From Scientific American: MOFFETT FIELD, Calif.鈥擡arth鈥檚 nearest neighbor, the moon, is far from being a 鈥渂een there, done that鈥� world in space science and exploration. That鈥檚 the message from scientists and engineers at NASA鈥檚 Lunar Science for Landed Missions Workshop, recently held here at the space agency鈥檚 Ames AV名湿 Center.
Between 1969 and 1972 a dozen U.S. astronauts voyaged there to scout stretches of the desolate, crater-pocked landscape as part of NASA鈥檚 Apollo program. But almost half a century after those fleeting forays, humans have yet to go back. Now a rising tide of spacefaring nations are poised to visit (or revisit) the moon, among them European countries, China, Russia, Japan, India and, of course, the U.S.
Calling them back is the fact that, of all destinations in the solar system, the moon is not only the most accessible but also one of the most scientifically interesting. Thought to have formed shortly after Earth itself from debris ejected by our young planet鈥檚 collision with a Mars-size protoplanet, the moon has been witness to nearly 4.5 billion years of our world鈥檚, along with the solar system鈥檚, history. Impact craters and trace elements captured on its airless surface record processes that also shaped Earth鈥檚 early years, but were wiped out by our own planet鈥檚 geologic processes. Precisely because it is so close, so inert and so dead, the moon may be the best place in the solar system to go to answer the question of how and why Earth became so active and alive.