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New Delhi: Prime Minister Narendra Modi announced Wednesday that a DRDO anti-satellite missile (A-SAT) successfully shot down a satellite in low earth orbit. Low earth orbit is defined as an orbit at an altitude of 2,000 km or less.

This comes as a big milestone in India’s defence technological capability, as the country joins the US, Russia, and China in the A-SAT club.

The orbiting satellite was at a 300 km altitude, which is safe enough for the pieces to enter the atmosphere and burn up completely, avoiding space debris.

However, the timing of the announcement has drawn flak from critics, who say that the NDA government has politicised this military technology. There is also the question of whether India violated international treaties by performing this test.

What is A-SAT used for?

Anti-satellite technology is any weapon or tool that is developed to shoot down satellites in space. While multiple nations possess working technology and even more possess design and theoretical plans, A-SAT has never been used in an actual conflict.

The development of A-SAT weapons for militaristic purposes started during the Cold War. Early plans took several forms: Energy weapons such as regular intense lasers or X-ray lasers that could damage satellites, nuclear explosions in space, and more. But no country could actually demonstrate or realise these plans fully until August 1970.

That year, Soviet military scientists were tasked with developing an interceptor to strike a satellite target, which they managed to realise. The United States followed suit over 15 years later, when an F-15 launched a missile at a defunct satellite from mid-air in September 1985.

China notoriously conducted an A-SAT exercise 11 years ago, breaking up the Fengyun-1C weather satellite into several thousand pieces at an altitude of over 800 km, drawing criticism internationally for creating dangerous levels of space debris.

Nonetheless, A-SAT technology has been consistently touted as being used to bring down defunct, malfunctioning or dangerous satellites if needed. Satellites can also start to de-orbit, slowly losing altitude and threatening to break up in space or hit other orbiting craft.

Sometimes, a large satellite can pass through the atmosphere, breaking up into very large chunks that can potentially kill and damage on land. These require to be broken up in orbit — at a safe altitude — before entering the atmosphere to ensure they disintegrate completely and safely.

This continues to remain the primary practical use for A-SAT technology, in a world where access to the Earth’s orbit is becoming easier and building satellites is getting cheaper, for now.


Also read: India takes space leap, shoots down satellite 300 km away: Modi


How does A-SAT work?

A-SAT technology works on the basis of expelling a small, hard projectile, called the ‘kinetic kill vehicle’ into a satellite. The orbiting craft travels at such high speeds that something the size of a big pebble hitting it would instantly break it up into hundreds of pieces.

As the orbit of a satellite is predictable and its location known at any given point in time, developing an A-SAT weapon is far simpler than developing ballistic anti-missile technology.

Mission Shakti

Mission Shakti was a technological mission conducted by the DRDO from the Dr A.P.J. Abdul Kalam Island launch complex, off the coast of Odisha. The DRDO’s Ballistic Missile Defence (BMD) interceptor was used, which is part of the ongoing ballistic missile defence programme, the Ministry of External Affairs clarified in a statement.

Some defence portals reported that the weapon was a derivative of the Prithvi Defence Vehicle missile interceptor.

Discussions for A-SAT capability had begun at the DRDO back in 2007, after the infamous Chinese A-SAT exercise. India had, at the time, been testing the Agni-V and BMD systems that could destroy other missiles.

The then-DRDO chief, V.K. Saraswat, stated in an interview that India had all the building blocks capable of developing A-SAT technology, but hadn’t received approvals from the government.

“India does not believe in weaponisation of space. We are only talking about having the capability. There are no plans for offensive space capabilities,” he had said.

However, 10 years on, things are radically different. Space is becoming crowded — the number of satellites in low earth orbit has risen, and spy satellites are becoming more common.

“The future of satellite technology is to launch-on-demand satellites to low earth orbit,” explained Dinesh Kumar Yadavendra, distinguished fellow at the Ministry of Defence’s Centre for Joint Warfare Studies and former scientific adviser at the Headquarters of the Integrated Defence Staff.

“This means that, say, during times of war, a nation could launch multiple satellites to observe the movement of enemy troops. China already is equipped with this technology, where 50 to 70 satellites could be launched at a moment’s notice when needed. To protect ourselves, it is important to arm ourselves against such technology, even though we also need to develop the same in the long run.”

A satellite orbiting at 300km would pass over the same location about every 90 minutes. If used in conflict in a scenario similar to what Yadavendra describes, the A-SAT would be a part of what is known in military nomenclature as Quick Reaction Force (QRF).

Then there is the additional complication of one country’s satellite falling on the surface or in the waters of another. In such a situation, the government is required to compensate the other country. As India launches an increasing number of student and experimental satellites, which often do not function in orbit and either just stay there without purpose or start to deorbit, a need might arise to shoot them down to prevent a risky crash on the surface.

