A "space harpoon" designed to catch a defunct satellite the size of a double-decker bus has passed a crucial earthbound test.
The one-metre long metal device was fired at 55mph into a 3cm-thick satellite panel, successfully deploying four barbs to lock it in place.
The harpoon, designed by Airbus UK, could be launched on a spacecraft in the 2020s in an attempt to snare the 8-ton EnviSat, which stopped working in 2012.
Pete Steele, a space systems engineer at Airbus, told Sky News that the captured satellite would then be dragged through the atmosphere, burning up as it goes.
"The problem with [EnviSat] is that it is now unresponsive," he said.
"We can't control it, we can't steer it, so we can't get out of the way of any debris that comes its way.
"If that does happen and the satellite does explode we will have a large cloud of debris, so it's important we get it down as soon as possible."
There are already half a million pieces of space junk larger than a tennis ball orbiting the Earth at 17,500mph.
Some of those are satellites that are no longer operational and pose a collision risk.
In 2009, a crash between a Russian and an American satellite produced a cloud of 2,000 fragments large enough to destroy other spacecraft.
The increasing number of orbiting objects raises the chance of Kessler syndrome – with a crash producing fragments that cause further collisions in a runaway series of explosions.
Alastair Wayman, the harpoon project manager, said: "It's a big risk if we carry on using space as we do at the minute.
"If we don't do anything, such as bringing out large pieces of space debris or implementing guidelines to make satellites de-orbit themselves at the end of mission, then this Kessler syndrome will present a real problem as we go forward."
A smaller version of the Airbus harpoon will be launched next month on the European Space Agency's RemoveDebris mission.
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It will be fired at a test rig from a distance of 2m to confirm that it operates as expected in zero gravity.
Even small fragments of junk put the International Space Station at risk, forcing the crew to take evasive action or even evacuate to the Soyuz spacecraft as a precaution.