24 Sep 2020

Of robots and law in space

Michelle Hanlon of the Center for Air and Space Law examines how laws governing our activities in space relate to the fast-growing field of robotics

Nasa's Perseverance, the largest, most complex rover ever sent to Mars, launched successfully on 30 July

Nearly 51 years ago, we watched in amazement as Neil Armstrong and Buzz Aldrin took humanity’s first off-world footsteps when they descended from their lunar module to the lunar surface. Few know that these human steps were preceded by numerous robotic missions sent by both the United States and the Soviet Union to provide scientists and engineers with a better understanding of the environment into which they intended to land astronauts. In addition to being technology demonstrators for landing techniques, these early missions generally provided photographic data, temperature and radar reflectivity readings.

Although humans have not returned to the Moon since the 1972 Apollo 17 mission, a number of robotic spacecraft and vehicles have made the journey, from the Soviet Luna 24 that returned a lunar sample in 1976 to China’s Chang’e 4. The Chang’e 4 achieved humanity’s first soft landing on the far side of the Moon in 2019 carrying Yutu-2, a rover that continues to return scientific data. While a human return is planned as early as 2024, robots will continue to play a very significant role in the exploration of space and the utilisation of space resources. Not only have both robotic and avatar technologies advanced exponentially,1 the cost, both financial and otherwise, of supporting a robot in space or another celestial body is markedly less than is needed to support a human. Moreover, with breakthroughs in the development and use of “miracle materials” like graphene2 lowering the cost of lightweight and durable materials, it will also be markedly cheaper to launch a robot than a human. The savings are widespread: lower mass means less propellant expenditure, sustainment can consist solely of electricity and with the threat of loss of life absent, less robust designs and testing can be used.

Indeed, one can easily picture a future wherein, whether on the lunar surface, the surface of an asteroid or on another celestial body, a fleet of robots – rather than humans – are conducting scientific experiments, analysing surface materials for potential utilisation, or even preparing sites for human habitation or work. With this in mind, it’s important to consider what laws would apply with respect to the activities of these robots. In particular, it must be emphasised that space law imposes greater obligations and responsibilities on states in respect of the activities of their nationals than is required in the terrestrial realm.

What happens if one robot damages another?

At present, the Moon remains mainly void of robotic activity. The Chinese Chang’e 4 lander and its Yutu-2 have been exploring the far side of the Moon since January 2019,3 but, while there are numerous sites that contain invaluable cultural heritage,4 it still remains fairly uncomplicated to avoid interference with the activities of others. However, as human presence on the Moon continues to expand, it becomes increasingly likely that such interference, and damage, will occur. What happens if one robot damages another?5

The Outer Space Treaty

There are four widely ratified conventions which govern activities in space.6 Negotiated in the 1950s and 1960s, the first, the Outer Space Treaty,7 enshrines two foundational principles: (1) the common interest in the exploration and use of outer space; and (2) the freedom of that exploration. To that end, it makes clear that neither the Moon nor any other celestial bodies shall be “subject to national appropriation by claim of sovereignty.”8 It also requires, among other things, that States Parties to the treaty pursue activities in outer space “in accordance with international law, including the Charter of the United Nations.”9

Importantly, Article VI makes it quite clear that all States Parties “bear international responsibility for national activities in outer space . . . whether such activities are carried on by government agencies or by non-governmental agencies . . . [and] the activities of non-governmental entities in outer space . . . shall require authorisation and continuing supervision by the appropriate State Party to the Treaty.”10 This language gives rise to four specific responsibilities: First, “State activities in outer space [must] comply with” the terms and conditions of the Outer Space Treaty.11 Second, the State has a “[d]uty to assure that nongovernmental national space activities comply with the Treaty.”12 Third, the State also has a duty “to subject non-governmental space activities to authorisation and continuing supervision.”13 Finally, the State assumes direct “responsibility for non-governmental space activities.”14 So although the Outer Space Treaty appears to only govern activities of States in space, States are in turn responsible for assuring their nationals act in a manner that meets its obligations.

Another point made very clear in the Outer Space Treaty and reconfirmed in the following Conventions is that each State Party “that launches or procures the launching of an object into outer space . . . and from whose territory or facility an object is launched, is internationally liable for damage to another State Party.”15 The breadth of this language is notable. The State remains responsible for any object it launches into space. There is no differentiation made between launchers and payload, nor based on destination or mission. If a State, or its national, launches anything into outer space, including any type of robot, it is responsible for that object and liable for any damage it causes.16

The Liability Convention

This burdensome responsibility is reinforced by the Liability Convention,17 according to which the “launching State” is liable for damage caused by its space object. Liability is absolute if damage occurs on Earth or to aircraft in flight, but is fault-based if damage occurs elsewhere.18 The definition of “launching State” parallels the language used in the Outer Space Treaty and thus also includes the “State which launches or procures the launching of a space object; . . . [and the] State from whose territory or facility a space object is launched.”19 While the term “space object” is not defined, extrapolating from the plain language of Article VI of the Outer Space Treaty, it must mean any object that is launched into outer space.