“It is important to remember that this was controlled, which means that we knew what would happen to the remnants of the explosion. All of the debris caused by Mission Shakti right now would come down over the next few weeks and burn up in the atmosphere safely.”

Which satellite was brought down?

Experts think that the satellite that was brought down was the MicroSat-R, which was launched in January on the PSLV-C44 mission.

“Since Mission Shakti was basically a DRDO effort, they couldn’t have shot down an ISRO satellite,” said Divyanshu Poddar, formerly of ISRO and founder of India’s first commercial model rocket company, Rocketeers.

“Microsat-R was a low-cost DRDO satellite roughly at the same orbital height as stated in Mission Shakti (300 km). Plus, it was launched fairly recently and the satellite specifications were quite bland, indicating that maybe it was designed to be a target for this mission.”


Also read: Modi govt pushes through A-SAT missile test that UPA had not permitted


India’s growing space strength

This mission adds to India’s powering up in the domain of space, following successful missions such as the Mars Orbiter Mission and the approval of the future Gaganyaan human spaceflight mission.

India is also a dominant nation when it comes to satellite and spacecraft missions — ISRO has undertaken over 100 missions, including different types of satellites such as earth observation, navigation, research, experimental, and student. India’s powerful satellites are an invisible presence in the everyday Indian life.

The impact on private industry and international reactions are yet to be seen. It is likely that several nations as well as private players will not take too kindly to this move, signifying what could be construed as an unnecessary escalation.

The question of timing

Commenting about the questionable pre-election timing of this test and its announcement, the MEA statement said: “The tests were done after we had acquired the required degree of confidence to ensure its success, and reflects the intention of the government to enhance India’s national security.”

The statement reiterated that India has no intention of entering in an arms race in outer space, and is against the weaponisation of outer space assets.

Did India violate international laws and conventions?

The 2007 Chinese A-SAT missile test saw a 750 kg satellite, then orbiting at 865 kilometres, break up into over 900 pieces, with the debris spreading across the altitude range of 200 km to 3,850 km — the entire gamut of the low earth orbit. These 900 pieces were only the ones that were big enough to be tracked — an estimated 35,000 pieces just larger than one centimetre had spread in space by the hundreds, posing a potential risk to any and every satellite in that whole swath of space.

The exercise greatly increased the risk of the entire debris cloud hitting the International Space Station, which orbits at 400 km and had multiple crew members on board, including Indian-American astronaut Sunita Williams.

India’s exercise was not even close to the scale of China’s, but it still does raise concerns among critics, one reason being the potential dangers posed by space debris.

Space debris operates exponentially. One piece of a debris cloud can hit another satellite, which can then create more debris, further propagating destruction. This cascading process is called Kessler’s Syndrome.

“Being a test, it probably did not affect the satellite of any other nation, and thus, is not an armed attack under the UN Charter which applies to outer space,” said Upasana Dasgupta, a doctoral candidate at the Institute of Air and Space Law, McGill University, Canada.

“However, it violates Article IX of the Outer Space Treaty, 1967, to which India is a party, and is bound by its provisions.”

The article reads: “In the exploration and use of outer space, including the moon and other celestial bodies, states parties to the Treaty shall be guided by the principle of co-operation and mutual assistance and shall conduct all their activities in outer space, including the moon and other celestial bodies, with due regard to the corresponding interests of all other states parties to the treaty.”

Dasgupta believes the test would have created debris which pose a risk to international orbiting objects, thus violating “corresponding interests” of other nations.

“Further, under the Liability Convention, 1972, if a space object collides with an aircraft or anything on the surface of earth, a nation is absolutely liable for the damages,” she added. “As we can all contemplate, the damages in these cases would be in millions of dollars.”

However, Yadavendra disagreed. “What China did was wrong, hitting a satellite at 800 km. That debris could remain in space for hundreds, even thousands of years. But at altitudes lower than 400 km, there is 100 per cent burn of all debris in a few weeks,” he said.

“There indeed continues to be debris in low earth orbit, because LEO satellites orbit at different altitudes while the threshold for burning is only 400 km and below.”

However, there have been exceptions to this rule. In the past, other hits to satellites have sent debris flying in unintended directions, causing the dangerous pieces to stay in space. In 2009, the American Operation Burnt Frost test saw a non-functioning satellite at 220 km hit and 174 pieces of debris identified. While most of it burned up over a few weeks, some pieces that were blasted into a higher orbit remained in space for nearly a year and a half.

It remains to be seen if the threat of space debris affects launches from the commercial sector.

The MEA statement, meanwhile, stated that India is not in violation of the Outer Space Treaty, which prohibits only weapons of mass destruction in outer space, not ordinary weapons.

This article has been updated with additional information on space debris.

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