Generation of trajectories by multiple planetary swingbys

This paper deals with a multiple planetary (Venus, earth, Jupiter) swingby problem and its application to generate various trajectories, including solar system escape, sun encounter, out-of-the-ecliptic, and retrograde trajectories which have been regarded as difficult to realize by the conventional direct launch technique. In order to obtain a favorable swingby sequence with a shorter flight time, the sub-optimal control strategy is proposed, in which a forward dynamic programming approach is partially applied. Results show that the proposed multiple planetary swingby process, especially the multiple earth-Venus-Jupiter swingby process, can be applicable to generate the above four trajectories with 3 to 4 km/sec required velocity increments and with a flight time of the order of 10 years.