Fast ion bombardment of ices and its astrophysical implications

Ices such as water, carbon dioxide, and methane are now known to be pervasive constituents of the solar system and probably of the interstellar medium as well. Many of these ices and ice-covered surfaces are exposed to bombardment by the energetic ions of space. Laboratory experiments have been carried out to study the effects of such bombardment. Surprisingly efficient erosion of ice layers is associated with electronic excitation of the ices by the ions. These results are a challenge to an understanding of the physical processes involved and have implications for a number of astrophysical problems of current interest.