The Outer Space Treaty and states’ obligation to remove space debris: a US perspective

Existing treaties and federal laws may be sufficient for the US to allow efforts to remove orbital debris. (credit: DARPA)

There is no denying of the fact that space debris is rapidly increasing and threatens the sustainable use of space by all. The implications of increased debris in space will be more severe for those countries, like the United States, that heavily depend upon space for their economic and strategic purposes.

The first known collision involving space debris occurred in space in 1996: Cerise, a French microsatellite orbiting at an altitude of 700 kilometer, and a fragment of space debris from an exploded third stage of an Ariane launcher collided.1 Debris in low-Earth orbit (LEO) has significantly grown since then. In 2007, the Chinese anti-satellite (ASAT) test created more than 2,000 new debris elements of trackable size in LEO.2 This was followed by the accidental collision in 2009 between Iridium 33 and Cosmos 2251, again creating more than 2,000 new debris elements.3 On February 3, 2015, a 20-year-old US military weather satellite exploded, and this created at least 43 new pieces of debris tumbling into different orbits around the Earth.4 It is estimated that, even without new launches, a collision is likely to happen in every five to ten years.5 The amount of space debris will continue to grow unless any remedial action is taken.6

The Kessler Syndrome is defined as the case where “two colliding objects in space generate more debris that then collides with other objects, creating even more shrapnel and litter until the entirety of LEO is an impassable array of super swift stuff. At that point, any entering satellite would face unprecedented risks of headfirst bombardment”.7 Kessler suggested that “the best way to avoid the exponential growth of the collisions was to reduce the number of non-operational spacecraft left in orbit”.8 The international study on the global space governance, carried out by an international group of over 80 experts, lends further support to Kessler’s suggestion. The study argues that the projections for orbital debris buildup are pessimistic, if satellites continue to use LEO without any regulation as to their placement and removal.9 Similarly, the European Space Agency (ESA) notes that active debris removal and compliance with post-mission disposal guidelines by newly-launched objects are essential to stabilize the growth of space debris.10 All these factors and opinions stress the necessity of space debris mitigation, specifically by active debris removal.

As the leading spacefaring nation, the US is greatly concerned with growing risks posed by space debris and, unsurprisingly, has been the world leader in debris mitigation efforts. This paper argues that no new legislation from the US Congress granting powers to the respective regulatory agencies to take steps toward active debris removal is required; both international law and the US national law vest those agencies with such powers.

Role of law and regulations in implementing technical solutions

International Law

The issue of space debris mitigation has not been explicitly addressed in the five United Nations (UN) treaties exclusively dealing with outer space and related activities.11 Nonetheless, several provisions of the Outer Space Treaty and the Liability Convention can be interpreted to demonstrate that they address debris mitigation, including active debris removal.

The first paragraph of Article I of the Outer Space Treaty provides that the exploration and use of outer space “shall be carried out for the benefit and in the interests of all countries, … and shall be the province of all [humankind]”.12 This implies that states have an obligation to mitigate debris, since space debris can certainly hinder this right of states to freely explore and use outer space. More specifically, Article IX of the Outer Space Treaty asserts:

In the exploration and use of outer space, … States Parties to the Treaty shall be guided by the principle of cooperation and mutual assistance and shall conduct all their activities in outer space … with due regard to the corresponding interests of all other States Parties to the Treaty. States Parties to the Treaty shall pursue studies of outer space, … and conduct exploration of them so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter and, where necessary, shall adopt appropriate measures for this purpose …13

Space debris of one state can endanger the space assets of other states. Thus, not taking necessary initiatives by the former to mitigate such debris will violate the principle of due regard enshrined in Article IX of the Outer Space Treaty. Furthermore, this provision imposes an obligation on States to, inter alia, pursue studies and conduct exploration of outer space “so as to avoid their harmful contamination”. Article IX also requires states to “adopt appropriate measures” to avoid harmful contamination of outer space. The presence of debris in outer space can arguably be considered as “harmful contamination” of this zone,14 and, therefore, states parties to the Outer Space Treaty must adopt appropriate measures, which may include active debris removal, to mitigate them.

