Additional evidence of water activity on Moon
Scientists have detected ice deposits near the Moon's north pole.
March 2, 2010
Provided by NASA Headquarters, Washington, D.C.
March 2, 2010
Mini-SAR map of the Circular Polarization Ratio (CPR) of the north pole of the Moon. Fresh, “normal” craters (red circles) show high values of CPR inside and outside their rims. This is consistent with the distribution of rocks and ejected blocks around fresh impact features, indicating that the high CPR here is surface scattering. The “anomalous” craters (green circles) have high CPR within, but not outside their rims. Their interiors are also in permanent sun shadow. These relations are consistent with the high CPR in this case being caused by water ice, which is only stable in the polar dark cold traps.
Photo by NASA
Using data from a NASA radar that flew aboard India's Chandrayaan-1 spacecraft, scientists have detected ice deposits near the Moon's north pole. NASA's Mini-SAR instrument, lightweight, synthetic aperture radar, found more than 40 small craters with water ice. The craters range in size from 1 to 9 miles (2 to15 kilometers) in diameter. Although the total amount of ice depends on its thickness in each crater, it's estimated there could be at least 1.3 trillion pounds (600 million metric tons) of water ice.
"The emerging picture from the multiple measurements and resulting data of the instruments on lunar missions indicates that water creation, migration, deposition, and retention are occurring on the Moon," said Paul Spudis, principal investigator of the Mini-SAR experiment at the Lunar and Planetary Institute in Houston. "The new discoveries show the Moon is an even more interesting and attractive scientific exploration and operational destination than people had previously thought."
During the past year, the Mini-SAR mapped the Moon's permanently shadowed polar craters that aren't visible from Earth. The radar uses the polarization properties of reflected radio waves to characterize surface properties. Results from the mapping showed deposits having radar characteristics similar to ice.
"After analyzing the data, our science team determined a strong indication of water ice, a finding which will give future missions a new target to further explore and exploit," said Jason Crusan, program executive for the Mini-RF Program for NASA's Space Operations Mission Directorate in Washington.
The results are consistent with recent findings of other NASA instruments and add to the growing scientific understanding of the multiple forms of water found on the Moon. The agency's Moon Mineralogy Mapper discovered water molecules in the Moon's polar regions, while NASA's Lunar Crater Observation and Sensing Satellite or LCROSS, detected water vapor.
Mini-SAR and Moon Mineralogy Mapper are two of 11 instruments on the Indian Space Research Organization's Chandrayaan-1. The Applied Physics Laboratory in Laurel, Maryland, performed the final integration and testing on Mini-SAR. It was developed and built by the Naval Air Warfare Center in China Lake, California, and several other commercial and government contributors.