The analysis, reported in Science, has looked at pockets of volcanic material locked within tiny glass beads. It found 100 times more water in the beads than has been measured before, and suggests that the Moon once held a Caribbean Sea-sized volume of water.
The find also casts doubt on aspects of theories of how the Moon first formed. A series of studies in recent years has only served to increase the amount of water thought to be on the Moon. The predominant theory holds that much of the water seen on the lunar surface arrived via impacts by icy comets or watery meteorites.
But this recent find is shedding light on how much water is contained in the Moon's interior, which in turn gives hints as to how - and from what - it formed.
In 2008, a team of researchers from the Carnegie Institution and Brown and Case Western Reserve universities analysed the water content found in samples of lunar magma returned by Apollo missions. They wrote in a Nature paper that the samples contained about 10 times more water than they expected. Read More