Moon Hit, Plume With Water Possible

A 2.5-ton spent rocket body barreled into a lunar crater on Friday, though there was no immediate sign of a dust plume, which NASA had hoped to scan for water.

"It's hard to tell what we saw there," said Michael Bicay, science director at NASA's Ames Research Center in Mountain View, Calif.

Debris from the impact could have flown horizontally, or perhaps didn't clear the crater's rim, lead mission scientist Anthony Colaprete told reporters.

"Some luck has to come to get the ejecta to fly in the direction you want it to fly," he said.

"I'm not convinced we haven't seen the ejecta," Colaprete added. "We just have to go back with a finer tooth comb."

The Lunar Crater Observation and Sensing Satellite mission (LCROSS) had the best view of the impact, which occurred at 7:31 a.m. EDT, but the picture didn't last long. Four minutes after its empty Centaur rocket motor crashed inside a crater named Cabeus, LCROSS plunged inside as well, possibly creating a second smaller plume of debris a few miles away.

Before plunging into the crater, LCROSS's infrared sensors detected some temperature variations from the crater, as well as changes in the spectra, a chemical breakdown of the reflected light.

While visually the impact, which was streamed live on the Internet, was a bust, Colaprete said, "We got the spectroscopic data and that's what really matters."

Unless one or both of the plumes were rich with water, NASA didn't expect results of the impacts to be immediately apparent.

Colaprete figured on three possible outcomes for the mission:

• The plume or plumes show small concentrations of hydrogen, possible bound in water molecules or as hydroxyl, which consists of a single oxygen molecule bound with a single hydrogen partner. This finding would be consistent with measurements of hydrogen made by several lunar orbiting spacecraft, dating back to the 1994 Clementine mission.


• No water or hydrogen is found. "This would be very surprising," Colaprete said," but it says something about the process by which hydrogen is implanted." It doesn't mean water or hydrogen isn't in the crater, just that it's more widely distributed than hoped, sort of a "raisin in the pudding analogy," he added.


• Strong concentrations of water detected. "If we hit it, it means the water is relatively easily accessible," Colaprete said.



Dozens of ground and space-based observatories were scanning the moon at the time of the impacts. NASA also coordinated an extensive observing campaign by the amateur astronomy community.

The LCROSS mission was a low-budget, tag-along to NASA's moon-mapping Lunar Reconnaissance Orbiter, which is scouting for landing sites for possible future human expeditions to the moon.

"Water is essentially energy. If there's water on the moon it can be used for manufacturing ... but most importantly water can be used for fuel. if we had it there, it could make exploration more sustainable," said Victoria Friedensen, program executive, for the LCROSS mission.

The only immediate result the LCROSS science team reported was a detection of sodium in the tenuous lunar atmosphere. Colaprete said the measurement jumped out as a result of heating from the impact.

"Something was thermalized down in the crater when we hit it. Temperatures got hot enough, reacted with the surface perhaps or reacted with the ambient atmosphere enough to excite sodium atoms," Colaprete said.

"Why an impact like this would excite it is a good question and that's something we're really going to follow up on," he said.

The highest priority of the mission is to comb the data for signs of water. Colaprete said he expects scientists will be reporting LCROSS results at the American Geophysical Union meeting in December.