There may soon be so much debris in orbit around the Earth that future space missions could become impossible, scientists have warned.

Researchers at the European Space Agency (ESA) have said that the amount of debris from man-made objects is about to reach “criticality”.

This means there is so much debris that it is colliding with other debris — generating particles of space junk at an accelerating rate.

The scientists said it would eventually surround the planet in so much speeding space junk that swathes of space will become inaccessible.

“If the current launch rate continues, then collisions will soon be 25 times higher than now. This would make space flight in low Earth orbits almost impossible,” ESA said.

“There are already 17,000 trackable objects larger than a coffee cup, which threaten working missions with catastrophic collision. Even a 1cm nut could hit with the force of a hand grenade.”

To tackle the problem, the space agency is designing a hunter-killer space probe to track down and destroy defunct satellites and so halt the growth of the burgeoning cloud, ‘The Sunday Times’ reported.

The e.DeOrbit probe would deploy a Roman gladiator-style array of nets and harpoons to first trap rogue satellites and then drag them downwards until they burn up in the atmosphere.

While the question remains how long it will take for the debris cascade to render space unusable, researchers said there are already certain orbits, popular with communication and military satellites, that could become unusable within a decade or two.

The worst affected are orbits of 800-965 km altitude that pass over the poles, because these already contain many of the 5,000 or so satellites launched by humanity since the space age began.

ESA said removing between five and 10 large satellites from space each year would be enough to stop the debris cloud growing.