Junk collectors
The first commitment to go beyond evaluating theoretical approaches has come from the Swiss Space Center (SSC), in Lausanne. Last year its scientists came up with the idea for CleanSpace One, a one-off spacecraft they intend to test by guiding it to recover one of the centre's own satellites. The design is inspired by the way sea anemones wrap their tentacles around their prey. It will have up to eight arms that can be unfurled and wrapped around pieces of debris.
“We thought that this debris issue is getting really important, so let’s launch the project to clean up in front of our own doorstep,” says Volker Gass, director of the SSC. “Once we pull it and hold it to our bosom we’re going to give the order to de-orbit the whole system. So actually we’re going to burn up on re-entry the catcher satellite and the catchee, the debris.”
Funding is a major issue for the project. Switzerland’s space budget is only a fraction of that spent by Nasa. If Gass can raise the required $11 million, he hopes to launch the experimental satellite within the next three to five years.
The United States, though not actively funding a debris removal program, is working on the problem. The US Air Force, for example, is developing a $3.5 billion “Space Fence”, a powerful new S-band radar system which uses a higher wavelength frequency than the current space surveillance radar to enable it to spot smaller chunks of debris. Defence companies Raytheon and Lockheed Martin are building prototypes.
“I like to describe the current system as tracking debris that is basketball size and the new system will see things softball size and even potentially smaller than that,” says Steve Bruce, vice president for Space Surveillance Systems at Lockheed Martin.
Darpa, in the meantime, is also pursuing a recycling approach. It proposes the launch of a robotic repair spacecraft called Phoenix to salvage and reuse components in order to rebuild decommissioned satellites. Rather than cleaning up the debris, the aim is to reduce the need for new satellites to be placed into orbit. “If this program is successful, space debris becomes space resource,” said Regina Dugan, the former Darpa director, when she announced the new project in 2010.
Of course, rebuilding a satellite with a robotic arm in space is easier said than done. The technology does not exist to do this sort of tricky rebuilding work autonomously, so a human would be required to guide the repair work. That means contending with the 10-second communications delay between the ground station and the spacecraft.
Glen Henshaw, a senior engineer at the Naval Research Laboratory in Washington, DC, which is working on the Darpa project, says: “There’s got to be a lot of smarts on board the spacecraft because, can you imagine driving your car down the Beltway, and there’s a ten second lag between when you turn the steering wheel and when the car turns? You’re probably going to crash."
Taking responsibility
But technology is only part of the issue. Another key obstacle is the lack of an underlying legal groundwork, according to Brian Weeden, of the Secure World Foundation, a Washington, DC-based think tank for space sustainability. Of the 22,000 pieces of debris being tracked by Norad today, the launch state and owner have been identified for only 16,000. Figuring out who owns space junk is essential for cleanup, because no country can unilaterally remove rubbish that may belong to someone else, and there are liability issues, according to Weeden. “Let’s say that you have Bob’s Debris Removal service and you go up there and your mission is to grapple with this rocket body, grab a hold of it and deal with it somehow, and in the process of doing so it explodes because it’s got leftover fuel inside,” he says.
