An analysis of data collected by NASA’s Moon Mineralogy Mapper (M3) has found compelling evidence for water ice on the Moon’s north and south poles.
Led by Shuai Li of both the University of Hawaii and Brown University, and by Richard Elphic of NASA’s Ames Research Center in California, a team of scientists discovered three specific signatures of water ice in the reflectance spectra collected by M3.
Launched with India’s Chandrayaan-1 spacecraft in 2008, M3 successfully detected the reflective properties of water ice on surfaces in the Moon’s polar regions and also directly measured the method by which the water molecules absorb infrared light. The latter enables scientists to determine whether water discovered is in a solid, liquid, or gaseous state.
M3 studied the lunar surface between November 2008 and August 2009.
“Previous observations indirectly found possible signs of surface ice at the lunar south pole, but these could have been explained by other phenomena, such as unusually reflective lunar soil,” a NASA statement noted.
Signatures of water ice found in the new study are located within 20 degrees of the Moon’s north and south poles, regions that are among the lunar surface’s coldest and darkest locations.
More ice is present in the south polar region, mostly at the bottom of craters that are perpetually in shadow. In the north polar region, the water ice is thinner and more scattered.
Temperatures at the bottom of craters that never receive sunlight never exceed minus 250 degrees Fahrenheit, due to the Moon’s very small axial tilt.
While the Moon’s surface has significantly less water ice than the surfaces of Mercury or Ceres, the water ice it does have is a valuable resource for future human exploration and even colonization.
“With enough ice sitting at the surface–within the top few millimeters–water would possibly be accessible as a resource for future expeditions to explore and even stay on the Moon, and potentially easier to access than the water detected beneath the Moon’s surface,” the NASA statement indicated.
Findings of the study have been published in the Proceedings of the National Academy of Sciences.