This story was updated 12:35 p.m. EDT.
WASHINGTON ? A NASA probe slammed into the moon Friday, in a bid to blast out a curtain of debris in which scientists hope to detect signs of water ice.
The $79 million LCROSS spacecraft, preceded by its Centaur rocket stage, impacted the lunar surface at the large south pole crater Cabeus at 7:31 a.m. EDT (1131 GMT) in what NASA Chief Scientist Jim Garvin called "the ultimate physics experiment."
"We keep finding evidence that there is water [on the moon]," NASA Administrator Charles Bolden told SPACE.com here. To find more with LCROSS "would be incredibly good news. It would be another place we can send humans," he added. Bolden said he had been following the last steps of the mission throughout the night.
The LCROSS probe beamed live images of the moon as its Centaur rocket stage headed for impact before making its own death plunge four minutes later. The two probes have crashed, mission managers assured, but whether LCROSS caught the much touted flash of the Centaur?s impact was not immediately clear.
?I can certainly report there was an impact,? NASA?s principal investigator Tony Colaprete told reporters after the $79 million lunar crashes. ?We saw the impact, we saw the crater ? we have the data we need to actually address the questions we set out to address.?
The target crater became larger and larger, with its bumpy relief becoming clearer, in the broadcast images as LCROSS sped toward the moon. There were gasps and then claps from the Newseum crowd here as the viewing screen filled with the image of the crater and then went white. Laughs followed as the Flight Director at Ames confirmed the successful impact and then proudly stood up in a televised broadcast.
Mission scientists watched the crash primarily from the probe?s operations center at NASA?s Ames Research Center in Moffett Field, Calif., but astronomers and amateur skywatchers also tuned in at observatories and other sites around the world ? including here at the Newseum, where more than 300 people watched the NASA impact broadcast on a huge 40-foot screen.
"This is the biggest screen I've ever seen," said one of the scores of people in the crowd of NASA employees, members of the press and public, including several bleary-eyed children.
Among the crowd were Apollo 11 astronaut Buzz Aldrin and Chip Cronkite, the son of late CBS TV news anchor Walter Cronkite, to whom the mission is dedicated.
"We hope this is just the first of many oases we find," Cronkite said.
NASA launched LCROSS ? short for Lunar Crater Observation and Sensing Satellite ? and the powerful Lunar Reconnaissance Orbiter (LRO) in June to hunt for evidence of water and ice on the lunar surface.
Ice on the moon
Scientists think that pockets of water ice might exist in the permanently shadowed craters of the lunar south pole ? thought to potentially be the coldest places in the solar system. Water has already been detected on the moon by a NASA-built instrument on board India's now defunct Chandrayaan-1 probe and other spacecraft, though it was in very small amounts and bound to the dirt and dust of the lunar surface.
NASA plans to return astronauts to the moon by 2020 for extended missions on the lunar surface. Finding usable amounts of ice on the moon would be a boon for that effort since it could be a vital local resource to support a lunar base.
Even if LCROSS does not turn up clear proof of water ice, that would be a major find, mission scientists said. It could mean that ice on the moon is not as uniformly distributed as suspected, or that water exists in concentrations too low to be measured by LCROSS instruments ? which would have repercussions for its value as a resource to astronauts, they added.
The LCROSS impact was also watched by several satellites that normally monitor Earth and spacecraft like the Hubble Space Telescope, Sweden?s Odin observatory and LCROSS's sister spacecraft, the LRO probe, which were due analyze the debris after the impact to look for signs of water ice.
"All eyes are on LCROSS today," Bolden said during remarks before the impact.
The crashes were expected to kick up tons of moon dirt and carve a new crater within the 60-mile (98-km) wide Cabeus. That new crater could be as large as 66 feet (20 meters) wide and 13 feet (4 meters) deep. In a pass over the lunar south pole later today, LRO will image the LCROSS impact crater.
Some 350 tons of moon dirt was expected to be blasted nearly 6.2 miles (10 km) above the lunar surface. Unlike past moon crashes by other probes, like Japan?s recent Kaguya mission, LCROSS slammed into the lunar surface at a steep angle and was slated to kick material up high enough to be illuminated by the sun as seen from Earth and other spacecraft.
Seasoned skywatchers on Earth equipped with 10 to 12-inch telescopes had a chance to spot the crash on their own, if they knew where to look.
?There's not going to be these grand, spectacular images of ejecta flying, kind of what you've seen in animations or cartoons,? Colaprete told reporters Thursday. ?It's going to be more of a muted shimmer of light, but that muted shimmer of light contains all the information we need to answer our questions.?
Scientists don't know yet whether or not they've detected water in the LCROSS ejecta, as it is expected to take some time to analyze the data.
- Video - Why Bomb the Moon?
- The Greatest Lunar Crashes Ever
- POLL: Just How Important is Water on the Moon?