PART I: Introduction

Decreasing launch costs and smaller, cheaper satellites have made it easier for states and private actors to launch spacecraft into Earth orbit. When combined with historic “fire and forget” launches, this has compounded the growing congestion particularly within low-Earth orbit (LEO). Of the approximately 28,000 objects in LEO tracked by the US Space Surveillance Network (SSN), only about 4,000 are operational satellites. Moreover, the amount of debris is likely under-counted as the SSN is only able to track objects greater than five-centimetres in diameter. This allows larger pieces of debris, such as non-functional spacecraft or abandoned launch vehicle stages to be easily tracked and catalogued. 

Debris pieces, however, can be, and often are, much smaller and may include fragmentation debris, flecks of paint, rogue screws or other component parts of a defunct spacecraft, which when travelling at high speeds, can result in a catastrophic collision. Indeed, as the amount of debris increases, so too does the probability of such a catastrophic collision event. This is a result of the Kessler Syndrome, which results in the creation of yet more debris, thus perpetuating an environment that is hostile to space- and Earth-based resources that depend upon the structural and technological integrity of spacecraft. Indeed, long-term modelling from both the European Space Agency (ESA) and NASA shows that even if all new launches were halted today, the density of space debris would continue to grow. While the canon of UN space law provides a legal foundation upon which states can launch their space activities, this body of law faces severe limitations which often preclude states from engaging responsibly in the space domain. Flexible treaty interpretation may be key to resolving some of these legal challenges, particularly as they pertain to space debris.

Space debris, inter alia, constitutes a mounting legal problem for both space-faring states and states dependent on space-based resources. The canon of outer space law, comprising five treaties and principles drafted and ratified throughout the 1960s and 1970s, chief amongst which is the Outer Space Treaty (OST), provides little insight into managing space debris. This is largely because the term “space debris” is absent from the treaty regime. The UN Committee on the Peaceful Uses of Outer Space (UN COPUOS), acting in concert with the Inter-Agency Space Debris Coordination Committee (IADC), have issued a number of soft law tools, including the Space Debris Mitigation Guidelines, which have generally been accepted by space-faring states. However, the Guidelines are non-binding and only pertain to future missions; they do not address the debris currently in orbit. As such, in recent years attention has been drawn to the practice of active debris removal (ADR) to stabilize the number of debris objects in the LEO environment. Thus, an interesting legal question arises in the face of the urgent need to remove large quantities of debris from LEO: do states have the right under international law to engage in ADR of debris created or left behind by the space activities of other states? 

PART II: Assessing “Space Debris” as “Space Objects”

While the UN and national space agencies maintain their own definitions of space debris, there is no internationally agreed upon legal definition of the term; reference is only made to the term “space object” in treaties and other legal language. The IADC Guidelines define space debris as: “all man-made objects including fragments and elements thereof, in Earth orbit or re-entering the atmosphere, that are non-functional”. Moreover, Article I of the Liability Convention defines “space object” as including the “component parts of a space object as well as its launch vehicle and parts thereof”. Given the absence of the term “space debris” from the canon of space law, it may be expedient to equate “space debris” with “space objects” in an attempt to simplify the application of international space law to the mounting debris problem. Ambiguity arises nonetheless as it remains unclear whether space debris can amount to “component parts” and thus fall squarely within the definition of “space object”. It is also worth noting that the definition provided by the Liability Convention is recognized only as a partial definition.

Two competing legal theories may be applied to bridge this gap. The Spatialist Approach seeks to identify a physical boundary between airspace and outer space and deems “space object” to cover any spacecraft, space vehicle, and satellite that is located in an extra-terrestrial environment. The Functional Approach defines “space objects” as any space instrument in an operational state, regardless of its physical location. A cursory comparison of these theories against the IADC definition reveals that the “non-functional” component falls short of the threshold outlined in the Functionalist Approach and thus, in principle, space debris does not constitute a space object. However, to deprive debris of this status would ignore the fact that debris poses the greatest and most common danger to space activities. To exclude it from the definition of space object would arguably undermine space safety and render the international space legal regime meaningless. Accordingly, it has become widely accepted by the space legal community that any object launched into outer space that satisfies the Spatialist Approach constitutes a space object, including debris.

There are a number of resulting legal implications that come from defining space debris as space objects, particularly as they relate to Article VIII of the OST, which delineates the state of registry (often the launch state) of the space object as the sole entity retaining de facto, and arguably de jure, “jurisdiction and control” of the object and its component parts. Given the permanent ownership Article VIII bestows upon the state of registry, other states would be hard-pressed to contact, interfere with, or remove the debris without the express consent of the launch state. By this logic, the permanency of jurisdiction and control underpins the launch state’s property rights over the object, conferring absolute authority over that object, even after it ceases operation and the launch state loses functional control over it. Article 20 of the International Law Commission’s Articles on State Responsibility underpins the basic international legal principle of consent, which applies to the case of space debris if it is understood as a space object, and is thus under the permanent jurisdiction and control of the launch state. 

Another implication stems from the distinction made between identifiable and unidentifiable objects. Namely, the origin of the debris in question must be capable of being identified alongside its state of registry. Where no state of registry exists or is not identifiable for a given piece of debris — likely because the debris object is too small or has been too severely damaged — the legal requirement of obtaining consent to remove it seems, prima facie, impractical. There is no preceding state practice for the transfer of jurisdiction and control over a space object, nor for its removal without consent of the launch state, or for removal in the event the launch state is unidentifiable.

