This set of NASA images, taken Oct. 9, 2009 by the LCROSS shepherding spacecraft, shows the Cabeus crater (center of images with smaller crater on rim) just after a Centaur rocket stage was due to crash into the moon at 7:31 a.m. EDT in a hunt for water ice. Starting from top left and moving clockwise in these images, the LCROSS probe draws ever closer to its own impact after the first hit.
Credit: NASA TV.
NEW YORK - Some observers hoping for a big blast from NASA's moon-slam experiment Friday were a bit disappointed.
Though NASA officials say they're thrilled with the impact of the LCROSS probe into the moon, some scientists and members of the public were left wondering why there was no obvious debris plume after the crash.
"I don't know about you, but I didn't see anything," said Columbia University astronomer Arlin Crotts, who was watching the impact on NASA TV with a group of scientists and students gathered at a "viewing party" for the event.
"I wanted an explosion," a Columbia graduate student said.
Instead the screen showed footage from the spacecraft as it moved closer and closer to the lunar surface. Then, suddenly, the screen went white. When footage came back, it showed the moon seemingly unperturbed.
Some SPACE.com readers also expressed disappointment.
"This was anti-climactic at best - there was absolutely no visible clue of any impact," wrote commenter HanShotFirst.
"Maybe they should change the headline from 'KAPOW!' to 'bloop' - I saw no evidence of an impact at all," wrote user gahmuret.
But NASA scientists stressed that just because the preliminary footage didn't show an obvious debris cloud, that doesn't mean there wasn't one. The goal of LCROSS's crash was to kick up material from the lunar surface and analyze the signature for signs of water or other interesting chemicals present in the moon dirt. NASA predicted the probes would create a plume of material 6.2 miles (10 km) high.
"I'm not convinced we haven?t seen the ejecta," said LCROSS principal investigator Tony Colaprete during a post-crash press conference. "I want to go back to those images and look at them carefully. You just never know how these things are going to go."
Colaprete explained that the footage broadcast on television wasn't as high resolution as the direct data available from the orbiting Lunar Reconnaissance Orbiter (LRO), which launched in June alongside the the LCROSS shepherd spacecraft and its separate impactor probe. Plus, he added, the main data scientists are interested in are not the visual images, but the spectra, which are taken with an instrument that separates light into its constituent wavelengths.
"I saw variations in the spectra," Colaprete said. "I'm thrilled, that's a very good sign. The spectra is where the science is."
NASA officials said they were elated by the results so far.
"It's been an exciting period," said NASA administrator Charlie Bolden, who called LCROSS "the third big event" to occur since he took on NASA's top post in July. The first two momentous occasions were the Apollo 11 40th anniversary and the recent rejuvenation of the Hubble Space Telescope.
The LCROSS mission was recently dedicated to the late journalist Walter Cronkite, who reported on many great events in space history, including the first U.S. moon landing. Cronkite's son Chip was on hand with reporters and NASA officials watching the LCROSS impact at Washington, D.C.'s Newseum Friday morning.
Cronkite called the event "fantastic" and said he hoped the results reveal water ice on the moon. He said his father "would loved to have been able to cover all these next missions," including possible future human trips to the moon.
SPACE.com senior writer Andrea Thompson contributed to this report from Washington, D.C.
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