Scientists analyzing data collected from Chandrayaan-2 have uncovered new signs that ice may exist beneath the Moon’s surface near its South Polar Region. The discovery comes from a detailed study conducted by researchers at Physical Research Laboratory using observations captured by the mission’s Dual Frequency Synthetic Aperture Radar system.
The study concentrated on permanently shadowed regions near the lunar south pole. These areas never receive sunlight and are considered some of the coldest locations in the entire solar system. Researchers paid special attention to smaller craters positioned inside larger permanently shadowed craters, which they referred to as “doubly shadowed craters,” according to a release issued by Indian Space Research Organisation.
Extremely cold conditions may preserve ice
Because these craters remain shielded from both sunlight and thermal radiation, temperatures there stay extremely low at nearly 25 Kelvin. Scientists believe such conditions are ideal for preserving water ice over extremely long periods of time.
A key part of the research relied on the Dual Frequency Synthetic Aperture Radar aboard the Chandrayaan-2 orbiter. The instrument, which operates using L and S band microwave frequencies, is the first fully polarimetric synthetic aperture radar developed specifically for lunar exploration.
Using the radar, scientists were able to look beneath the Moon’s surface and study how radar signals reflected back from subsurface layers.
Through advanced radar polarimetric analysis, researchers identified signal patterns that match what would be expected if subsurface ice deposits were present beneath the floors of four doubly shadowed craters in the lunar south polar region.
New radar method could improve ice detection
The research also proposes a more refined radar based approach for identifying underground ice deposits on the Moon.
According to the scientists, Circular Polarization Ratio values above 1 combined with Degree of Polarization values below 0.13 may point towards volumetric scattering caused by buried ice deposits.
The Degree of Polarization is a radar parameter that measures how much of the reflected signal maintains its original polarization after interacting with material on or below the surface. Researchers say this technique helps distinguish genuine ice signatures from reflections caused by rough rocky terrain.
Among the craters analysed during the study, one crater measuring around 1.1 kilometres across inside the larger Faustini crater stood out as the strongest candidate for containing subsurface ice.
Scientists said the conclusion was supported not only by radar data but also by the crater’s unusual lobate rim structure.
A lobate rim morphology refers to a rim shape that appears flow like or segmented into lobes. Researchers believe the crater may have formed when an impact penetrated an underground ice layer, creating the distinctive surface pattern visible today.
