New radars and optical telescopes under NETRA project being deployed

With space junk posing increasing threat to Indian assets in space, the Indian Space Research Organisation (ISRO) is building up its orbital debris tracking capability by deploying new radars and optical telescopes under the Network for Space Objects Tracking and Analysis (NETRA) project.

A space debris tracking radar with a range of 1,500 km and an optical telescope will be inducted as part of establishing an effective surveillance and tracking network under NETRA, ISRO chairman S. Somanath told The Hindu. The government has given the go-ahead for the deployment of the radar, which will be capable of detecting and tracking objects 10 cm and above in size. It will be indigenously designed and built, he said.

Radars and optical telescopes are vital ground-based facilities for keeping an eye on space objects, including orbital junk. ''We plan to have two such radars deployed 1,000 km apart for spatial diversity. At present, we have a Multi Object Tracking Radar at Sriharikota range, but it has a limited range. To protect our space assets, we need to augment our capabilities,'' Mr. Somanath said.

Data released by the ISRO last week point to an increasingly grim scenario. For protecting its space assets, the ISRO was forced to perform 19 collision avoidance manoeuvres (CAM) in 2021, of which 14 were in Low Earth Orbit (LEO) and five in the geostationary orbit, according to ISRO's Space Situational Assessment for the year. The number of CAMs jumped from just three in 2015 to 12 in 2020 and 19 in 2021.

Last year, the space agency monitored 4,382 events in LEO and 3,148 events in the geostationary orbit where space objects closely approached Indian assets. Fragments from the Fengyun-1C satellite (part of the anti-satellite test (ASAT) by China in 2007) and the Cosmos 2251-Iridium satellite collision in 2009 accounted for the maximum number of these threats. The observations also covered 84 ‘‘close approaches of less than one km’‘ between Starlink satellites and Indian assets.

Space junk or debris consist of spent rocket stages, dead satellites, fragments of space objects and debris resulting from ASAT. Hurtling at an average speed of 27,000 kmph in LEO, these objects pose a very real threat as collisions involving even centimetre-sized fragments can be lethal to satellites. ISRO's efforts towards space situational awareness (SSA) is coordinated by the SSA Control Centre in Bengaluru and managed by the Directorate of Space Situational Awareness and Management at the ISRO headquarters.

ISRO officials say the volume of debris is likely to go up in the coming years with the increase in space missions globally. Globally, 2021 saw the highest space object-to-launch ratio, the ISRO report noted. ''In other words, more space objects are placed in orbit per launch. In 2020, 522 objects were placed in space with 102 launches compared to 1,860 objects in 135 launches in 2021,'' it said.