Spacecraft Swarm Dynamics and Control About Asteroids

This paper presents a novel methodology to control spacecraft swarms about singleasteroids with arbitrary gravitational potential coefficients. This approach enablesthe use of small, autonomous swarm spacecraft in conjunction with a mothership,reducing the need for the Deep Space Network and increasing safety in future as-teroid missions. The methodology is informed by a semi-analytical model for thespacecraft absolute and relative motion that includes relevant gravitational effectswithout assuming J2-dominance as well as solar radiation pressure. The dynamicsmodel is exploited in an Extended Kalman Filter (EKF) to produce an osculating-to-mean relative orbital element (ROE) conversion that is asteroid agnostic. Theresulting real-time relative mean state estimate is utilized in the formation-keepingcontrol algorithm. The control problem is cast in mean relative orbital elements toleverage the geometric insight of secular and long-period effects in the definitionof control windows for swarm maintenance. Analytical constraints that ensurecollision avoidance and enforce swarm geometry are derived and enforced in ROEspace. The proposed swarm-keeping algorithms are tested and validated in high-fidelity simulations for a reference asteroid mission.