Heat Flow and Thermal State of the Crust of the Icy Galilean Satellites

Abstract

The use of lithosphere strength indicators (as for example the effective elastic thickness of the lithosphere or the depth to the brittle-ductile transition) can give clues on the surface heat flow and the thermal state of the ice crust of icy satellites, which in turn has profound implications for our understanding of the internal evolution, and the possible existence of internal oceans, in these planetary bodies. As shown in this review, this kind of approximations has found very high (and possibly recent) surface heat flows for Europa, and ancient high heat flows for Ganymede. On the other hand, the heavily cratered of Callisto suggests a cold and inactive outer ice shell throughout the entire history of this body.However, irrespective of the greatly different geology recorded on the surface of the icy Galilean satellites, there are evidences from orbital magnetic observations internal oceans in all them. By combining heat flow estimations and the existence of internal oceans, a more complete description of the thermal history of the icy Galilean satellites should emerge.