Water ice exists in large quantities in many small craters near the Moon's north pole, according to a new study.
Spudis et al. present initial results from the miniature synthetic aperture radar (Mini-SAR) experiment on board the Indian Chandrayaan 1 spacecraft, which mapped most of the area near the north pole of the Moon between February and April 2009. The Mini-SAR instrument collected data on the polarization of radio waves reflected off the lunar surface.
These data give the researchers insight into lunar surface features. For instance, high values of the circular polarization ratio (CPR) indicate either surface roughness or ice.The observations suggest that water ice exists in many of the small craters in permanent darkness near the north pole of the Moon. According to the scientists' analysis, the CPR values recorded indicate that this ice must be at least 2-3 meters (6.5-9.8 feet) thick.
The researchers note that the ice is not distributed evenly over the lunar surface, suggesting that it may have been deposited through an episodic deposition process such as comet or asteroid impact. Because these lunar craters near the north pole are in permanent shadow, ice would remain stable there indefinitely.
The new study supports and extends other recent discoveries of water on the Moon.
Title: Initial results for the north pole of the Moon from Mini-SAR, Chandrayaan-1 mission, P. D. Spudis: Lunar and Planetary Institute, Houston, Texas, USA, et al, Geophysical Research Letters (GRL) paper DOI: 10.1029/2009GL042259, 2010