Shooting A Satellite Is Incredibly Hard, And Why India's Mission Shakti Is So Very Impressive

Today, Prime Minister Narendra Modi had a major announcement to make. In a successful test, India managed to shoot down a Low-Earth Orbit (LEO) satellite.

This, he says, makes our country a space superpower, the fourth of its kind in the world.

Before this, only three other countries have developed the ability to target satellites with munitions; the US, Russia, and China. So if that's such a small group to achieve the feat, just how complex is the task?

The anti-satellite (ASAT) payload uses India's Agni-V missile to deliver. We'd first successfully tested this missile back in 2012. At the time, it was an intercontinental ballistic missile with an effective range of about 5,500km. To travel, it had to ascend about 600km before re-entering the atmosphere along its trajectory. Since most military satellites orbit at a range of about 2,000km, it clearly already had the physical capability to perform this feat.

The 50-tonne missile is composed of a two-stage rocket, with a third stage being a booster developed by the DRDO attached to the warhead itself. With 2012's Agni V, that boosted the missile to a whopping Mach 20 in its terminal stage. And since it was meant to be a ballistic missile defence system, it needed accurate navigation to intercept enemy warheads.

For this, the DRDO indigenously developed and installed ring laser gyros to control orientation, and an accelerometer to measure the acceleration. It also had its own navigation system, an onboard backup navigation redundancy, and fault tolerance software.

At the time, the DRDO had no sensors on the missile itself, instead requiring ship and land-based tracking systems, as well as radar and telemetry systems. It's unclear just how the defence ministry has managed to overcome this in the hypothetical instance the missile needs to be launched into space.

As for targeting satellites, the tracking there is somewhat simpler. For the former Ballistic Missile Defense (BMD) system, it was designed to track and have the missile intercept a 0.1 square meter target over 1,000 km away. A satellite is orders of magnitude larger and has less maneuverability. Additionally, satellites can be fairly easily tracked from Earth and, once their position and orbit have been identified, you can predict their flight path to the millisecond.

There are other factors to consider however, when targeting another country¡¯s satellite. For one thing, Earth¡¯s orbit is full of debris from old satellites and rockets that a missile would have to avoid. It¡¯s not possible to even manually steer a ballistic missile at the speed it would travel, especially since it would have to move incredibly fast to avoid countermeasures. So they need to rely on space junk mapping data from organizations like the North American Aerospace Defense Command (NORAD). However, in a hypothetical situation where ASATs are launched as part of a brewing war, that would probably be problematic to obtain.

Additionally, the missile¡¯s tracking needs to be 100 percent accurate in order to hit the right target. After all, it does no one any good to accidentally end up hitting a private company¡¯s satellite or, worse, a crewed space station.

The only thing this missile needed to become lethal in space was the ability to give the kill vehicle the ability to home in on a satellite as it would an enemy missile. For that, it already had infrared and radar frequency receivers. Additionally, the DRDO needed to improve their Long Range Tracking Radar (LRTR) previously in use. The communications systems to give orders to the missile meanwhile were already in place.

In this particular test, it was confirmed that the satellite destroyed was an unused Indian orbiter about 300km above the Earth's surface, so it's unclear just what the outer range of the ASAT missile is. It's still a huge milestone for India, putting among the foremost world powers in space.