The conception of space exploration and use as the province of all mankind is a founding principle of space law, enshrined in the Outer Space Treaty (OST) to ensure peace in outer space. In the years since the OST was drafted, the principle has retained its relevance over the years and finds expression in the Principle of Non-Appropriation, which prevents states from appropriating any celestial body in part or as a whole through claims of sovereignty, occupation or any other means. As settlements on celestial bodies move closer to reality, space law must find a place for these settlements or risk obsolescence. This paper argues for a rethinking of property rights, and eventually of sovereignty itself, in relation to the Principle of Non-Appropriation. It will explore what shape, if any, private property could take in a system where states are prohibited from claiming territory. It recommends a fresh look at the term ‘celestial body’ to apply only to larger bodies like planets and moons while excluding smaller bodies like asteroids and comets. Settlements on the newly defined celestial bodies could be defined as space objects to allow the launching states to maintain control over them. No existing state shall exercise jurisdiction over the settlements; rather an international body could grant private rights over plots of celestial bodies stopping short of absolute ownership. The paper further argues that in such a situation, the possibility of larger settlements declaring independence would have to be considered a legal possibility.