LRO Investigations: LAMP Analysis of Aristarchus Crater

The study of lunar pyroclastic deposits (LPD) enables the classification of volcanic eruption styles in the Moon's early history. Aristarchus crater is well-known for its glassy pyroclastic blanket, surrounding the Copernican-age impact crater. Nearby flow features rich in pyroclastic materials, such as Vallis Schröteri, make Aristarchus a unique record of the Moon's volcanic history. NASA's Lunar Reconnaissance Orbiter (LRO) carries a far-ultraviolet (far-UV) spectrograph named the Lyman Alpha Mapping Project (LAMP) with a bandpass of 57-197 nm. LAMP observes the pyroclastic deposit at Aristarchus crater as an area of high off band (155-184 nm) to on band (130-155 nm) albedo (Off/On) ratio, and provides compositional information about the pyroclastic deposit. Previous LAMP observations of lunar swirls suggest that regions of high off/on band ratios may indicate highly feldspathic compositions. Using robust linear regressions, we compare the average off/on band ratios observed at Aristarchus to off/on band ratios derived from laboratory spectra for several different minerals such as anorthite, olivine and augite. Employing this method we identify mineral deposits in Aristarchus' pyroclastic blanket, to help constrain the blanket's mineral assemblage and petrology. We will present preliminary far-UV detections of minerals at Aristarchus crater.