Johnson R. E.
Description:
Laboratory data is needed on electronically-induced desorption from low-temperature solids: ices, organics, hydrated salts, glasses and certain minerals. Many bodies in the outer solar system are bombarded by relatively intense fluxes of fast ions and electrons as well as solar UV photons. This can cause both changes in their optical reflectance as well as desorption of atoms and molecules from their surfaces. Stimulated desorption produces Na and K 'atmospheres' above the 'rocky' surfaces of the moon and Mercury and H2O, H2 and O2 'atmospheres' about icy outer-solar system bodies. Since theses bodies contain other surface materials, direct detection by spacecraft or remote detection by telescopes of the desorbed atoms and molecules can be used, along with laboratory data, to determine the surface composition and geological processes occurring on distant bodies. This paper describes the relevance of stimulated desorption to the ambient neutrals and plasma in Saturn's magnetosphere, in preparation for CASSINI's arrival, and to the production of atmospheres on the moons of Jupiter being studied by the Galileo spacecraft.