Opinion: To Tackle Space Debris, ISRO’s “Swachh Antriksh Abhiyan”

Space may be the last frontier, but surprise, surprise, there is both pollution and congestion in outer space. Yes, all human-made. A 2023 assessment by the Indian Space Research Organization (ISRO) finds there are 27,000 catalogued space objects, of which 80 per cent is space debris.

“There are millions of space objects less than 10 cm in size that are uncatalogued and pose a very dangerous situation for space assets,” says S Somanath, ISRO chairman.

Another threat of space debris comes from anti-satellite tests, and such weapons capability exists only with China, US, India and Russia. 

The picturesque and flawless launch of India’s workhorse rocket PSLV or Polar Satellite Launch Vehicle on the morning of July 30 had its own share of pre-launch drama.

“There was traffic congestion in space above Sriharikota and the launch was postponed by one minute,” confirms the ISRO chief. It was scheduled for 6.30 AM but the rocket finally lifted off at 6.31 AM. Technically, it is described as “space conjunction at the 500 km plus orbit which is densely packed with satellites”.

In addition the “Made in India, Made for Singapore” launch of July 30 also saw India conducting for the first time a unique orbit lowering experiment for the spent stage of the PSLV rocket. The fourth stage of the PSLV, which was orbiting at 536 km above earth, was on purpose lowered to a 300 km orbit with the help of specific manoeuvres (there were two). Somanath says, “This was part of ISRO’s voluntary ‘Swachh Antriksh Abhiyan’ or the keep space clean endeavor to reduce space debris”.

According to him, the 500 km low earth orbit is a highly valued orbit, and it was voluntarily vacated by ISRO in the spirit of “vasudhaiva kutumbakam’ – as applied to space. Incidentally, by reducing the orbit to 300 km, the wasted 4th stage of PSLV will reenter Earth and burn out in 30 days, as compared to the 18 years it may have lasted in the higher orbit.

A quick disposal of solid waste in space.

India also safely deorbited the defunct Meghatropiques satellite. Occasionally, space junk shows up on beaches, as it did in Australia.  

Using sophisticated radar, optical instruments and orbiting satellites, the US Space Command estimates there 26,783 space objects of 10 cm or larger and millions of smaller objects like peeled off paint flecks etc.

Almost 40% of the space objects belong to the US; about 28% belong to Russia and former USSR; another 19% belong to China, says ISRO in its Space Situational Assessment Report’ released in March.

In contrast, India has contributed just 217 space objects – a mere 0.8% of the global space debris.

India’s stewardship of keeping the space environment free of solid waste pollution has been highlighted by Union Science Minister Jitendra Singh. “ISRO has been taking necessary measures to safeguard all its space assets from intentional and accidental close approaches by space objects including operational spacecraft and space debris objects,” said Mr Singh. He added that space situational awareness activities have many strategic implications.

These include identifying and monitoring other operational spacecraft with close approaches, having an overpass over the Indian region, intentional manoeuvres with suspicious motives and reentry within the Indian region, he said.

At last count, ISRO had 52 operational satellites in orbit. Six defunct satellites and 105 pieces of space debris (rocket bodies and fragments) from India are still in orbit, says Somanath. In all, India has launched 130 satellites – 73 in low earth orbit (LEO) and 54 in geostationary orbit (GEO). There is one in the Mars orbit, Mangalyaan; three satellites are in the moon orbit as part of the Chandrayaan series. Since the launch of the Aryabhatta satellite in 1975, India has satellites touching almost every facet of daily life in India, from weather forecasting to television communication to powering India’s vast digital infrastructure. Somanath says as of now, India has no evidence of any recorded Indian space asset losses due to collisions. But India did lose the INSAT 2D and GSAT-6A satellites in mysterious circumstances.

It is estimated that with over 50 functional satellites, India’s space assets are worth over Rs 50,000 crore and need full protection, since in a way, India’s economy has become dependent on these critical birds in the sky.

With the ‘ISRO System for Safe and Sustainable Space Operations Management’ (IS4OM) set up last year, the space agency regularly analyses data to predict approaches of other space objects close to Indian space assets. In 2022, in-house Space Object Proximity Analysis (SOPA) generated about 14,000 alerts for close approaches within 1 km. Additionally about 13,000 close approach alerts were received from the US Space Command. These were reassessed using more accurate orbital data of India’s operational satellites.

Critical close approaches require a Collision Avoidance Maneuver (CAM) to safeguard operational spacecraft. A total of 22 CAMs were executed in 2022, including one for the lunar orbit. The risk is palpable. Anil Kumar A K, head of IS4OM that issues these alerts, says, “ISRO strives for containing the threats from manmade space debris.” India operates a multi object tracking radar at Sriharikota that can track objects up to an 800 km altitude; a more powerful version is also cooking.

Space start-up Digantara Aerospace, incubated by the Indian Institute of Science Bengaluru, calls itself a new space cartographer. Its founder Rahul Rawat says they hope to create a version of ‘Google Map’ for outer space that will help space agencies navigate the traffic mess. It may be called the Digantara map of the solar system.

The ISRO report asserts: “It may be noted that two catastrophic collisions which have contributed to sudden unprecedented increase of Low Earth Orbit (LEO) population are the Chinese Anti-Satellite Test (ASAT) in 2007 at an altitude of 865 km and the collision of Iridium 33, an operational satellite with the derelict satellite COSMOS 2251 at 780 km altitude. Till date, these are the major contributors to space debris by a single event. Nearly 550 objects are still orbit from Russian ASAT conducted at 450 km altitude on 21st November, 2021. It is estimated that some of the objects from this ASAT have very long orbital life.”

In 2019, India conducted an anti-satellite weapons test codenamed “Shakti”, where its own satellite Microsat-R was shot down by an Indian missile at an altitude well below 300 km. It was estimated that more than 100 pieces of space debris were created and, per reliable estimates, the last of the Shakti debris decayed on 14 June 2022. Officials from the Defense Research and Development Organization (DRDO) said India conducted its ASAT test in a highly responsible manner, so the debris burnt out.

A bigger and much more insidious threat to future space assets is the massive web of small satellite constellations being created today. Leading the pack is Space X, the private space company owned by Elon Musk, which plans to build a constellation of 12,000 small satellites as part of the Starlink venture, and later wants to add another 30,000 satellites in the second generation.

Somanath says, “Ever since the inception of the Indian space program, space-based assets have played a pivotal role in nation-building by providing crucial services in the field of communication, weather and resource-monitoring, navigation, etc. However, the ever-growing space object population including that of operational satellites and orbital debris and the associated collision risks pose a serious threat to the safe and sustainable use of outer space.”

The increasing congestion of earth’s orbits, he said, posed a looming threat of collisions among larger debris that could trigger a self-sustained cascading process of further collisions, known as the Kessler syndrome. “This could result in a drastic increase in the density of space debris, rendering outer space inaccessible for future generations,” said the ISRO chief.

ISRO’s “Swachh Antriksh Abhiyan” is a step towards safe and sustainable utilization of outer space. 

(Pallava Bagla is co-author of book ‘Reaching for the Stars, India’s Journey to Moon, Mars and, Beyond’ published by Bloomsbury) 

Disclaimer: These are the personal opinions of the author.