Saturday science subject: Moon water

— 5:39 PM on September 26, 2009

Well, how about that? No need to go looking all the way on Mars for extraterrestrial water. As Science reports, three independent groups have found evidence of water on our Moon:

A less dry moon makes its debut courtesy of the Moon Mineralogy Mapper (M3) that has been orbiting the moon onboard India's now-defunct Chandrayaan-1 spacecraft. A spectrometer, M3 detected an infrared absorption at a wavelength of 3.0 micrometers that only water or hydroxyl--a hydrogen and an oxygen bound together--could have created.

But spectroscopists had long distrusted any sign of water in lunar data because Apollo moon rocks were so bone-dry. So M3 team members asked the researchers operating the spectrometer on NASA's EPOXI spacecraft to take a look as it passed the moon last June on its way to comet Hartley 2. EPOXI observations confirmed the M3 detection, as did a reanalysis of Cassini spectrometer data taken in 1999 on its way to Saturn. The three analyses are reported in separate papers in tomorrow's issue of Science.

We're not quite talking about lunar lakes, though—the water resides at very low concentrations in rocks. Science talks of "at most a part per 1000 water in the outermost millimeter or two of still very dry lunar rock." In other words, you'd reportedly need to harvest a plot the size of a baseball diamond to get a "decent drink of water" for one astronaut.

Still, the discovery might just help if we establish a lunar colony. New Scientist reports on a NASA microwave device that could allow astronauts to gather water without too much trouble:

[Edwin Ethridge of NASA's Marshall Space Flight Center and William Kaukler of the University of Alabama] used an ordinary microwave oven to zap simulated lunar soil that had been cooled to moon-like temperatures of -150 °C. . . . Keeping the soil in a vacuum to simulate lunar conditions, they found that heating it to just -50 °C with microwaves made the water ice sublimate, or transform directly from solid to vapour. The vapour then diffused out from higher-pressure pores in the soil to the low-pressure vacuum above.

On the moon, the vapour could be collected by holding a cold metal plate above the soil. The rising water vapour would then condense as frost onto the cold plate and "you could scrape it off", Kaukler says.

Gathering lunar water wouldn't just be about letting astronauts avoid recycled urine, either. New Scientist says the water could also be split into oxygen and hydrogen (presumably using solar energy) to make rocket fuel for the return trip, thereby cutting costs.

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