Low-Earth-Orbit Packing: Implications for Orbit Design and Policy

As more and more operators propose and deploy large constellations, the finite orbital volume in low Earth orbit (LEO) is becoming increasingly congested. Over the last several years, we have been developing a proposal for LEO orbital coordination that uses carefully designed slots in nested concentric shells to avoid the potential for hazardous close approaches between participating spacecraft in their mission orbit. Such a slotting structure provides several benefits, including a reduction in orbital risk, clear analytic tools to understand the opportunity costs associated with a particular shell and slot design, and methods to assess and improve the efficiency with which operators make use of LEO. This paper offers a high-level description of key findings from our previous work on shell design under orbital perturbations and slot reconfiguration, with an emphasis on applications for assessing the efficiency of orbital use. It then explains how these methods could be used for a variety of policy and regulatory purposes, including assessing the efficiency of orbital use, remaining potential admissible slot locations that preserve compatibility, and the efficacy of capacity-expanding measures. Various potential implementation pathways for slotting are presented and compared. Several best practices for safe and efficient constellation design are proposed.