New sail for satellites will help keep space clear of debris

Equipping new satellites with a special ‘sail’ to bring them out of orbit could cut down on the amount of junk floating in space.

There are hundreds of thousands of manmade items floating in Earth’s orbit.

But only around 5000 of those items are operational satellites – the rest is just junk and debris, ranging from frozen balls of astronaut’s urine to a football that survived the Challenger disaster.

This junk field, which is most congested in low-earth orbit (within 2km of the surface) is starting to become a problem. It poses a risk to useful satellites, and if it gets worse it could make it impossible for new space launches to happen safely.

A number of organisations are looking to tackle the issue. We recently reported on a satellite equipped with a large net and harpoon to sweep up space junk.

On top of this, the Inter-Agency Space Debris Coordination Committee has proposed that all new low-earth orbit satellites should be taken out of orbit within 25 years. But that’s not an easy thing to do – sending a rocket up to fetch your old satellite is expensive.

However, scientists at the Defence Science and Technology Laboratory (Dstl) have come up with a solution. The Daedalus experiment has been investigating a ‘de-orbit sail’ called Icarus.

It’s just 25 micrometres thick, and consists of a heat-resistant polyimide film coated in aluminium. The sail would be installed on new satellites before launch, and could be deployed when they reached the end of their useful life.

In theory, when deployed the sails will increase drag, causing the satellite to slowly re-enter Earth’s atmosphere and burn up.

“It’s vitally important that we remove satellites that have reached end of life so they don’t remain in orbit as pieces of space junk,” said Sean Murphy, a principal scientist on the project at Dstl. “Space junk clutters up the space environment and ultimately pose a hazard to the useful satellites we rely on.”

The experiment is in the testing phase. A Canadian satellite called CanX-7 used its de-orbiting sail in May and is expected to burn up in the atmosphere in around two years.

Two more satellites have also been fitted with de-orbit sails as part of this early test, which will measure the drag increase created by the sail, and its effect on trajectory.