Multi-Wavelength Photometry of the Icy Saturnian Satellites

The light reflected from planetary surfaces and measured by remote sensing instruments is affected not only by the composition of the surface but by the physical structure of the surface. The structure of the surface is characterized by both endogenic and exogenic processes. We investigate the effects of these processes on the surfaces of the icy Saturnian satellites using photometric studies at multiple wavelengths in the UV-IR region. We model solar phase curves at many wavelengths using data from the Cassini Ultraviolet Imaging Spectrograph (UVIS) and Visual Infrared Mapping Spectrometer (VIMS). This is a powerful dataset because the combination of IR and UV wavelengths allows us to distinguish between large and very small grains, and to probe the particle interiors and surfaces. The investigation will provide critical insight into the evolution of the moon regoliths and an understanding of their current environments. We focus on the solar phase curves of Enceladus, Dione and Iapetus. Preliminary results include single scatter albedos for Enceladus and Dione in the far-UV (~180 nm) that are significantly lower than in the visible, suggesting a strong absorption edge in the near-UV. We also focus on the opposition surges to understand the contributions of coherent backscatter and shadow hiding, and any wavelength dependence thereof.