Saturn's Satellite Rhea

Bright streaks and blotches are visible against a darker back-ground on the surface of Saturn's satellite Rhea, seen in this Voyager 1 image taken Nov. 11, 1980 from a range of 1,925,000 kilometers (1,196,000 miles). Even the dark areas, thought to be water frost and ice, are fairly bright with about 50 percent reflectance. The bright streaks may be related to impacts by objects that throw out pulverized ice grains from beneath the ice-covered surface. Some of the bright streaks are not straight but have a curved appearance similar to the grooved, icy terrain on Jupiter's satellite Ganymede seen in Voyager photographs taken at this resolution. Scientists do knot yet know if a satellite of Rhea's size (approximately 1,500 kilometers or 900 miles in diameter) can have an active thermal history like Ganymede's, but higher resolution photographs taken by Voyager should reveal clues to its history. The Voyager Project is managed by the Jet Propulsion Laboratory for NASA.