Moon Crash: Where’s the Water?

Oct 13, 2009 12:27pm

The lesson, perhaps, of Friday's lunar impact by the LCROSS mission was to be careful what you wish for.  To the engineers who made the mission happen, it worked perfectly.  They hit the shadowed crater for which they had aimed, gouged out a 60-foot crater as they'd hoped, and did it for $79 million — which is plenty of money, but a lot less than the half-billion that shuttle missions have been estimated to cost, and a lot, lot less than the $797 billion in last year's stimulus package.

For the scientists hoping to see evidence of lunar ice, it was another story.  They had counted on — and talked about — the giant plume of debris they had hoped to see.  They were publicly cautious in advance of impact, but also said that if there large amounts of ice in the shadowed floor of Cabeus crater, they might know within hours.

In the end, no joy.  If there was a debris plume it wasn't visible, and there was no immediate evidence of ice.  Not the best result if you were counting on it for a future moon base (of which there's a cool graphic HERE).

The LCROSS satellite, which trailed the crashing Centaur booster by 400 miles, recorded a small flash of heat (see picture above), and hints of sodium in the soil, but no water so far.  The operators of the Hubble telescope, which watched from earth orbit (correcting typo spotted by a commenter–thank you), reported late Friday that they did not see either H2O or hydroxyls — HO, the ionized form of water that shows up when molecules have been broken up by solar radiation or the energy of impact.

"A preliminary analysis of the STIS spectra do not show any clear evidence for hydroxyl, but further analysis is needed," said Hubble co-investigator Alex Storrs in an online statement.

Lunar Reconnaissance Orbiter, circling the moon, passed over Cabeus crater just 90 seconds after impact, and spotted warming, but that's food for analysis, not proof of water.

None of this means back-to-the-drawing-board yet.  There may be plenty of ice hidden in the lunar soil, and LCROSS may have just missed it, or it's hidden in the spectrometer readings it took.  So there's some work to be done. Paul Spudis of the Lunar and Planetary Institute has an informed take on the mission's origins and shortcomings; take a look HERE.In the meantime, with apologies to Rodgers and Hart, many thanks to a commenter named rufadoop for providing this little gem last week:"Blue moon/You saw me standing alone/Without a dream in my heart/Without a love of my…KABOOM!"

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