3.1. Prohibition of the appropriation of outer space

Because of its very high level of recognition among States (UN COPUOS, 2017b) and its customary character (Hobe et al., Reference Hobe and De Man2017; von der Dunk, Reference von der Dunk2015), the 1967 OST became the central international legal source of the law of outer space. One of its key provisions is Article II, which states that “outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.”

For the opponents of space mining, this provision means that nothing in outer space might be ‘appropriated’ because, in their view, any extraction – whether by a State or a non-governmental entity – of any material from any celestial body necessarily implies a kind of such ‘appropriation’ (Volynskaja, Reference Volynskaja2016). Another chain of arguments is based on the differentiation between various forms of activities in outer space provided by Article I OST, which separates the freedoms of its “exploration” and “use,” also including “exploitation” of outer space (De Man, Reference De Man2017). If there are no constraints on the exploration of outer space, then any ownership of space minerals would imply the prevention of others from using the same matter; by this logic, only the use of outer space without property rights to space resources could correspond to international law (De Man, Reference De Man2017).

This thread of argumentation is considered to be further supported by the existence of the later adopted 1979 Agreement Governing the Activities of States on the Moon and Other Celestial Bodies (Moon Agreement). In line with this postulate, it prohibits, in its Article 11(3), that any “natural resources in place” shall become the property of any entity or person (De Man, Reference De Man2017). From this prohibition are exempted only undefined “samples” of minerals from celestial bodies, which may be used for scientific purposes, as well as “minerals and other substances” of celestial bodies used in “quantities appropriate for the support of the missions” of the States Parties of the Agreement (Article 6).

However, the purpose of space mining activities is considered to be neither any ‘appropriation’ of parts of outer space nor of space resources in situ. Instead, the sole aim of any such activities is their extraction, use and commercialization, without any territorial demands or titles as to the celestial bodies (or parts thereof) concerned (Mizushima et al., Reference Mizushima, Fujii and Ishido2017).

The argument, which sees in the use or exploitation of a space mineral by one subject a limitation of the same right of another subject, is difficult to contest by other means than analogy with space exploration. As has been recognized by the drafters of the OST in its Articles IX and XII, a purely scientific project in one area of outer space could de facto prevent research at the same site by a subject from another State. To avoid such situations, the Treaty pre-envisages a system of international consultations aimed at avoiding any harmful interference with operations.

It should also be stressed that the Moon Agreement has been ratified by only 18 States Parties (UN COPUOS, 2019b); thus, its limitations concerning space activities resulting from the common heritage principle are binding only upon its Parties, and it cannot constitute international customary law. Additionally, there is a Joint Statement of its States Parties dating from 2008 and proclaiming that the common heritage of mankind principle does not constitute an obstacle to space mining initiatives (UN COPUOS, 2008).

Finally, this liberal line of thought points to the legal regime of the High Seas under the 1982 UN Convention on the Law of the Sea (UNCLOS) and, in particular, to the regulation of fishing, which allows the States Parties, in principle, to freely fish on the High Seas. This is a relevant analogy with space resources. Article 87 UNCLOS grants States Parties of the treaty the freedom to fish on the High Seas, subject to specific conditions in “due regard for interests of other States in their exercise of the freedom of the high seas.” Furthermore, Article 116 UNCLOS postulates that “all States have the right for their nationals to engage in fishing in the high seas,” subject to their treaty obligations and the rights and duties of coastal States (Freestone, Reference Freestone2009; Wright et al., Reference Wright, Rochette, Blom, Currie, Durussel, Gjerde and Unger2016).

There are also discussions as to whether the term ‘celestial bodies’ should be redefined. Currently, according to the International Astronomical Union, known natural objects that can be found in the solar system include the Sun, the planets, the Moon, the moons of other planets, near-Earth objects, asteroids, comets, dwarf planets, trans-Neptunian objects and Kuiper Belt objects (Lyall & Larsen, Reference Lyall and Larsen2009). Discussions on these categorizations have resulted in proposals to exclude smaller asteroids under a minimum diameter from the term ‘celestial body’ (Marboe & Friedl, Reference Marboe, Friedl, Blount, Moro-Aguilar, Masson-Zwaan and Schrogl2019), which would eliminate those from the prohibition of appropriation.

3.2. Outer space as ‘province of all mankind’

According to Article I OST, the freedom of exploration and the use of the Moon and other celestial bodies are “the province of all mankind.” The Cologne Commentary on Space Law considers this rule as “one of the most important, but also of the most disputed provisions of the entire Outer Space Treaty” (Hobe et al., Reference Hobe, Schmidt-Tedd and Schrogl2009), and it concludes that the notion of “province of mankind” brings this lead provision of the Treaty “in line with the legal regulation of human activities in other common spaces, such as activities on the High Seas and the Deep-Sea Bed” (Hobe et al., Reference Hobe, Schmidt-Tedd and Schrogl2009).

