More water on the moon.

Researchers analyzing data from the Lunar Prospector, the tiny robot that has been orbiting the moon since January, have drastically upped their estimate of the amount of frozen water buried beneath the lunar poles. In March, the Prospector team suggested that craters in permanent shadow at the north and south poles could hide 300 million metric tons of ice (SN: 3/14/98, p. 166). After refining models of how water might be delivered to the surface, the team now says that the poles may contain as much as 600 billion metric tons, with the north pole harboring perhaps 15 percent more of the precious resource than the south.

William C. Feldman of the Los Alamos (N.M.) National Laboratory and his colleagues report the new findings in the Sept. 4 SCIENCE. The evidence is indirect. Prospector's measurements indicate that the poles have a higher abundance of hydrogen than elsewhere on the moon, and the team asserts that the hydrogen is almost certainly tied up in water.