INDIRECT OPTIMIZATION OF LOW-THRUST EARTH ESCAPE TRAJECTORIES

Indirect optimization is used in this paper to compute fuel-optimal earth escape trajectory. By shooting backward in time we convert the unknowns from initial Lagrange multipliers to orbit states at the final time. The three-dimensional long-time fuel-optimal escape trajectory with control constraint is designed by first solving a two-dimensional short-time fuel-optimal escape trajectory without control constraint; then using a curve fitting technique to generate initial guess for the final state. This accuracy and efficiency of the proposed method is demonstrated on a low thrust escape trajectory optimization problem.