Constraining Earth’s orbital capacity via operational feasibility

Abstract

Earth’s orbital environment has grown increasingly congested as the cost of satellite deployment has fallen dramatically in the twenty-first century. In the absence of cost constraints, other limitations, including sustainability considerations, may soon become the primary barriers to further expansion. Assessments of orbital carrying capacity help map these emerging constraints to sustainable levels of satellite activity. While most prior efforts in defining capacity have focused on constraining satellite populations to avoid runaway debris growth, other factors also warrant attention. This work introduces an operational feasibility constraint that limits the acceptable rate of close approaches between tracked objects, beyond which the cadence of collision avoidance maneuvers would make operations infeasible. Using the full public U.S. catalog of two-line elements in low Earth orbit, approximate conjunction nodes are identified based on Keplerian orbit geometries. The resulting operational capacity framework is used to evaluate the sustainability of current orbital populations and to identify key trends in recent history to inform future deployments and operator behavior. By defining operational criticality, occupation, and capacity in consistent and interpretable units, this work shows how satellite populations interact and, if overpopulated or uncoordinated, stifle each other’s ability to operate effectively.