Lunar Colony Setback

Since the Clementine mission of 1994, scientists have entertained an unlikely possibility-- that water ice existed in substantial quantities in permanently shadowed crater floors. Even though the Moon has no atmosphere, and even though Apollo samples brought back were bone dry, Clementine results suggested water ice might exist on the floor of Shackleton Crater.

Well, maybe not. Japan's lunar probe Kaguya Selene has studied the floor of Shackleton, and found no evidence of large water ice deposits, though it's still possible that water ice may be mixed with the soil. The study did confirm, however, that the permanently shadowed part of the crater is easily cold enough to preserve ice indefinitely.

If easily accessible water ice does not, in fact, exist on the Moon, the establishment of a lunar base is made more difficult; water will need to be brought from Earth, along with everything else. On the other hand, NASA has been planning to site its base near the lunar south pole largely because that's where the water supposedly was. If there is no usable ice, that may free NASA to look at the entire lunar nearside when deciding where to put the first permanent human base on another wor;d.