3. Identify and assess deposits containing volatiles (easily evaporated materials).

Anhydrous lunar soils do not give up adsorbed water easily. Many hours after being purged with dry air, samples from Apollo missions continued to show spectra indicating the presence of water.

Previous lunar probes indicated that the lunar poles contain deposits of hydrogen, which may be in the form of water ice. Interestingly, when material as dry as that of the Moon's surface comes into contact with water, it holds the water tightly. Experiments with Apollo samples showed that lunar soils release water only at temperatures above 150°C (302°F). Even the sunlit surfaces near the lunar poles never come close to such temperatures, and the permanently shadowed areas are of course much colder. So any water that may have accumulated there eons ago is likely still to be there. Determining the nature of this polar material is of great interest both for science (water ice could be ancient material deposited by comets, for example) and for exploration (water ice would be an extremely valuable resource for future astronauts). Using near-infrared spectroscopy, M³ will be able to directly identify the presence of water in these areas.