NEAR-INFRARED SPECTRAL GEOMETRIC ALBEDOS OF CHARON AND PLUTO - CONSTRAINTS ON CHARONS SURFACE-COMPOSITION

The spectral geometric albedos of Charon and Pluto are derived at near -infrared wavelengths (1.4-2.5 mu m) from measurements obtained in 198 7. Comparisons of these to theoretical calculations are used to place constraints on the identity and relative abundances of surface ices on Charon. These comparisons suggest that widespread regions of pure CH4 ice do not occur on Charon and that if CH4 is abundant on Charon then it is large grained (approximate to 5 mm) and is likely mixed at the granular level with H2O ice, and possibly CO2 ice. (C) 1996 Academic P ress, Inc.