Integration of lunar polar remote-sensing data sets: Evidence for ice at the lunar south pole

In order to investigate the feasibility of ice deposits at the lunar south pole, we have integrated all relevant lunar polar data sets. These include illumination data, Arecibo ground-based monostatic radar data, newly proces sed Clementine bistatic radar data, and Lunar Prospector neutron spectromet er measurements. The possibility that the lunar poles harbor ice deposits h as important implications not only as a natural resource for future human l unar activity but also as a record of inner solar system volatiles (e.g., c omets and asteroids) over the past billion years or more. We find that the epithermal neutron flux anomalies, measured by Lunar Prospector, are coinci dent with permanently shadowed regions at the lunar south pole, particularl y those associated with Shackleton crater. Furthermore, these areas also co rrelate with the beta = 0 circular polarization ratio (CPR) enhancements re vealed by new processing of Clementine bistatic radar echoes, which in turn are colocated with areas of anomalous high CPR observed by Arecibo Observa tory on the lower, Sun-shadowed Wall of Shackleton crater. Estimates of the extent of high CPR from Arecibo Observatory and Clementine bistatic radar data independently suggest that similar to 10 km(2) of ice may be present o n the inner Earth-facing wall of Shackleton crater. None of the experiments that obtained the data presented here were ideally suited for definitively identifying ice in lunar polar regions. Ely assessing the relative merits of all available data, we find that it is plausible that ice does occur in cold traps at the lunar south pole and that future missions with instrument s specifically designed to investigate these anomalies are worthy.