Character and Spatial Distribution of OH/H ₂ O on the Surface of the Moon Seen by M ³ on Chandrayaan-1

Lunar Water The Moon has been thought to be primarily anhydrous, although there has been some evidence for accumulated ice in permanently shadowed craters near its poles (see the Perspective by Lucey , published online 24 September). By analyzing recent infrared mapping by Chandrayaan-1 and Deep Impact, and reexamining Cassini data obtained during its early flyby of the Moon, Pieters et al. (p. 568 , published online 24 September), Sunshine et al. (p. 565 , published online 24 September), and Clark et al. (p. 562 , published online 24 September) reveal a noticeable absorption signal for H 2 O and OH across much of the surface. Some variability in water abundance is seen over the course of the lunar day. The data imply that solar wind is depositing and/or somehow forming water and OH in minerals near the lunar surface, and that this trapped water is dynamic.