BENGALURU: The search for water-ice on the Moon could take a significant step forward with new findings from Chandrayaan-3’s Chandra’s Surface Thermophysical Experiment (ChaSTE). The experiment, conducted by the Vikram lander, has provided unprecedented in-situ temperature measurements from a high-latitude lunar regolith (soil), shedding new light on the Moon’s thermal environment and the potential for water-ice deposits.
“Water-ice prospecting is a crucial step in unlocking the Moon’s potential for supporting human habitat and furthering exploration. Lunar temperatures not only dictate water-ice, but also drive other aspects of science and exploration,” K Durga Prasad from Isro’s Physical Research Laboratory (PRL), told TOI.
The new findings from the team, including Prasad, Chandan Kumar, Ambily G, Kalyana Reddy P, Sanjeev K Mishra, Janmejay Kumar, Dinakar Prasad Vajja, Aasik, Tinkal Ladiya, Arpit Patel, Murty SVS, Amitabh and PRL director Anil Bharadwaj, have been published in the journal Nature Communications Earth & Environment. The research led by the PRL team comprises people from multiple Isro centres.
ChaSTE measured surface temperatures of up to 355K (82°C) at the lunar south pole region — 25K higher than the expected 330K. Scientists attribute this increase to the lander’s placement on a sunward-facing local slope of 6°.
“This discovery highlights how small-scale topographical variations at high latitudes can significantly alter surface temperatures, a phenomenon less pronounced in equatorial regions,” Prasad said.
He pointed out that prior to the Chandrayaan-3 mission, global lunar temperatures were mapped through remote sensing, but direct in-situ measurements were limited to the Apollo 15 and 17 missions, which primarily focused on equatorial regions. ChaSTE’s new data bridges this critical knowledge gap, offering insights into the Moon’s thermal behaviour at high latitudes.
Stable conditions for Water-Ice
Using numerical models based on ChaSTE’s observations, the team suggests that larger poleward-facing slopes exceeding 14° may provide stable conditions for water-ice deposits. These areas receive less solar radiation and thus maintain lower temperatures, making them more viable for future lunar exploration and potential human habitation.
“Unlike the extreme polar regions, these sites offer a technically less challenging yet scientifically valuable alternative for resource prospecting… Understanding lunar thermophysics is essential for multiple reasons, including mission safety, resource exploration, and long-term habitat establishment,” Prasad said.
The low thermal conductivity of the lunar regolith acts as a blanket, causing significant temperature variations within just a few centimetres of the surface. “By measuring these temperature gradients, ChaSTE has not only refined our understanding of lunar surface conductivity but has also provided crucial data for future missions seeking sustainable exploration solutions,” he said.
As space agencies around the world set their sights on the Moon for long-term missions, findings from ChaSTE reinforce the importance of selecting optimal landing and resource extraction sites. These discoveries could play a vital role in shaping future lunar colonisation efforts and the potential extraction of vital resources, such as water-ice, to support human exploration beyond Earth.
The data from Chandrayaan-3’s ChaSTE experiment will continue to be analysed, with further insights expected in upcoming research publications.
It is noteworthy that India’s Chandrayaan-1 was the first mission to identify water molecules on the lunar surface and is, in many ways, responsible for the renewed global interest in countries returning to the Moon. Finding water on the Moon has been one of the most common endeavours of several lunar missions in the recent past.
