The Ebb and Flow of Water on the Moon
Paul Lucey



The scientific view of the abundance of water on the Moon has varied wildly with time, including drastic changes in perception in the last decade. The Apollo samples left the lunar science community with the impression that the Moon was completely dry, in large part because no minerals were found that incorporated water or hydroxyl (OH) in their structures. However, in 2008 two key measurements proved water was much more abundant than perceived. High precision measurements of hydrogen in lunar volcanic glasses showed clear evidence of either water or hydroxyl at the 10's of parts per million level, and three spacecraft detected a 3 micron water or hydroxyl band on the lunar surface.

At present there are three loosely related areas of research on lunar water: Water in the lunar interior; water on the lunar surface; and water cold trapped in extremely low temperature surfaces in the lunar polar regions. I will describe these subject areas and related controversies, but emphasize how surface water is detected, and how Earth-based astronomy can and is contributing to the understanding of the origin and evolution of water on the Moon.