Trigger Angle Targeting for Orbital Rendezvous

Abstract

Orbital rendezvous missions often have a co-elliptic approach phase where a chaser vehicle approaches an object with a near-constant relative altitude and relative velocity. A well known orbital rendezvous technique is to trigger the Terminal Phase Initiation (TPI) maneuver when the apparent elevation of the target reaches some nominal angle. The best elevation trigger angle on which to initiate the final transfer maneuver must balance favorable performance characteristics and desirable operational simplicity. A detailed analysis is given deriving the best trigger angles and showing how these results correlate to past missions and how they could potentially influence future ones.