Plane trajectories of optimal transfer of spacecraft with low thrust from elliptical orbit to geostationary one

Low-thrust maneuvers from high-elliptical orbits are of peculiar interest because they allow reducing of fuel consumption in comparison with high-thrust maneuvers and reducing of duration of flight and of destructive influence of radiation belts in comparison with spiral boost from low near-circular orbits. With the help of maximum principle the optimization problem is reduced to two-boundary problem and is solved by modified Newton method. A method based on the idea of transferring from approximately optimal trajectory to an optimal one, which allows getting initial data for solving two-boundary problem is described. Two modifications of the problem are considered: the first — with permanent propulsion, the second — with ability of switching the propulsion off and on. The direction of low thrust is unconstrained. The comparison of two types of trajectories and control is done.