[Structure interne et dynamique des grands satellites de glace.]
Les données magnétiques de la mission Galiléo sont compatibles avec l'existence d'un ocean à l'intérieur des grands satellites de glace de Jupiter. D'autre part, la tectonique d'Europe suggère l'existence de mouvements de convection dans la cryosphère de glace I. La viscosité de la glace est un paramètre clé pour modéliser l'évolution thermique et l'évolution orbitale de ces satellites. Grâce aux données de laboratoire et à celles obtenues sur les glaciers terrestres, ce papier montre que la dissipation de chaleur par effets de marée est si importante qu'elle permet d'expliquer la présence d'un océan à l'intérieur d'Europe. L'ammoniaque est un autre paramètre important car sa présence abaisse tellement la température de fusion des hydrates qu'un océan ne peut totalement cristalliser. Un modèle de structure interne est proposé pour Titan et cette prédiction sera confrontée aux données de la mission Cassini–Huygens qui est en orbite autour de Saturne depuis le 1 juillet 2004.
The magnetic data returned by the Galileo mission suggest that deep oceans are present within the icy Galilean satellites. In addition, tectonic features on Europa are consistent with models of subsolidus convection within the outer ice I layer. Ice viscosity is a key parameter for modeling the thermal and orbital evolution of these large satellites. Using laboratory experiments and glacier measurements, this article shows that tidal heating is a strong source of internal heating which may explain the presence of a deep ocean within Europa. Another key parameter is the composition of ice. The presence of ammonia, which is likely in Saturn's sub-nebula, decreases so much the melting point temperature of ice that it would inhibit the complete freezing of the ocean. Predictions for the internal structure of Titan are made and will be checked by the Cassini mission which started orbiting Saturn on 1st July 2004.
Mot clés : Satellites de glace, Mission Galiléo, Mission Cassini–Huygens, Titan, Viscosité des glaces
Christophe Sotin 1 ; Gabriel Tobie 1
@article{CRPHYS_2004__5_7_769_0, author = {Christophe Sotin and Gabriel Tobie}, title = {Internal structure and dynamics of the large icy satellites}, journal = {Comptes Rendus. Physique}, pages = {769--780}, publisher = {Elsevier}, volume = {5}, number = {7}, year = {2004}, doi = {10.1016/j.crhy.2004.08.001}, language = {en}, }
Christophe Sotin; Gabriel Tobie. Internal structure and dynamics of the large icy satellites. Comptes Rendus. Physique, Volume 5 (2004) no. 7, pp. 769-780. doi : 10.1016/j.crhy.2004.08.001. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2004.08.001/
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