Navigation (orbit determination and guidance) on the heliocentric transfer trajectories; approach for rendezvous with a comet; estimation of the gravitational constant in a coast arc near the comet; and maneuvers within the irregular gravitational field of a comet are discussed. In the cruise or heliocentric transfer phase, orbit determination is ground-based and fairly conventional. For guidance, a feedback algorithm derived from optimal control theory is very effective, provided that a very small amount of thrust variation by throttling is permitted. Satisfactory autonomous navigation in the approach phase was simulated. Determination of the gravitational factor was simulated in a coast phase near the nucleus. Difficulties were encountered in orbit determination and correction (by feedback-driven thrusting) due to the irregular gravitational field and shape of the nucleus; the latter corrupts measurements. The difficulties are not insurmountable.
Navigation for Low Thrust Interplanetary Missions
1986
135 pages
Report
No indication
English