|A colour image of the Compton-Belkovich region taken from Chandrayaan-1
New Delhi, Sept. 7: Indian space scientists have detected signatures of water originating from deep within the lunar interior in a volcanic region of the moon at a concentration that they say is higher than hitherto observed anywhere on the lunar surface.
Scientists at the Space Applications Centre (SAC), Ahmedabad, studying images relayed by India’s Chandrayaan-1 spacecraft four years ago, have spotted spectral signatures of water molecules up to a concentration of 0.5 grams per 100 grams lunar rock.
The findings from SAC provide fresh evidence for magmatic water from the deep lunar interior on the moon’s surface reported two weeks ago by US-based scientists. Both research groups used an instrument called the Moon Mineralogy Mapper, or M3, on Chandrayaan-1, India’s first lunar orbiter launched in October 2008 that was lost nine months later due to instrument failures.
In 2009, Indian and American scientists had used M3 observations and discovered water molecules in polar regions of the moon. But the water observed then was believed to be a thin layer of surface water produced by particles from the sun striking the lunar surface.
In the new study, Satadru Bhattacharya and his colleagues at the SAC examined images of an area called the Compton-Belkovich volcanic complex located on the far side of the moon, a 32km by 18km region, and found spectral lines indicating water molecules.
“We’ve found evidence for an unusually large amount of water in a rather unique geological region away from any polar region,” Prakash Chauhan, a senior geophysicist at SAC and a team member told The Telegraph.
The Compton-Belkovich region is unusually rich in radioactive thorium and silica. The findings have appeared in the journal Current Science, published by the Indian Academy of Sciences.
The earlier concentrations of water observed on the lunar surface near the polar regions, Chauhan said, had values below 0.3 grams per 100 grams of lunar rock.
Planetary geologist Rachel Klima at the Applied Physics Laboratory at the Johns Hopkins University in the US and her colleagues had two weeks ago also reported the presence of magmatic water in a lunar impact crater named Bullialdus near the lunar equator. Their observations were reported last month in the journal, Nature Geoscience.
“This internal magmatic water provides clues about the moon’s volcanic processes and internal composition, which helps us address questions about how the moon formed and how magmatic processes changed as it cooled,” Klima said in a media release last month.
A US-based scientist who has studied the Compton-Belkovich area for more than a decade said the new findings from SAC are “exciting” as they may help explain an unusual example of extended magmatic activity on the moon.
“These results show that the moon still has surprises for us — as exemplified by the well-preserved silicic volcanic complex,” Brad Jolliff, professor of space sciences at the Washington University, St Louis, in the US, told this newspaper.
The discovery of evidence for magmatic water would compel planetary geologists to tweak current ideas about the formation of the moon. There is widespread agreement that the moon formed early in the history of the solar system when a Mars-like object collided with the Earth.
But such a collision would have raised temperature up to 7000 degrees causing all the hydrogen to boil away. “The discovery of magmatic water,” Chauhan said, “implies that all the hydrogen did not boil away but remain trapped at certain locations of the moon.”
Scientists believe the Compton-Belkovich area and the Bullialdus crater provide independent evidence for magmatic water from two widely separated sites on the lunar surface.
“Evidence from independent multiple sites helps raise confidence about such results,” Alberto Saal, associate professor at Brown University in the US told this newspaper. “The importance is to get a consensus on how much water the moon has.”