Indirect Optimization of Low Thrust Escape Trajectories.

At present, most of the research on low thrust escape trajectory optimization were limited to planar escape or unconstrained engine model. Using the indirect method, the unknown parameters of the two-point-boundary-value-problem were bounded in a hyper unit sphere by multiplying a positive unknown parameter to the fuel optimal performance index. Firstly, the two-dimensional short-time fuel-optimal escape trajectory without control constraint was solved by the homotopy method and curve fits technology. Finally, the three-dimensional long-time fuel-optimal escape trajectory with control constraint was solved. This method is validated to be high-accuracy, good-convergence and efficient for low thrust escape trajectory optimization. [ABSTRACT FROM AUTHOR]