There is now cast-iron evidence for water on the Moon

IF HUMAN BEINGS should ever wish to build bases on the Moon, those bases will need water. Residents will require it not only for their own sustenance but also as a raw material for rocket fuel to power adventures farther afield—Mars, for example. Given the cost of blasting things off the surface of Earth, however, such a base would be best served by finding its water locally. A pair of studies published on October 26th, in , will therefore raise the hopes of would-be lunar settlers.One, led by Paul Hayne of the University of Colorado, Boulder, shows that more of the Moon’s surface is in perpetual shadow than was previously believed. This matters because ice—the form in which any lunar water is likely to exist—would be stable and long-lived in such cold, shaded regions. Most of the lunar surface is bathed in harsh ionising radiation from the sun, so any water molecules present would swiftly be torn apart or disappear into space. But Dr Hayne’s work calculates that there are around 40,000 square kilometres of these ice-preserving “cold traps” on the Moon.