OPTIMAL RANGE OBSERVABILITY TRAJECTORY PLANNING FOR PROXIMITY OPERATIONS USING ANGLES-ONLY NAVIGATION

A method for planning spacecraft trajectories with optimal range observability using angles-only navigation is presented. All feasible transitions of a chaser spacecraft between two relative trajectories with respect to a non-cooperative resident space object (RSO) are considered. The approach is more flexible, from an operations point of view, than point-to-point transfers and allows the mission planner to specify start and end conditions that result in any desired type of relative motion. The dynamics are modeled by linearized relative equations of motion in a quasi circular planetary orbit. A geometry-based metric is used to develop a cost function which evaluates observability along trajectories, given an arbitrary thrusting maneuver. The optimization procedure returns the exit and entry conditions, relative states, necessary for transfer between initial and target trajectories, respectively. By assuming impulsive maneuvers, the relative dynamics are parameterized in terms of linear relative-orbit-elements, thereby reducing the number of variables to a single time-dependent parameter per trajectory. The transfer between trajectories is constrained in terms of the fuel used per burn, collision avoidance with the RSO, eclipse conditions, and obstructions by neighboring celestial bodies in the sensor field of view. Numerical simulation results are presented which give a representative example of proximity operations in geosynchronous orbit. A simple Monte Carlo validation procedure uses a continuous-discrete extended Kalman filter to produce preliminary navigation performance results.