Human Nature, Escape Velocity, and the Line Between Chattel and Territory in Outer Space: A Criterion for Appropriability of Natural Celestial Objects

The Outer Space Treaty’s non-appropriation principle leaves unresolved a fundamental definitional question: where lies the boundary between a natural object small enough to be appropriable in toto as chattel and one large enough to constitute non-appropriable celestial territory? Existing proposals—arbitrary size thresholds, technology-dependent tests of movability, or functional analogies—either lack principled grounding or prove unstable under advancing capabilities. This article advances a criterion rooted in the invariant physical nature of the human person. Drawing on the biomechanics of the high jump, it identifies the vertical liftoff velocity achievable by an unaided human (~4 meters per second) as the relevant threshold. An object whose surface escape velocity falls below that threshold is one from which a reasonably able person could permanently depart by ordinary muscular effort; it is therefore chattel. An object whose escape velocity exceeds the threshold functions as inescapable ground and remains territory.

The resulting transition occurs at a radius of roughly 3–4 kilometers for typical densities—large enough to supply a stable, technology-invariant bright line, yet small enough to leave the great majority of near-Earth asteroids on the appropriable side. The criterion is tested against concrete cases: the sample-return targets Itokawa, Ryugu and Bennu, Jim Benson’s late-1990s declaratory claim proposal, and the concepts examined in NASA’s cancelled Asteroid Redirect Mission. In each instance the analysis distinguishes classification (chattel versus territory) from the ordinary possessory requirements of acquisition, continuity of control, and abandonment. Small bodies and retrieved meter-scale masses may be reduced to exclusive possession in toto; title endures only so long as effective control is maintained and is lost upon abandonment. The approach thereby reconciles the non-appropriation principle with the emerging reality of commercial and scientific activity among the smaller bodies of the Solar System, while preserving the open character of the commons for any object not actually reduced to and retained under possession.