Until now, Earth's moon has been thought to lack water.
But the Clementine spacecraft, sent up in January 1995 to test sensors that can find and track missiles, has, as an unexpected extra, detected a pond of what may be ice--deep within a crater double the size of Puerto Rico.
Anthony Cook, of Los Angeles' Griffith Observatory, pointed out that if water is available on the moon, more extensive exploration becomes possible there. This is because the water needed to support human lifestyles does not need to be rocketed from Earth.
Rick Lehner, of the Pentagon's Ballistic Missile Defense Organization, described the discovery. A press conference, involving the Pentagon and NASA, took place on December 3, 1996, and Paul D. Spudis of Rice University's Lunar and Planetary Institute, with his colleagues, further clarified matters.
The moon's apparent ice formation is between 10 and 100 feet deep and is the size of a little lake. Because the crater's temperatures are almost always as cold as a place can get, water from at least one crashing comet's tail was unable to escape its frigid environment in the solar system's deepest known hole, at the moon's south pole.
The find was initially publicized in the November 29 issue of Science.
But James B. Garvin of Goddard Space Flight Center expressed skepticism that the radar signature involved indicated water, reported the December 4 Washington Post.