OPTIMIZATION OF DELTA-V EARTH-GRAVITY-ASSIST TRAJECTORIES

An analysis of delta-velocity Earth-gravity-assist (Delta V-EGA) traje ctories is carried out by using an indirect optimization method. in co mparison to previous literature, the eccentricity of the Earth's orbit is taken into account, and simplifying assumptions, concerning the po sition and direction of velocity impulses, are removed. However, the f ocus is on the application of the theory of optimal control to complex interplanetary missions and Delta V-EGA trajectories are only illustr ative examples. In particular, it is shown that the optimization of th is kind of mission, according to the patched-conic approximation, can be obtained by considering only the two-body problem equations in the heliocentric frame, The necessary optimum conditions for the Earth fly by are extended to consider a minimum-height constraint, which is freq uently required in this maneuver. The procedure is also capable of rec ognizing when a numerical solution is only suboptimal and a powered fl yby could improve the mission.