摘要：

The mysterious permanently shadowed regions (PSRs) over the Moon’s poles remain as a high-priority in lunar science because of potential water ice deposits. In the recent lunar Mini-RF radar observations, a class of anomalous craters was found to have high circular polarization ratio (CPR) only in their interior but not exterior to their rims, and most of these anomalous craters contain PSRs. Previous investigators found that radar anomalous craters are overabundant over the lunar polar regions, and interpreted high CPRs as originating from a large quantity of water ice. In our study, we systematically analyzed >4000 impact craters across the Moon and quantified potential factors for the high CPR values. We found that there is no apparent difference in CPRs between the polar and nonpolar radar anomalous craters. Most radar anomalous craters are relatively young with a large depth/diameter ratio, suggesting that radar anomalous craters are just a stage of normal crater evolution, not agent for water ice deposits.