Space Debris Removal: The Engineering Missions Racing to Clean Up 9,000 Tons of Orbital Junk

In 1978, NASA scientist Donald Kessler published a paper describing a scenario that has since become one of the defining concerns of the space age: if the density of objects in low Earth orbit reaches a critical threshold, collisions between debris generate more debris, which causes more collisions, in a self-reinforcing cascade that could eventually render certain orbital shells permanently unusable. The Kessler Syndrome, as it is now called, is no longer a theoretical concern. The orbital environment in 2026 contains over 27,000 tracked objects larger than 10 centimetres and an estimated 100 million fragments larger than 1 millimetre — each capable of disabling or destroying an operational satellite on impact.

## The Scope of the Problem

The debris population has been accumulating since Sputnik. China's anti-satellite test in 2007, which destroyed the Fengyun-1C weather satellite and created approximately 3,500 tracked fragments. The accidental Iridium-Cosmos collision in 2009, which was the first hypervelocity collision between two intact satellites, added another 2,300 tracked objects. Multiple other ASAT tests and fragmentations have contributed additional debris fields.

The most congested shell is roughly 550–1,000 km altitude in low Earth orbit — precisely the range targeted by commercial mega-constellations including SpaceX Starlink, Amazon Kuiper, and OneWeb. Starlink alone has launched over 6,000 satellites into this zone. The combination of increasing operational satellites and existing debris creates collision risk that scales nonlinearly with density.

## ESA ClearSpace-1: The First Commercial ADR Mission

The European Space Agency's ClearSpace-1 mission, targeting launch in 2026, is the first contracted active debris removal mission. The target is the Vespa payload adapter from ESA's Vega rocket — a 112-kg object in an approximately 800-km orbit that has been there since 2013. ESA contracted ClearSpace SA, a Swiss startup spun out of EPFL, to design and operate the capture mission.

ClearSpace-1 uses a four-arm robotic capture approach: the chaser spacecraft approaches the tumbling Vespa adapter, deploys four articulated robotic arms to encompass it, and then deorbits both vehicle and target together. The engineering challenge is significant — Vespa is not equipped with any docking interface or attitude control, is tumbling in a potentially unpredictable pattern, and must be captured without collision damage that would create additional debris.

## Alternative Capture Approaches

Different ADR approaches suit different target sizes and types. **Harpoons** have been tested in orbit by Astroscale's predecessor programs — a spring-loaded harpoon penetrates the target and a tether attaches the debris to the chaser. Simple and relatively low-mass, but effective only for objects that can accept a penetrating impact without fragmenting. **Nets** can capture tumbling objects that harpoons cannot safely penetrate — the net is deployed from a short range and cinches around the target. ESA's RemoveDEBRIS mission tested net capture in 2018 and achieved the first on-orbit net capture demonstration.

**Ion beam shepherding** is a non-contact approach: a spacecraft directs a stream of ions at a debris object, slowly transferring momentum to nudge it into a decaying orbit. No physical contact is required, eliminating the capture dynamics problem — but it is extremely slow, requiring continuous thrust over days to weeks to meaningfully deorbit a large object.

## Economics and Liability

The fundamental problem with active debris removal is economic: nobody wants to pay for it. The objects being removed typically have no commercial value, the removing entity receives no revenue from the cleaned orbital shell, and the operators who benefit from debris removal — satellite companies operating in the cleaned zone — face no direct cost from the debris that currently exists.

The Liability Convention of 1972 establishes that the launching state is liable for damage caused by space objects, but it provides no mechanism for compelling debris removal or for distributing the cost of cleanup among those who benefit from it. This creates a classic commons problem: the incentive to remove debris is collective, but the cost falls on individual actors.

Proposed solutions include national regulations requiring satellite operators to demonstrate deorbit capability as a condition of launch licensing, orbital debris fees or insurance requirements, and international coordination through the UN Committee on the Peaceful Uses of Outer Space. None has been implemented at the scale necessary to address the existing debris population. In 2026, ESA's ClearSpace-1 and Astroscale's commercial servicing missions represent the beginning of an ADR industry, but the pace of debris generation from new launches still substantially exceeds the pace of planned removal.

Space Debris Removal: The Engineering Missions Racing to Clean Up 9,000 Tons of Orbital Junk

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