Non-consensual ADR poses an additional dilemma as the opposing interests of the launch state and those of other states, are not prioritized under international law. Finally,the OST and subsequent treaties do not consider the functional or non-functional nature of the space object when applying these important legal definitions. Without a basis to make the legal distinction between functional spacecraft and debris, there is consensus that even non-functional spacecraft, both as a whole or in parts, constitutes a “space object” for the purposes of the treaties and thus carries with it all the legal ramifications thereof.

PART III: Practical Interpretations of Article VIII 

In light of the mounting problem posed by space debris to both current and future space operations, exceptions to the principle of “permanency of jurisdiction and control” in Article VIII ought to be considered. Indeed, a contemporary and practical reading of Article VIII of the OST suggests that such jurisdiction granted to the state of registry should be considered non-exclusive. With this in mind, two situations arise in which the termination of such jurisdiction and control may be examined. 

(a)  An Express or Implied Act of Abandonment 

A practical interpretation and application of Article VIII suggests that the legal jurisdiction and control over a registered space object, including debris, ceases to exist when there is either an express or implied act of abandonment on the part of the state of registry. This would see the state of registry make a public declaration waiving its ownership over the object in question, and would not be presumed until such a declaration is made. However, a space object could still be implied to be abandoned if the state of registry has not made any attempt to recover or de-orbit the object. Should these conditions be met, it can be argued that non-functional objects may be considered abandoned and thus not subject to national jurisdiction and control. 

(b)  A State of Peril Scenario

A second practical interpretation and application of Article VIII suggests that when a registered space object, including debris, poses a threat to the space activities of other states parties to the OST, jurisdiction and control are nullified. In this scenario, the removing state should follow three steps: first, notify the state of registry of the threat posed by its debris; second, consult with the state of registry to allow it to undertake its own removal operation; and third, independently verify that removal of the debris object is necessary. Support for such a proposition may be gleaned from customary international law as it pertains to prescriptive jurisdiction, which would allow a state to regulate a space object if the object meets one of the four criteria, namely: (1) territorial jurisdiction; (2) nationality jurisdiction; (3) effects jurisdiction; or (4) national security jurisdiction. In this state of peril scenario, a removing state may invoke national security jurisdiction if the debris object in question poses a security threat to its national space activities.

PART IV: Analysis & Conclusion

It is clear that existing mitigation measures alone are insufficient to constrain the propagation of space debris in LEO. Indeed, both the ESA and NASA recommend that at least five debris objects be removed per year in order to stabilize the debris population, but no such action has been completed thus far. While the space legal regime provides the legal framework for states’ activities in space, there are severe limitations, particularly within the OST, that preclude space-faring states from engaging in responsible stewardship of an increasingly fragile environment. The treaties relevant to the space legal regime were negotiated against the backdrop of a geopolitical competition between the two global superpowers at the time, for whom the most significant causes of tension were claims of ownership over areas of space and radio interference. 

Space activities were in their nascent stages, and mutual assurances were made that neither state would interfere with the other’s spacecraft and that each would retain its ownership rights. As such, current legal hurdles for ADR arise when, in the absence of explicit consent, a state needs to protect its spacecraft from an impending collision by diverting or removing another state’s debris. The superiority of ownership rights, pursuant to Article VIII of the OST, prevents state parties from mitigating the threats posed to their space operations through ADR when the state owners of the debris object are uncooperative or unidentifiable. As such, a flexible interpretation of the treaty may be the key to resolving some of these legal challenges. 

There is no provision in the OST that explicitly characterizes ownership of a space object as indefinite; Article VIII simply provides that ownership of a space object is “not affected by [its] presence in outer space”. While the OST provides for states parties’ “use” of outer space, there is similarly no temporal limit on occupying any area of space for any given use purpose. Constructively interpreting OST language could limit “use” such that eternal occupation of orbits is outlawed once the object in question ceases to function. The International Telecommunications Union (ITU) employs an analogous recognition of the “use” of an orbital position in a congested frequency spectrum, which is a prerequisite to a state’s right to occupy that position. This is underpinned by Article 44 of the Constitution of the ITU. Finally, as stipulated by Article IX of the OST, states parties are obligated to act in “due regard” and be “guided by the principle of cooperation and mutual assistance” with other states that are party to the OST in the conduct of their space activities. Article IX also underpins states’ obligation to refrain from “harmful contamination” of the space environment. While space law provides little guidance on conduct in specific issue areas, international standards from both CIL and international environmental law recognize the obligation of states to ensure that activities within their jurisdiction respect the environment in which they are operating and prevent transboundary harm to other states.

If space debris is understood to be a space object, and if the OST is applied literally, then states do not have the legal right to remove debris caused by the space activities of other states. However, given the mounting threat posed to all states by increasing amounts of space debris, and the contamination of a res communis environment, a more flexible interpretation of the OST ought to be pursued. The adoption of OST language interpretation in a manner consistent with the original intention of the international community, pursuant to Article IX, circumvents the need to ratify a treaty amendment or the creation of a new treaty regime. Such widespread interpretation may also crystallize into CIL supporting the use of ADR by all space-faring states to the benefit of all.

Alexandra Chronopoulos is a recent graduate of the Norman Paterson School of International Affairs (NPSIA) at Carleton University where she specialized in the study of international organizations and global public policy. Her research interests lie in outer space policy and governance, particularly issues related to space debris, inter-state cooperation in space, and the intersections of international law and the private sector within the space domain. She previously held a position as a Strategic Analyst embedded within the Royal Canadian Air Force at the Department of National Defence in Ottawa, Canada and is currently embarking upon a new role at the European Space Policy Institute (ESPI) in Vienna, Austria. She can be found and contacted on LinkedIn at: <>.

Photo via Wikimedia Commons

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