New Constraints on the Volatile Deposit in Mercury’s North Polar Crater, Prokofiev

Abstract We present new high-resolution topographic, illumination, and thermal models of Mercury’s 112 km diameter north polar crater, Prokofiev. The confirm previous results that water ice is stable at the surface within permanently shadowed regions (PSRs) Prokofiev for geologic timescales. largest radar-bright region in confirmed to extend up several kilometers past boundary its PSR, making it unique on Mercury hosting a significant area outside PSR. near-infrared normal albedo distribution Prokofiev’s PSR suggests presence darkening agent rather than pure ice. Linear mixture predict least roughly half be covered with this dark material. Using improved altimetry we place an upper limit 26 m deposit thickness. 1 baseline topographic slope roughness are lower non-radar-bright floor, although difference not statistically when compared floor’s natural variations. These constraints nature volatile will inform future missions, such as BepiColombo.