Water on the Moon: a Billion Gallons

Oct 21, 2010 — -- Water on the moon? Scientists used to think it was as dry as, well, lunar dust.

But after a year of analysis NASA today announced that its LCROSS lunar-impact probe mission found up to a billion gallons of water ice in the floor of a permanently-shadowed crater near the moon's south pole.

That's enough, said researchers, to fill 1,500 Olympic-size swimming pools, all from one crater.

If there is ice there, it probably exists in other places on the moon as well. They also found silver, mercury, carbon monoxide and ammonia.

LCROSS was an empty rocket stage that was deliberately crashed into the moon last year, while a small satellite trailing it took chemical measurements of what it kicked up. Its target, a crater called Cabeus, was chosen because it is so deep that sunlight never reaches the bottom -- and any ice there, mixed in the soil, would never have a chance to vaporize. The ice might have remained frozen there for billions of years.

"To our surprise, some of the permanently shadowed regions had no water, but some of the areas that receive sunlight occasionally did have water," said William Boynton of the University of Arizona, a member of the research team.

The LCROSS researchers had already announced preliminary findings last November -- about a third less water than they reported today -- and refined their numbers in the months since. Their conclusions appear today in the journal Science.

Finding large amounts of water on the moon could be important, not just for science, but for future exploration by astronauts. Water, essential for human survival, would be heavy and expensive for spacecraft to bring from earth. But if astronauts land near ice deposits, as NASA has long hoped, they could, in effect, live off the land.