Chandrayaan-2 orbiter finds water on lunar surface – Times of India

NEW DELHI: Though Chandrayaan-2 mission lander hard-landed on the lunar surface in 2019, its orbiter is doing wonders as one of the eight key scientific instruments on board it has detected the “unambiguous presence of hydroxyl and water molecules” on the lunar surface. The findings will certainly give a heads-up to Isro as it is scheduled to launch its next lander-specific lunar mission Chandrayaan-3 in 2022.
Indian researchers used the data obtained by the orbiter’s imaging infrared spectrometer (IIRS), meant to collect information from the Moon’s electromagnetic spectrum, to understand the lunar mineral composition. Three strips on the Moon’s surface were analysed by an IIRS sensor for hydration presence.
“The initial data analysis from IIRS clearly demonstrates the presence of widespread lunar hydration and unambiguous detection of OH and H2O signatures on the Moon between 29 degrees north and 62 degrees north latitude,” said the findings of Indian researchers that were recently published in Current Science journal. Plagioclase-rich rocks have been found to have higher OH or possibly H2O molecules when compared to mare regions, which were found to have more dominance of OH at higher surface temperature, it said.
The study, authored by scientists, including former Isro chairman A S Kiran Kumar, from Indian Institute of Remote Sensing (IIRS), Dehradun, Ahmedabad-based Space Applications Centre, Bengaluru-based U R Rao Satellite Centre and the Isro headquarters, says the discovery is “significant for future planetary exploration for resource utilisation”, as several international missions, both manned and unmanned, to the Moon are lined up in the next few years.
India’s first moon mission Chandrayaan-1, launched in 2008, had first confirmed the presence of water when an instrument on board it — Moon Mineralogy Mapper or M3— belonging to Nasa’s JPL, first detected widely distributed hydration signatures across the Moon using 3 µm spectral response. However, due to limited spectral coverage of M3 (only up to 3 µm), the exact nature of the hydration signatures could not be ascertained. This made discrimination between OH and H2O detection difficult, said the report. But IIRS on-board Chandrayaan-2, which was launched on 22 July 2019, is not only indigenous but has also been designed to measure lunar reflected and emitted solar radiation in 0.8–5.0 µm spectral range. Its high spatial resolution (~80 m) and extended spectral range is most suitable to completely characterise lunar hydration (2.8–3.5 µm region) attributed to the presence of OH and H2O.
The report from the data also observed that the brighter sunlit highland regions at higher latitudes of the Moon were found to have higher hydroxyl or possibly water molecules, that is enhanced hydration, compared to the large basaltic plain regions where hydroxyl appeared to be dominant, especially at higher surface temperature.
The thermal stability of these hydration features depends upon how they interact with one another, with the surface and their environment at particular temperature range and therefore provides important clues about their origin and evolution, the research paper said.

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