According to Article VI of the Outer Space Treaty, states are responsible for their national space activities, whether carried out by government bodies or non-governmental entities.15 States need to authorize and continuously supervise such activities of their non-governmental entities. Article VII holds a launching state internationally liable to compensate for damage caused by its space object or component parts to another state party to the Outer Space Treaty or to its natural or juridical persons.16 The Liability Convention expands these provisions and further provides that liability to pay compensation is absolute if damage is caused on the surface of the Earth or to aircraft in flight.17 Exoneration from such liability is possible if it can be established that “the damage has resulted either wholly or partially from gross negligence or from an act or omission done with intent to cause damage on the part of a claimant State or of natural or juridical persons it represents”.18 For damage caused “elsewhere than on the surface of the Earth to a space object of [another] launching State or to persons or property on board such a space object”, liability to pay compensation arises if fault can be attributed to the launching State or of persons for whom it is responsible.19

The Liability Convention defines “launching state” as a state that launches or procures the launching of a space object, or from whose territory or facility a space object is launched.20 The Registration Convention contains the same definition.21 The launching or procurement of the launching of a space object by a private company is legally considered to be an action of the launching state of the nationality of that company.

It can, therefore, be submitted that, if space debris of a launching state or its private entity causes damage, the launching state must pay compensation to the victim state or its natural or juridical persons. It can also be submitted that, if a launching state does not constantly monitor and control its space debris and such debris causes damage to a space object of another state while in outer space, the launching state will be required to pay compensation to the latter, since the former is at fault by failing to continuously supervise its national space activities, whether carried out by government bodies or non-governmental entities or both.

In this respect, a crucial question arises as to whether or not space debris can be categorized as a “space object.” Article I(d) of the Liability Convention and Article I(b) of the Registration Convention define space object: “The term ‘space object’ includes component parts of a space object as well as its launch vehicle and parts thereof.”22 It is true that this definition does not mention “space debris.” It is also true that this definition has not differentiated “functional” objects from “non-functional” ones. Hence, it can be submitted that “space debris”, whether a non-functional object or a fragment of an object, falls within the definition of “space object.”23 It should be noted that a non-functional piece of Soviet satellite, Cosmos 954, was considered to be a space object, when it crashed into Canada and gave rise to the liability of Soviet Union, which paid C$3 million to Canada for causing damage on Canadian territory.24 Therefore, the launching state has a responsibility to continuously monitor its debris and, to avoid liability to pay compensation for damage caused by it, perform active debris removal.

Since the UN space treaties do not explicitly address the issue of space debris mitigation, several attempts at the international level have been made to address the same. Examples include the space debris mitigation guidelines of the Inter-Agency Space Debris Coordination Committee (IADC)25 and the UN Committee on the Peaceful Uses of Outer Space (UNCOPUOS).26 These two soft law instruments contain guidelines with respect to post-mission disposal. These guidelines are not legally binding. Nonetheless, several states follow these guidelines. For example, the debris mitigation standard practices of the US government are very similar to these guidelines and provide for post-mission disposal of space objects.27 In Austria, an authorization to conduct space activities shall be issued if, among other things: “appropriate provision has been made for the mitigation of space debris,” “the space activity does not cause harmful contamination of outer space or celestial bodies or adverse changes in the environment,” and “the operator has made provision for the orderly termination of the space activity.”28 Provision for space debris mitigation has to be made according to the state of the art and in due consideration of the internationally recognized space debris mitigation guidelines.29

In Canada, one of the conditions to obtain a license for remote sensing space systems is to have a system disposal plan, which is satisfactory to the concerned Minister and provides for, inter alia, “the protection of the environment, public health and the safety of persons and property.”30 Furthermore, there need to be arrangements satisfactory to the respective Minister “relating to the guarantee of the performance of the licensee’s obligations under the system disposal plan.”31 Likewise, in France, any authorization to perform space operations may include requirements to ensure, inter alia, the safety of persons and property, the protection of public health and the environment, particularly to limit risks related to space debris.32 The website of the UN Office for Outer Space Affairs (UNOOSA) contains a compendium of space debris mitigation standards adopted by states and international organizations.33

