But the much-hyped moon show that had been expected to accompany the impact, however, turned out to be a flop—no billowing plumes of dust and ice visible through backyard telescopes or on NASA TV. The low-impact impact had one NASA expert musing that LCROSS may have struck a "dry hole."
At 7:31 a.m. ET, a 2.2-ton empty rocket shot from the LCROSS probe hit the crater Cabeus A on the moon's south pole (more on the LCROSS mission's moon target).
Four minutes later LCROSS (Lunar Crater Observation and Sensing Satellite) performed its own kamikaze dive—the final act in its mission to detect evidence of water ice in the moon's shadowed craters.
"We Saw the Impact," NASA Says
Whether or not sky-watchers could see the LCROSS crashes, NASA insists they happened.
"I can certainly report that there was an impact," LCROSS principal investigator Anthony Colaprete said at a NASA press conference this morning. "We saw the impact and we saw the crater."
When the rocket crashed into the moon, though, cameras on LCROSS registered no discernable change in the crater—at least to the untrained eye.
"It was hard to tell what we saw there," said Michael Bicay, science director at NASA Ames Research Center in California, during live coverage on NASA TV.
A closer inspection of LCROSS impact images, though, has revealed a small white speck that scientists think is the debris thrown up by the first crash, but it will take time for scientists to determine whether it is evidence of water on the moon, NASA says. (See "There's Water on the Moon, Probes Confirm.")
"I'm not going to say anything about water or no water, but we got the data that we need" to address the question, LCROSS principal investigator Colaprete said.
(Read more about moon exploration.)
LCROSS Enthusiast: "Nothing Was Seen"
For many amateur astronomers who got up early to watch the crashes through telescopes or on NASA TV, the crashes were a bit anticlimactic.
"We had telescopes [as wide as] 32 inches [81 centimeters], and nothing was seen," said Siegfried Jachmann, vice president of the Salt Lake Astronomical Society in Utah.
Weather conditions at Utah's Stansbury Park Observatory Complex were everything an astronomer could ask for this morning, Jachmann said.
"The moon is very high in the sky, right on the meridian," he said. "It's perfectly placed right above Orion ... If anyone would've had a shot of seeing it, it was us."
Despite the disappointment, he said just after impacts, "the mood is good."
Moon Impact Highly Visible Via "Imagination Filter"?
Several hundred miles west in San Diego, California, there was some debate about whether the impacts had been visible from Earth.
"We have some people who say they saw it," said Bob Austin, president of the San Diego Astronomy Association. But that could be the result of what he called an "imagination filter."
On the United States' East Coast, the sun was too bright for watching the LCROSS impact, but that didn't stop people from congregating to watch the show on NASA's live Internet video feed.
Jason Kendall, a volunteer "solar system ambassador" with NASA, had organized a viewing at a New York City café.
The public excitement about LCROSS brought to mind the first Apollo moon landing, he said. "It's very evocative."
Did LCROSS Crash Into a "Dry Hole"?
Scientists say it could be days before data transmitted by LCROSS are fully analyzed. If no evidence for lunar water is found, that will be a significant finding in itself, Bicay of NASA's Ames center said.
It could mean water doesn't exist on the moon or that there's very little water or that it's only patchy.
"Like an old Texas wildcatter," Bicay said, "we may have hit a dry hole."