“Humanity is likely past the stage where merely halting new debris is insufficient to curb orbital pollution. It is therefore expedient to not only prevent new debris but also actively remove existing threats through debris remediation.”

An ever-increasing number of space debris, including over 36,500 objects larger than 10 cm and more than a million exceeding 1 cm, threaten to render our planet’s orbits unusable. Most proposals to address this risk focus on limiting the creation of new debris, also known as debris mitigation. However, beyond a critical number of debris, the risk of runaway collisions—where debris continuously generates more debris—increases. In 1978, NASA expert Donald Kessler predicted this tipping point could be reached within 30 to 40 years. Consequently, humanity is likely past the stage where merely halting new debris is insufficient to curb orbital pollution. It is therefore expedient to not only prevent new debris but also actively remove existing threats through debris remediation.

Current Situation

In 2022, ClearSpace and Astroscale were awarded £4 million from the UKSA to design missions to remove space debris through active-debris removal. The UK’s first national space debris removal mission is scheduled for 2026. Credit: ClearSpace and UKSA

Debris remediation functions by identifying dangerous debris and either shifting their orbit or de-orbiting them entirely. Various actors have proposed active debris removal vehicles equipped with claws, tethers, or nets. Another option is to bombard debris with lasers to “nudge” them out of their current orbit, which enables collision avoidance and potential deorbit. Though the technology remains at an early stage, every space power is pursuing debris remediation projects.

As early as 2022, China established a lead when its Shijian-21 satellite was reported to have successfully dragged a defunct satellite into a graveyard orbit. In January 2024, Astroscale, a Singapore-based Japanese company, successfully demonstrated technology capable of de-orbiting a piece of debris with magnetic capture. The European Space Agency plans to launch ClearSpace-1 in 2026 in a bid to achieve the first debris de-orbit. The U.S. Senate unanimously passed a bill to direct NASA to launch a national debris remediation program in November of last year. Although governments and companies have shown enthusiasm in ramping up debris remediation endeavors, multiple challenges stand in the way of effective active debris removal. 

Economic Challenges  

From research and development to operational costs, debris remediation is a resource intensive pursuit, raising questions over who should foot the bill. As every spacefaring actor would benefit from cleaner orbits, a free rider problem and the ensuing Tragedy of the Commons loom. Alternatively, responsibility for funding the cleaning could be assigned to those actors who generated the debris. The United States, Russia, and China together generated 95% of the debris in orbit today. Nevertheless, the likelihood of convincing these geopolitical rivals to pool funds to clean up space for everyone else appears slim.

A May 2024 NASA report weighing the costs and benefits of debris remediation suggests active debris removal makes economic sense, with benefits hundreds of times higher than the upfront cost. This is not only true for the low hanging fruit — large debris in dense orbits — but also for centimeter-sized debris. Whereas this is an encouraging signal for a potential space sustainability market, providers will face difficulties in the absence of an explicit client. 

Legal Challenges 

The six UN treaties governing human activities in space were all signed before 1980, and do not adequately address the legal challenges raised by debris remediation. International law does not offer a solid definition of debris, let alone an explicit roadmap to handle legal issues. The Outer Space Treaty (OST) clearly assigns ownership of spacecraft and debris to the state that registered them. Hence, a debris remediation mission would likely require the consent of the debris owner, assuming it can even be traced. The OST also enjoins spacefaring nations to conduct space activities with “due regard” to others’ interests, but never defines the scope of the “due regard” obligation.

In the case of an international debris remediation mission, questions of jurisdiction and export control arise. Liability in the case of failed missions is also insufficiently defined. The world needs more up-to-date and precise legal frameworks, but it is unclear if the requisite political consensus can be found.

Political Challenges 

Whereas curbing excessive debris is a common challenge for all states, debris remediation may still prove to be a thorny political issue. Active debris removal is a dual-use technology. The ability to interfere with the trajectory of a debris implies the ability to interfere with active satellites too, making any debris remediation method a potential space weapon. The concerns the U.S. Government recently showed when a suspected Russian orbital weapon approached a U.S. reconnaissance payload illustrate just how sensitive states are towards allowing their assets to be approached.

Outside of non-binding UN-led initiatives, the world’s three largest debris producers barely cooperate on debris. Mistrust between great powers has stood in the way of effective global space sustainability governance, and can make active debris removal an escalatory issue. A lack of diplomacy threatens to fragment the global space policy landscape with insufficient overlap and cooperation.

Looking ahead

The rising international awareness of the threats posed by orbital debris and the emergence of key research emphasizing the net benefits of debris remediation are causes for hope. As launch and development costs subside, proposals for a debris marketplace shift the paradigm of debris from space trash to valuable resources. Multilateral efforts are expected to help bridge the legal and political gaps, with space situational awareness data likely to be part of discussions in the upcoming 67th session of UN COPUOS, scheduled for June 19-28, 2024. Such initiatives are the first steps of a much-needed global conversation on the future of both debris mitigation and remediation.



Meet the author

Theo Picard, recent graduate with a Dual Masters in International Relations from Sciences Po Paris and Peking University, is a winner of the 2024 UNOOSA Space4Youth Essay Competition. Specializing in space diplomacy and sustainability, Theo advocates for innovative space policy solutions in the Asia-Pacific region and beyond.