Testing technology to clear out space junk
According to current estimates, there are more than 40,000 objects – equivalent to some 7,600 tonnes – of space junk floating in Earth orbit, posing significant collision threats to satellites and space stations. The RemoveDEBRIS project is aimed at performing key active debris removal (ADR) technology tests in search of the best ways to clean up space.
The RemoveDEBRIS project was developed by a consortium of companies that include Airbus. An experimental satellite was designed and built – and is operated in-orbit – by Airbus’ Surrey Satellite Technology Limited (SSTL) subsidiary. The spacecraft features three Airbus technologies to perform active debris removal: a net and a harpoon to capture space junk, as well as a Vision Based Navigation (VBN) system to validate debris-tracking techniques in orbit with cameras and LIDAR. The mission is led by the UK’s Surrey Space Centre (SSC) at the University of Surrey.
In addition to the traceable manufactured objects in Earth orbit, there are many millions of pieces of debris too small to be tracked in and around the planet – all of which can be considered threats to spacecraft and satellites.
Airbus, its Surrey Satellite Technology Ltd subsidiary, along with France’s ArianeGroup (a joint company of Airbus and Safran) are all part of the RemoveDEBRIS programme consortium, which is co-funded by the European Union’s Seventh Framework Programme. Other members of the collaboration are the University of Surrey’s Space Centre in the UK, Inria (the French national research institute for digital science and technology), The Netherlands’ Innovative Solutions in Space, Switzerland’s CSEM (a private, non-profit research and technology organisation) and South Africa’s Stellenbosch University.
The 100-kg. RemoveDEBRIS satellite was released from the International Space Station in June 2018.
Its deployable net experiment was developed by Airbus in Bremen, Germany, and conceived to target debris up to two metres in diameter and with a mass of up to two tonnes. For the September 2018 demonstration, a cubesat target representing an element of space debris was launched from the RemoveDEBRIS spacecraft and targeted by the net at a distance of several metres. The cubesat was successfully captured, with the target/net combination subsequently floating away to deorbit and burn up upon atmospheric re-entry. Developing the net technology took some six years of various tests place in drop towers, during parabolic flights, as well as in thermal vacuum chambers.
For the Vision Based Navigation demonstration, designed by Airbus in Toulouse, France, the goal was to test 2D cameras and 3D LIDAR (light detection and ranging) technology in tracking a released cubesat’s rotation and movement away from the RemoveDEBRIS satellite. The test was performed in October 2018 and saw the spacecraft take images of the deployed target cubesat and its surroundings using the on-board technology. As an accuracy check, the cubesat then transmitted its true location based on GPS data, testing the VBN system’s accuracy. After the experiment, the target was set to re-enter the atmosphere and burn up.
The RemoveDEBRIS harpoon was developed at Airbus’ Stevenage, United Kingdom facility. During a test that took place in February 2019, the harpoon was fired at a satellite panel mounted on a boom that was extended from the RemoveDEBRIS spacecraft. Travelling at a speed of 20 metres per second, the harpoon successfully impacted – and penetrated – the target panel, confirming its ability to capture space debris.
The programme’s fourth and final experiment – set to take place in March – will test a drag sail developed by the Surrey Space Centre that will pull the RemoveDEBRIS spacecraft into the Earth’s atmosphere and force the satellite to deorbit in approximately eight weeks – as opposed to more than two and a half years it would take to do so naturally.