BENGALURU: Scientists from Isro’s Space Applications Center (SAC) have identified a promising landing zone in the rugged south polar region of the Moon for India’s first lunar sample return mission, Chandrayaan-4. A detailed terrain study using images from the Chandrayaan-2 Orbiter High Resolution Camera (OHRC) has shortlisted a one-square-kilometre patch near Mons Mouton as the safest option for touchdown. The study, carried out by Amitabh, K Suresh, Ajay K Prashar, Kannan V Iyer, Abdul S, Shweta Verma Trivedi and Nitant Dube, has been accessed by TOI.Chandrayaan-4 will be ISRO’s most complex lunar mission. The spacecraft will include a propulsion module, a descender module, an ascender module, a transfer module and a re-entry module. The descender and ascender stack must soft-land on the Moon, collect samples and launch them back to lunar orbit for return to Earth.Selecting the right site is crucial. Engineers must ensure gentle local slopes, adequate sunlight for at least 11-12 days, clear radio visibility to Earth, and minimal hazards such as craters and boulders. The lander design limits the acceptable slope to about 10° and requires boulders smaller than 0.32 meters.Earlier assessments based on coarser data had highlighted several candidate areas between 84° and 90° south latitude. The new work focused on five zones around Mons Mouton, analyzing them with sharper OHRC stereo images at 32-centimetre resolution. One site was discarded because it lay in permanent shadow.Researchers generated digital elevation models at a fine grid of 0.32 meters and studied terrain undulations, illumination patterns and hazard distribution. Four locations, labeled MM-1, MM-3, MM-4 and MM-5, were compared on parameters such as mean slope, height range and the number of safe landing grids of 24 by 24 meters.Among them, the MM-4 area — at latitude minus 84.289° and longitude 32.808° — emerged as the front-runner. It showed the lowest hazard level at 9.89%, an average slope of 5° and the highest count of 568 safe grids. The region also offered favorable illumination and limited shadowing from nearby terrain.Other sites carried higher risks. MM-1 and MM-3 recorded hazard levels above 12%, while MM-5 provided only 72 safe grids within the target area. Elevations across the sites ranged from 4,800 to over 6,100 metres, reflecting the broken topography of the lunar south pole.Scientists say the analysis demonstrates how high-resolution imaging can guide precise landing decisions. The OHRC data allowed them to map craters, boulders and slopes with a clarity not available during earlier missions.If approved by the landing site selection committee, the MM-4 patch will host India’s first attempt to bring back pieces of the Moon. Success would place Isro among a small group of space agencies capable of returning extraterrestrial samples, opening a new chapter in the country’s planetary exploration programme.
