Water permeates the moon, somehow spills to surface
Findings published in the latest edition of Nature Geoscience reveal that water from deep within the Moon’s ancient interior has made its way to the surface.
The report marks the first time such remote detection of this type of lunar water has been achieved, made possible by NASA's Moon Mineralogy Mapper (M3). Planetary geologists say the discovery is an exciting contribution to the rapidly changing understanding of lunar water.
“For many years, researchers believed that the rocks from the Moon were ‘bone dry' and that any water detected in the Apollo samples had to be contamination from Earth,” said Rachel Klima, a member of the NASA Lunar Science Institute's (NLSI) Scientific and Exploration Potential of the Lunar Poles team.
“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,” Klima says.
“This surficial water unfortunately did not give us any information about the magmatic water that exists deeper within the lunar crust and mantle, but we were able to identify the rock types in and around Bullialdus crater,” said co-author Justin Hagerty, of the U.S. Geological Survey, “such studies can help us understand how the surficial water originated and where it might exist in the lunar mantle.”
The finding was only possible with the precise manoeuvring of the M3 aboard the Indian Space Research Organisation's Chandrayaan-1 spacecraft, which allowed it to fully image the lunar impact crater Bullialdus.
“The rocks in the central peak of the crater are of a type called norite that usually crystallizes when magma ascends but gets trapped underground instead of erupting at the surface as lava. Bullialdus crater is not the only location where this rock type is found, but the exposure of these rocks combined with a generally low regional water abundance enabled us to quantify the amount of internal water in these rocks,” Klima writes.
“This impressive research confirms earlier lab analyses of Apollo samples, and will help broaden our understanding of how this water originated and where it might exist in the lunar mantle,” said NLSI Director Yvonne Pendleton.
The study ‘Remote detection of magmatic water in Bullialdus Crater on the Moon’ is available online.