Chandrayaan-2 water discovery on Moon: Signs of water-ice found beneath the Moon's South Pole craters

India's Chandrayaan-2 mission has delivered a finding that could matter well beyond the boundaries of space science.

Researchers analysing radar data from the orbiter have found compelling evidence of water-ice sitting beneath the surface of craters near the Moon's South Pole, a region so cold and so permanently cut off from sunlight that it has long been considered one of the most promising places in the solar system to look for preserved ice. The discovery adds meaningful scientific weight to what has become one of the most consequential questions in modern lunar exploration: is there accessible water on the Moon, and where exactly is it?

The instrument behind the find

The data comes from the Dual Frequency Synthetic Aperture Radar, or DFSAR, a specialised imaging instrument aboard the Chandrayaan-2 orbiter. Designed to probe both the surface and subsurface of the Moon using microwave imaging, it operates across two frequency bands and holds the distinction of being the first fully polarimetric synthetic aperture radar to be deployed on a lunar mission.

Where researchers looked, and what they found

The study, carried out by scientists at the Physical Research Laboratory in Ahmedabad, focused on a specific, rarely examined category of terrain: craters nested within permanently shadowed regions near the lunar South Pole, referred to as doubly shadowed craters.

These are locations that receive no direct sunlight and are also shielded from indirect thermal radiation. Temperatures in these areas drop to around minus 248 degrees Celsius, close to 25 Kelvin. At those extremes, water-ice can survive for billions of years without sublimating.

Using radar polarimetric analysis, the team identified signatures beneath the floors of four such craters that are consistent with subsurface ice. A key part of the work involved developing a more reliable method to separate genuine ice signals from radar noise generated by rough, rocky surfaces, a problem that had complicated earlier research in this area.

The technique combines two radar measurements: Circular Polarization Ratio and Degree of Polarization. Readings where the former exceeds one and the latter falls below 0.13 point toward what scientists call volumetric scattering, a radar response linked to ice beneath the surface rather than rocks on top of it.

The strongest candidate

Among the four craters, one stood out. A small crater roughly 1.1 kilometres across, sitting inside the larger Faustini crater, showed the most persuasive combination of radar evidence and physical characteristics. Its rim carries what geologists describe as lobate features — flow-like formations that researchers believe may have been shaped when an ancient impact broke through an ice-bearing layer beneath the surface.

Why it matters

Water on the Moon is not just a scientific curiosity. For future long-duration missions, it represents a potential source of drinking water, oxygen, and, through chemical processing, rocket fuel. The ability to extract and use resources already present on the Moon, rather than transporting everything from Earth, is central to how space agencies are planning extended human presence beyond our planet.

The South Pole has drawn particular attention in recent years precisely because of these possibilities. India's Chandrayaan-3 mission made a successful landing near the polar region in 2023. These latest findings from Chandrayaan-2 deepen the scientific case for what that region may hold.

They also serve as a reminder of the orbiter's quiet persistence. The lander that accompanied Chandrayaan-2 was lost during its descent in 2019, but the orbiter has continued operating and producing research-grade data ever since, contributing steadily to a body of knowledge that extends well beyond India's own programme.