NASA's LCROSS crashes on the moon

by Erin Wayman
Thursday, January 5, 2012

The first LCROSS rocket nears impact while the second spacecraft follows. NASA

LCROSS enroute to the moon. NASA

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Usually, NASA hopes its space probes land safely at their destinations. This morning, the agency was planning for a big explosion on the moon — all in the hopes of confirming the presence of water on our nearest neighbor.

In June, NASA sent its LCROSS (Lunar Crater Observing and Sensing Satellite) mission to the moon. The plan was to drive a rocket into the moon’s south pole and kick up dust and debris — possibly sending the ejected material as much as 10 kilometers above the moon’s surface. A second spacecraft following the rocket would then collect data on the debris' chemistry, sending that information back to Earth before also crashing on the moon minutes later.

And today at 7:31 a.m. EDT, that’s what happened. But, the mission’s scientists say, it’s too early to say anything about the presence of water on the moon.

“There was an impact,” said Anthony Colaprete, LCROSS principal investigator, at a press conference this morning. “We saw the crater. We have the data we need to address the question we set out to address."

LCROSS scientists set their sights on the lunar south pole because it’s home to craters, like the Cabeus crater, that are in permanent darkness and therefore have the right conditions for water-ice to exist. In 1999, NASA’s Lunar Prospector detected hydrogen in those craters, providing the initial evidence that the moon’s south pole did indeed have water. If that frozen water does exist, the LCROSS collision would have exposed those particles to sunlight, which would have vaporized the water and allowed LCROSS instruments to detect the water’s hydrogen and hydroxyl ions.

It may take days, weeks or even months before LCROSS scientists can say whether they found water-ice. Of course, if they do find water, it may not be too much of a surprise. Just last month, scientists announced three NASA missions independently detected minute amounts of water all across the moon’s surface (although they could not say in what form this water exists).

Although the mission's scientists were happy with today's crash-landings, some enthusiastic onlookers who watched the collision streaming live on NASA TV or through their telescopes were a bit disappointed: They didn't see an impressive plume rise up from the crash. Colaprete noted there could be several reasons why this was the case — for example, the debris may have hit something that scattered the material more laterally. Yet, he said, he wasn’t convinced the plume hadn’t been captured on LCROSS' cameras and said the team would have to review the data more carefully. He also said that his “initial eyeballing” of the last images that were taken by the LCROSS camera indicate the crater was about the size the team expected.

And as Colaprete repeatedly reiterated at this morning’s press conference, it’s not the visible data of the collision that really matter — it’s the spectral data that will say whether the moon’s south pole is home to water. And the spectral data returned by LCROSS are something Colaprete and his colleagues are excited about. “I see something in the spectrometer data, but I can’t say more than that,” Colaprete said.

And for all those EARTH readers who plan to attend the American Geophysical Union’s fall meeting, you too may see something in that spectral data. Colaprete promised the team will present their findings at the meeting.

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