Proximity Operations of On-Orbit Servicing Spacecraft using an Eccentricity/Inclination Vector Separation

This paper investigates a proximity operations concept able to realize the demanding requirements for on-orbit servicing spacecraft, while providing an efficient collision avoidance strategy and reduced propellant consumption. In contrast to a traditional rendezvous approach where the evaluation of the collision risk is only based on considerations done in the orbital plane, here a relative eccentricity/inclination vector separation concept is proposed which promises improved flexibility, robustness and reduced inter-spacecraft separations at a minimal collision risk. In this paper the novel proximity operations concept, originally developed for geostationary satellites and already used to operate low Earth orbit formations, is adopted to support far and mid range operations of on-orbit servicing non-cooperative vehicles. After addressing the effects of the relevant differential perturbations, suitable nominal relative motion geometries are derived based on a real-world navigation accuracy analysis. Radar tracking data and GPS navigation solutions for the client and servicer satellites respectively are used to trade minimum safety separations and characteristics of the rendezvous entry gate. Finally a fuel-efficient formation keeping and reconfiguration strategy is designed based on analytical solutions of the proposed linear motion mode