3. Non-Appropriation of the Moon and Other Celestial Bodies
12 Before the space flights, the Moon and other celestial bodies were considered res nullius; this meant that claims of sovereignty on the basis of an effective occupation were theoretically possible. However, already UN resolutions dealing with outer space activities preceding the Outer Space Treaty (eg UNGA Res 1721 [XVI] of 1961) declared outer space and other celestial bodies as not being subject to national appropriation and prepared the floor for changing their regime into res extra commercium.
13 The entry into force of the Outer Space Treaty turned this rule into a binding provision of universal international law. Article II OST provides for the ban of national appropriation of the Moon and other celestial bodies by claims of sovereignty, by means of use or occupation, or by any other means. Unfortunately, the adjective national opens the door for discussions whether an appropriation of the Moon or parts thereof by private natural or juridical persons other than States or international organizations is allowed.
14 Article 11 MA goes further: it prohibits any appropriation of the Moon, celestial bodies, or their natural resources; the addressees of this comprehensive ban are not only States and international organizations, but explicitly also non-governmental entities or natural persons. As the exploitation of natural resources of the Moon and other celestial bodies is about to become feasible, an international regime governing such exploitation shall be established among the States Parties of the Moon Agreement (Art. 11 (5) MA).
15 At present, there are two exceptions from the non-appropriation rule as formulated by the Moon Agreement: one of them regards the right to use minerals and other substances of celestial bodies in quantities appropriate for the support of space missions in the course of scientific investigations (Art. 6 (2) MA). The second one concerns the right to collect and removenot closely defined or quantifiedsamples of minerals and other substances from celestial bodies (Art. 6 (2) MA).
https://opil.ouplaw.com/display/10.1093/law:epil/9780199231690/law-9780199231690-e1198?d=%2F10.1093%2Flaw%3Aepil%2F9780199231690%2Flaw-9780199231690-e1198&p=emailA8olYPSiQpjo2&print#:~:text=13%20The%20entry%20into%20force,or%20by%20any%20other%20means.