It can be argued that two international law principles mainly related to environmental protection, which are binding on states, impose an obligation on states to actively remove debris. It is an established customary international law principle that states have a sovereign right to exploit their own resources, and the simultaneous responsibility to ensure that activities within their jurisdiction or control do not cause damage to the environment of other states or of areas beyond the limits of national jurisdiction.34 Therefore, states possess the sovereign right to conduct space activities, but, concurrently, are under an obligation to ensure that such activities do not cause damage to outer space, i.e. areas beyond the limits of its jurisdiction.35 The continuous presence of space debris is injurious to the outer space environment and, thus, States need to, inter alia, actively remove debris for which they are responsible.

The general international law principle of preventive action imposes an obligation on States to adopt measures to prevent “damage to the environment, and otherwise to reduce, limit or control activities that might cause or risk such damage”.36 In the Iron Rhine Arbitration, the arbitral tribunal of the Permanent Court of Arbitration asserted, “Environmental law and the law on development stand not as alternatives but as mutually reinforcing, integral concepts, which require that where development may cause significant harm to the environment there is a duty to prevent, or at least mitigate, such harm … This duty … has now become a principle of general international law”.37 Interestingly, in the Pulp Mills case, the International Court of Justice pointed out “the principle of prevention, as a customary rule.”38 Hence, the principle of prevention or preventive action requires states to actively remove debris created by their activities.

United States national law

The US national law provides for the mitigation of space debris. As noted, the US has its own debris mitigation standard practices: U.S. Government Orbital Debris Mitigation Standard Practices.39 These standard practices “encompass all program phases, from initial concept development to space hardware disposal, focusing on: the minimization of intentional debris releases and the occurrence of accidental explosions; the avoidance of hazardous collisions; and, responsible disposal of space hardware.”40 These standard practices serve as the overall US government “space debris mitigation technical guidance and as the foundation for specific orbital debris mitigation requirements issued by individual [US] Government departments and agencies”, including the Federal Aviation Administration (FAA) and the Federal Communications Commission (FCC).41

Section 25.114(d) of Title 47 of the Code of Federal Regulations (entitled “Applications for space station authorizations”) states that each application for space station authorizations submitted to the FCC must contain information in narrative form related to, among other things, post-mission disposal. The application must, inter alia, contain:

  • “A statement that the space station operator … has assessed and limited the probability of the space station becoming a source of debris by collisions with small debris or meteoroids that could … prevent post-mission disposal”;42
  • “A statement that the space station operator has assessed and limited the probability of accidental explosions … after completion of mission operations”;43 and
  • “A statement detailing the post-mission disposal plans for the space station at end of life, including the quantity of fuel—if any—that will be reserved for post-mission disposal maneuvers. For geostationary-Earth orbit space stations, the statement must disclose the altitude selected for a post-mission disposal orbit and the calculations that are used in deriving the disposal altitude. The statement must also include a casualty risk assessment if planned post-mission disposal involves atmospheric re-entry of the space station. In general, an assessment should include an estimate as to whether portions of the spacecraft will survive re-entry and reach the surface of the Earth, as well as an estimate of the resulting probability of human casualty. Applicants for space stations to be used only for commercial remote sensing may, in lieu of submitting detailed post-mission disposal plans to the [FCC], certify that they have submitted such plans” to the National Oceanic and Atmospheric Administration (NOAA) for review.44

Similar information must be contained in the applications for an experimental authorization involving a satellite system45 and the pre-space notifications by the license grantee of each amateur space station.46 The FCC regulations require the relocation of a space station authorized to operate in geostationary orbit “at the end of its useful life, barring catastrophic failure of satellite components, to an orbit with a perigee with an altitude of no less than: 36,021 km + (1000·CR·A/m) where CR is the solar radiation pressure coefficient of the spacecraft, and A/m is the Area to mass ratio, in square meters per kilogram, of the spacecraft”.47

