Can the World’s First Space Sweeper Make a Dent in Orbiting Debris?

Decades of space exploration have left a shroud of space junk enveloping Earth. They’re much more than a minor inconvenience—functional satellites, space shuttles that ferry astronauts back and forth and the International Space Station (ISS) all have to dodge and weave through the detritus. Earlier this year, a gaping hole was discovered in a 58-feet-long arm of the ISS, thought to be caused by an object too tiny to track. The incident came just eight months after the ISS sidestepped another, larger piece of debris. Earth’s debris field now includes 27,000 cataloged objects—from paint chips to spent rocket stages—all which threaten to damage spacefaring investments that cost millions of dollars.

“It's probably the one of the most important environmental problems of our time,” says Hugh Lewis, an astronautical engineer at the University of Southampton in the United Kingdom. Like climate change, he says that the issue of space debris stems from humans polluting and abusing a common resource, in this case, the environment of space. “It’s a technological problem we’ve created, … driven by our own choices.”

To combat this issue, Astroscale Inc., a private Japan-headquartered company, has devised several commercial spacecrafts tasked with decluttering space. The company is on track to deliver the world’s first garbage truck for removing defunct satellites in 2024, and today announced its prototype completed its first demonstration in space. Although experts say that one active debris remover isn’t enough to solve the problem, it is an important move toward protecting valuable equipment in space, including satellites that aid with everything from weather forecasts to GPS navigation.

“Those services are under threat,” says Lewis. “That threat is the destruction of the satellites, or the disruption to the services because we have to maneuver the satellites to avoid the space debris.”

Astroscale’s efforts are one of the first, tiny steps towards cleaning up debris. Its flagship mission is ELSA, short for “end-of-life services by Astroscale.” ELSA will drag satellites that are no longer operating down from high altitudes to the planet’s natural incinerator: the oxygen-rich atmosphere at lower Earth orbits. Both the space-cleaner and satellite will burn up here before they hit the surface of the Earth. In March this year, Astroscale launched its prototype ELSA-d (d stands for demonstration) to test its proximity capture technology. It contains two satellites: a chaser and a target that will proxy as a hunk of wreckage. Each satellite is equipped with a magnetic docking plate so that the chaser can latch onto its target.

The satellite pair successfully performed the first of four catch-and-release demos for debris disposal today. In this first test, the chaser validated its magnetic capture system by separating with the target then snagging it at close range. All the while, on-the-ground mission control recalibrated ELSA-d's sensors and verified its operational procedures. In the coming months, ELSA-d will undergo challenges of increasing complexity, from the chaser snagging prey that’s drifting away to pursuing a freely tumbling target and plucking it from its flightpath. ELSA-d’s fourth and final test will represent a full-service mission, in which the chaser inspects the target at close range and allows its human operators to make a go-no-go decision on the cleanup. In a fiery finale, both target and catcher will head down to lower Earth orbit to burn up in the atmosphere.

“Once those technologies are demonstrated and the global community sees that [ELSA] is a really big step towards active debris removal and end-of-life services, they're going to embrace this as more of a reality,” says Mike Lindsay, Astroscale’s chief technology officer. “Hopefully they'll incorporate that possibility into their own plans” as they prepare the next generation of satellites, he adds.

Just like any other mission, Astroscale’s endeavor carries a potential risk of failure, but “all things being equal, I have no reason to believe that their demonstration won't be successful,” says Moriba Jah, an astrodynamicist and space environmentalist at the University of Texas, Austin who wasn’t involved in the ELSA project. Although a single vehicle can’t make an immediate difference in a decades-long problem, he opines that ELSA-d is a small but important first step. “We need to start doing something,” he says. “It's going to take many helpful things to actually start making a difference.”

Astroscale's Space Debris Removal Mission, ELSA-d - ConOps Video

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While Astroscale is optimistic that a string of successful demonstrations will attract new clients, its cleanup program still hinges on space entities opting to pay for its services. No international entity or law mandates space users clean up after themselves when their satellites litter, and so space has become a junkyard for failed experiments. Earth’s inky backyard is a classic example of the tragedy of the commons, whereby a joint ownership of a good between multiple countries incentivizes everyone to exploit it and no one to take care of it. While the Inter-Agency Space Debris Coordination Committee has prepared a set of international guidelines for managing space debris and minimizing pollution in future missions, no enforcement mechanism is in place to ensure members adhere to it.

