As plans are announced to grab decaying rocket parts with harpoons and nets, Daniel Bardsley looks at the threat debris poses today
From chips in satellite windows to flying metal particles, tackling space debris is a challenge that's out of this world
A redundant satellite may weigh as much as a couple of tonnes, a mass that might be floating through space uncontrolled and at risk of striking other material in the same orbit.
This one large piece of debris is bad enough – but if the satellite was involved in a collision, it could fragment into thousands of pieces, each capable of causing damage.
The issue of space debris has hit the headlines this week with the news that, over the next few months, a project called RemoveDEBRIS will test three technologies to capture space debris, namely a harpoon, a net and a drag sail.
Because of the high speeds involved, objects that might seem harmless to us could be major hazards out in the final frontier.
For example, it was reported in 2016 that a 7mm chip in the window of the International Space Station may have been caused by the high-speed impact of a paint chip just a few thousandths of a millimetre across.
Collisions could wipe out satellites essential for functions such as providing internet connectivity or mobile phone connections.
Space debris has been accumulating for six decades but, as the UAE continues preparations for its 2021 Mars mission, awareness of the dangers it poses is growing too, as are efforts to deal with the hazards.
“Not only are we fully aware there are lots of these objects, but that very small objects can cause quite serious damage,” said Laurence Blacketer, of the University of Southampton in the United Kingdom, who studies the movement of space debris.
There are as many as 40,000 pieces of space debris, together weighing about 8,000 tonnes and ranging from old satellites to fragments generated by collisions.
Funded by the European Union, the €15.2 million (Dh68.7 million) RemoveDEBRIS initiative, which began several years ago, now aims to determine the effectiveness of the methods it has been developing. It involves a 100kg washing machine-sized device to collect the debris.
The project also includes testing a lidar navigation system that could help to improve ways of tracking debris.
“So far, nobody has tried actively to remove the junk. This will be the first,” said Professor Guglielmo Aglietti, director of the Surrey Space Centre at the University of Surrey in the United Kingdom, which is co-ordinating RemoveDEBRIS.
“We have to do both things: we have to prevent the situation getting worse and remove some of the larger debris.”
He said there was a “very good hope” that the technology would prove effective at collecting debris and that a “proof of concept” of the type that the project aims to achieve could spark interest from companies that could undertake clean-up work.
“We think companies would be willing to make a service,” said Prof Aglietti.
Once captured, debris could be put into a space craft that was returning to Earth and then disposed of on arrival.
Guidelines from the Inter-Agency Space Debris Co-ordination Committee (IADC) have attempted to reduce the amount of debris in space. Mr Blacketer said these guidelines suggest, for example, that when equipment is used in space, detachable pieces are tethered so that they cannot break free.
Efforts are also made to remove junk material from useful orbits and put it, instead, into “graveyard orbits”, where it cannot cause damage to functioning satellites.
Separate to RemoveDEBRIS is another European initiative, e.Deorbit, co-ordinated by the European Space Agency. This project has looked at the potential of using robotic arms and nets to capture a 1.6-tonne satellite called Envisat and bring it into Earth’s atmosphere within the next five years so it burns up on re-entry.
The removal of space debris is seen as particularly important because collisions mean that, even if no more devices were put up into space, the number of pieces of debris would increase.
Aside from actual missions to test out ways of removing debris, researchers such as Mr Blacketer are trying to better understand the properties of space debris.
“We’ve started to realise at the very least we need to understand how these objects are behaving in order to be able to react to any potential issues that may occur in future,” he said.
“I’m using a normal optical telescope to look at these objects and determine what the motion is.”