Any drop to drink?

Space exploration

Any drop to drink?

Nov 13th 2009
From Economist.com

There is water—or, at least ice—on the moon

Reuters

 

 

THE moon is covered with seas, oceans and bays, the result of astronomers from past centuries whose imaginations out-ran the capabilities of their instruments, and who assumed that the Earth’s nearest neighbour was not that dissimilar to its mother planet. Modern astronomers know different. The moon is airless, waterless, weatherless and lifeless. Or so it would appear. But some have clung to the hope that the waterless bit applies only to liquid water, and that there might be places on the moon which harbour ice.

 

The places in question would be deep in craters at the moon’s poles—places, in other words, where the sun don’t shine. The ice, the hope went, would have arrived on board comets that crash at random on to the moon’s surface. Calculations suggest that enough of these would have fallen into the perpetual darkness of some of the polar craters, over the billions of years those craters have existed, to build up a reasonable supply of frozen water. And that, inevitably, has got the space cadets who wish to build permanently crewed bases on the moon in a tizzy. Any base would need a water supply. If that water did not have to be shipped from Earth, then the cost of establishing one might be brought down from the totally ridiculous to the merely absurd.

 

Friday 13th of November, then, has brought good luck to the proponents of lunar bases. The preliminary results of an experiment conducted by NASA, America’s space agency, suggest there is indeed ice on the moon.

 

The experiment was carried out on October 9th, when NASA famously “bombed” the moon. The target was a crater called Cabeus, which is 100km from the moon’s south pole. The bombs were, first, the upper-stage booster of a probe called LCROSS (Lunar Crater Observation and SensingSatellite) and then, five minutes later, the LCROSS probe itself. During that five minutes, the instruments on LCROSS gathered data on the plume of debris thrown up by the booster’s impact and transmitted them hastily back to Earth. The impact of LCROSS was monitored by a second probe, the Lunar Reconnaissance Orbiter.

 

In the weeks since the double impact, NASA’s scientists have been analysing these results, and on Friday the scientists announced that the results suggest the presence of water in Cabeus. The telltales are specific “lines” in the spectrum of infra-red light from the plume. These correspond to the frequencies of light given off when water molecules are energetically excited. The investigators, led by Anthony Colaprete of NASA’s Ames Research Centre in California, were unable to explain the spectral lines in question by any other combination of plausible chemicals, so are pretty sure that water is what they have found. That finding is reinforced by a second set of lines, in the ultraviolet part of the spectrum, which indicate the presence in the plume of hydroxyl radicals. Hydroxyl is HO, as opposed to water’s H₂O, and it is usually the result of water molecules decomposing.

 

In truth, the result is not that surprising. There is always excitement when water is discovered anywhere but Earth. Since it is composed of the commonest element in the universe and the third commonest, however, it is actually quite abundant. The LCROSS finding is, nevertheless, a successful confirmation of an intriguing hypothesis. In due course, maybe, the spiritual heirs of Roald Amundsen and Robert Falcon Scott will fulfill the space-cadets’ dream by visiting the moon’s south pole and confirming that there is ice there in person.

 

 

http://www.economist.com/sciencetechnology/displayStory.cfm?story_id=14889162&source=features_box3