The moon, our nearest celestial neighbor, still carries its share of mysteries, especially when it comes to the role of water in its past and present. Just last year a surprising series of studies indicated that the lunar surface is dusted with water molecules; another much-heralded experiment showed that at least some polar craters on the moon appear to be lined with water ice. Those stores of ice would be valuable resources to future moon visitors, who could count on a local source of water for an extended stay on the lunar surface.