18 November 2009

Water on the moon

The big ball of rock we learned about as kids turns out to be full of surprises. Like water, for example. Who knew the moon had water in its rocks? Actually, a little thought about what rocks are and what they are made of should make this recent discovery a lot less surprising. Rocks, and the minerals that make them up, contain a lot of oxygen. That oxygen is typically bound up in oxides, silicates, hydroxides, and whatnot, but it is present in great abundance. Hydrogen is the most abundant element in the universe, and free protons in the solar wind could provide a ready source of hydrogen ions capable of reacting with the oxygen in lunar minerals. In fact, the presence of water, or at least hydroxyl groups, in the lunar regolith has been speculated on since the early 1960s. Water molecules could not exist on or near the moon's surface, but they could certainly exist in the bedrock or deep within shadowed craters. (The LCROSS mission probed such a crater.) These recent findings, exciting as they are, don't do much more than confirm some long-held hypotheses about our near neighbor. The mechanisms of lunar water creation, transport, and storage are barely beyond the speculative stage, and the presence of something like large-scale polar ice is still awaiting discovery. Nonetheless, water on the moon is pretty damn cool, don't you think?

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