Comparative study of the diachronic evolution of the geological and volcanological environments of the earth with the saturnian satellites Titan and Enceladus.

摘要

This thesis presents on the study of the environment of Titan and Enceladus, Saturn’s satellites observed by the Cassini-Huygens mission. Various aspects of the geology of Titan are presented focusing on the characteristics of the surface geological features and processes,the internal structure and the correlation with the atmosphere. The morphotectonic features are presented on the basis of terrestrial models. Moreover, Titan areas probably correlated with the interior are tested against a geophysical model of tidal distortion and found to conform with localisation and internal dynamics. We then study the surface albedo and composition of specific Titan areas (Hotei Regio, Tui Regio, Sotra Patera) –determined by the PCA method- based on data from Cassini/VIMS (0.4–5 μm) on which a radiative transfer code is applied with the most updated spectroscopic parameters. Monitoring of these areas showed surface albedo changes in the course of 1-3.5 yrs, implying dynamic exogenic-endogenic processes that affect the surface and compatible with cryovolcanism in the case of Sotra Patera. Processes that form the surface of Enceladus are also discussed. In addition, the analogies with the Earth's surface and possible internal processes on the icy satellites are being explored. The astrobiological implications of this work are discussed within the framework of the quest for habitable environments in our outer Solar system. These studies are related to the preparation of future space missions to the systems of Jupiter and Saturn and payload capability. Finally, public awareness and perspectives of this research are discussed.