The expected confirmation of the presence of water ice on the surface of the Moon has been found in the darkest and coldest parts of its polar regions. According to a recent paper published in Proceedings of the National Academy of Sciences (PNAS), these ice deposits are irregularly distributed and could be old. While in the south pole, most of the ice is concentrated in the lunar craters, the ice of the north pole is more extensive, but dispersed.
Most of the newly discovered ice is found in the shadows of the craters near the poles, where the warmest temperatures never reach -156ºC. Due to the slight inclination of the axis of rotation of the Moon, sunlight never reaches these regions.
The team of scientists that has made the discovery, from the universities of Hawaii and Brown and the Ames Research Center of NASA in Silicon Valley of California (USA), used data from the Moon Mineralogy Mapper (M3) instrument of the NASA to identify three specific signatures that definitely prove there is water ice on the surface of the Moon.
M3, aboard the Chandrayaan-1 spacecraft, launched in 2008 by the Space Research Organization of India, collected data that not only collected the reflective properties that we would expect from the ice, but could also directly measure the distinctive way in which Its molecules absorb infrared light, so it can differentiate between liquid water or steam and solid ice.
Previous observations had indirectly found possible signs of surface ice at the lunar south pole, but these could have been explained by other phenomena, such as the unusually reflexive lunar soil.
With enough ice on the surface, within the first few millimeters, water is likely to be accessible as a resource for future expeditions to explore and even stay on the Moon, and potentially easier to access than water detected below the satellite’s surface.
It seems that little by little, the Earth ceases to be the only body with water in the solar system. A few weeks ago, Science website published the discovery of a large lake of liquid water also in the polar regions of Mars, and the data collected by the New Horizons probe revealed at the time that Pluto exists a large underground ocean.