The 1979 Moon Agreement reiterates the “province of mankind” principle (Article 4). However, the Moon, celestial bodies and their natural resources are additionally declared by Article 11(1) to be “the common heritage of mankind” (CHM). This principle can be understood as an idea of intergenerational equity in that it couples the preservation of the environment with its use by future generations (Jakhu et al., Reference Jakhu, Freeland, Hobe, Tronchetti, Hobe, Schmidt-Tedd and Schrogl2013). However, the Cologne Commentary refers to the fact that “there is no unique feature or specific meaning of the CHM in all its manifestations.” While different interpretations may be put forward, the proper meaning of the CHM can only be determined in the context of its use and for the purpose of the future applicable regulatory regime (Jakhu et al., Reference Jakhu, Freeland, Hobe, Tronchetti, Hobe, Schmidt-Tedd and Schrogl2013).

In the body of the Moon Agreement, in addition to CHM's relation to the prohibition of the appropriation of natural resources on celestial bodies in Article 11(3), this principle finds its expression in Article 11(5), which envisages the establishment of an international regime to govern the exploitation of these resources when “such exploitation is about to become feasible.” This obligation can be interpreted as a duty of its States Parties to make good faith efforts to convene an international conference and to negotiate for the purpose of reaching an agreement; “however, they would not be bound to reach an agreement on an international regime,” and the proposed international conference might even “reject the principle CHM, or give it a new and liberal scope” (Jakhu et al., Reference Jakhu, Freeland, Hobe, Tronchetti, Hobe, Schmidt-Tedd and Schrogl2013).

The modification mechanisms of both treaties (Article XV resp. 17) or the convening of an international conference as envisaged by Article 18 of the Moon Agreement have not yet been called upon. In 1994, 10 years after the entry into force of the Moon Agreement, the Resolution of the UN General Assembly A/RES/49/34 of 30 January 1995 took note of the recommendation of the UN COPUOS that the General Assembly, at its current session, in considering whether to revise the Moon Agreement, should not take any action (paragraph 42). The present discussions about the future international regime shall be described below.

3.3. Protection of the environment

Parallel to the questions of the appropriation of space resources and the future international regime, there are already several provisions of the UN space treaties that are relevant for the protection of the environment of outer space and that frame the way in which space ‘mining’ might be performed in the future. It can be stated, however, that those norms are of a general character and cover only a small part of the whole spectrum of space resources activities.

Article IX OST requires that States pursue studies of outer space, including the Moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination. At the same time, it obliges spacefaring nations to avoid adverse changes in the environment of the Earth resulting from the introduction of extra-terrestrial matter and, when necessary, to adopt appropriate preventative measures. The problem is the narrow scope of application of this obligation. A literal interpretation of the second paragraph limits the duty of States Parties to avoid harmful contamination only in the pursuance of “studies of outer space” and “space exploration.”

Second, the core element of the second paragraph is the concept of “harmful contamination” and the related duty upon States Parties to avoid it. However, it is not sufficiently precise as to which type of degradation of the outer space environment is prohibited and to what extent (Kramer, Reference Kramer2014). The presence of the term ‘harmful’ suggests at first that contamination is not per se prohibited, and thus that exploration activities are lawful even if, to a limited degree, contamination is caused (Lyall, Reference Lyall2010). In addition, the term ‘contamination’ lacks a definition. This seemingly leaves it open to cover both biological and non-biological kinds of contamination, thus encompassing the release of chemical and radioactive contaminants (Lyall, Reference Lyall2010). However, it hardly covers environmental modifications of different kinds, such as the alteration of the topography and geology of a celestial body, which could be a consequence of large-scale human activities such as space mining. The generic terms ‘appropriate measures’ and ‘where necessary’ further water down any rigorous content of the obligation.

These problems are partially remedied by the 1979 Moon Agreement, whose Article 7(1) concerns environmental protection. It widens the scope of Article IX OST by explicitly including the “exploitation” phase of space activities and by stating the duty of States Parties to “prevent the disruption of the existing balance” of the environment of celestial bodies. Such disruption can take place through the introduction of “adverse changes,” through its “harmful contamination through the introduction of extra-environmental matter,” or “otherwise.” Although the concept of the ‘harmful contamination’ of celestial bodies remains undefined, it is beyond doubt that these specifications give a more substantial meaning to the provision. As stated above, however, the Moon Agreement has a very limited number of States Parties.

