Definitions list
Click one of the letters above to advance the page to terms beginning with that letter.
  • telemetry
    Information stream conveying data, transmitted by radio waves, from a spacecraft to Earth.
  • telescope
    Optical instrument used to magnify images of distant objects.
  • telescope
    Optical instrument with at least one mirror, used to observe distant objects, especially stars.
  • telluric
    Refers to planets that share similarities with Earth, particularly its size, solid surface and relative proximity to the Sun. There are 4 telluric planets in the Solar System: Mercury, Venus, Earth itself and Mars.
  • test
    Activity designed to measure and evaluate the characteristics of an element or item of equipment by subjecting it to specific environmental or operating conditions.
  • test facility
    Test installation used to study the behaviour and characteristics of spacecraft and systems. A test facility usually comprises a test rig or test stand, measuring instruments and safety systems.
  • thermal protection
    Protective coating that keeps the temperature inside a spacecraft within the required range for it to operate correctly.
  • thrust
    Force produced by a booster. It is the result of the ejection of a large mass of gas at high velocity. Thrust is expressed in newtons (N). Tonnes (T) are sometimes incorrectly used as the unit of thrust but in fact indicate the equivalent mass that a force is capable of lifting.
    How launchers work
  • tide
    Periodic variation in the level of the oceans due to the gravitational action of the Moon and Sun. The Earth’s surface also rises and falls imperceptibly under the same action, only to a much lesser extent. In astronomy, a tide denotes any of the cyclic deformations of one celestial body caused by the gravitational forces exerted by others. In some cases, these forces may tear small bodies apart (see Roche limit).
  • tour à chute libre
    Installation destinée à l’expérimentation en impesanteur.
  • tracking radar
    Radar capable of keeping track of a spacecraft and locating it automatically.
  • transmitter
    Electronic device generating electromagnetic waves that radiate out and can travel long distances.
  • transmitter beacon
    Device comprising a transmitter of electromagnetic waves, designed for location and data collection. For example, an Argos transmitter.
  • transponder / repeater
    Device on a telecommunications satellite designed to amplify, transmit or regenerate radio signals collected by receiving antennas.
  • transpondeur
    Terme à éviter. Utiliser répéteur.
  • troposphere
    The lowest layer of Earth’s atmosphere. Its thickness varies from 6 km to 17 km. Temperature in the troposphere drops steadily as altitude increases, by 6°C per kilometre.
  • TsUP flight control centre
    Flight control centre for Russian spacecraft, located in Kaliningrad, on the outskirts of Moscow.
  • turbopump
    System comprising rotating pumps and a turbine, often used in liquid-propellant rocket engines.