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No Ice on the Moon
eldavojohn writes "In 1994, there was speculation that there might be a southern ice cap on the moon — something our exploration of it could take advantage of. Unfortunately, recent evidence has come to light revealing that this probably isn't true." From the article: "If there is any ice at the South Pole, it probably comes from tiny, scattered grains that probably account for only one or two percent of the local dust, the authors suggest. "Any planning for future exploitation of hydrogen at the Moon's South Pole should be constrained by this low average abundance rather than by the expectation of localized deposits at higher concentrations," the paper says soberly. The research involved sending a radar signal from the Arecibo telescope in Puerto Rico. The signal hit the southern lunar region and the reflection was picked up by the Green Bank Telescope in West Virginia." Well, it looks like we're going to have to hit Hoth before we hold that kegger on the moon."
Science fiction writers (the hard- variety) like Stephen Baxter have been lamenting the likelyhood of this eventuality for years now. Not that it isn't nice to at least have some closure, but on the other hand it seems like the news is little more than the last nail in the coffin for the most obvious pas-de-terre between Earth and space.
There is one book--Manifold Space, I think it might be--that muses upon the notion that there may be some water deeply buried (e.g. 20+ kilometres) the surface, and all the difficulties involved in getting to it (e.g. standard mining techniques developed on Earth wouldn't work there for a host of reasons). Excellent book/series, incidentally. Strongly recommended for any space science enthusiasts.
Actually this is incorrect, the secondary reflector would have blocked the radio waves, just as the secondary
mirror of an optical telescope blocks light. FWIW, I wrote the control software and firmware for an instrument on the current Green Bank telescope, and have been working with radio telescopes for 17 years, so I do know what I am talking about.
Mmm, actually, the way it worked is this:
(1) Clementine observed a particular wiggle in the radar reflection. At the time, it was thought the only reasonable way to get that wiggle was to have the radar reflect off ice. Huzzah! Ice! (Well, not really. It hasn't been directly observed -- no one's held it in their hand -- but it seemed no other explanation would account for the wiggle.)
(2) Now someone has come up with an alternative explanation for the wiggle, and demonstrated that you can get it from areas (sunlit areas) which really shouldn't have ice. Throws cold water, so to speak, on the idea that only ice can make the radar signature wiggle.
But does this mean no ice? Nope. Now we have two explanations for Clementine's observation: ice or some surface roughness thingy. Which is the right cause? Could be ice, could be merely rough rocks, could be both.
So it's not that ice on the Moon has been disproved. It's that a previous proof (or strong suggestion of) ice on the Moon has been shown to be in error. Doesn't mean the ice isn't there. Just means we no longer know (or think we know) whether it is or not. Have to go take a shovel and find out, I think.
Sublimation is solid to gas. Deposition is gas to solid.
Vaporization is conversion to gas, regardless of original state (sublimation and evaporation are both types of, and the only types of, vaporization).
And my CAPTCHA is "inform".
OK, whoever gave this a +1 Informative mod - hand over your Geek Card! You are no longer a card-carrying Geek. Please take a Dork card on your way out. (Geeks know that radio waves and light are two different ways to refer to the same thing, and that yes, it matters if you block it when you're talking about a telescope observing any part of the spectrum.)
If you mod me down, I shall become more powerful than you could possibly imagine.