Sometimes, what goes up doesn’t come back down — instead, it becomes a problem.
Junk is accumulating in space at a fantastic pace, millions of pieces orbit the Earth, from broken satellites to lost screws and tiny hunks of splintered paint. The International Space Station has to dodge it. Sometimes, space junk crashes into other space junk, creating more space junk. And while there have been many proposals for technologies to capture and destroy it, there’s not been a system-level plan for dealing with it in a comprehensive way.
This week, researchers at England’s University of Surrey published a paper outlining how to better deal with our celestial litter. The basic idea: make space more sustainable by using less material, repairing what’s already up there, and recycling the junk we can’t repair — and doing it systemically, industry-wide.
While this sounds pretty basic to Earth-dwellers already long-familiar with reduce, re-use, recycle, it really is a “fairly new” concept for the space industry, said Michael Dodge, a professor of space studies at the University of North Dakota, who was not involved in the study. “I’ve never seen it presented this way,” he said. “It’s an area that needs to be discussed further.”
There are currently more than 25,000 pieces of space junk larger than 4 inches in diameter circling the Earth, according to documentation from NASA. Add in smaller bits and that number soars to more than 100 million. Altogether, our space trash weighs upwards of 10,000 tons, according to a 2022 report by the agency.
And that junk makes an impact. Debris left bullet-like cracks in the windshield of the space shuttle Challenger during Sally Ride’s first flight in 1983. The Hubble Space Telescope was hit by space junk on multiple occasions, including a collision that punctured through its antenna dish. Meanwhile, two large crashes between satellites in 2007 and 2009 created enough new debris to now account for more than one third of all catalogued space junk, NASA reported.
The big fear lurking behind these incidents is the Kessler Syndrome — the risk that, once enough objects are in low-Earth orbit, one collision could set off a chain reaction of crashes littering that part of space with enough junk that it’s no longer usable. Damage to satellites and global communications systems means space junk could reduce global GDP by 1.95% if no solution is found, according to a 2023 paper in the journal Space Policy.
There are efforts to mitigate the problem, experts told CNN. SpaceX has created re-usable rockets. A company called Astroscale is developing a robotic arm capable of catching dead satellites. But individual technology solutions aren’t enough on their own, said Jin Xuan, associate dean of research and innovation at the University of Surrey and one of the paper’s authors.
“People must have systems thinking,” Xuan said. “When you focus on individual technologies, you’ll miss the opportunities.” For example, he told CNN, perfecting a robotic arm to remove dead satellites is less important if you design the satellites differently from the beginning — to be refuellable, or to burn up in the atmosphere at the end of their lives.
A more sustainable system would coordinate existing technologies, such as AI collision avoidance systems on satellites, with new ideas like repurposing space stations as platforms for repairing or recycling space junk, and ensuring companies and countries are thinking about how to end the life of an object as it’s designed, according to the report.
Xuan has seen these principles work in other industries. His research is normally focused on sustainability strategies for chemical manufacturing. The space industry has been “focused on safety and economic value, but sustainability hasn’t been a priority,” Xuan said. “There’s an opportunity to learn from other sectors.”
But trying to make space sustainable comes with challenges that don’t exist on the ground, Dodge said. The laws and politics of space, in particular, cause big complications.
The Outer Space Treaty is the primary governing document for the major players in space, he told CNN. One provision states “that once you launch an object into space it’s your object forever,” Dodge said. That means every used rocket booster, every dead satellite, remains the property of the entity that originally launched it.
This rule exists because countries have historical reasons to be concerned about other countries messing with their satellites and space stations.
“One of the potential troubles with any technology designed to recycle or to refurbish technologies in space, is that those very same technologies could be used as a weapon,” Dodge said. A robot arm could disable a working military satellite just as easily as it picks up a dead one, for example.
As a result, it’s currently illegal for a country to clean up debris created by another country. When Astroscale, the company developing tools capable of collecting and removing space junk, has tested its technology they’ve had to account for that rule, Dodge said. For example, if they want to capture a UK-owned object, then they also have to also launch from the UK.
Recycling space junk could be nearly impossible if you need permission from every country that owns the objects before you clean them up. But, another part of the treaty requires countries to avoid contaminating space — which could be interpreted to mean you have to clean up your space junk, Dodge said.
And that could be a very important part of making space recycling happen.
“People are interested in these sustainability ideas. They want to try it,” Xuan said. “But it’s all about the money and whether there’s an incentive.”
Correction:
A previous version of this story included a quote that misstated the timeline on Astroscale test launches. This story has been updated.