Ahmedabad: Scientists from the Ahmedabad-based Physical Research Laboratory on Wednesday identified strong evidence of subsurface ice in some of the coldest craters near the Moon’s south pole using data from Chandrayaan-2, the Indian Space Research Organisation (ISRO) said in a release. The observations were made by the Dual Frequency Synthetic Aperture Radar (DFSAR) onboard the Chandrayaan-2 orbiter.
Notably, the DFSAR is a microwave imaging instrument capable of probing beneath the Moon’s surface. The study concentarted on “doubly shadowed craters,” which are special craters located inside permanently shadowed regions (PSRs) of the Moon.
“Due to continuous shielding from sunlight and thermal radiation, these regions remain extremely cold (temperatures ~25K) and are considered favorable locations for preserving water-ice over long geological timescales,” the ISRO said in a press release.
Scientists managed to identify radar signatures consistent with the possible presence of subsurface ice beneath the floors of four doubly shadowed craters in the lunar South Polar Region.” The study proposes a refined radar-based criterion for identifying subsurface ice, where Circular Polarization Ratio (CPR) values greater than 1 together with Degree of Polarization (DOP) values lower than 0.13 indicate volumetric scattering potentially associated with subsurface ice,” the ISRO stated.
Notably, DOP is a radar polarimetric parameter that measures how much of the reflected radar signal retains its original polarisation state after interacting with the surface or subsurface material.
Among the investigated craters, one crater of 1.1 km diameter within Faustini crater shows particularly strong evidence of subsurface ice near the Moon’s south pole. It was supported by both radar observations. Meanwhile, there is also distinctive lobate-rim morphological characteristics. A lobate-rim morphology refers to flow-like or lobed appearance, suggesting the impact may have penetrated subsurface ice, producing the observed lobate-rim crater.
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“These findings provide important new insights into the distribution of lunar polar volatiles and have significant implications for future lunar exploration missions, including identification of potential ice-bearing regions for future landing and in-situ resource utilization (ISRU) activities,” the ISRO said.
