Evidence for water ice on the Moon: Results for anomalous polar craters from the LRO Mini-RF imaging radar
Article first published online: 3 OCT 2013
©2013. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Planets
Volume 118, Issue 10, pages 2016–2029, October 2013
How to Cite
2013), Evidence for water ice on the Moon: Results for anomalous polar craters from the LRO Mini-RF imaging radar, J. Geophys. Res. Planets, 118, 2016–2029, doi:10.1002/jgre.20156., et al. (
- Issue published online: 15 NOV 2013
- Article first published online: 3 OCT 2013
- Accepted manuscript online: 11 SEP 2013 04:51PM EST
- Manuscript Accepted: 9 SEP 2013
- Manuscript Revised: 28 AUG 2013
- Manuscript Received: 6 DEC 2012
 The Mini-RF radar instrument on the Lunar Reconnaissance Orbiter spacecraft mapped both lunar poles in two different RF wavelengths (complete mapping at 12.6 cm S-band and partial mapping at 4.2 cm X-band) in two look directions, removing much of the ambiguity of previous Earth- and spacecraft-based radar mapping of the Moon's polar regions. The poles are typical highland terrain, showing expected values of radar cross section (albedo) and circular polarization ratio (CPR). Most fresh craters display high values of CPR in and outside the crater rim; the pattern of these CPR distributions is consistent with high levels of wavelength-scale surface roughness associated with the presence of block fields, impact melt flows, and fallback breccia. A different class of polar crater exhibits high CPR only in their interiors, interiors that are both permanently dark and very cold (less than 100 K). Application of scattering models developed previously suggests that these anomalously high-CPR deposits exhibit behavior consistent with the presence of water ice. If this interpretation is correct, then both poles may contain several hundred million tons of water in the form of relatively “clean” ice, all within the upper couple of meters of the lunar surface. The existence of significant water ice deposits enables both long-term human habitation of the Moon and the creation of a permanent cislunar space transportation system based upon the harvest and use of lunar propellant.