Prospecting For Lunar Water on the Moon

Settling alien worlds is thirsty work - especially on the lunar surface.

The next time you look at the Moon, pause for a moment and let this thought sink in: People have actually walked on the Moon, and right now the wheels are in motion to send people there again.

The goals this time around are more ambitious than they were in the days of the Apollo program. NASA's new Vision for Space Exploration spells out a long-term strategy of returning to the Moon as a step toward Mars and beyond. The Moon, so nearby and accessible, is a great place to try out new technologies critical to living on alien worlds before venturing across the solar system.

Whether a moonbase will turn out to be feasible hinges largely on the question of water. Colonists need water to drink. They need water to grow plants. They can also break water apart to make air (oxygen) and rocket fuel (oxygen+hydrogen). Furthermore, water is surprisingly effective at blocking space radiation. Surrounding the 'base with a few feet of water would help protect explorers from solar flares and cosmic rays.

more - Artwork by Pat Rawlings for Nasa NASA is gearing up to send humans back to the Moon

The problem is, water is dense and heavy. Carrying large amounts of it from Earth to the Moon would be expensive. Settling the Moon would be so much easier if water were already there.

It's possible: Astronomers believe that comets and asteroids hitting the Moon eons ago left some water behind. (Earth may have received its water in the same way.) Water on the Moon doesn't last long. It evaporates in sunlight and drifts off into space. Only in the shadows of deep cold craters could you expect to find any, frozen and hidden. And indeed there may be deposits of ice in such places. In the 1990s two spacecraft, Lunar Prospector and Clementine, found tantalizing signs of ice in shadowed craters near the Moon's poles - perhaps as much as much as a cubic kilometer. The data was not conclusive, though.

To find out if lunar ice is truly there, NASA plans to send a robotic scout. The Lunar Reconnaissance Orbiter, or "LRO" for short, is scheduled to launch in 2008 and to orbit the Moon for a year or more. Carrying six different scientific instruments, LRO will map the lunar environment in greater detail than ever before.