Water and other volatiles on the moon: A review

Abstract

This paper presents a review of research findings on the various forms of water on the Moon. First, this is the water of the Moon’s interior, which has been detected by sensitive mass spectrometric analysis of basaltic glasses delivered by the Apollo 15 and Apollo 17 missions. The previous concepts that lunar magmas are completely dehydrated have been disproved. Second, this is H2O and/or OH in a thin layer (a few upper millimeters) of the lunar regolith, which is likely a result of bombardment of the oxygen contained in the lunar regolith with solar wind protons. This form of water is highly unstable and quite easily escapes from the surface, possibly being one of the sources of the water ice reservoirs at the Moon’s poles. Third, this is water ice associated with other frozen gases in cold traps at the lunar poles. Its possible sources are impacts of comets and meteorites, the release of gas from the Moon’s interior, and solar wind protons. The ice trapped at the lunar polars could be of practical interest for further exploration of the Moon.