Mapping the Vertical Structure of the Lunar Regolith in Volcanic Regions and at Constellation Sites

The upper ten meters of the lunar regolith contains stratigraphy that provides geologic insight, and these upper layers are also what future in-situ instruments will interact with. We use a combination of remote sensing data from ground-based radar observations (Arecibo and Green Bank Telescope at wavelengths of 12.6 cm and 70 cm) and the Lunar Reconnaissance Orbiter spacecraft (Diviner, Mini-RF) to determine how the regolith structure varies across volcanic terrains and possible future landing sites. Radar can detect buried units and provide a measure of roughness, while thermal infrared data provides complimentary information on the surface and near-surface rock abundance in the upper centimeters. Radar and infrared wavelengths are also sensitive to different sized rocks, which can be used to determine where there are increased numbers centimeter-sized rocks. A comparison of these data sets reveals significant differences in regolith stratigraphy across targets. For example, small rilles on the Aristarchus Plateau to the northeast of the Constellation Aristarchus 2 site are surrounded by rock-poor deposits and are likely a secondary source of pyroclastic materials. Some rilles, such as Rima Birt, are surrounded by pyroclastics that change in depth and/or embedded rock abundance along the length of the rille. We will present results from our data analysis and subsequent mapping, focusing on rilles, pyroclastic deposits, and Constellation Region of Interest targets including the Apollo sites.