NASA signed its first CRS contracts in 2008 and awarded $1.6 billion to SpaceX for twelve cargo Dragon and $1.9 billion to Orbital Sciences for eight Cygnus flights, covering deliveries until 2016. Both companies evolved or created their launch vehicle products to launch the spacecraft (SpaceX with The Falcon 9 and Orbital with the Antares). SpaceX flew its first operational resupply mission (SpaceX CRS-1) in 2012. Orbital Sciences followed in 2014 (Cygnus CRS Orb-1). In 2015, NASA extended CRS-1 to twenty flights for SpaceX and twelve flights for Orbital ATK. A second phase of contracts (known as CRS-2) was solicited in 2014; contracts were awarded in January 2016 to Orbital ATK Cygnus, Sierra Nevada Corporation Dream Chaser, and SpaceX Dragon 2, for cargo transport flights beginning in 2019 and expected to last through 2024. In March 2022, NASA awarded an additional six CRS-2 missions each to both SpaceX and Northrop Grumman (formerly Orbital). Northrop Grumman successfully delivered Cygnus NG-17 to the ISS in February 2022. In July 2022, SpaceX launched its 25th CRS flight (SpaceX CRS-25) and successfully delivered its cargo to the ISS. The Dream Chaser spacecraft is currently scheduled for its Demo-1 launch in the first half of 2024.
Commercial Crew Program (2011–present)
The Commercial Crew Program (CCP) provides commercially operated crew transportation service to and from the International Space Station (ISS) under contract to NASA, conducting crew rotations between the expeditions of the International Space Station program. American space manufacturer SpaceX began providing service in 2020, using the Crew Dragon spacecraft, while Boeing's Starliner spacecraft provided service in 2024. It was on contract for 6 missions, but after the first mission nearly ended in disaster and left the two astronauts stranded on the ISS for six months, NASA froze its contract with Boeing. NASA has contracted for six operational missions from Boeing and fourteen from SpaceX, ensuring sufficient support for ISS through 2030. The spacecraft are owned and operated by the vendor, and crew transportation is provided to NASA as a commercial service. Each mission sends up to four astronauts to the ISS, with an option for a fifth passenger available. Operational flights occur approximately once every six months for missions that last for approximately six months. A spacecraft remains docked to the ISS during its mission, and missions usually overlap by at least a few days. Between the retirement of the Space Shuttle in 2011 and the first operational CCP mission in 2020, NASA relied on the Soyuz program to transport its astronauts to the ISS. A Crew Dragon spacecraft is launched to space atop a Falcon 9 Block 5 launch vehicle and the capsule returns to Earth via splashdown in the ocean near Florida. The program's first operational mission, SpaceX Crew-1, launched on November 16, 2020. Boeing Starliner operational flights will now commence with Boeing Starliner-1 which will launched atop an Atlas V N22 launch vehicle. Instead of a splashdown, Starliner capsules return on land with airbags at one of four designated sites in the western US.
Artemis (2017–present)
Since 2017, NASA's crewed spaceflight program has been the Artemis program, which involves the help of US commercial spaceflight companies and international partners such as ESA, JAXA, and Canadian Space Agency. Artemis would be the first step towards the long-term goal of establishing a sustainable presence on the Moon, laying the foundation for companies to build a lunar economy, and eventually sending humans to Mars. The Orion Crew Exploration Vehicle was held over from the canceled Constellation program for Artemis. Artemis I was the uncrewed initial launch of Space Launch System (SLS) that would also send an Orion spacecraft on a Distant Retrograde Orbit. The first step toward returning astronauts to the Moon, Artemis II, briefly placed a crew of four into a lunar flyby in April 2026. Artemis III, planned for mid-2027, was originally planned to conduct the first crewed lunar landing since Apollo 17; in February 2026, the mission was changed to a low Earth orbit docking test of Orion. The landing was pushed to Artemis IV, planned for early 2028. In support of the Artemis missions, NASA has been funding private companies to land robotic probes on the lunar surface in a program known as the Commercial Lunar Payload Services. As of March 2022, NASA has awarded contracts for robotic lunar probes to companies such as Intuitive Machines, Firefly Space Systems, and Astrobotic. On April 16, 2021, NASA announced they had selected the SpaceX Lunar Starship as its Human Landing System. The agency's Space Launch System rocket will launch four astronauts aboard the Orion spacecraft for their multi-day journey to lunar orbit where they will transfer to SpaceX's Starship for the final leg of their journey to the surface of the Moon. Until 2026, NASA additionally planned the construction of the Lunar Gateway, a small space station in lunar orbit designed primarily for non-continuous human habitation. In March 2026, NASA canceled the project in favor of a Moon Base. In 2017, NASA was directed by the congressional NASA Transition Authorization Act of 2017 to get humans to Mars-orbit (or to the Martian surface) by the 2030s.
Commercial LEO Development (2021–present)
The Commercial Low Earth Orbit Destinations program is an initiative by NASA to support work on commercial space stations that the agency hopes to have in place by the end of the current decade to replace the "International Space Station". The three selected companies are: Blue Origin (et al.) with their Orbital Reef station concept, Nanoracks (et al.) with their Starlab Space Station concept, and Northrop Grumman with a station concept based on the HALO-module for the Gateway station.
Robotic exploration
NASA has conducted many uncrewed and robotic spaceflight programs throughout its history. More than 1,000 uncrewed missions have been designed to explore the Earth and the Solar System.
Mission selection process NASA executes a mission development framework to plan, select, develop, and operate robotic missions. This framework defines cost, schedule and technical risk parameters to enable competitive selection of m