With respect to licenses issued for the operation of private remote sensing space systems, the license must specify that the licensee shall, inter alia, “upon termination of operations under the license, make disposition of any satellites in space in a manner satisfactory to the President.”48 Therefore, one of the conditions of such license is that the licensee “shall dispose of any satellites operated by the licensee upon termination of operations under the license in a manner satisfactory to the President. The licensee shall obtain approval from the Assistant Administrator [for Satellite and Information Services, NOAA] of all plans and procedures for the disposition of satellites as part of the application process.”49 In this regard, the license applicant needs to “submit a plan for post-mission disposition of any remote-sensing satellites owned or operated by the applicant. If the satellite disposition involves an atmospheric re-entry the applicant must provide an estimate of the total debris casualty area of the system’s components and structure likely to survive re-entry.”50

These post-mission disposal requirements are similar to the IADC and UN COPUOS mitigation guidelines. A list and brief description of US national laws and policies concerning space debris mitigation standards can be found in a working paper of the UN COPUOS Legal Subcommittee.51


Undoubtedly, the US is very much concerned with increasing risks posed by space debris and thus has been the world leader in space debris mitigation efforts. Moreover, for the purpose of ensuring compliance with its international obligations, the current US regulatory regime imposes conditions to obtain an authorization or license to conduct any type of space activity. Some of the conditions relate to space debris mitigation measures that ought to be taken by space system operators. These measures include the de-orbiting of satellite at end of life (25-year rule) and would possibly include other techniques of active debris removal. There is no need for any new legislation from the US Congress to give powers to the concerned regulatory agencies, including FAA, FCC, and NOAA, to take steps toward active debris removal.


