Optimal Trajectory Design of Spacecraft Using Multi-flyby

Abstract

This paper proposes an optimal design method of a trajectory of spacecraft using multi-flyby. In recent years, many deep space explorations have been conducted, and it is necessary to minimize the fuel consumption for these missions. Therefore, a trajectory of spacecraft that minimizes the fuel consumption with the mission constraints satisfied is determined by numerical optimization. In order to cope with complicated orbits with many flybys and severe constraints, this paper extends the multiple gravity assist (MGA) problem, and proposes a new optimal trajectory design algorithm. We newly add two discrete optimization variables to the MGA problem: the number of revolutions before flyby, and selection of multiple solutions to the Lambert problem. In the proposed algorithm, trajectory optimization is recursively executed by adding a flyby target one by one, instead of optimizing the entire trajectory with multi-flybys at once. The validity of the proposed algorithm is demonstrated by numerical experiments with two scenarios of Parker Solar Probe and Solar Orbiter. In addition, the relation between the number of flybys and fuel consumption is also examined, which shows the trade-off relationship between the two.