Searching for surficial water ice in lunar permanently shaded regions (PSRs) with ShadowCam

Airless bodies such as the Moon, Mercury, and Ceres have permanently shaded regions (PSRs) that can cold trap water ice. Mercury and Ceres have substantial ice deposits in their PSRs, but lunar water ice distribution remains uncertain because of sparse detections and limited data. Here, we assessed surficial water ice in lunar PSRs using high-resolution observations from ShadowCam onboard the Korea Pathfinder Lunar Orbiter. We used the high-reflectance and forward-scattering optical properties to search for water ice in lunar PSRs. We found no evidence of widespread water ice in PSRs at abundances above the detection limit of 20 to 30 wt % but could not rule out widespread low-content water ice. A few small locations with both high reflectance and forward-scattering behavior were observed, which could be consistent with >10 wt % ice. Future missions with low detection limits (<1 wt %) of water ice can test our findings.