Effets des marées sur la dynamique des satellites de Jupiter et de Saturne

Abstract

Tidal effects induce a secular acceleration of planetary satellites. Such accelerations have not been detected yet with enough reliability for Jovian and Saturnian satellites, but we can hope a close detection for J-1 Io and S-3 Tethys thanks to the progress of dynamical modelisation and the improvement of astrometric observations. This work deals with the two topics. The main purpose is to improve the modelisation of motions and our understanding of resonances. This thesis also contributes to the study of the dynamical history of the Galilean satellites while studying the consequences of De Haerdtl's inequality 7:3 between Ganymede and Callisto. It is shown that this inequality induces a stochastic layer recently crossed by the system. Thanks to a frequency analysis, it is proved that this chaos is in fact Chirikov diffusion induced by overlaps of several resonances, which are clearly identified. This result leads to the conclusion that De Haerdtl's inequality has to be taken into account in every study on the formation of the laplacian resonance between Io, Europa and Ganymede. Moreover this work, as a first approach of the observational signature of tidal effects, deals with reduction of mutual events which occured in 1995 in the Saturnian system and with observation and reduction of mutual events of Galilean satellites of the last PHEMU campaign, in 2003. This reductions contribute to the improvement of ephemerides.

Date of Award	2005
Original language	French