Satellites of the Outer Planets: Thermal Models

Abstract

Steady-state thermal models for the large satellites of the outer planets strongly indicate that their interiors are currently maintained at temperatures well above the ice-ammonia eutectic temperature by the decay of long-lived radioisotopes of potassium, uranium, and thorium. The present-day steady-state thermal structure of a representative satellite, J IV (Callisto), is shown to be characterized by the presence of a thin icy crust over a deep liquid mantle, with a dense core of hydrous silicates and iron oxides. Some dynamical consequences of this model are briefly discussed.