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View Diary: Moonbomb Live (106 comments)

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  •  Elaboration sought. (3+ / 0-)

    A Japanese satellite in fact just wrapped up a year-long mission orbiting the moon, including looking into the polar craters, and found no evidence of water--an inconvenient truth not much taken up here. Instead, when an Indian satellite recently reported a water "signature" in some data, that was trumpeted from the rooftops.

    These two findings seem to be mutually contradictory. Are you able to shed some more light on this? If the spectral readings from India's Chandrayaan (ISRO MIP/NASA M3) could be used to establish that water trace exists (and apparently confirmed from the data recorded on earlier NASA missions) in many parts of the moon, when why would that not hold for the spectral recordings from the Japanese mission, or for that matter that from any other recent mission with sufficiently high precision instrumentation?

    Did you know that Indians invented the # 0 and the decimal/binary systems: a primer on Indian mathematics.

    by iceweasel on Fri Oct 09, 2009 at 06:50:38 AM PDT

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    •  Water water everywhere (2+ / 0-)
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      iceweasel, QuestionAuthority

      The "water on the moon" craze started about 10 years ago when the Clementine spacecraft found decreased neutron flux at the lunar poles, indicating (perhaps) that neutrons formed by radioactive decay in the moon's crust were being absorbed by hydrogen, in the form of H2O.

      Even if true, the hypothetical amount of water in the lunar regolith, as the kids say, would have been about 1%--i.e., about the water content of concrete. Not exactly convenient for use, although it could be said that there was a lake's worth if however many gazillion tons of regolith are considered. So that finding kind of languished.

      The idea that the polar craters have water took things up a notch, with the hope that solid ice might be found right on the surface.

      This came out fairly recently:

      Japan's now-finished lunar mission found no water ice

      "However, [Selene imaging] indicates that exposed relatively pure water-ice deposits are lacking on the floor [of Shackleton Crater]," according to the Japanese report. Japanese scientists said in Houston they could not find water ice anywhere else in craters near the Moon's rugged south pole, one of the primary NASA justifications for flying the LCROSS mission.

      The LRO press kit mentions two competing theories for why Clementine saw decreased neutron flux at the poles, both involving absorption of same by hydrogen: either in water form, or alternatively hydrogen deposited from solar wind could be more stable and accumulate more due to the cold polar temperatures.

      So the hydrogen detected by Clementine and Chandrayaan-1 (by inference from neutron flux measurements) could be just that deposited by the solar wind, not water or ice. It's all in the interpretation, or a one scientific wag put it, "if I hadn't believed it I wouldn't have seen it!"

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