The lunar dud for space enthusiasts has become a watershed event for NASA.
Spacecraft that crashed into the moon last month kicked up a relatively small plume. But scientists have confirmed the debris contained water – 25 gallons of it – making lunar exploration exciting again.
Experts have long suspected there was water on the moon. So the thrilling discovery announced Friday sent a ripple of hope for a future astronaut outpost in a place that has always seemed barren and inhospitable.
"We found water. And we didn't find just a little bit. We found a significant amount," Anthony Colaprete, lead scientist for the mission, told reporters as he held up a white water bucket for emphasis.
He said the 25 gallons of water the lunar crash kicked up was only what scientists could see from the plumes of the impact.
Some space policy experts say that makes the moon attractive for exploration again. Having an abundance of water would make it easier to set up a base camp for astronauts, supplying drinking water and a key ingredient for rocket fuel.
"Having definitive evidence that there is substantial water is a significant step forward in making the moon an interesting place to go," said George Washington University space policy scholar John Logsdon.
The October mission involved two strikes into a permanently shadowed crater near the south pole. First, an empty rocket hull slammed into the Cabeus crater. Then, a trailing spacecraft recorded the drama live before it also crashed into the same spot four minutes later.
Though scientists were overjoyed with the plethora of data beamed back to Earth, the mission was a public relations dud. Space enthusiasts who stayed up all night to watch the spectacle did not see the promised giant plume of debris.
NASA scientists had predicted the twin impacts would spew six miles of dust into the sunlight. Instead, images revealed only a mile-high plume, and it was not visible to many amateur astronomers peering through telescopes.
Members of the blue-ribbon panel reviewing NASA's future plans said the discovery doesn't change their conclusion that the program needs more money to get beyond near-Earth orbit. The panel wants NASA to look at other potential destinations like asteroids and Mars.
"This new and terrific result reassures us about lunar resources, but ... the challenges currently facing the human spaceflight program remain," Chris Chyba, a Princeton astrophysicist who is on the panel, said in an e-mail.
President George W. Bush had proposed a more than $100 billion plan to return astronauts to the moon, then go on to Mars; a test flight of an early version of a new rocket was a success last month. President Barack Obama appointed the special panel to look at the entire moon exploration program. The decision is now up to the White House, and NASA's lunar plans are somewhat on hold until then.
As for unmanned exploration, previous missions had detected the presence of hydrogen in lunar craters near the moon's poles, possible evidence of ice. In September, scientists reported finding tiny amounts of water in the lunar soil all over the moon's surface.