The find, reported in the journal Science, came courtesy of a Department of Defense satellite named Clementine. Sent to the moon in 1994 to test the space-readiness of “Star Wars” technology, Clementine spotted a large dark region in an ancient crater called the South Pole-Aitken Basin. Since 1961, scientists have suspected that areas of permanent darkness on the lunar surface might be cold enough to retain volatile substances like water that otherwise boil off into space. Researchers used Clementine’s radio antenna as a radar emitter to peek into the bottom of the crater and saw reflections that look like ice–roughly 3.5 million cubic feet of water.
Or so they think for now. When the orbital probe Lunar Prospector arrives at the moon next fall, one of its missions will be to check. “I’m not going to bet my life on this,” says Paul Spudis, a geologist at the Lunar and Planetary Institute, who co-wrote the study. “But I’m reasonably certain this was a positive result. You’ve got to live with uncertainty. That’s the space business.” What a business. The ice could provide water for a lunar colony–a dream as ambitious as the hunt for the white whale.
