Ices on the satellites of Jupiter, Saturn, and Uranus

Three satellites of Jupiter, seven satellites of Saturn, and five satellites of Uranus show spectroscopic evidence of H2O ice on their surfaces, although other details of their surfaces are highly diverse. The icy surfaces contain contaminants of unknown composition in varying degrees of concentration, resulting in coloration and large differences in albedo. In addition to H2O, Europa has frozen SO2, and Ganymede has O-2 in the surface; in both of these cases external causes are implicated in the deposition or formation of these trace components. Similarly O-3 is found in the surface ices of Ganymede, Dione, and Rhea, probably induced by the effects of magnetospheric particles. Variations in ice exposure across the surfaces of the satellites are measured from the spectroscopic signatures. While H2O ice occurs on the surfaces of many satellites, the range of bulk densities of these bodies shows that its contribution to their overall compositions is highly variable from one object to another.