NASA: Water is widespread on the moon

NASA scientists on Thursday announced surprising findings about water in unexpected places: molecules covering the entire moon surface of the moon, and sheets of pure ice beneath fresh craters on Mars.

"This was thought to be impossible, to have water on the surface of the moon in hot sunlight, especially at the equator let alone the high latitudes," said Roger Clark, a scientist working with NASA's Cassini spacecraft, one of three that teamed up to confirm the water's presence. "So it's a really profound discovery."

The more widespread presence of water could provide astronauts with a readily accessible resource and reduce the mission cost of shipping water from Earth.

It also raises new questions about the moon's geology and formation and about other unexpected places in the solar system where water might form, the scientists said.

Though the amount of water molecules and related hydroxyl – one atom of hydrogen and one of oxygen - discovered is greater than imagined, the moon contains less water than the driest desert on Earth.

"When we say 'water on the moon,' we are not talking about lakes, oceans or even puddles," said Carle Pieters, principal investigator for a spectrometer on an Indian probe that recently orbited the moon.

Rather, she said, it means molecules mixed with rock and dust in the top millimeters of the moon's surface.

Moon rocks returned by Apollo astronauts who visited equatorial regions held a tiny amount of water - enough to fill a tablespoon.

The recent findings, published in the journal Science, suggest at most one pint of water could be extracted from every 1,000 pounds of topsoil.

In two weeks, NASA plans to crash a rocket stage and spacecraft launched this summer from Cape Canaveral into the moon's south pole, hoping to excavate evidence of water ice in a freezing, permanently shadowed crater.

The big surprise of the Thursday's results was that water molecules were not confined to the poles or shadowed craters, but existed even in hot regions where the temperature can exceed water's boiling point.

Scientists working with the NASA's Deep Impact spacecraft noticed a fluctuation of molecules during a lunar day as temperatures heated and cooled.

"Regardless of the location or the terrain type, the entire surface of the moon will be hydrated during at least part of the lunar day," said Jessica Sunshine, deputy principal investigator for Deep Impact.

The water's source is unknown.

One possibility is that hydrogen in solar wind interacts with oxygen in lunar regolith. Influences from meteorites or interior gases are also possible.

If the solar wind hypothesis is true, Sunshine said, it suggests the same process might form water on other oxygen-rich bodies without atmospheres in the inner solar system, including Mercury and many asteroids.

Later Thursday, scientists reported discoveries made with the Mars Reconnaissance Orbiter, which launched from Cape Canaveral in August 2005.

New craters suggest thin sheets of ice beneath the Martian surface extend further from the poles than thought, and that Mars' climate was more humid in the relatively recent past of the last 10,000 years than known before.

"The observations showed us that the buried ice on Mars is much more extensive than we thought, but also that the ice is a lot purer than we thought," said Shane Byrne of the University of Arizona.

The scientists expected a 50-50 mix of ice and dirt, but found nearly pure, white ice.

Ironically, one of the craters was within 350 miles of where NASA's Viking 2 probe landed in 1976. It couldn't quite dig deep enough to hit the ice.

"If Viking 2 had just been able to dig down a few more inches, it would have hit ice, and that would have been major discovery for our understanding of Mars," said Selby Cull of Washington University in St. Louis. "It was literally inches away from our robotic fingertips, and instead it's taken more than 30 years to finally make this discovery."

IMAGE NOTES:
Top: This image of the moon is from NASA's Moon Mineralogy Mapper on the Indian Space Research Organization's Chandrayaan-1 mission. It is a three-color composite of reflected near-infrared radiation from the sun, and illustrates the extent to which different materials are mapped across the side of the moon that faces Earth. Small amounts of water and hydroxyl (blue) were detected on the surface of the moon at various locations. This image illustrates their distribution at high latitudes toward the poles. Blue shows the signature of water and hydroxyl molecules as seen by a highly diagnostic absorption of infrared light with a wavelength of three micrometers. Green shows the brightness of the surface as measured by reflected infrared radiation from the sun with a wavelength of 2.4 micrometers, and red shows an iron-bearing mineral called pyroxene, detected by absorption of 2.0-micrometer infrared light. Image credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS.

Bottom: The High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter took these images of a fresh, 6-meter-wide (20-foot-wide) crater on Mars on Oct. 18, 2008, (left) and on Jan. 14, 2009. Each image is 35 meters (115 feet) across. This crater's depth is estimated to be 1.33 meters (4.4 feet). The impact exposed water ice from below the surface. It is the bright material visible in this pair of images. The change in appearance from the earlier image to the later one resulted from some of the ice sublimating away during the Martian northern-hemisphere summer, leaving behind dust that had been intermixed with the ice. The thickening layer of dust on top obscured the remaining ice. This crater is at 43.28 degrees north latitude, 164.22 degrees east longitude. Image Credit: NASA/JPL-Caltech/University of Arizona