Scientists from NASA's Jet Propulsion Laboratory in Pasadena, California, and the Indian Space Research Organisation's Space Applications Centre in Ahmedabad announced Thursday a landmark joint discovery: compelling radar evidence of a liquid water reservoir roughly 1.4 kilometres beneath the Tharsis volcanic plateau on Mars. The finding, published simultaneously in the journals Science and Nature Astronomy, represents the most geographically precise and independently corroborated detection of subsurface liquid water ever reported on the Red Planet.

The discovery emerged from a two-year collaborative analysis combining SHARAD radar sounder data aboard NASA's Mars Reconnaissance Orbiter with subsurface sounding measurements collected by India's Mars Orbiter Mission 2, which has been operational since its insertion into Martian orbit in late 2024. Researchers identified a high-reflectivity anomaly approximately 180 kilometres in diameter, consistent with a brine lake kept liquid by residual geothermal heat from the still-volcanically active Tharsis region. Dr. Sunita Vyas, lead investigator at ISRO's Space Applications Centre, described the signal as 'unambiguous by every metric we applied.'

'What distinguishes this detection from earlier, contested findings near the south polar layered deposits is the thermal environment,' said Dr. Michael Sori of Purdue University's Department of Earth, Atmospheric, and Planetary Sciences, an independent reviewer of the study. 'Tharsis retains enough internal heat that liquid brines are thermodynamically plausible without requiring exotic antifreeze chemistry. This location makes the find far more credible.' Previous claims of subsurface water near Mars' south pole, reported by the European Space Agency's MARSIS instrument in 2018 and subsequent studies, had been challenged over whether temperatures in that region could sustain liquid water.

The announcement immediately intensified discussions within the astrobiology community and at NASA headquarters in Washington, D.C., where agency administrator Bill Nelson called the discovery 'a turning point in the human understanding of where life in our solar system may be possible.' ESA representatives in Paris welcomed the findings and indicated that the upcoming ExoMars Rosalind Franklin rover mission, scheduled for landing in 2029, may have its scientific objectives expanded in light of the new data. China's National Space Administration also issued a statement noting that the findings would inform payload selections for its planned Tianwen-3 sample-return mission.

Civil society groups focused on planetary protection raised immediate concerns, urging NASA, ISRO, and the Committee on Space Research to convene an emergency working group before any future missions target the Tharsis region. 'If there is liquid water, there may be extant microbial life,' said Dr. Kennda Lynch of the Lunar and Planetary Institute in Houston, a leading planetary protection advocate. 'We have international obligations under the Outer Space Treaty to proceed with extreme caution.' Both NASA and ISRO confirmed they would submit the discovery for review by COSPAR's Planetary Protection Panel before any follow-on mission proposals are formally drafted.