A Stable and Sustainable Maximum Orbital Capacity in Low Earth Orbit

Abstract The population of satellites in Low Earth Orbit has recently witnessed a significant increase due to the advancements in satellite technology, the reduction of launch costs, and the deployment of large constellations of satellites. This raises concerns about the orbital capacity, essentially the ability of the Low Earth Orbit environment to sustain a certain number of satellites without unsustainable levels of risk due to space debris or collisions. More in-orbit collisions can generate debris that further threatens operational satellites and human spaceflight missions. The open-source MIT Orbital Capacity Assessment Tool is adopted to estimate the maximum number of satellites that fit in the very Low Earth Orbit, 200-900 km altitudes, under equilibrium points and failure rate of satellites as constraints. The results show an opposite trend between active satellites and debris for a sustainable centuries-long space environment: the number of active satellites decreases with altitude, while the amount of debris increases, reflecting the novel mechanism implemented for the dynamics of imparting the change in velocity to each new debris. The number of active satellites that can potentially fit at very low altitudes is in the range of hundreds of thousands to millions, due to a stronger atmospheric drag. Our results provide a theoretically stable upper boundary for the Low Earth Orbit capacity, supported by a first-ever comparison and validation analysis between a source-sink model of the space environment population with Monte-Carlo methods.