Despite previous research indicating otherwise, new data shows that water is widely distributed across the surface of the Moon and not confined to a particular region or type of terrain.
The new research, which is the result of data analyzed from two lunar missions, could aid NASA scientists in understanding the origin of water on the Moon and if could be used as a resource.
If the Moon has accessible water, future explorers could potentially use it as drinking water or convert it to hydrogen and oxygen for rocket fuel or oxygen to breathe.
“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,” Joshua Bandfield, a senior research scientist with the Space Science Institute and lead author of the new study, said in a statement. “The presence of water doesn’t appear to depend on the composition of the surface, and the water sticks around.”
The researchers created a detailed model from measurements made by the Diviner instrument on NASA’s Lunar Reconnaissance Orbiter (LRO). They then applied the temperature model to data gathered earlier by the Moon Mineralogy Mapper—a visible and infrared spectrometer that NASA’s Jet Propulsion Laboratory provided for India’s Chandrayaan-1 orbiter.
The new findings suggest that widespread and relatively immobile water may be present primarily as hydroxyl—which does not remain on its own for long, either attacking molecules or attaching itself chemically to them. Hydroxyl would therefore have to be extracted from minerals in order to be used.
The researchers also suggest that any water present is not loosely attached to the surface.
“By putting some limits on how mobile the water or the OH on the surface is, we can help constrain how much water could reach the cold traps in the polar regions,” Michael Poston of the Southwest Research Institute, said in a statement.
While the current theory is that hydroxyl and/or water is created by the solar wind hitting the lunar surface, it is also possible that they come from the Moon itself, slowly released from deep inside minerals where it has been locked since the Moon was formed.
Sorting out what happens on the Moon could also help researchers understand the sources of water and its long-term storage on other rocky bodies throughout the solar system.
Previous studies have suggested that more water was detected at the Moon’s polar latitudes and that the strength of the water signal waxes and wanes in conjunction with the lunar day. Some researchers have proposed that water molecules can “hop” across the lunar surface until they enter extremely cold regions called cold traps in the dark reaches of craters near the north and south poles.
However, most of the evidence has come from remote-sensing instruments that measured the strength of sunlight reflected off the lunar surface. When water is present, instruments pick up a spectral fingerprint at wavelengths near three micrometers, which lies beyond visible light and in the realm of infrared radiation.
The surface of the Moon can also get hot enough to emit its own light, in the infrared region of the spectrum. The challenge is to disentangle this mixture of reflected and emitted light, which would require very accurate temperature information.