The Registration Convention

As a logical antecedent to the burden of liability, Article VIII of the Outer Space Treaty references a “registry” of objects launched into space to be maintained by each State Party and indicates that the State “shall retain jurisdiction and control over such object while in outer space.”20 This registration process is further detailed in the Registration Convention.21 The salient point is that ownership – and its attendant responsibility – is not affected by the fact that an object is in space. Nevertheless, the registration requirement is intended more to support situational awareness in space than it is to affirm ownership.

In sum, applying both Articles VI and VII of the Outer Space Treaty, the Liability Convention and the Registration Agreement, a State Party is responsible, or could be held responsible, for any damage caused by a robot or rover if the robot is:

  • its own
  • owned by its national
  • constructed by its national
  • operated by its national
  • carrying an instrument developed by it
  • carrying an instrument developed by its national
  • one for which it may be considered a launching State, that is a robot:
    • that was launched from its territory
    • that was launched from its facility
    • whose launch was procured by it or its national
    • that it or its national launched

Under current law, even the sale of a space object from one state or entity to another will not absolve a launching State from its treaty imposed liability. This is an especially important consideration given that when two or more States may be considered the launching State, they will be “jointly and severally liable for any damage caused.”22 Thus, given a robot built by a private company based in Japan, purchased by a private company based in France and launched by a US launch vehicle from New Zealand, Japan, France, the US and New Zealand could be jointly and severally liable for any damage caused.

The foregoing discussion demonstrates that a State may be held liable for damage caused by an object – or robot – in numerous circumstances based on its responsibility for its national or its status as a launching State. Liability also arises under customary international law, wherein it is generally recognised that an illegal act, or the breach of an international obligation, will give rise to a responsibility to repair, or make reparation.23 That being said, liability is not necessarily absolute. The victim of damage will have to show either that the damage occurred as a result of the fault of the accused perpetrator, or that an international legal obligation has been breached.

The Outer Space Treaty contains at least three relevant international legal obligations, breach of which could also give rise to liability. These are encapsulated in Article IX, which indicates, in pertinent part, that State Parties shall: 1) “conduct all their activities in outer space including the Moon and other celestial bodies, with due regard to the corresponding interests of all other States”; 2) “conduct exploration of them so as to avoid their harmful contamination”; and 3) refrain from activities which “would cause potentially harmful interference with activities of other States.” 24 Thus, a State or entity whose equipment is damaged by the activity of a robot from another State or entity has recourse against:

  • the entity whose robot caused the damage, whether a State or a private entity;
  • the State or States where the private entity or entities claim nationality as part of the international responsibility of that State pursuant to Article VI;
  • the State or States where the private entity or entities are nationals for failure to assure that the national activities were carried out in conformity with the Outer Space Treaty as required by Article VI;
  • the State or States where the private entity or entities are nationals for failure to adequately authorise and supervise that entity as required by Article VI;
  • the launching States pursuant to Article VII;
  • the State or States where the private entity or entities are nationals for failure to act with due regard to the corresponding interests of all other States; and
  • the State or States where the private entity or entities are nationals for failure to avoid the harmful interference.

Dispute resolution

Should damage occur, or an international obligation be violated, with respect to a space object, the Liability Convention sets forth the dispute resolution process. First, the State which suffers damage “or whose natural or juridical persons suffer damage may present to a launching State a claim for compensation for such damage”25 through “diplomatic channels.”26 Note that claims must be made at the State level, and can be made against any launching State. If diplomatic negotiations prove fruitless after one year, the parties “shall establish a Claims Commission.27 Each State will select one member of the Commission, and those two members will select a third, who will become the Chair.28 The Commission will have one year to render a decision which shall be final and binding but only if the parties have agreed. “[O]therwise the Commission shall render a final and recommendatory award, which the parties shall consider in good faith.”29 This process, as cumbersome as it appears, has yet to be implemented.

The Rescue and Return Agreement

It is worth noting that the Rescue and Return Agreement30 deals primarily with the rescue of human astronauts. Nonetheless, it does require that any “objects launched into outer space or its component parts found beyond the territorial limits of the launching authority shall be returned to or held at the disposal of representatives of the launching authority.”31 The context of the Return and Rescue Agreement suggests that it is intended to apply only to space objects that are found on Earth, however, this particular provision is vague and its terms have yet to be tested.