Moreover, ELSA is only built to clean up objects weighing less than one metric ton, or roughly 2,200 pounds, that have magnets placed on them. But the most damaging objects in space are the large rocket boosters jettisoned in the late 1900s to early 2000s. These objects are wildcards; their speeds, trajectories and positions are challenging to parse, complicating any practical plan for their disposal. They’re also supersized, weighing nearly ten metric tons each. Not only are they too big to currently be collected, they also may not entirely burn up in the atmosphere if they hurl towards Earth.

Still, Astroscale’s space sweeper services are crucial for chipping away at a gargantuan problem as it focuses on the smaller, newer satellites that will be launched as mega constellations. Companies like SpaceX and Amazon plan to deploy satellites by the thousands over the next few years, and ELSA could collect these satellites when they inevitably glitch. If ELSA’s demonstrations are successful, Astroscale hopes that private companies will take the initiative to install magnetic plates on their satellites and contract its services to dispose of their derelict satellites. One company is already on board: the U.K.-based company OneWeb. The organization has fitted its latest satellites with ELSA-compatible docking plates. Moreover, OneWeb awarded Astroscale $3.3-million in funding earlier this year to prepare the debris-removal technology for the real-deal: ELSA-m. The commercial version of the space garbage collector, ELSA-m will retrieve multiple retired satellites in a single mission, a move that will significantly reduce costs.

Lindsay predicts that the market for active space debris removal will be strong. “People are going to be much more ready to pay for this service and remove objects that they see as threats... because they need to protect their investments, their assets in space.”

“Developing the technology is critical,” says Jah, but he’s also skeptical, because the global community has yet to put a number on the value of removing any one object in space. As such, Astroscale can’t advertise how much exactly clients are getting out of its end-of-life services, and customers have no basis to evaluate how much the services are worth to them. While morally laudable, “cleaning up debris for the sake of cleaning it, there's no solid business case to that,” says Jah. Technological development for active debris removal takes time, and so does the push to convince regulatory bodies to standardize the definitions of each debris object’s hazard—a number Jah calls the “space traffic footprint.” He adds, “these things need to be pursued in parallel.”

The cheapest and easiest solution to curb the debris dilemma is not to create debris in the first place, says Marlon Sorge, a principal engineer and aerodynamicist at Aerospace Corporation in El Segundo, California who wasn’t involved in Astroscale’s projects. Spacecraft-launching entities need to reduce the chances their missions fail, because these dead objects only end up as junk and add to the growing debris problem. Active debris removal such as the Astroscale’s offerings should be a back-up to the mitigation plans that all space firms need to prioritize.

“If you don't do the mitigation, the rest of it won't make a difference,” says Sorge.

The normal failure rate of satellites can soar as high as 40 percent, depending on the type. Even a failure rate as low as 2.5 percent, as SpaceX’s satellite constellation Starlink boasts, will still translate to thousands of dead objects circling the sky in the years to come. So, that level of compliance still needs improvement, says Sorge. “But making your satellites so reliable that you never have to have any dead satellites is also not realistic,” he adds, “which is where the active debris removal comes in.”

While companies dream up solutions, the public can still help. Sorge says that individuals recognize the severity of space debris more readily now than three decades ago when he first started in the field. Lewis, Jah and Sorge all agree that public support can nudge the direction of public policy. A fussier public can make the case to the government to enforce good behavior among space users by mandating all space entities to clean space up after themselves after every mission. Experts say consumers should factor space sustainability into everyday purchasing decisions by questioning whether service providers with dealings in space take concrete action towards debris prevention and removal. These tiny steps could indirectly influence the leaders of the space industry to reduce space pollution.

Shi En Kim | | READ MORE

Shi En Kim is a Washington, D.C.-based freelance science journalist. Her work has appeared in National Geographic, Scientific American, the Atlantic, Popular Science and others. In 2021, she interned at Smithsonian magazine as an AAAS Mass Media Fellow.