ISRO-SAC instrument finds hydroxyl and water molecules on Moon

ISRO's homegrown instrument aboard Chandrayaan-2 detected the unambiguous presence of hydroxyl and water molecules on the Moon.

 ISRO-SAC instrument finds hydroxyl and water molecules on Moon

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• The story: The Indian Space Research Organisation’s (ISRO) homegrown instrument aboard Chandrayaan-2 detected the unambiguous presence of hydroxyl and water molecules on the Moon with the precision of differentiating between the two. The findings also suggests that the presence of these correlates with mineralogy and latitudinal location.
• Details: Imaging infrared spectrometer (IIRS), an imaging instrument that collects information from the electromagnetic spectrum for understanding the mineral composition of the lunar surface with each element possessing a ‘spectral signature’ unique to itself, was developed by Ahmedabad-based unit of Space Applications Centre (SAC) of ISRO. Capable of operating in the wavelength of 0.8 to 5 micrometre, the relatively broader range within which the indigenous instrument for water detection can image, is a first for IIRS capabilities on India’s second moon mission. The discovery is being hailed as critical for future planetary exploration and resource utilisation.
• Earlier mission: While the first Moon mission of Chandrayaan-1 in 2008 carried a similar instrument called Moon Mineralogy Mapper (commonly known as M3) capable of detecting water, the range of detection was lower — between 0.4 to 3 micrometre — and was also developed by NASA’s Jet Propulsion Laboratory and was not indigenous to ISRO.

1. The higher wavelength range of IIRS permits for better accuracy in results.
2. In September 2009, results published of the M3 instrument data had shown detection of absorption features on the polar regions of the surface of the moon “usually linked to hydroxyl- and/ or water-bearing molecules,” as NASA states.
3. Remote detection of water and/or hydroxyl signatures on the lunar surface is of significant importance as it provides clues to understand the various sources and water production mechanisms. Accurate detection of water and hydroxyl on the Moon in the three micrometre wave band region requires a thermal correction to reflected sunlight from Moon due to high daytime temperature…which contributes an additional thermal signal in the reflectance spectra.

• How formed: The most common and widespread process for the formation of hydroxyl and water on the Moon is considered to be due to interaction of solar winds with the lunar surface, a process termed as ‘space weathering’. Space weathering along with the impact from small meteorites often lead to chemical changes on the surface of the moon ultimately leading to formation of either the volatile and reactive hydroxyl molecules or the more stable form of water molecules.
• Chandrayaan-2: It was aimed to widen the scientific objectives of Chandrayaan-1 by way of soft landing on the Moon and deploying a rover to study the lunar surface, as ISRO states on its website. While the soft landing failed, thus losing the lander and rover and the associated five payloads, the orbiter which was carrying eight scientific payloads for mapping the lunar surface and to study the outer atmosphere of the Moon has successfully continued to send back crucial scientific data. The mission life of the Orbiter was planned to be of one year but has exceeded expectations and is expected to serve for seven years.

 

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