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4DTV
4DTV was a proprietary integrated receiver/descrambler for C-band and Ku-band big-dish satellite television, developed by General Instrument and later sold by Motorola, receiving both analog and DigiCipher II digital signals from 1997.
A-GPS
A-GPS, or Assisted GPS, is a positioning method where a mobile device's GPS receiver uses network-delivered assistance data to get a location fix within seconds.
A. S. Kiran Kumar
A. S. Kiran Kumar, born Aluru Seelin Kiran Kumar in 1952, is an Indian space scientist who served as Chairman of ISRO from 2015 to 2018.
A2100
The A2100 is a family of geostationary satellite buses built by Lockheed Martin, introduced in the mid-1990s for commercial communications satellites and later adapted for military, navigation, and weather spacecraft.
Abe M. Zarem
Abe M. Zarem was an American engineer who worked on the Manhattan Project, built ultrafast cameras, and founded Electro-Optical Systems, maker of the first practical ion engine.
Able (rocket stage)
Able was an upper rocket stage derived from Vanguard components, flown atop Thor and Atlas boosters in 1958 to 1960 for early satellites and lunar probes.
Active Response Gravity Offload System
The Active Response Gravity Offload System (ARGOS) is a robotic facility at NASA's Johnson Space Center in Houston that simulates reduced gravity for crew training and testing.
Aditya-L1
Aditya-L1 is India's first space-based solar observatory, launched by ISRO on September 2, 2023, to observe the Sun from a halo orbit around the Sun-Earth L1 point.
Advanced Composition Explorer
The Advanced Composition Explorer, also known as the ACE spacecraft, is a NASA probe launched in 1997 that measures solar wind and cosmic rays from the Sun-Earth L1 point.
Advanced Stirling radioisotope generator
The Advanced Stirling Radioisotope Generator (ASRG) was a NASA and Department of Energy project converting plutonium-238 heat into about 130 watts of electricity, canceled in 2013.
Aerobee
The Aerobee was an American two-stage, liquid-propellant sounding rocket developed by Aerojet for the U.S. Navy from 1946, flying until 1985 and opening X-ray astronomy.
Aerobraking
Aerobraking is a spacecraft maneuver that uses atmospheric drag on repeated passes to shrink an elliptical orbit into a circular one, saving rocket fuel; Magellan first demonstrated it at Venus in 1993.
Aerocapture
Aerocapture is an orbit-insertion technique using a single atmospheric pass to slow a spacecraft into orbit instead of a propellant burn, studied since the 1980s but never flown.
Aerojet Rocketdyne
Aerojet Rocketdyne was an American rocket propulsion manufacturer formed in 2013 by the merger of Aerojet and Pratt & Whitney Rocketdyne, acquired by L3Harris in 2023.
Aeronomy of Ice in the Mesosphere
Aeronomy of Ice in the Mesosphere (AIM) was a NASA satellite launched in 2007 to study noctilucent clouds; it operated 16 years, far beyond its planned two, until 2023.
Aerospike engine
The aerospike engine, also called the aerospike rocket engine, is a rocket engine whose exhaust expands against a central plug, making the nozzle altitude compensating at all altitudes.
Aerozine 50
Aerozine 50 is a rocket fuel of equal parts hydrazine and unsymmetrical dimethylhydrazine (UDMH); paired with nitrogen tetroxide, it ignites on contact and powered Titan rockets and Apollo spacecraft engines.
Aestus
Aestus is a pressure-fed rocket engine burning MMH and nitrogen tetroxide that powered the upper stage of Europe's Ariane 5 launcher, including ATV and Galileo missions, until 2018.
AGILE (satellite)
AGILE, the Astro-rivelatore Gamma a Immagini LEggero, was a small Italian Space Agency gamma-ray astronomy satellite that observed the high-energy sky from 2007 until 2024.
Air rocket
An air rocket is a non-pyrotechnic rocket launched by a burst of compressed air from a pump, stomp bladder, or compressor, with no engine; it coasts ballistically after leaving the tube.
Airbus Defence and Space
Airbus Defence and Space is the defense and space division of the European aerospace group Airbus SE, formed in 2014, making the Eurofighter Typhoon, A400M airlifter, and communications satellites.
Airlock
An airlock is a sealable chamber letting people pass between a pressurized spacecraft and vacuum without losing cabin air, standard for spacewalks since Leonov's 1965 EVA through the Volga.
Akatsuki
Akatsuki, also designated PLANET-C, was JAXA's Venus Climate Orbiter, launched in 2010; after a failed 2010 orbit insertion it reached Venus in 2015 and studied its atmosphere for over 8 years.
Alan Bean
Alan LaVern Bean was an American NASA astronaut, the fourth person to walk on the Moon on Apollo 12 in 1969, and the only moonwalker to become a painter.
Alan Shepard
Alan Bartlett Shepard Jr. was an American NASA astronaut and naval officer, the first American in space aboard Freedom 7 in 1961 and commander of Apollo 14 in 1971.
Albert D. Wheelon
Albert D. "Bud" Wheelon (1929–2013) was an American physicist who founded the CIA's Directorate of Science and Technology in 1963, oversaw spy satellite programs, and later led Hughes Aircraft.
Alcântara Space Center
The Alcântara Space Center (Centro de Lançamento de Alcântara) is Brazil's satellite launch center, run by the Brazilian Air Force on the Maranhão coast since 1983.
Alcubierre drive
The Alcubierre drive, also known as the Alcubierre warp drive or Alcubierre metric, is a theoretical faster-than-light propulsion concept proposed by Miguel Alcubierre in 1994.
Alexei Leonov (Алексе́й Архи́пович Лео́нов)
Alexei Arkhipovich Leonov (Алексе́й Архи́пович Лео́нов, 1934 to 2019) was a Soviet cosmonaut who made the first spacewalk in 1965 and commanded the 1975 Apollo-Soyuz mission.
Alfred Worden
Alfred Merrill Worden, also known as Al Worden, was an American Air Force officer and NASA astronaut who orbited the Moon alone on Apollo 15 in 1971.