The Defence Research and Development Organisation (DRDO) has revealed additional details about the successful test-firing on 27 March of its first anti-satellite (ASAT) missile that destroyed one of the country’s own satellites in space

Briefing the media on 6 April, DRDO head G Satheesh Reddy stated that the 13 m-high, three-stage interceptor missile, which was fitted with two solid-propellant rocket motor stages and a hit-to-kill capable ‘Kill Vehicle’ (KV), was employed to target the satellite under ‘Mission Shakti’ (Strength).

He said the KV’s onboard advanced terminal guidance system, which featured a strap-down (non-gimballed) imaging infrared (IIR) seeker and an inertial navigation system that used ring-laser gyroscopes (RLGs), detected and tracked the 740 kg MICROSAT-R Earth observation satellite at an altitude of 283 km in low-Earth orbit (LEO).

The DRDO-designed satellite had been specially launched by the Indian Space Research Organisation (ISRO) two months earlier for the ASAT missile test, which had been under planning since 2016 and had also undergone numerous simulation trials.

Reddy explained that after the two rocket motor stages had taken the ASAT missile to the required height and velocity, the nose tip heat shield was ejected and the IIR seeker, located within the very front of the nose, locked onto the target satellite, guiding the KV towards it at a “closing speed” – the velocity of the target and KV combined – of 10 km per second.

Corrections to the KV’s flight were made using a thrust-vector control (TVC) system comprising larger thrusters at the top of the KV’s rear cylindrical body at roughly its centre of gravity and smaller thrusters near the rear of the KV. Although the DRDO showed videography of the tested TVC system used for the KV, it is not clear whether the thrusters are liquid or solid propellant-based, but they are most likely the latter.

Within seconds, the missile hit the satellite with a 10 cm accuracy, Reddy said, comparable with the “best reported performance of ASAT missiles”.

He said the radar, data, and communication links of the DRDO-designed ballistic missile defence (BMD) system that were deployed across a wide ground span had effectively tracked the entire satellite interception by the ASAT missile.

“The ASAT missile’s guidance and control algorithm was developed to intercept satellites [at an altitude of more than] 1,000 km, but the mission was planned at the lowest possible orbit of 283 km, well below the orbit of other space objects to avoid the threat of debris,” said Reddy.

The interception, he stated, was “specially designed” to strike the satellite at an angle so as to ensure “minimal debris”.

Reddy said the ISRO had “deliberately” launched the target satellite into an orbit under 300 km to ensure that it remained about 120 km below the International Space Station (ISS).

“Some of the debris has already decayed,” the DRDO head said in response to US officials from NASA, who have claimed that ‘Mission Shakti’ has raised the danger of 200–300 pieces of debris from the targeted satellite striking the ISS by about 44%.