What does a circular space economy actually mean?

Orbital congestion and debris now threaten space operations, yet current solutions like deorbiting are purely linear: launch, use, discard. Earth's circular economy model—reusing and recycling resources rather than mining new ones—hasn't been adapted to space. This paper defines a circular space economy for the first time, laying out how to close resource loops in three domains: within space systems, across Earth's space industry, and on other planets. It's the conceptual framework needed to shift from deorbiting satellites to repairing, refueling, and reusing them.