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Fiche 1,  Justifications,  Anglais

Record number: 1, Textual support number: 1 CONT

The calculations for the ISS [International Space Station] quasi-steady acceleration environment can be compared to a set of formal design requirements which state that 50 percent of the ISPR [International Standard Payload Rack] locations within the U.S. Lab, Columbus and the JEM must have quasi-steady accelerations below 1 ug for periods of 30 continuous days a total of 6 times per year. The operation of the Station in Microgravity Mode is designed to produce these 30 day intervals. The quasi-steady acceleration vector has an additional directional stability requirement stating that the component perpendicular to the vector's orbital average must be less than or equal to 0.2 [mu] g. To meet this requirement the Station's attitude must be controlled during orbit so that it maintains a constant position relative to the LVLH [Local Vertical/Local Horizontal] axes.  2, fiche 1, Anglais, - quasi%2Dsteady%20acceleration%20environment

Record number: 1, Textual support number: 2 CONT

The quasi-steady state acceleration level is determined primarily by the combined effects of atmospheric drag (due to the finite residual Earth's atmosphere at the orbital altitude of the ISS), and gravity gradient stabilisation of the ISS. Gravity gradient stabilisation uses the principle that a body in orbit around the Earth will tend to rotate about it's centre of mass, as each part of the body will tend to follow it's own orbit. It will normally oscillate about a mean orientation, but will eventually remain in a stable orientation with respect to the Earth. The normal orientation for the ISS is the Torque Equilibrium Attitude discussed earlier. The resultant combination of atmospheric drag, gravity gradient and other secondary effects produce a set of gravity contours (i.e., locations of equal gravity level) which define the quasi-steady state microgravity environment of the ISS.  3, fiche 1, Anglais, - quasi%2Dsteady%20acceleration%20environment

Record number: 1, Textual support number: 1 OBS

quasi-steady acceleration environment: term officially approved by the International Space Station official approval Group (ISSOAG).  4, fiche 1, Anglais, - quasi%2Dsteady%20acceleration%20environment

Fiche 1,  Justifications,  Français

Record number: 1, Textual support number: 1 OBS

Les modèles d'analyse dynamique (DAC 8) pour l'ISS [International Space Station] prévoient un environnement caractérisé par des vibrations de l'ordre du milli-g (10-4 g) plutôt que des conditions de véritable microgravité (10-6 g) en raison des activités et des divers éléments de l'ISS qui causent des vibrations intempestives (gigue gravitationnelle). Les travaux antérieurs menés à bord de la navette et de Mir ont montré que le milieu est caractérisé par des vibrations aléatoires continues, orientées dans tous les sens, avec des accélérations de l'ordre du milli-g et des crêtes dépassant souvent les 10 milli-g.  2, fiche 1, Français, - milieu%20gravitationnel%20quasi%20stable

Record number: 1, Textual support number: 2 OBS

milieu gravitationnel quasi stable : terme uniformisé par le Groupe de travail de la terminologie de la Station spatiale internationale (GTTSSI).  3, fiche 1, Français, - milieu%20gravitationnel%20quasi%20stable

Fiche 1,  Justifications,  Espagnol