The goal of these researchers is to study solar photon sputtering of molecular water ices from the vacuum ultraviolet through the extreme ultraviolet wavelength region in the laboratory. The temperatures for the ices will be chosen to simulate realistic planetary conditions. Sputtering of atoms and molecules from surfaces of astronomical materials is an important process for mass transfer and evolution in a number of astronomical environments, such as comets, asteroids, icy planets, satellites, rings, and interstellar dust grains. The excitation sources for sputtering are solar photons, solar wind, magnetospheric particles, and micrometeorites. Experiments on sputtering by energetic ions have been carried out in several laboratories. However, this is not the case for solar photon sputtering. Current theories and model calculations assume that the solar photon energies are directly converted into heat which controls the vaporization of the astronomical material. Mass loss due to sputtering has not been included since the required data are not available. The experiments performed by Drs. Wu and Judge should supply those data.
