Surface modifications by charged particles

Optical data have revealed some albedo patterns on the surfaces of planetary satellites that can be connected to the external environment. It is well known from laboratory experiments that charged particles can modify ice in a number of ways. But less is known about the specifics. A complicating factor is that surface regions are typically weathered simultaneously by a large number of agents (dust grains, photons, charged particles) each with a range of properties (e.g., electrons over a wide energy range). In the past, connecting surface modifications with weathering agents has been most successful when the number and kind of agents can be restricted. Situations when this is true include the closed field line region of Ganymede and the leading hemispheres of Mimas and Tethys. This talk will review some of the recent advances in satellite surface weathering and expand the methods by which connections between in situ measurements and optical remote sensing can be established.