Energetic electronic processes on extraterrestrial surfaces

Astronomical bodies without atmospheres are subject to irradiation with energetic photons and particles. The resulting surface alterations are evident in the optical reflectance spectra discernible through remote optical sensing from Earth. Here I review the most important processes initiated by electronic excitations and ionizations by ions. These include electronic desorption or sputtering, chemical reactions, and charge transfer. It is argued that dissociative electron attachment and Auger initiated desorption play a role in desorption of ice mantles on grains in dense interstellar molecular clouds. The paper describes the essentials of laboratory simulations and points out to opportunities for atomic collision physicists to contribute to important astrophysical and planetary problems, including the evolution of galactic matter and the possible extraterrestrial genesis of life. (c) 2005 Elsevier B.V. All rights reserved.