More details about the implementation of Article IX OST and Article 7 of the Moon Agreement can be found in the Planetary Protection Policy formulated by the Committee on Space Research (COSPAR), a Scientific Committee of International Council for Science (ICSU) established in 1958. The updated policy (COSPAR, 2005) recommends the adoption of specific measures that should be taken before and after space missions (e.g., to meet specific criteria on spacecraft cleanliness). These measures are differentiated in the extent to which the specific target body (e.g., the planet or an asteroid) is of interest for understanding the origins and evolution of life (Hofmann, Reference Hofmann2010). The formal limitation of COSPAR standards consists in the fact that – as in Article IX OST – they concentrate on scientific research, not on commercial space activities; furthermore, they do not go beyond the protection of outer space and the Earth against biological contamination. It has been discussed, however, how the scope of the policy could be extended in the future.

4.1. General national space legislation protecting sustainability

As an example, the US national space law comprises the National Environmental Policy Act (United States, 1970), which must be complied with by space missions during their launch and re-entry phases. It requires the Federal Aviation Administration's Office of Commercial Space (FAA AST) to integrate environmental values into its decision-making processes concerning commercial launch or re-entry activities (FAA AST, 2019).

Other examples are the Russian 1993 Law on Space Activity (Russian Federation, 1993), which requests all participants in space activities to take any necessary measures in order to avoid any threat to the environment.

Environmental criteria are part of the licensing procedures inter alia the 1986 UK Act on Outer Space Activities (United Kingdom, 1986), the 1998 Australian Space Activities Act (Commonwealth of Australia, 1998, 2019), the 2005 Belgian Law on the Activities of Launching, Flight Operation or Guidance of Space Objects (Belgium, 2014), the 2006 Space Activities Act of The Netherlands (The Netherlands, 2006), the French Law on Space Activities (Article 4) of 2008 (France, 2008), the Austrian Act on Authorization of Space Activities and the Establishment of a National Space Registry of 2011 (Austria, 2011), the Danish Outer Space Act of 2016 (Denmark, 2016) and the 2018 Finnish Act on Space Activities (Finland, 2018).

The Government of Luxembourg prepared a general Draft Law on Space Activities in 2018, which is being discussed in Parliament within the present legislative period (for the current state of the legislation, see Chambre des Députés, 2019). The project contains provisions dealing with the protection of the environment; for example, if the space activity authorized by the respective Minister of Luxembourg would amount in a danger for a non-specified ‘environment’, the authorization can be withdrawn (Article 9). However, with the exception of launch activities and space object registration, space resources activities are exempted from the scope of this general Draft Law (Article 2).

4.2. Specific space resources legislation

In view of the planned intensity of space resources activities, first the USA and later Luxembourg adopted specific legislation devoted to these projects.

The 2015 US Commercial Space Launch Competitiveness Act (United States, 2015) made the USA the first country to have adopted a national regulatory framework for space mining activities. Its aim is to “facilitate commercial exploration for and commercial recovery of space resources by United States citizens” (§ 51302). The Act defines a “space resource” as an “abiotic resource in situ in outer space,” including minerals and water (§ 51301 (2)), and an “asteroid resource” as a “space resource found on or within a single asteroid” (§ 51301 (1)). Title IV of the Act authorizes citizens of the USA “to possess, own, transport, use, and sell the asteroid resource or space resource” that they obtain “in accordance with applicable law, including the international obligations of the United States” (§ 51303).

The Act does not contain any specific provision dealing with the sustainability of space resources activities. The National Environmental Policy Act (United States, 1970) is focused on launch and re-entry activities only. However, the commercial exploration and recovery of space resources by US citizens should be “consistent with the international obligations of the United States” (§ 51302 (a)). Consequently, the conditions of Article IX OST cannot be ignored.

The 2017 Law on the Exploration and Use of Space Resources of Luxembourg was inspired by the US model. The law was adopted on 27 July 2017 and entered into force on 2 August 2017. The legislation deals generally with “space resources” without making a distinction between space and asteroid resources. Article 1 of the Law declares that “space resources are capable of being appropriated.” Article 16 of the Law deals with the “responsibility for damage.” According to this provision, the operator is fully responsible for any damage caused at the occasion of the mission, including all preparatory works and duties.

The Law does not explicitly mention the environmental criteria among the conditions that have to be met when applying for the authorization of the space resources mission. Similarly to the US Law, Article 2(2) of the Law states that an authorized operator may only “carry out the activity” in space resources area “in accordance with … the international obligations of Luxembourg.” As in case of the USA, this obligation leads to Article IX OST and – even if only implicitly – to the obligation to comply with its planetary protection provisions.