BACKSCATTERING FROM FROST ON ICY SATELLITES IN THE OUTER SOLAR-SYSTEM

THE surfaces of most satellites in the outer Solar System are covered, at least in part, by water frost1. Extensive analysis of the photometry of these icy satellites has shown that their surfaces are remarkably backscattering (refs 2-5; A.V. and J.V., manuscript in preparation). We present two extreme models of how frost and ice might be intermixed on a typical satellite surface: areal (checkerboard mixing) and intimate mixing. Applying such models to selected representative satellite data, we find that the frost component of the surfaces of these outer satellites must itself be backscattering, unlike its terrestrial counterpart. The difference may arise because frost particles can have much more complex internal textures under the low-temperature and low-gravity conditions of the outer satellites than is the case on Earth. © 1990 Nature Publishing Group.