Accretional heating of the satellites of Saturn and Uranus.

A model developed specifically for accretional heating of small icy satellites of massive planets was used to investigate the effects of various parameters on the accretional heating of the Saturn and Uranus satellites. It was shown that accretional heating is completely dominated by cisplanetary impactors, with substantial deposition of heat occurring well below a satellite's surface. Three parameters that have large uncertainties were found to affect accretional temperature profile: the Safronov parameter for cisplanetary impactors, the fraction of impactor energy deposited below the surface, and the exponent in the impactor size-distribution equation. For most satellites, the depth of maximum heating and the maximum temperature reached have smooth positive dependences on satellite size. Accretional heating of these satellites is insufficient to melt H2O ice, but, if NH3 or CH4 are present, accretional heating may produce a warm buoyant mobile zone tens of kilometers below the surface.