Orbit determination strategy and accuracy for a Comet Rendezvous mission

Orbit determination during the postrendezvous phases of the Comet Rendezvous/Asteroid Flyby mission is described. The orbit determination process is discussed, with emphasis placed on optical imaging of landmarks, Doppler tracking, and the effects of nongravitatio nal accelerations. Rotational dynamics are introduced for the cometary nucleus. State estimation errors are given for spacecraft trajectory prediction and cometary nucleus attitude prediction. Estimation errors are also given for physical parameters that describe the cometary nucleus such as moments of inertia and gravity field harmonics. The orbit determination performance in support of science instrument pointing while in orbit about the nucleus is described.