Indian researchers team finds endogenous water on the Moon
A research team from the Space Applications Centre (SAC) of the Indian Space Research Organisation (ISRO) in Ahmedabad, led by Satadru Bhattacharya, has found evidence of water of volcanic origin water that has originated from deep within the Moons interior rather than water-bearing igneous surface lunar material detected hitherto by different lunar missions including Chandrayaan-1.
Thus far scientists had believed lunar rocks were bone dry and that any water detected in lunar samples was either due to contamination from the Earth or produced by solar wind and other exogenous extra-lunar sources. Significantly, the concentration of the water detected by Indian researchers 0.55 per cent by weight is the highest ever found on the Moon, according to Prakash Chauhan, a member of the team.
The finding is based on an analysis of high-resolution spectral data of the Compton-Belkovich Volcanic Complex (CBVC) region on the far side of the Moon obtained by the NASA instrument Moon Mineralogy Mapper (M3), which was sent aboard the Indian lunar mission Chandrayaan-1. Unlike the earlier detection of water and hydroxyl molecules in the polar region of the Moon by Chandrayaan-1 and other missions, CBVC is a non-polar region. A 2011 work on the geology of the CBVC region by B. L. Jolliff and others had found it to be highly rich in silica, which makes its geology totally different from that of the polar regions. The Indian finding has been reported in the latest on-line edition of the journal Current Science.
The Indian work comes close on the heels of a similar finding based on M3 data on the central peak of the volcanic crater Bullialdus, which was reported by R. Klima and associates in Nature Geoscience about a fortnight ago. Crater Bullialdus is in the equatorial region of the Moon and Klima and company had suggested that the water signatures observed could be of magmatic or volcanic origin as the non-polar Bullialdus crater region is an unfavourable environment for solar wind to produce significant amounts of water on the surface. The independent Indian work, which pertains to a different volcanic region altogether, too has led to the conclusion that water in the CBVC could have originated from episodic events of volcanic eruption and effusion of silicic magma. It thus has thus not only confirmed the presence of magmatic water but has also provided a quantitative estimate of it.
The presence of endogenous water/hydroxyl molecules was inferred from the distinct and prominent absorption lines in the 2800 nm wavelength region observed in spectra of the Compton-Berkovich Thorium Anomaly (CBTA) region of the complex. The CBTA region is an area of high concentration of radioactive thorium of about 5.3 microgram/gram while the surrounding areas contain only 0.06 microgram/gram of thorium. It has an area of 32 km x 18 km.
The work of Klima and others too had found an enhancement of concentration of elements such as Thorium in the central peak of Bullialdus. The two findings together suggest that all the endogenous hydrogen present at the time of formation of Moon did not boil off and remained trapped at the certain locations on the Moon associated with primary magmatic minerals such as thorium. The presence of such endogenous water could call for revision of models of Moons origin, points out Dr. Chauhan.
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Scientists detect magmatic water on Moon's surface
The detection of lunar water that originates deep within our satellites interior will help astronomers better understand its composition.
Scientists have detected magmatic water water that originates from deep within the Moons interior on the surface of the Moon. These findings represent the first such remote detection of this type of lunar water and were arrived at using data from NASAs Moon Mineralogy Mapper (M3).
The discovery represents an exciting contribution to the rapidly changing understanding of lunar water, said Rachel Klima from Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.
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 Klima. 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.
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 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.
In 2009, the M3, aboard the Indian Space Research Organizations Chandrayaan-1 spacecraft, fully imaged the lunar impact crater Bullialdus. Its within 25° latitude of the equator and so not in a favorable location for the solar wind to produce significant surface water, Klima said. 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.
After examining the M3 data, Klima and her colleagues found that the crater has significantly more hydroxyl a molecule consisting of one oxygen atom and one hydrogen atom compared to 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, Klima said.
The internal magmatic water provides information about the Moons volcanic processes and internal composition, Klima said. Understanding this internal composition helps us address questions about how the Moon formed and how magmatic processes changed as it cooled. 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 detection of internal water from orbit means that scientists can begin to test some of the findings from sample studies in a broader context, including regions that are far from where the Apollo sites are clustered on the near side of the Moon. Now we need to look elsewhere on the Moon and try to test our findings about the relationship between the incompatible trace elements, e.g., thorium and uranium, and the hydroxyl signature, Klima said. In some cases, this will involve accounting for the surface water that is likely produced by interactions with the solar wind, so it will require integration of data from many orbital missions.
This impressive research confirms earlier lab analyzes of Apollo samples and will help broaden our understanding of how this water originated and where it might exist in the lunar mantle, said Yvonne Pendleton from the NASA Lunar Science Institute.
Scientists detect magmatic water on Moon's surface | Astronomy.com