On August 21st, 2018 we learned about

The Chandrayaan-1 spacecraft confirms relatively accessible supplies of ice on the Moon’s surface

If humans get thirsty on their way to Mars, it looks like we’ll be able to stop for drinks on our own Moon. Despite its reputation for being nothing more than a dusty target for asteroid strikes, researchers are solidly convinced that the Moon’s north and south poles are both home to water ice. If there proves to be a significant amount of frozen water, it could be a crucial resource for humans or spacecraft spending time in space.

Cold craters as ice cube trays

While the Moon’s surface is generally a dry, inhospitable place, it’s actually fairly conceivable to find water ice at the north and south poles. The Moon rotates with hardly any tilt to its axis, only 1.54 degrees, compared to the Earth’s 23.5-degree tilt, so the north and south poles don’t experience seasonal changes in their exposure to the Sun. With the Sun never being “overhead” at these locations, deeper craters can cast constant shadows on their interiors, maintaining temperatures below -250 degrees Fahrenheit. At this time, it’s unknown if this water was originally delivered by an icy comet or some other means, but there’s a good chance that it has remained frozen in these craters for a very long time.

The origin of the water might be revealed once a physical sample can be acquired. For now, the ice has been identified by examining a number of features with the Moon Mineralogy Mapper (M3) instrument aboard the Chandrayaan-1 spacecraft. Even with the dust and darkness in these polar craters, the M3 was able to measure the reflectivity, infrared light absorption and other properties that all point to frozen H2O being on the Moon.

Accessible ice

There’s likely more ice buried deeper in the Moon, but these patches are exciting thanks to how close they are to the surface. Even though it likely has a lot of dirt mixed into it, it would still be accessible enough to be of use to humans or robots visiting the Moon in the future. Water is pretty heavy to get off the Earth, so any supplies of water for drinking, irrigating or even splitting to gain access to oxygen, would be a welcome resource for astronauts traveling outside low Earth orbit.

Source: Ice Confirmed at the Moon's Poles, Jet Propulsion Laboratory News