THERMAL-BEHAVIOR OF ROCKY MATERIAL IN CONTACT WITH ICE

A large class of bodies in the solar system consists of ices mixed wit h ''dusty'' or ''rocky'' material (e.g., comets, rings, icy satellites ). In the present paper we study the thermal behavior of such a mixed body in response to irradiation by the Sun, In contrast to the traditi onal approach, where the effects of a dust mantle are considered from a macroscopic point of view, we focus on the behavior of single grains or boulders. A three-dimensional model for a dust particle, or a piec e of refractory dark material in contact with a volatile ice surface, is presented. Example solutions are calculated, which illustrate the i nfluence of different heat transfer paths (radiation, conduction), the particle size, and the contact area (Hertz factor) upon the solutions . Subsequently, our model is used to interpret some results of a recen t comet simulation experiment, and, finally, it is applied to estimate the temperature contrasts on the surface of the icy satellites of Jup iter and Saturn.