After a month of analysis -- and some doubt -- NASA today announced that its LCROSS lunar-impact probe mission found "significant quantities" of water ice in the floor of a permanently-shadowed crater near the moon's south pole.
"We are ecstatic," said Anthony Colaprete, NASA's LCROSS project scientist.
LCROSS -- an empty rocket stage that crashed into the moon on Oct. 9 while a small satellite trailing it took chemical measurements of what it kicked up -- has now been confirmed to have found frozen water, NASA said at a briefing from the Ames Research Center in Mountain View, Calif.
The scientists were initially hesitant to say what they had found after the impact, because the chemical signature of water had to be teased out of spectrometer readings -- very complex readouts of the lunar chemistry.
"This is not your father's moon," said Greg Delory of the University of California, Berkeley, who took part in the analysis. "Rather than a dead and unchanging world, this may in fact be a very dynamic one."
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 been planning to do since the Bush administration ordered a return to the moon, they can, in effect, live off the land.
The ice could be melted for drinking and cooling of spacecraft systems -- and beyond that, it can also be broken down into its components -- hydrogen and oxygen. Hydrogen could be used as rocket fuel; oxygen could be used for breathing.
Colaprete said it was an exacting process, as scientists worked for weeks to analyze the data sent back by the LCROSS satellite.
"It wasn't an 'Aha!' moment" when they found water, he said. "It's really been a 'Holy Cow' moment every day, as we found out more and more."
How much water did they actually find? The immediate answer, Colaprete said, is that the satellite measured about 24 gallons in the debris from the 60-foot crater gouged out by the crashing rocket. The ice was mixed in with rock and dust, so its chemical signature -- H2O -- was mixed in with the myriad minerals to be found in lunar soil.
There could be much, much more ice in the crater where LCROSS crashed, and in others near the lunar south pole, where the angle of the sun is so shallow that sunlight never reaches the bottom of some craters, and ice might have remained frozen for billions of years.
The scientists were asked whether they were toasting their find with Champagne or water, and they laughed.
"We have not had time to enjoy it," said Colaprete.
He said the confirmation came about two weeks ago, but the science team wanted to be sure before saying anything.
"We vetted it, and vetted it, and vetted it again. I'm sure we'll do some celebrating now."
There is no saying whether astronauts will get to use that ice any time soon, though. A panel appointed by the Obama administration said in October that NASA's budget is not large enough for its current plans to fly astronauts to the moon and eventually Mars.
The White House is reviewing the panel's recommendations, and may change NASA's marching orders.