Space exploration has now developed into an area of global economic growth, with the involvement of superpower states and various private companies. The rapid advancement of space technology over the past decade has enabled non-state actors, including private companies such as SpaceX, Blue Origin, and Virgin Galactic, to take on central roles in satellite launches, orbital infrastructure development, space tourism, and moon resource exploitation plans. The development of space commercial activities certainly requires adjustments to the international space law regime. Uncertainty in regulations regarding ownership, exploitation rights, and the distribution of space resource benefits (benefit-sharing mechanism) can lead to risks of inequality and potential conflicts. Additionally, the different principles of “freedom of exploration” in the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space of 1967 (Outer Space Treaty) and “common heritage of mankind” in the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies of 1979 (Moon Agreement) further complicate the achievement of global consensus. Hence, this article explores the tension between the principle of freedom of exploration and the common heritage of mankind toward space resources, arguing that lessons from the law of the sea may offer a pathway toward a more equitable framework for governing space resources. This represents an attempt to harmonize these principles to create a space legal regime that is equitable, sustainable, and inclusive for all countries.
Freedom of Exploration in the Outer Space Treaty
The international space law regime recognizes the principle of freedom of exploration as stated in Article 1 of the Outer Space Treaty. The exploration and use of outer space, including the moon and other celestial bodies, is free and open to all states without discrimination of any kind and must be carried out in the interests of all mankind. States have the right to conduct scientific research freely and are encouraged to cooperate internationally in this process. Furthermore, Article 2 of the Outer Space Treaty also establishes the principle of non-appropriation, whereby outer space and celestial bodies cannot be claimed by any state as its property.
Although the principles of freedom of exploration and non-appropriation contained in the 1967 Outer Space Treaty promote the values of equality and open access, their implementation is highly dependent on the technological and economic capacities of each state—which in practice perpetuates the concept of “first come, first served,” thereby strengthening the dominance of developed states in space exploration. Furthermore, while the Outer Space Treaty explicitly prohibits territorial sovereignty claims based on the principle of non-appropriation, there is debate over the legality of ownership of extracted resources. In practice, the principle of non-appropriation has shifted with technological advances, with the United States claiming the moon rocks from the Apollo missions as state property, as well as similar moves by the Soviet Union, which demonstrates the emergence of consistent state practices in recognizing ownership over the results of space resource extraction. The absence of significant objections from the international community has the potential to establish a new pattern of customary international law practice. This development risks creating structural inequality for developing countries that do not have access to space technology, thereby further excluding them from opportunities to utilize space resources globally.
In practice, the principle of freedom of exploration is widely utilized by developed states with sufficient technological capacity and economic resources, such as the United States, Russia, China, and European Union states. Developing states, which are still technically and financially behind, realistically do not have the same opportunities to actively participate in space exploration in this New Space era. As a result, the principle of freedom of exploration creates an illusion of formal equality but fails to achieve substantive justice, as real opportunities remain concentrated among established states and corporations in the space sector. Thus, the freedom of exploration as stated in the 1967 Outer Space Treaty tends to reinforce the global status quo of inequality rather than address such disparities.
Common Heritage of Mankind in the Moon Agreement
The international space law regime also recognizes the principle of common heritage of mankind, which is introduced more explicitly in Article 11(1) of the Moon Agreement. The article states that the moon and its resources are the common heritage of mankind. The article emphasizes the prohibition of unilateral claims of national sovereignty, use, or occupation of the moon and other celestial bodies, and requires the establishment of an international regime to regulate the exploration and utilization of space resources in a fair and non-discriminatory manner. This balances the freedom of exploration with the obligation to share the benefits of exploration, ensuring that advancements in space technology do not widen the gap between developed and developing states.
In this case, the principle of common heritage of mankind is considered a more advanced principle than the principle of res communis because the principle of common heritage of mankind emphasizes regulation through an international regime, which is carried out for the common good and accompanied by a fair distribution of benefits.
The principle of common heritage of mankind, which is explicitly formulated in the 1979 Moon Agreement, has not gained widespread international acceptance and is even considered a failed international agreement. Many states, including those with significant space capabilities such as the United States, Russia, and China—also known as “the Big Three”—have not signed, acceded to, or ratified this agreement. The absence of a specialized international institutional structure capable of regulating and ensuring the fair distribution of moon resources exploration outcomes has further hindered the full implementation of the principle of the common heritage of mankind. Developing states, which would be the most benefited if the principle of the common heritage of mankind were implemented, have not received tangible benefits. As a result, the principle of the common heritage of mankind remains normative and idealistic due to the lack of adequate political and institutional support.
The Difference between Freedom of Exploration and Common Heritage of Mankind
According to Article 31(1) of the 1969 Vienna Convention on the Law of Treaties (VCLT), a treaty shall be interpreted in the light of the ordinary meaning of its text, in the context of the object and purpose of the treaty. Terminologically, the word “freedom” in the principle of freedom of exploration tends to emphasize the freedom of states to use an area without restrictions on sovereignty, ownership, or joint supervision. Meanwhile, the term “common” in the principle of common heritage of mankind tends to indicate that the territory or resources in question are “commonly owned” by humanity, not by any single state, and therefore their use must be collectively regulated for the common good. Conceptually, the two principles have fundamental differences, with freedom of exploration emphasizing openness and non-discrimination (Article 1 of the 1967 Outer Space Treaty), while common heritage of mankind also emphasizes equitable distribution and collective governance (Article 11(7) of the 1979 Moon Agreement).
Article 31(2) of the VCLT clarifies that “context” includes not only the treaty’s text, preamble, and annexes, but also any related agreement made by all parties and any instrument made by one or more parties—which is also accepted by the others as related to the treaty. In addition, Article 31(3) of the VCLT emphasizes that interpretation must also take into account the agreement and practice of the parties after the treaty was made, as well as other relevant provisions of international law. In this context, the interpretation of the principle of freedom of exploration and the common heritage of mankind must be seen through the development of state practices and international legal instruments related to outer space resources. The practice of space exploitation encompassed by freedom of exploration has the potential to create inequality between developed and developing countries in access and utilization of these resources. However, the difference between the principle of freedom of exploration and the common heritage of mankind reflects the normative tension between freedom and justice in the management of outer space, while also marking a shift in discourse from a liberal economic approach to a communal economic approach in international law.
Lessons from the Law of the Sea
As a reflection, the international law of the sea, particularly through the 1982 United Nations Convention on the Law of the Sea (UNCLOS), provides an important perspective in understanding the tension between the principles of freedom of exploration and common heritage of mankind in the context of outer space. Under Article 87 of UNCLOS, the principle of freedom of the sea allows for freedom of navigation and exploration in the high seas, similar to the principle of freedom of exploration in the Outer Space Treaty. However, the exploitation of deep-sea mining in the Area is strictly regulated by the provisions of the common heritage of mankind as outlined in Chapter XI of UNCLOS. These provisions are accompanied by the establishment of the International Seabed Authority (Articles 156-185 of UNCLOS), an international body authorized to regulate, grant permits, and distribute the benefits of deep-sea mining activities fairly. This demonstrates that the principle of the common heritage of mankind can be implemented concretely when supported by adequate institutionalization and mechanisms. Thus, as a reflection of the international legal regime of the sea, the principle of the common heritage of mankind in the context of outer space requires a similar international institution that guarantees equal participation and fair distribution of benefits, as well as addresses structural inequalities between developed and developing states in space resources exploration.
