Definitions list
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abortedDescribes an operation interrupted prematurely due to a failure. For example, an aborted launch.
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acceptance testTest designed to verify that a product complies with specifications.
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aerocaptureUse of friction against a planet’s atmosphere to slow a spacecraft for insertion into orbit.
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aeronomyStudy of the upper reaches of the atmosphere of Earth or other planets.
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aerospaceRelating to aeronautics and space.
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aircraft / aeroplaneHeavier-than-air flying machine kept in the air by reaction of the atmosphere, without the reaction of the ground.
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airlockCompartment that seals off a habitable part of a spacecraft from space. Astronauts go through an airlock when performing an extravehicular activity.
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airshipLighter-than-air craft capable of obtaining lift in a gaseous atmosphere without engine propulsion.
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albedoFrom the Latin word albedo, meaning “whiteness”. The albedo is the fraction of light reflected or scattered by a body. Its value is between 0 and 1.
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altimetryTechnique for measuring height using a radar beam, for example to map the topography of the ocean surface. Altimetry also yields information about the Earth’s geoid, ocean circulation, wave heights, sea state and wind speed.
How altimetry works
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alunirSe poser sur la Lune. Terme à proscrire. Utiliser atterrir
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anechoic chamberClosed chamber whose walls are lined with an absorbent material that does not reflect electromagnetic or acoustic waves. Used to simulate the vacuum of space.
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anisotropyProperty of being directionnally dependant. The properties of an anisotropic object will differ according to the direction of measurement.
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apesanteurSynonyme d’impesanteur. Ce mot est déconseillé en raison des risques de confusion pour l’oreille entre « la pesanteur » et « l’apesanteur ».
Qu'est-ce que l'impesanteur ?
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apoapsisPoint on a satellite’s orbit farthest from the body about which it is orbiting. Specific terms are used for individual bodies, for example, apogee (Earth), apolune (Moon), apojove (Jupiter) and aphelion (Sun).
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apogeePoint on an Earth-orbiting satellite’s orbit farthest from Earth.
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apogee kick motorRocket engine on board a satellite used near apogee to impart the thrust required to obtain a circular orbit, or, more generally, to raise its altitude at perigee, in which case the target altitude is the apogee. This type of thruster is used, for example, to boost a man-made satellite into geostationary orbit.
How orbital manoeuvres work
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arrimageFixation d’une charge utile à l’intérieur ou à l’extérieur d’un vaisseau spatial. Terme à proscrire, utiliser amarrage.
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artificial satellite / man-made satelliteObject built on Earth and designed to orbit around a celestial body. Since 1957, more than 4,000 man-made satellites have been launched into orbit around the Earth, as well as the Sun, Moon, Mars and Venus. The vast majority of artificial satellites (95%) are unmanned.
How satellites work
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asteroidSmall planet in the Solar System, varying in size from 1,000 kilometres to a fraction of a kilometre. There are thought to be at least 1 million asteroids more than one kilometre across. Most are between the orbits of Mars and Jupiter.
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astrometryBranch of astronomy dealing with the position and motions of celestial objects.
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astronautOccupant of a spacecraft (U.S., Europe).
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astronauticsScience of travel in space. From the French astronautique, a term coined by Joseph-Henri Rosny in 1927.
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astronomical unit (AU)Unit of distance equal to the radius of Earth’s orbit around the Sun, that is, 149,597,870 km. Used to express distances in the Solar System.
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astronomyScience that studies the positions, motions and structure of celestial objects (stars, planets, galaxies, natural satellites, etc.)
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astrophysiqueBranche de l’astronomie qui étudie la physique et l’évolution des diverses composants de l’Univers.
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atmosphereGaseous envelope shrouding certain planets in the Solar System. Earth’s atmosphere is the barrier that separates us from space.
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attitudePosition of a spacecraft with respect to three reference axes. Synonym: orientation.
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avionicsElectronic and computer equipment used to fly an aircraft or spacecraft.
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aérosolsL’atmosphère se compose de molécules de gaz et de petites particules solides et liquides en suspension dans l’air, appelées aérosols. Certains aérosols sont naturellement produits par les volcans, les embruns (océans), le sable, ou l’érosion de surface provoquée par le vent. D’autres aérosols résultent de l’activité humaine, comme la poussière issue des activités agricoles, la fumée résultant de la combustion de la biomasse et des énergies fossiles, du brouillard induit de manière photochimique par les pollutions de véhicules. Les gouttes et cristaux de glace résultant de la condensation de l’eau sont aussi des aérosols.