Scientists Detect Moon's Internal Water on Lunar Surface

Scientists have been aware that there's ice on the moon for some time. Now, though, they've discovered something else about the lunar surface. It turns out that there's magmatic water, which is water that originates from deep within the moon's interior, on the lunar surface.

In 2009, the M3 aboard the Indian Space Research Organization's Chandrayaan-1 spacecraft fully imaged the lunar impact crater Bullialdus. Located within 25 degrees latitude of the equator, this crater is not in a favorable location for the solar-wind to produce significant surface water. The rocks in the central peak of the crater are called norite, which usually crystallize when magma ascends but gets trapped underground instead of erupting at the surface as lava. By examining the data that M3 collected about this crater, the scientists made some surprising findings.

"For many years, researchers believed that the rocks form the moon were 'bone dry,' and that any water detected in the Apollo samples had to be contamination from Earth," said Rachel Klima, one of the researchers, in a news release. "About five years ago, new laboratory techniques used to investigate lunar samples revealed that the interior of the moon is not as dry as we previously thought. Around the same time, data from orbital spacecraft detected water on the lunar surface, which is thought to be a thin layer formed from solar wind hitting the lunar surface."

It turns out that the crater has significantly more hydroxyl, a molecule that consists of one oxygen atom and one hydrogen atom, than its surroundings. "The hydroxyl absorption features were consistent with hydroxyl bound to magmatic minerals that were excavated from depth by the impact that formed Bullialdus crater," said Klima. This finding could mean a better understanding of what lies beneath the lunar surface.

"Understanding this internal composition helps us address questions about how the moon formed, and how magmatic processes changed as it cooled," said Klima "There have been some measurements of internal water in lunar samples, but until now this form of native lunar water has not been detected from orbit."

The findings are published in the journal Nature Geoscience.