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The findings, published in the journal npj Space Exploration on May 6, are based on observations from Chandrayaan-2’s Dual Frequency Synthetic Aperture Radar (DFSAR), a microwave imaging instrument capable of studying the lunar surface and subsurface using L-band and S-band radar frequencies.

The research led by Rishitosh K Sinha focused on rare “doubly shadowed craters” located inside permanently shadowed regions (PSRs) of the Moon. These areas never receive direct sunlight and remain extremely cold, with temperatures dropping to around 25 Kelvin, making them ideal locations for preserving water ice over geological timescales.

Using advanced radar polarimetric analysis, researchers identified radar signatures consistent with buried ice beneath the floors of four doubly shadowed craters in the lunar south polar region.

The team, also comprising Rajiv R Bharti, Kinsuk Acharyya, Sanjay K Mishra, Neeraj Srivastava, and Anil Bhardwaj, developed a refined radar-based method for detecting subsurface ice by combining two radar measurements: Circular Polarisation Ratio (CPR) values greater than 1 and Degree of Polarisation (DOP) values lower than 0.13. According to the scientists, this combination helps distinguish genuine ice-related radar signals from reflections caused by rough rocky terrain.

One of the strongest ice candidates identified in the study is a small 1.1-kilometre-wide crater located inside the larger Faustini crater near the lunar south pole. Researchers say the crater showed both strong radar signatures and unusual lobate-rim surface features, suggesting the impact penetrated buried ice layers beneath the surface.

The DFSAR instrument onboard Chandrayaan-2 is also significant because it became the first fully polarimetric synthetic aperture radar sent to study the Moon.

Scientists say the findings could play an important role in future lunar exploration missions by helping space agencies identify potential ice-rich regions for astronaut landings and in-situ resource utilisation (ISRU) activities.

Water ice on the Moon is considered one of the most valuable resources for future long-term lunar missions because it could potentially be converted into drinking water, breathable oxygen, and rocket fuel.

The discovery also adds to growing international interest in the Moon’s south pole, which has become a major target for upcoming missions from NASA, China, India, and other space agencies planning sustained lunar exploration.