The Moon, at least at the bottom of a deep, dark cold crater near its south pole, seems to be wetter than the Sahara, scientists reported Thursday.
In lunar terms, that is an oasis, surprisingly drenched for a place that had long been thought by many planetary scientists to be utterly dry.
If astronauts were to visit this crater, they might be able to melt 10 to 13 gallons of water out of eight wheelbarrows worth of soil. The water, if purified, could be used for drinking or broken apart into hydrogen and oxygen. The oxygen would be air for breathing and with the hydrogen could be used as rocket fuel to get home or travel farther out to asteroids or Mars.
“That is a very valuable resource,” said Anthony Colaprete, principal investigator of NASA’s Lunar Crater Observation and Sensing Satellite — or LCROSS, for short — which made the observations as it, by design, slammed into the Moon a year ago. “This is wetter than some places on Earth.”
The Sahara sands are 2 percent to 5 percent water, and the water is tightly bound to the minerals, Colaprete said. In the lunar crater, which lies in perpetual darkness, the water is in the form of almost pure ice grains mixed in with the rest of the soil, and it is fairly easy to extract. The ice is about 5.6 percent of the mixture and, given the uncertainties, possibly as high as 8.5 percent, the LCROSS scientists found.
“That is a large number, larger than I think anyone was anticipating,” Colaprete said.
Extrapolating, he said there could be 1 billion gallons within the crater.
The $79 million LCROSS mission piggybacked on the Lunar Reconnaissance Orbiter, which was launched in June 2009 and has been mapping out the lunar surface for a future return by astronauts. LCROSS steered the empty second stage of the rocket, which otherwise would have just burned up in the Earth’s atmosphere, onto a collision course with the Moon.
In October 2009, as it neared impact, the spacecraft released the empty second stage and slowed down slightly so that it could watch the stage’s 5,600-mph crash into a 60-mile-wide, two-mile-deep crater named Cabeus. Quickly transmitting its gathered data to Earth, LCROSS met the same demise four minutes later.
For people who watched the live Webcast video transmitted by LCROSS, the event was a disappointment, with no obvious plume from the impacts. But as they made a closer analysis of the data, scientists found everything they were looking for, and more. In November, the team reported that the impact had kicked up at least 26 gallons of water, confirming suspicions of ice in the craters.
The new results increase the water estimate to about 40 gallons, and by estimating by amount of dirt excavated by the impact, calculated the concentration of water for the first time.
Articles reporting the LCROSS results appear in Friday’s issue of the journal Science.