Korea Develops Reusable 'Space Janitor' to Clear Orbital Debris

A small towing plate pops out from a metal box-shaped body the size of a rice cooker and instantly latches onto a piece of debris. Once the adhesive-coated towing plate pulls the debris closer, a robotic arm extends from the body to secure it. Then, from the rear of the body, a golden square sail measuring 10 meters on each side unfurls. The sail, which at first glance resembles aluminum foil, is made of aluminum-deposited PET film just 12 micrometers thick — tougher and sturdier than it looks. The golden sail serves to gradually lower the orbit of space debris. The wide sail catches solar radiation pressure and the thin atmospheric drag in low orbit, reducing speed without any fuel. As the debris slows, it descends to progressively lower orbits and eventually reenters the atmosphere, where most of it burns up. "The space debris removal system being developed by KARI consists of two parts: a 'removal satellite' that approaches the debris, and an 'orbit departure device' that attaches to the debris and carries out the actual deorbiting," said Kim Min-gi, a researcher on the space exploration team at the Korea Aerospace Research Institute (KARI), in an interview on June 10. "Unlike conventional single-use methods, this system can perform multiple missions, making it reusable." In February this year, KARI developed a solar sail-based orbit departure device designed to capture and remove the rapidly increasing space debris in low Earth orbit, and successfully completed a ground demonstration. The key achievement is the proposal of a reusable removal model that overcomes the limitations of conventional approaches, which required deploying expensive satellites on a single-use basis. Most space debris removal operations involve a cleanup satellite directly approaching and capturing a target before inducing atmospheric reentry — a structure that typically consumes one satellite per mission. To overcome this limitation, KARI separated the system into an "orbit departure device" that actually removes the debris and a "removal satellite" that carries and deploys the devices. A single removal satellite carries multiple orbit departure devices, enabling repeated operations. "Space debris removal is an ongoing task, so cost and reusability will inevitably become critical," Kim said. "The core of this technology lies in transforming the cleanup satellite from a disposable piece of equipment into a system capable of repeated operation." He added, "The solar sail can secure a large deceleration surface area with almost no propellant, raising the feasibility of actual missions even with a compact device." KARI originally developed the device as a next-generation propulsion technology for deep-space exploration. However, in response to the rapidly deteriorating space environment, the institute expanded its research to repurpose the sail — originally designed to harness sunlight for forward propulsion — as a "drag sail" that slows debris and lowers its orbit. "Even with the same sail, its role changes depending on which direction it is deployed," Kim explained. "If the sail is angled forward, it catches solar radiation pressure and becomes a propulsion device. If deployed in the opposite direction, it increases drag and becomes an orbit departure device." In other words, a single technology can serve as either a means of propulsion toward deep space or a tool for pulling down space debris. According to the European Space Agency (ESA), approximately 40,000 objects are currently tracked in Earth's orbit. Of those, only about 11,000 are operational satellites. The rest are defunct satellites, rocket upper stages, and fragments from explosions and collisions. Smaller untracked debris is far more numerous. ESA estimates more than 50,000 objects larger than 10 centimeters in diameter, more than 1.2 million fragments larger than 1 centimeter, and more than 130 million fragments between 1 millimeter and 1 centimeter. Even debris of that size can puncture satellite walls or destroy critical equipment when it strikes at hypervelocity. The situation is likely to worsen. ESA warns that if launches continue at the current pace and fragmentation events persist, the number of debris pieces could keep growing from collisions among existing objects alone — even with no additional launches. This is the so-called Kessler syndrome. Low Earth orbit is particularly vulnerable because it is where communications, Earth observation, and constellation satellites are concentrated. As satellite numbers rise, so do avoidance maneuvers, leading to increased fuel consumption, shortened lifespans, and higher operating costs. For these reasons, a growing consensus in the international community holds that the space debris problem cannot be solved by technology alone. Mia M. Bennett, a geography professor at the University of Washington, suggested in a commentary published in Communications Engineering in May last year that "space debris response should be viewed not as a matter of post-launch cleanup technology, but as an issue of managing a satellite's entire lifecycle." The international community is accordingly strengthening governance. The U.S. Federal Communications Commission (FCC) introduced the so-called "five-year rule," requiring low Earth orbit satellite operators to deorbit within five years of mission completion — a far stricter measure than the longstanding 25-year guideline. ESA is also pursuing a "zero debris" approach aimed at leaving no fragments in future missions. As governance tightens, the importance of developing cost-effective cleanup satellite technology grows. "Having the technology doesn't mean you can clean up right away," Kim said. "Going forward, space competitiveness will likely be judged not just by how much you launch, but by how long and safely you operate and how responsibly you clean up."

Korea Develops Reusable 'Space Janitor' to Clear Orbital Debris

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