AUTONOMOUS ORBIT DETERMINATION SYSTEM FOR EARTH SATELLITES

A new system for autonomous satellite navigation using only horizon trackers and star sensors is developed and investigated. Simulations employing performance characteristics of off-the-shelf hardware have demonstrated that the algorithm presented is capable of subkilometer accuracy. Unlike many previous studies, however, this system is not limited to the determination of an Earth satellite's current position. By using a two-step technique combined with a general perturbations model, this method allows the air-drag effects on the orbit to be estimated and incorporated into future position predictions. This is accomplished vis a simple, yet accurate, modification to the perturbations equations.