17 February 2012
A proposed satellite designed to clean up space debris could help prevent damage to the hundreds of craft orbiting the Earth.
Researchers at Swiss technology institute EPFL have announced the launch of the CleanSpace One project to build the first in a family of craft that can track down and grab old satellites and pull them back to Earth, reducing the risk of orbital collisions.
Space debris is a growing concern for authorities, as the abandoned satellites, rocket stages and other rubbish around the Earth that threaten to collide with live craft are increasingly breaking into thousands of fragments, which can also cause serious damage.
‘Space agencies are increasingly finding it necessary to take into consideration and prepare for the elimination of the stuff they’re sending into space,’ said EPFL’s Swiss Space Center director Volker Gass.
‘We want to offer and sell a whole family of ready‐made systems, designed as sustainably as possible, that are able to de‐orbit several different kinds of satellites.’
EPFL is already developing an ultra-compact motor to enable the CleanSpace craft to adjust its trajectory after launch so that it can match the orbital plane of its target.
When the target, which will be travelling at 28,000km/h at an altitude of 630–750km, is within range the clean-up satellite will use a gripping mechanism inspired by a plant or animal example to grab hold of the debris.
Finally CleanSpace One will come out of orbit, pulling the target with it through the Earth’s atmosphere where both craft will burn up on re-entry.
NASA is monitoring 16,000 objects larger than 10cm in diameter travelling around the Earth at speeds of several kilometres per second, primarily in low earth orbit — less than 2,000km in altitude.
CleanSpace One will cost around CHF10m (£6.9m) to design, build and launch, and will result in one of Switzerland’s two small ’picosatellites’ being pulled out of orbit.
‘A de-orbiting satellite has never been attempted before,’ EPFL spokesman Michael Mitchell told The Engineer. ‘Our goal is to prove to the scientific and industrial community that the global idea is feasible, of which we are very confident.
‘The very first prototype needs to have a simple design that is sure to work. Once this has been proven, other options — multiple de-orbits, retrieving old satellites back to earth, bigger devices — are sure to follow.’
Who would be willing to pay for clean-up satellites has yet to be determined, but Mitchell stressed that the goal of the project was to prove that it was feasible.
The European Space Agency (ESA) has adopted recommendations that require satellites to be de-orbited after 25 years.
And the rising cost of satellite insurance, which is currently around $20bn (£12.7bn) per craft, could also force satellite operators to act to reduce existing space debris.
But Surrey University’s Dr Vaios Lappas, who is developing sails to drag future satellites out of orbit, told The Engineer that without regulation or a very cost-effective solution, industry would be hesitant to add de-orbiting systems to satellites.
On the topic of technology to pull down existing space debris he said: ‘I don’t think it will happen if it’s on a commercial model. It’s a very interesting engineering and research topic but I don’t see that working unless it is heavily subsidised by big space agencies.’
Dr Hugh Lewis, who is developing space debris simulation models at Southampton University, said there was a growing consensus on the removal of debris and space companies saw it as a potential market.
‘Asking governments to pay for it is one route by which we can get this done but that’s not necessarily the best way,’ he told The Engineer.
‘Another way to do it is to ask all spacecraft operators to pay into a pot from which you dip into to pay for removal.
‘The other way is through insurance, so that you provide the incentive to remove space junk. If you can reduce the risk to your spacecraft you can pay a lower premium, then it’s worth going up to remove objects that will enable that to happen.’