Space needs robots. However, it is a hostile, complex environment, both physically and legally. What is unavoidable is the fact that accidents will happen in space, most likely between robots before they occur between humans. Under current space law, which is rooted in sovereign activity and responsibility, simple accidents could quickly escalate into diplomatic quagmire. It is imperative that companies and States clarify, standardise and generally rethink responsibility, liability and dispute resolution.

Michelle Hanlon is Co-Director of the Center for Air and Space Law

1. Shiho Takezawa & Hiromi Horie, Space Exploration’s Next Frontier: Remote- Controlled Robonauts, Bloomberg.com (May 16, 2020), available online.
2. See Henry Hanlon, Analysis of the Materials and Energy Cost to Manufacture Graphene by Roll-Based Chemical Vapor Deposition, (May 8, 2020)(unpublished B.S. Thesis, Massachusetts Institute of Technology)(on file with author).
3. China’s Chang’e-4 Probe Survives 500 Earth Days on Moon’s Far Side, Xinhuanet.com (May 17, 2020).
4. Such sites include where Luna 2 hard-landed on the Moon in 1959, marking themfirst time a human-made object ever reached another celestial body, and the Sea of Tranquility, host to numerous objects that memorialise the Apollo 11 mission (which delivered the first humans to ever set foot on another celestial body).
5. One can envision an instance where damage is caused directly, for example when one robot impacts and damages or otherwise incapacitates another. However, damage can also be indirect. Lunar dust is abrasive and makes the lunar environment a difficult one in which to operate, thus even approaching too close to another robot could cause irreversible damage. “Problems were experienced during Lunar Roving Vehicle (LRV) excursions, with much dust being kicked-up and covering exposed areas . . . leading to increased friction at mechanical surfaces. The resulting abrasive effect of dust increased wear and tear, which significantly limited the lifetime of surface equipment.” See Otis R. Walton, Adhesion of Lunar Dust, NASA/CR-2007-214685 (Apr. 2007), available online.
6. A fifth treaty, the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, 5 December 1979, 1363 UNTS 3 (entered into force 11 July 1984), is not discussed as it has only been ratified by eighteen countries. Significantly, it has not been ratified by those considered to be the “major” spacefaring countries, the United States, Russia and China. Comm. on the Peaceful Uses of Outer Space, Status of International Agreements relating to activities in outer space as at 1 January 2019, U.N. Doc. A/AC.105/C.2/2019/CRP.3 (2019).
7. 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 (entered into force 10 October 1967) [Outer Space Treaty].
8. Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, art. II, Jan. 27, 1967, 18 U.S.T. 2410, 610 U.N.T.S. 205 [hereinafter Outer Space Treaty].
9. Id., art. III.
10. Id., art. VI.
11. Bin Cheng, Article VI of the 1967 Space Treaty Revisited: “International Responsibility,” “National Activities,” and “The Appropriate State,” 26 J. SPACE L. 7, 13
12. Id.
13. Id.
14. Id. at 14.
15. Id., art VII.
16. The term “outer space” is not defined in any of the treaties or elsewhere in international law, and indeed, the delineation between air and space continues to be debated by the international community. See On Its Fifty-First Sess., Matters relating to the definition and delimitation of outer space Historical summary on the consideration of the question on the definition and delimitation of outer space, U.N. Doc. A/AC.105/769 (Jan. 18, 2002).
17. Convention on the International Liability for Damage Caused by Space Objects, Mar. 29, 1972, 24 U.S.T. 2389, 961 U.N.T.S. 187 [Liability Convention].
18. Id., arts. II, III.
19. Id., art. I(c).
20. Id., art. VIII.
21. Convention on Registration of Objects Launched into Outer Space, 6 June 1975, 1023 UNTS 15 (entered into force 15 September 1976).
22. Liability Convention, supra note 17, art. V.
23. Chorzów Factory Case (Ger. v. Pol.), Merits), 1928 P.C.I.J., (Ser. A) No. 17, at 47 (Sept. 13).
24. Outer Space Treaty, supra note 5, art. IX.
25. Liability Convention, supra note 17, art. VIII.
26. Id., art. IX.
27. Id., art. XIV.
28. Id., art. XV.
29. Id., art. XIX.
30. 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 (entered into force 3 December 1968).
31. Id., art. 5.3.


This content is available to subscribers only. To continue reading...

Sign in to your account

Take a one-month free trial

If you aren't a subscriber, please sign up for a one-month free trial to access all Robotics Law Journal content, including:

  • All premium online content
  • Daily newsletters
  • Breaking news alerts

If you require further information, please email subscriptions@roboticslawjournal.com or contact call us on +44 (0) 20 7193 5801.