Explainer: ISRO’s mission possible: Debris-free space

The Indian Space Research Organisation (ISRO) has achieved a milestone by demonstrating sustainable space operations. On April 4, as part of India’s vision to ensure Debris-Free Space Missions (DFSM) by 2030, it brought back the rocket used for the Space Docking Experiment (SpaDeX) mission.

ISRO managed the successful disposal of the residual part of the PSLV-C60 rocket that was launched in December 2024. The specially configured upper stage of PSLV-C60 was brought back into the Earth’s atmosphere and descended into the Indian Ocean without leaving a trail of junk in space.

What is space debris

Space debris is any non-functional object humans leave in space. It can come from rocket-launching material and defunct satellites or from metal, screws, paint flakes, and other smaller items.

The European Space Agency estimates that more than 1 million pieces of orbital debris a cm or larger, and more than 30,000 pieces bigger than 10 cm, litter the low-Earth orbit (up to 2,000 km above the Earth’s surface).

Potential risk

The orbital debris goes round the Earth at nearly 10 km per second and risks colliding with communication, monitoring and astronomy satellites. Experts say that even a single paint flake at that speed can damage or destroy a satellite.

Explosions in orbit, triggered by residual energy stored in fuel and batteries aboard spacecraft and rockets, are a significant source of debris. Spacecraft hit with debris can explode into thousands of shards and cascade the danger multiple times. Anti-satellite missile tests that destroy satellites also create such space debris.

Minimising damage

Increasing government and private space traffic is pushing up the combined mass and area taken up by space trash.

Current attempts to minimise debris formation and prevent crashes revolve around re-entry burn up exercises for spent spacecraft, and debris avoidance manoeuvres for satellite launches.

India’s commitment

The DFSM initiative was announced by Somanath S, the then chairman of ISRO, at the 42nd Annual Meet of the Inter-Agency Space Debris Co-ordination Committee (IADC) at Bengaluru on April 16, 2024.

The ISRO System for Safe and Sustainable Space Operations Management (IS4OM) was the nodal point in implementing the DFSM with the support of other entities of the Department of Space.

Miscalculations

Re-entry into the atmosphere is calculated to maximise the chances of the final fall over oceans, but mishaps do take place occasionally.

In March last year, a battery pack released from the International Space Station landed on a home in Florida, USA. According to NASA, the hardware, which should have burnt up, survived re-entry into the Earth’s atmosphere.

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