Using data from three spacecraft that recently made close passes by the moon, U.S. researchers said they found proof that a thin film of water coats the surface of the moon's soil in some places.
The teams, made up of researchers from Brown University, the University of Maryland and the U.S. Geological Survey, used spectroscopic measurements taken from the moon's surface by NASA's Cassini and Deep Impact spacecraft and India's Chandrayaan 1 satellite.
All three spacecraft detected the oxygen-hydrogen chemical bond in many places on the lunar surface, including areas with temperatures that, during the day, reach the boiling point of water.
(Naturally, the greatest concentrations of the OH bond were found in the coldest regions near the two poles.)
But detecting the OH bond is not a smoking gun indicator for water. The instruments could just as easily be detecting hydroxyl, composed of one oxygen and one hydrogen atom.
In contrast, water has two hydrogen atoms and one oxygen.
In one of the trio of papers, each dealing with data from a different spacecraft, University of Maryland researchers Lori Feaga and Jessica Sunshine wrote that they found clear evidence for hydroxyl and water, using measurements taken by the Deep Impact spectrometer.
How much water, you ask?
The L.A. Times reports:
The amount of water in any one place is tiny. Clark estimated it at about a quart per ton of soil.
The moon "is almost as wet as a bone," Lucey said in an e-mail interview with The Times. "It is in the form of an imperceptible film on soil grains, perhaps several molecules thick."
Previously, there was no confirmed evidence at all that water currently exists on the moon. The Apollo missions of the 1960s and 1970s returned with rocks that contained small amounts of trapped water, but scientists decided at the time that the rocks had been contaminated by water from Earth.
Still, technology has not been developed to harvest or make do with such minute amounts of water.
So where did the water come from? The researchers suspect it came from comets colliding with the moon -- an intergalactic cross-pollination, if you will. Another theory is that the moon harbors water beneath its surface, and meteorites crashing into the lunar surface unearthed bits of it.
A final theory is that the solar wind -- a stream of charged hydrogen and helium particles that flow outward from the sun -- may be pairing with oxygen in the moon's soil.
Regardless of how it got there, the presence of water indicates that our solar system is less biologically barren than previously thought -- and perhaps ripe for human colonization.
The discovery also gives new hope for plans for NASA to return to the moon by 2020, a goal originally declared by the George W. Bush administration but recently found.
The three papers will appear in this week's edition of Science magazine.
This post was originally published on Smartplanet.com