Investigating Signatures of Space Weathering Processes in the Far-UV Using LRO-LAMP

Space weathering processes such as solar wind sputtering and micro-meteorite bombardment are ongoing processes which alter the spectral properties of the lunar regolith. Effects of these processes can be investigated by analyzing regolith reflectance in the far-UV using data from the Lyman Alpha Mapping Project (LAMP) onboard the Lunar Reconnaissance Orbiter (LRO). One of the diagnostic features of space weathering is a blue slope in the reflectance spectrum at long far-UV wavelengths. This spectral bluing effect is caused by nanophase iron, which is created when the solar wind interacts with the lunar regolith. Using LAMP's spectral mapper, we create daytime and nighttime maps of the lunar surface in the form of spectral data cubes which contain both spatial and spectral information. We then determine the spectral slope of each spatial pixel in our maps by making a linear fit to the albedo spectrum in the Water Band (164-173 nm) and Off Band (175-190 nm) wavelength ranges, following the method in Hendrix et al., 2012. For this study, we first focus on the southern wall of South Pole crater Amundsen, which displays possible signatures of space weathering in LAMP Lyman- albedo maps. Amundsen is an ideal location for analyzing the effects of space weathering due to its highly-illuminated equator-facing terrace walls in close proximity to Permanently Shaded Regions (PSRs) in the northern side of the crater. We then compare the spectral slope results from Amundsen with the South Pole region as a whole, and with similar non-polar complex craters.