Widespread Moon Water Could Sustain Explorers and Even Fuel Rockets

Lunar explorers could potentially use water as a resource in the future. NASA's Goddard Space Flight Center

Scientists have discovered that water, or its relative hydroxyl, may be widely distributed across the surface of the moon—contradicting earlier research placing it mostly at the poles.

If moon water is widespread and easily accessible, explorers could use it for drinking water, oxygen or even rocket fuel.

"When you split water molecules, you end up with oxygen and hydrogen, critical components for breathable air and rocket fuel" explained Michael Poston, a Southwest Research Institute scientist and co-author of the research, in a statement.

The results were published in Nature Geoscience.

Earlier studies have suggested water was mostly present at the poles of the moon, and that water signals varied according to the lunar day (29.5 Earth days).

Some scientists thought water molecules "hopped" across the lunar surface until they reached regions so cold that water vapor could get trapped for billions of years. Craters near the moon's poles might house these "cold traps."

Scientists can probe the moon for water by analysing sunlight reflected off its surface. Remote-sensing instruments can detect a fingerprint for water in this light.

But the surface of the moon can become hot enough to emit its own light as well. Researchers must tease apart these signals to refine their water estimates.

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The team behind this latest project created a lunar temperature model to do just that. They built a model using data from NASA's Lunar Reconnaissance Orbiter, and applied it to spectrometry results gathered by the Chandrayaan-1 orbiter's Moon Mineralogy Mapper.

"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 Boulder, Colorado, and lead author of the study, in a NASA statement. "The presence of water doesn't appear to depend on the composition of the surface, and the water sticks around."

Hopping or sticking?

Instead of mostly hopping to the cold traps of the poles, water seems to persist across the moon. This immobility suggests it may primarily exist in the form of hydroxyl (OH).

Unfortunately for lunar explorers, hydroxyl is less ideal than the more familiar H2O.

"Hydroxyl is a more reactive relative to water and not as attractive as water in terms of supporting a lunar station," said Poston.

Hydroxyl is more ready to attack molecules or stick to them than H2O. This means explorers would need to extract the substance from minerals to actually use it.

Any H2O that is present on the moon would be steady and perhaps even static.

"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," said Poston in the NASA statement.

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Scientists now need to figure out whether they have found water, hydroxyl, or both—and how these chemicals got there.

"The next step is to determine whether it's water, hydroxyl, or a mixture of the two—and where it came from," Poston said. "Is it from external sources, delivered by comet or asteroid impacts? Is it from internal processes on the Moon itself, such as ancient volcanism? Or could it be an ongoing process of the solar wind reacting with lunar materials to create OH or H2O?"