In A First, Chandrayaan-2 Radar Study Finds New Evidence of Subsurface Ice Near Moon’s South Pole

Scientists analysing radar data from India’s Chandrayaan-2 mission have identified what may be some of the clearest signs yet of subsurface water-ice hidden beneath craters near the Moon’s south pole, strengthening hopes that frozen reserves could support future lunar missions.

The study, led by researchers from the Physical Research Laboratory (PRL) in Ahmedabad and published in NPJ, focused on unusual “doubly shadowed” craters buried within permanently shadowed regions (PSRs) of the lunar south pole. Shielded from both sunlight and reflected thermal radiation, these craters remain among the coldest known places in the solar system, with temperatures falling to nearly 25 Kelvin (-248C), making them prime locations for preserving ancient ice deposits.

Using observations from the Dual Frequency Synthetic Aperture Radar (DFSAR) aboard the Chandrayaan-2 orbiter, the team detected radar signatures that point to the possible presence of subsurface ice beneath four shadowed craters. The instrument, operating in L- and S-band microwave frequencies, is the first fully polarimetric radar sent to study the Moon and allows scientists to distinguish between rocky terrain and buried ice through subtle differences in reflected radar signals.

The researchers proposed a new radar-based method for identifying ice-bearing regions, combining high Circular Polarization Ratio (CPR) values with low Degree of Polarisation (DOP) measurements. According to the team, this combination is more consistent with volumetric scattering caused by buried ice than with reflections from rough rock surfaces, which have often complicated earlier lunar ice studies.

One crater inside the larger Faustini crater basin stood out in particular. The roughly 1.1km-wide depression showed both strong radar signatures and distinctive “lobate-rim” features — flow-like formations that researchers suggest may have formed when an impact struck ice-rich subsurface material. The crater’s morphology, together with its radar characteristics, has been interpreted as particularly compelling evidence of buried ice deposits.

The findings add to growing international interest in the Moon’s south polar region, which has become a focal point for future exploration because of its potential water resources. Water-ice on the Moon could eventually be converted into drinking water, breathable oxygen and rocket fuel, making it a strategically valuable resource for long-term human exploration.

India’s Chandrayaan programme has increasingly positioned itself within that global effort. While Chandrayaan-3 achieved a historic soft landing near the lunar south pole in 2023, the latest findings suggest that Chandrayaan-2 — despite its failed lander mission — continues to yield significant scientific returns through its orbiter payloads.

The research was carried out by Rishitosh K. Sinha, Rajiv R. Bharti, Kinsuk Acharyya, Sanjay K. Mishra, Neeraj Srivastava and Anil Bhardwaj.