Previous experiments have confirmed the existence of small amounts of water across the Moon, although most technologies cannot distinguish between water, free hydrogen ions and hydroxyl.
An instrument known as a heterodyne spectrometer could zoom in on particular frequencies to definitively identify and locate water sources on the Moon. It requires a stable, high-powered, terahertz laser - which is also small enough to take on space missions - and this has now been prototyped by Nasa.
“This laser allows us to open a new window to study this frequency spectrum,” said Dr Berhanu Bulcha, an engineer at Nasa’s Goddard Space Flight Center.
“Other missions found hydration on the Moon, but that could indicate hydroxyl or water. If it’s water, where did it come from? Is it indigenous to the formation of the Moon or did it arrive later by comet impacts? How much water is there? We need to answer these questions because water is critical for survival and can be...