Researchers at Brown University in the US examined glass beads, a type of volcanic crystal gathered during the Apollo 15 and 17 missions in the 1970s, and found they contained similar volumes of water to Earth's basalt rock.

The leaders of the study, which has been published in Nature Geoscience, cite the parallels as evidence that parts of the moon contain a similarly large amount of water. This, they believe, could be useful for future lunar missions as it means water could potentially be extracted rather than carried from home.

"Other studies have suggested the presence of water ice in shadowed regions at the lunar poles, but the pyroclastic deposits are at locations that may be easier to access," said lead author Dr. Shuai Li, formerly of Brown University and now at the University of Hawaii.

"Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward, and our results suggest a new alternative."