SALTS AN EUROPA SURFACE DETECTED BY GALILEOS NEAR-INFRARED MAPPING SPECTROMETER

Reflectance spectra in the 1- to 2.5-micrometer wavelength region of t he surface of Europa obtained by Galileo's Near Infrared Mapping Spect rometer exhibit distorted water absorption bands that indicate the pre sence of hydrated minerals, The laboratory spectra of hydrated salt mi nerals such as magnesium sulfates and sodium carbonates and mixtures o f these minerals provide a close match to the Europa spectra. The dist orted bands are only observed in the optically darker areas of Europa, including the lineaments, and may represent evaporite deposits formed by water, rich in dissolved salts, reaching the surface from a water- rich layer underlying an ice crust.