Global Color Variations on Io

The Galileo multispectral imaging of Io has augmented existing Voyager color data by extending the sensitivity to near-infrared wavelengths. Global four-color coverage was obtained during Galileo's first two orbits, at resolutions ranging from 10-23 km/pixel and phase angles from four to 55 deg. This paper presents preliminary spectral maps of the global distribution of low albedo materials (usually associated with volcanic centers), bright red deposits, yellow materials, and SO2 frost. Initial efforts have concentrated on the global distribution of the bright red materials, presumably pyroclastic deposits such as produced by the currently active plume Pele. Compositional candidates for the bright red materials include metastable short-chain elemental sulfur (S4 and S3) and ferric oxide materials.