  1. See Mark Ward, “Satellite injured in space wreck”, New Scientist 2044 (24 August 1996).
  2. See Leonard David, “China’s Anti-Satellite Test: Worrisome Debris Cloud Circles Earth”, (2 February 2007).
  3. See Brian Weeden, “2009 Iridium-Cosmos Collision”, SWF Fact Sheet (10 November 2010).
  4. See Brian Berger & Mike Gruss, “20-year-old Military Weather Satellite Apparently Exploded in Orbit”, SpaceNews (27 February 2015).
  5. See e.g. Ram S Jakhu & Joseph N Pelton, eds, Global Space Governance: An International Study (Springer, 2018) Chapter 14 [forthcoming].
  6. See European Space Agency, “Space Debris: Active Debris Removal” [ESA, “ADR”].
  7. Michelle La Vone, “Kessler Syndrome”, Space Safety Magazine.
  8. Ibid.
  9. See Jakhu & Pelton, supra note 5, Chapter 14.
  10. See ESA, “ADR”, supra note 6. The ESA considers that, although the IADC mitigation measures will reduce the growth of space debris, “long-term proliferation is still expected, even with full mitigation compliance, and even if all launch activities are halted. This is an indication that the population of large and massive objects has reached a critical concentration in LEO”. Ibid.
  11. The five UN treaties are: Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, 27 January 1967, 610 UNTS 205 [Outer Space Treaty]; Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched Into Outer Space, 22 April 1968, 672 UNTS 119 [Rescue Agreement]; Convention on International Liability for Damage Caused by Space Objects, 29 March 1972, 961 UNTS 187 [Liability Convention]; Convention on Registration of Objects Launched into Outer Space, 6 June 1975, 1023 UNTS 15 [Registration Convention]; Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, 5 December 1979, 1363 UNTS 3 [Moon Agreement].
  12. Outer Space Treaty, supra note 12, art I.
  13. Ibid, art IX.
  14. See e.g. Vladlen S Vereshchetin, “Outer Space” in Max Planck Encyclopedia of Public International Law, at paras 19-21; Sergio Marchisio, “Article IX” in Stephan Hobe, Bernhard Schmidt-Tedd & Kai-Uwe Schrogl, eds, Cologne Commentary on Space Law (Köln: Carl Heymanns Verlag, 2009) vol 1, 169 at 176-77.
  15. Outer Space Treaty, supra note 12, art VI.
  16. Ibid, art VII.
  17. Liability Convention, supra note 12, art II.
  18. Ibid, art VI(1).
  19. Ibid, art III.
  20. Ibid, art I(c).
  21. Registration Convention, supra note 12, art I(a).
  22. Liability Convention, supra note 12, art I(d); Registration Convention, supra note 12, art I(b).
  23. See Lesley Jane Smith & Armel Kerrest, “Article I (Definitions)” in Stephan Hobe, Bernhard Schmidt-Tedd & Kai-Uwe Schrogl, eds, Cologne Commentary on Space Law (Köln: Carl Heymanns Verlag, 2013) vol 2, 104 at 114-15.
  24. DISINTEGRATION OF COSMOS 954 OVER CANADIAN TERRITORY IN 1978, Canadian Department of External Affairs Communique No 27 (2 April 1981).
  25. Inter-Agency Space Debris Coordination Committee, IADC Space Debris Mitigation Guidelines, IADC-02-01, Revision 1 (September 2007).
  26. UN, Office for Outer Space Affairs, Space Debris Mitigation Guidelines of the Committee on the Peaceful Uses of Outer Space (Vienna: UN, 2010).
  27. See U.S. Government Orbital Debris Mitigation Standard Practices, 2001 [US Debris Mitigation Standards].
  28. Austrian Federal Law on the Authorisation of Space Activities and the Establishment of a National Space Registry (adopted by the National Council on 6 December 2011), § 4(1).
  29. Ibid, § 5.
  30. Remote Sensing Space Systems Act, SC 2005, c 45, s 9(1)(a).
  31. Ibid, s 9(1)(b).
  32. LOI no. 2008-518 du 3 juin 2008 relative aux op&ecute;rations spatiales, NOR : ESRX0700048L, art 5.
  33. See UNOOSA, “Compendium of space debris mitigation standards adopted by States and international organizations”.
  34. See Legality of the Threat or Use of Nuclear Weapons Case, Advisory Opinion, [1996] ICJ Rep 226 at 241-42. See also “Report of the Commission to the General Assembly on the work of its fifty-third session” (UN Doc A/56/10) in Yearbook of the International Law Commission 2001, vol 2, part 2 (New York: UN, 2007) at 148 (UNDOC.A/CN.4/SER.A/2001/Add.1 (Part 2)); Award in the Arbitration Regarding the Iron Rhine Railway (Belgium v Netherlands) (2005), ICGJ 373 at para 222 (Permanent Court of Arbitration) [Iron Rhine Arbitration]. The Trail Smelter arbitration gave birth to this established customary international law principle. See Trail Smelter Arbitration (United States v Canada) (1938), 3 RIAA 1905 at 1965, reprinted in 33 AJIL 182 (Arbitrators: Charles Warren, Robert AE Greenshields, Jan Frans Hostie).
  35. See also Marchisio, supra note 15 at 171, 177.
  36. Philippe Sands et al, Principles of International Environmental Law, 3rd ed (New York: Cambridge University Press, 2012) at 200 [footnotes omitted].
  37. Iron Rhine Arbitration, supra note 35 at para 59.
  38. Case concerning Pulp Mills on the River Uruguay (Argentina v Uruguay), [2010] ICJ Rep 14 at 55, para 101.
  39. US Debris Mitigation Standards, supra note 28.
  40. Compendium of space debris mitigation standards adopted by States and international organizations: Contribution of the United States of America, UNCOPUOS Legal Subcommittee, 43rd Sess, UN Doc A/AC.105/C.2/2014/CRP.15/Add.1 (2014) at 2.
  41. Ibid.
  42. 47 CFR § 25.114(d)(14)(i) (2016).
  43. 47 CFR § 25.114(d)(14)(ii) (2016).
  44. 47 CFR § 25.114(d)(14)(iv) (2016).
  45. 47 CFR § 5.64(b) (2016).
  46. 47 CFR § 97.207(g)(1) (2016).
  47. 47 CFR § 25.283(a) (2016).
  48. 51 USC § 60122(b)(4) (2015).
  49. 15 CFR § 960.11(b)(12) (2017).
  50. 15 CFR Part 960, Appendix 1, s V(C) (2017).
  51. See UN Doc A/AC.105/C.2/2014/CRP.15/Add.1, supra note 41.