Internal Structure of Ganymede

Abstract

Ganymede is the largest satellite in the solar system and the third among the sequence of the Galilean Moons in the Jupiter system. It is a typical icy satellite of the outer solar system composed of silicate rock and ices with a silicate-to-ice mass ratio of about 60-40 wt.-percent. As inferred by its moment of inertia derived from Galileo Doppler tracking data Ganymede is highly differentiated consisting of an iron-rich core, a silicate mantle and an outermost H2O-layer with the latter being most likely separated into high-pressure ice phases, a liquid water ocean and an outermost ice-I layer of several tens of km thickness. The separation between silicates and metal is further consistent with the detection of a magnetic dipole field, generated inside the core. In this chapter we review the current knowledge on Ganymede's interior and evolution mainly based on Galileo data and theoretical modeling.