Helping to solve the scrapheap challenge (Image: Surrey Space Centre)

The first spacecraft designed to do away with itself was unveiled on Friday. It will try out an idea that could stop space getting clogged up with junk orbiting the Earth.

The debris of abandoned spacecraft and satellites is building up in low Earth orbit. This zero-g scrapheap has grown by 40 per cent in the past four years alone, with the US air force now tracking 19,000 orbiting objects larger than 10 centimetres across. And as chunks of debris strike each other, they fragment further – presenting still more threat of collision to working spacecraft.

The diminutive CubeSail craft, measuring 30 by 10 by 10 centimetres and weighing just 3 kilograms, has been designed at the Surrey Space Centre at the University of Surrey in Guildford, UK. It has a solar sail that it can use for propulsion – harnessing the pressure of sunlight, just as a boat’s sail harnesses the pressure of the wind – but it can also use the sail as an “orbital brake” to help it de-orbit to a fiery death in the atmosphere.


Splice the mainbrace

CubeSail, funded by the pan-European aerospace company EADS Astrium, will be launched into low Earth orbit late next year. At an altitude of 700 kilometres, the “nanosatellite” will unfurl its 5-by-5 metre sail, initially to test its usefulness for propulsion.

But after that experiment is complete, says Surrey Space Centre’s project chief Vaios Lappas, the solar sail will be turned away from the sun and its efficiency as an orbital brake will be tested.

Even at this high altitude there are rarefied molecules of the Earth’s atmosphere, and drag from those molecules eventually slows satellites in low Earth orbit enough to bring them to destruction in a blazing re-entry through the thicker layers of the atmosphere below. The sail should increase that drag and send the craft to its doom all the sooner: instead of taking decades to de-orbit, it could take just a couple of years.

If CubeSail works, future satellites could be fitted with similar sails that would be deployed when their useful life ends and they become space junk, says Lappas.

Or swarms of CubeSails could be flown into orbit, attach themselves to space junk and help de-orbit it faster.

Stuck in space

But the history of spacecraft that unfurl or inflate devices in orbit is not a happy one: components often fail or get stuck. The Surrey team hopes that the novel mechanism of spring-loaded steel booms that is to deploy its sail will work as well in space as it has on Earth. “We have tested them at 1 g but not at zero g,” says Lappas. “That’s the challenge we face.”

“A US satellite called Aerocube 3 attempted to test an inflatable drag augmentation device last year. However, the deployment was unsuccessful,” says Nicholas Johnson at Johnson Space Center in Houston, Texas, NASA‘s chief scientist for orbital debris. “Several earlier attempts to deploy solar sails and similar devices have also encountered problems.”

Joanne Wheeler, a London-based lawyer specialising in space law, welcomes the move – but with a caveat. “Anything that can be done to alleviate the space debris issue is worth trying,” she says. “But organisations have to realise that they cannot simply de-orbit any piece of debris they think poses a risk. Even defunct satellites remain the lawful property of the launching country – so full permission from that state will be required.”

And that, she says, will not be straightforward: there is currently no internationally agreed definition of space debris.