After years of searching, NASA has found evidence of liquid water on the Moon. Two separate studies have been published in recent days, with water found deep in polar craters and predicted in polar "cold traps". While scientists have long suspected there to be water on the Moon, it is now almost certain and possibly much more widespread than previously thought. These new findings have a number of positive implications or the future of lunar exploration, with water possibly useful for resource extraction and rocket fuel among other applications.

The first study was carried out by NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA). They confirmed water on the sunlit surface of the Moon, with this discovery possibly indicating water distribution across the entire lunar surface. Led by Casey Honniball from NASA's Goddard Space Flight Center, SOFIA found the signature of water either trapped in glass or between grains of sand. The study detected water molecules on the Moon's southern hemisphere in a location known as Clavius Crater, which is one of the largest craters visible from Earth.

According to Dr Honniball, "For the first time we have unambiguously detected molecular water on the sunlit Moon... Prior to this it was believed water could not survive on the sunlit Moon... Our detection shows that water may be more widespread on the surface of the Moon than previously thought and not constrained to only the poles." According to Paul Hertz, director of the Astrophysics Division in the Science Mission Directorate at NASA, “Now we know it is there. This discovery challenges our understanding of the lunar surface and raises intriguing questions about resources relevant for deep space exploration.”

The second paper used new theoretical models, based on temperature data and high resolution images, to refine predictions of where water molecules might occur. Along with cold traps found in permanently shadowed areas near the poles, there could be additional small cold traps where conditions permit water ice to accumulate. The team calculates that 0.1% of the total lunar surface is cold enough to trap water as ice, on a scale of centimetres or decimetres. The vast majority of these icy cold traps are likely to be found at high latitudes near the lunar south pole, with this information highly useful in narrowing down future landing sites.

Both of these discoveries strengthened data from 2018 uncovered by India's Chandrayaan-1 spacecraft, which revealed tiny patches of exposed ice in some of the same shadowy craters. Water represents an important resource that can be used for life-support, air supply, resource extraction, and even fuel. Water could be used in simple chemical reactions to extract useful resources from the soil, and also used as rocket fuel in the form of liquid hydrogen and liquid oxygen. With water, the Moon has greater potential to become a refuelling base, with lower gravity and lack of atmosphere providing the perfect launchpad for the rest of the Solar System.