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Arnaldo Tamayo Méndez
Arnaldo Tamayo Méndez, also known as Arnaldo Tamayo, is a Cuban military officer and cosmonaut who in September 1980 became the first Cuban and first Latin American in space.
Arnold Engineering Development Complex
The Arnold Engineering Development Complex (AEDC) is a US Air Force ground-test complex at Arnold Air Force Base, Tennessee, operating wind tunnels and rocket engine test cells.
ART-XC
ART-XC, formally the Mikhail Pavlinsky ART-XC telescope, is a Russian hard X-ray telescope aboard the Spektr-RG observatory, launched in 2019, performing all-sky imaging surveys in the 4–30 keV band.
Artemis Base Camp
Artemis Base Camp is NASA's planned infrastructure for a sustained human presence at the lunar South Pole, combining a surface habitat, two rovers, power systems, and resource equipment.
Artemis I
Artemis I was NASA's uncrewed test flight of the Space Launch System rocket and Orion spacecraft, launched November 16, 2022, and splashing down 25 days later.
Artemis II
Artemis II was the first crewed mission of NASA's Artemis program, a 10-day lunar flyby in April 2026 carrying Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen.
Artemis III
Artemis III is a planned 2027 NASA crewed mission in which four astronauts in Orion dock with commercial lunar lander test articles in low Earth orbit.
Artemis program
The Artemis program is NASA's effort to return astronauts to the Moon, establishing a long-term presence near the lunar South Pole and preparing for missions to Mars.
Arthur Rudolph
Arthur Rudolph (Arthur Louis Hugo Rudolph) was a German rocket engineer who ran V-2 production with concentration camp labor and later managed NASA's Saturn V program, leaving the US in 1984.
Artificial equilibrium point
An artificial equilibrium point (AEP) is a position in the three-body problem where a spacecraft can hover because continuous low thrust or solar radiation pressure supplements gravity; the idea was proposed by Dusek in 1966.
Artificial gravity
Artificial gravity, also called simulated gravity, simulates gravity in space by spinning a craft so centrifugal acceleration acts as gravity; proposed to counter weightlessness, it has never flown operationally.
Aryabhata (आर्यभट) (satellite)
Aryabhata (आर्यभट) was India's first artificial satellite, a 360 kg scientific spacecraft named for the 5th-century mathematician, launched by a Soviet rocket on 19 April 1975.
ASCENT (propellant)
ASCENT (Advanced Spacecraft Energetic Non-Toxic), formerly AF-M315E, is a hydroxylammonium nitrate green monopropellant developed by the Air Force Research Laboratory as a higher-performance hydrazine replacement.
Asgardia
Asgardia, formally the Space Kingdom of Asgardia, is an unrecognized micronation announced by Igor Ashurbeyli in October 2016, intended to exist on satellites and the Moon.
AsiaSat
AsiaSat, formally Asia Satellite Telecommunications Company Limited, is a Hong Kong-based satellite operator founded in 1988 that owns six in-orbit satellites serving broadcast and telecom customers.
Assembly of the International Space Station
The assembly of the International Space Station was the phased on-orbit construction begun in November 1998, joining more than 40 elements delivered by Space Shuttle and Russian rockets.
AST SpaceMobile
AST SpaceMobile is a Texas-based satellite company building a low Earth orbit constellation to provide 4G and 5G cellular broadband directly to unmodified smartphones, partnering with operators like AT&T and Verizon.
Asteroid Redirect Mission
The Asteroid Redirect Mission, also known as the Asteroid Initiative, was a proposed NASA mission to move an asteroid boulder into lunar orbit, canceled in 2017.
Astra (satellite family)
Astra is a family of geostationary communications satellites operated by Luxembourg's SES, launched since 1988 and carrying direct-to-home TV and radio across Europe from fixed orbital positions such as 19.2° East.
Astra 19.2°E
Astra 19.2°E, also called Astra 1, is the orbital position used by Luxembourg operator SES for its co-located Astra satellites, delivering over 850 TV channels across Europe.
Astra 1A
Astra 1A was a Luxembourgish geostationary communications satellite launched in December 1988 for SES, the first satellite of the Astra fleet and Europe's first high-power direct-to-home TV satellite.
Astra 28.2°E
Astra 28.2°E is a geostationary orbital position operated by SES that serves as the principal satellite TV position for the United Kingdom and Ireland, carrying Sky and Freesat.
Astranis Space Technologies
Astranis Space Technologies is a San Francisco company founded in 2015 by John Gedmark and Ryan McLinko that builds and operates small, dedicated geostationary communications satellites called MicroGEO.
Astrionics
Astrionics is the electronics discipline of spacecraft: the onboard avionics systems, components, instruments, and functional elements that allow a spacecraft to operate and fulfill its mission.
Astris
Astris, short for Ariane Smart Transfer and Release In-orbit Ship, is an ESA kick stage for Ariane 6 that moves payloads between orbits, including geostationary and lunar ones.
Astrobotic Technology
Astrobotic Technology is a space company in Pittsburgh, Pennsylvania, founded in 2007, that builds lunar landers and rovers and is one of NASA's Commercial Lunar Payload Services providers.
AstroForge Odin
Odin was a deep space spacecraft built by the American asteroid-mining company AstroForge, launched in 2025 to fly by near-Earth asteroid 2022 OB5 before contact was lost.
Astronaut
An astronaut is a person trained and qualified to serve as a crew member aboard a spacecraft, with Russian crew members called cosmonauts and Chinese crew members taikonauts.
Astronaut selection and candidate screening
Astronaut selection and candidate screening is the multi-stage process by which agencies such as NASA and ESA screen applicants on qualifications, medical fitness, and psychological suitability, selecting classes roughly every four years.
Astronaut training
Astronaut training is the multi-year program that turns selected astronaut candidates into people certified to fly in space, covering spacecraft systems, spacewalking, robotics, languages, and survival.