There's Water on the Moon, Probes Confirm

September 24, 2009

The long-standing theory of the moon being bone dry is now all wet.

That's because large swaths of the lunar surface are saturated with water—or at least the ingredients needed to make water, a suite of new studies confirm.

A trio of satellites—including India's recently lost lunar probe, Chandrayaan-1—picked up the light signature of water (H2O) or hydroxyl (OH) or both while mapping the moon.

The other two probes that found moon water are NASA's Cassini and Deep Impact spacecraft.

But don't go planning a lunar pool party just yet: The water or hydroxyl molecules on the moon are bound to other molecules and exist in trace amounts over the entire lunar surface.

Still, scientists estimate there is about a quart of water and/or hydroxyl for every cubic yard of lunar soil. (Get the facts on moon exploration.)

The surprise finding suggests moon water may be a renewable resource, created constantly as a result of interactions between charged particles from the sun and the lunar surface. (Take a moon quiz.)

"The Heck With Hydrogen"

The news comes close on the heels of NASA's announcement that its Lunar Reconnaissance Orbiter recently detected large amounts of hydrogen, a possible marker for water, at the moon's south pole.

Larry Taylor, a planetary geologist at the University of Tennessee, said his team's findings go one step further.

"All [the LRO scientists] can say is they've found hydrogen," said Taylor, a co-author on one of the new studies, which is based on data from Chandrayaan-1. "We're saying, The heck with the hydrogen! It might actually be water."

Taylor and his team think the lunar water and/or hydroxyl are created when hydrogen in the form of protons from the sun's solar wind strike oxygen-rich minerals and glasses on the moon's surface.

"You have protons and you have an oxygen looking for somebody, and they make a marriage," Taylor said.

Moon Water a Mind Changer

It's unclear at present whether the satellites detected water or hydroxyl on the moon, but both substances could prove useful to future lunar missions.

Even if the lunar soil contains only hydroxyl, Taylor said, that hydroxyl can be extracted and combined with lunar hydrogen to form freshwater.

A ready supply of water on the moon would in turn reduce the payloads that would need to be taken into space to maintain a future lunar outpost.

LCROSS, a probe that will soon smash into a permanently shadowed crater on the moon, might help answer some of the lingering questions.

The controlled impact will send up a plume of material into the light, so scientists can get a better look at what's inside.

Overall, Taylor noted that he had previously been a staunch proponent of the dry-moon theory, but he is elated to be proven wrong.

"That's how science goes," he said. "It's about changing your mind about things."

Findings appear online September 24 on the Science Express Web site.

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