Probe Detects Frozen Water on Moon

By Alan Boyle MSNBC

March 5 - A spacecraft orbiting the moon has detected frozen water in craters at the poles, NASA announced Thursday. Scientists said the ice appeared to be widely distributed, with a couple of gallons of water in a cubic yard of lunar soil.

THE SCIENTISTS said the ice could provide fuel for future spaceships and lunar colonies for centuries - if it could be efficiently mined from supercold regions of the moon.

Alan Binder, principal investigator for the Lunar Prospector mission, told reporters at a Thursday news conference, "There is water there, we are certain of that."

"Getting the water out of the soil is a simple thing," Binder said. The trick, he said, would be "getting the soil out of the very, very cold areas."

Lunar Prospector is a 4-foot-high, drumlike spacecraft observing the moon from a pole-to-pole orbit about 60 miles above the surface. The purpose of the $63 million mission - NASA's first foray to the moon in 25 years - is to survey the lunar surface using a variety of scientific instruments.

The mission could determine whether the moon is still geologically active, whether it has a dense core and whether it contains potentially valuable reserves of fusion fuel or metals. But it was the question about lunar ice that was most intriguing to planetary scientists.

MAKES BASE MORE FEASIBLE

Substantial reserves of water ice would make it much easier to establish a permanent lunar base for exploiting the moon's resources. Scientists could also set up a deep-space observatory free of interference from earthly sources.

The presence of water ice at both lunar poles was strongly indicated by data from the spacecraft's neutron spectrometer, mission scientists said in a news release.

However, the moon's water ice was not concentrated in polar ice sheets, they cautioned.

"While the evidence of water ice is quite strong, the water `signal' itself is relatively weak," said William Feldman, co-investigator and spectrometer specialist at the Department of Energy's Los Alamos National Laboratory in New Mexico. "Our data are consistent with the presence of water ice in very low concentrations across a significant number of craters."

Assuming a water-ice depth of about a foot and a half - the depth to which the neutron spectrometer's signal can penetrate - scientists estimate that the data are equivalent to an overall range of 11 million to 330 million tons of lunar water ice, depending upon the assumptions of the model used.

The ice appears to be dispersed over 3,600 to 18,000 square miles of deposits across the moon's north pole, and another 1,800 to 7,200 square miles across the southern polar region. Twice as much of the water ice mixture was detected by Lunar Prospector at the moon's north pole as at the south, the scientists said.

NOT ENTIRELY UNEXPECTED

Although it may sound like a Jules Verne tale, finding frozen water on the moon doesn't exactly come as a surprise. Data returned in 1994 from a Defense Department spacecraft called Clementine indicated that there might be ice deep within craters at the moon's south pole. But that conclusion was based on radar echoes from the lunar surface, and skeptics proposed alternate explanations for the results.

Lunar Prospector used its spectrometers to look for an excess of hydrogen, which in turn indicated the presence of water.

When the probe was launched Jan. 6, scientists said they hoped to resolve questions about lunar ice in the first month of the mission. For weeks, NASA's Ames Research Center and the Lunar Research Institute, both based in California, fended off media inquiries about Lunar Prospector's findings.

ORIGIN OF THE ICE

Scientists say lunar ice would most likely come from comets falling into deep craters at the moon's poles. The depths of such craters would be in perpetual darkness, since the crater walls would block the sun's rays. Thus, the water ice from comets would be preserved from evaporation.

In the far future, the ice could be used to supply humans on the moon with drinking water and to produce fuel as well.

Don't expect Lunar Prospector to provide photographs of icy regions, however. In accordance with NASA's budget-conscious philosophy, the drumlike spacecraft has three types of spectrometers, a magnetometer and an electron reflectometer - but no camera.