Water ice found in the Moon's darkest polar craters
Wednesday, August 22, 2018, 15:36 - Ice on the Moon! A new study has discovered numerous deposits of ice in the Moon's darkest polar craters, and these deposits will not only be excellent locations for future exploration, but could also provide a crucial resource for lunar colonization, but also future space missions.
For years, scientists have speculated that craters near the Moon's north and south pole could hold deposits of water ice, right at the surface, ready to be extracted for study and for use by human explorers.
Researchers focused their search for water ice at the poles because, with the Moon's only slight axial tilt (roughly 1.5° compared to Earth's 23.5° tilt), the bottoms of many of the deeper craters in those regions are in perpetual shadow. Sunlight never reaches the surface at the base of the crater, thus temperatures there stay colder than -150°C, and sunlight can't melt any water that may exist there.
Despite the constant scrutiny and study the Moon receives due to NASA's Lunar Reconnaissance Orbiter, up until now, there has only been speculation and indirect evidence for water ice in these sunless regions.
Now, a new study using data from NASA's Moon Mineralogy Mapper, flying on board India's Chandrayaan-1 spacecraft, has finally provided the direct evidence that scientists have needed to say - definitively - there is water ice in these dark craters.
Blue dots on the Moon’s south pole (left) and north pole (right), indicate the location of surface water ice deposits, detected by NASA’s Moon Mineralogy Mapper instrument. The darker regions on the map indicate the coldest, thus much of the ice is concentrated at the darkest and coldest locations, in the shadows of craters. Each of these dots represents a square, ~280 metres on a side. Credit: NASA
According to NASA:
These ice deposits are patchily distributed and could possibly be ancient. At the southern pole, most of the ice is concentrated at lunar craters, while the northern pole’s ice is more widely, but sparsely spread.
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.
In their paper, published in the journal PNAS on August 20, the researchers say that some of this water ice is mixed up with lunar dust and rock,
While the Moon has only an extremely thin atmosphere, which would expose surface water to space, the extremely low temperature would prevent the ice from sublimating into space.
Water on the Moon very likely originates from meteorite impacts, comet debris, interactions between the solar wind and oxygen-bearing minerals, or a combination of all three.
"Learning more about this ice, how it got there, and how it interacts with the larger lunar environment," NASA said, "will be a key mission focus for NASA and commercial partners, as we endeavor to return to and explore our closest neighbor, the Moon."