In a development that could take us close to quantifying water content on the lunar surface, an instrument aboard Chandrayaan-2, launched by the Indian Space Research Organisation (ISRO) in 2019, has managed to pick up signals of all major water-bearing molecules on the Moon, according to a paper to be published by Indian scientists in Current Science on Tuesday.
Chandrayaan-2’s predecessor Chandrayaan-1, launched in 2008, was among the lunar craft that conclusively picked up signatures of water on the Earth’s only natural satellite.
This was possible because of Moon Minerology Mapper (M3), an imaging spectrometer developed by NASA’s Jet Propulsion Laboratory, flown on Chandrayaan-1.
M3 found that hydroxyl and water (OH/H2O) molecules are widely distributed in the Moon’s polar regions and in some isolated places in the equatorial regions.
Lunar orbiter intact
However, due to a limitation in M3 mapping ability, the scientists were unable to map out all water-bearing molecules on the Moon. Subsequently, scientists at ISRO’s Space Applications Centre (SAC), in Ahmedabad, designed a superior instrument called Imaging Infrared Spectrometer (IIRS), which was capable of overcoming this shortcoming and used it on Chandrayaan-2 launched in July 2019.
Though this lunar mission was a partial failure, as a lander, which was part of the mission failed to land on the Moon smoothly making it dysfunctional, the lunar orbiter is still intact and continues to send images of the lunar surface.
The latest paper to which researchers from two ISRO institutions – Indian Institute of Remote Sensing (IIRS) Dehradun and SAC – contributed mainly showed how early results from analysing data from the more sophisticated spectrometer aboard Chandrayaan-2 managed to get a better picture of the water content on the Moon.
The scientists used a physics-based thermal correction to offset the reflectance from the lunar surface, which has high daytime temperature.
“The new data, along with the method used by IIRS for the thermal correction, will lead to improved quantitative estimates of water content on the Moon,” Prakash Chauhan, the Director of the Dehradun-based IIRS, who is the corresponding author of the Current Science paper, told BusinessLine .
Data awaited
He said they have been able to quantify the water content on the lunar surface, and found that it could be up to 800 parts per million at multiple locations, even beyond polar regions that have reasonably high water content.
“As more data from the mission will be available in future, we will be able to learn more about OH and H2O production and hydration processes on the Moon,” said Chauhan.