A new analysis of data from India's Chandrayaan-1 mission and NASA's Lunar Reconnaissance Orbiter suggests that Moon's water may be widely distributed across the surface, not confined to a particular region or type of terrain.
The water appears to be present day and night, though it was not necessarily easily accessible, according to the study published in the journal Nature Geoscience.
"We find that it doesn't matter what time of day or which latitude we look at, the signal indicating water always seems to be present," said Joshua Bandfield, a senior research scientist with the Space Science Institute in the US, and lead author of the new study.
"The presence of water doesn't appear to depend on the composition of the surface, and the water sticks around," Bandfield added.
The results contradict some earlier studies, which had suggested that more water was detected at the Moon's polar latitudes and that the strength of the water signal waxes and wanes according to the lunar day (29.5 Earth days).
The findings could help researchers understand the origin of the Moon's water and how easy it would be to use as a resource.
If the Moon has enough water, and if it is reasonably convenient to access, future explorers might be able to use it as drinking water or to convert it into hydrogen and oxygen for rocket fuel or oxygen to breathe.
The new finding of widespread water suggests that it may be present primarily as OH, a more reactive relative of H2O that is made of one oxygen atom and one hydrogen atom.
OH, also called hydroxyl, does not stay on its own for long, preferring to attack molecules or attach itself chemically to them. Hydroxyl would therefore have to be extracted from minerals in order to be used.
For the study, the researchers analysed data from the Moon Mineralogy Mapper spectrometer onboard the Chandrayaan-1 spacecraft.
They came up with a new way to incorporate important temperature information, creating a detailed model from measurements made by the Diviner instrument on NASA's Lunar Reconnaissance Orbiter, or LRO.
The researchers are still discussing what the findings tell them about the source of the Moon's water.
The results point toward OH and/or H2O being created by the solar wind hitting the lunar surface, though the team did not rule out that OH and/or H2O could come from the Moon itself, slowly released from deep inside minerals where it has been locked since the Moon was formed.