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The Moon’s Interior Might Be Wet

ByWill SullivanNOVA NextNOVA Next

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Much of the moon’s interior may contain water, new research finds.

Scientists from Brown University found evidence of water from satellite imaging of the remains of volcanic eruptions across the surface of the natural satellite. Since this material was expelled from below the moon’s surface, this suggests that the water came from the moon’s mantle. And nearly all the volcanic, or pyroclastic, deposits studied contained evidence of water, suggesting that the water is spread out across the planet’s whole interior and is relatively plentiful.

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Evidence from ancient volcanic deposits suggests that lunar magma contained substantial amounts of water, bolstering the idea that the moon's interior is water-rich.

Here’s’s Samantha Mathewson talking to Ralph Milliken, the study’s lead author:

“Our work shows that nearly all of the large pyroclastic deposits also contain water, so this seems to be a common characteristic of magmas that come from the deep lunar interior,” Milliken said. “That is, most of the mantle of the moon may be ‘wet.’ ”

Scientists first began to suspect that the moon contained more than trace amounts of water back in 2011, when volcanic glass beads from the Apollo 15 and 17 missions were found to contain similar amounts of water to volcanic rock on Earth, suggesting that near the source of the Apollo samples, the moon’s interior contains as much water as Earth’s.

But the possibility remained that these samples were anomalous, and that the rest of the moon’s interior contained very little water. The fact that Milliken’s team, which published the research yesterday in

Nature Geosciences , was able to find water in so many places suggests that the Apollo beads are representative of the entire mantle.

What’s impressive about this research is that it detects the presence of water without even landing on the moon. Satellite equipment measured the wavelengths of sunlight reflected by the moon in order to determine the minerals and compounds contained on the surface.

This finding raises the question of the water’s origin. Scientists previously believed that the collision that formed the moon produced too much heat for water to survive. So either the collision wasn’t too hot, or something else must have brought the moon its water.

Photo Credit: Olga Prilipko Huber