Trajectory optimization by making use of the closed solution of constant thrust-acceleration motion

The problem of fuel optimal rendezvous and transfer maneuvers in a central gravitational field is considered. By using analytical results and a parametrization of the control functions, the original optimal control problem can be solved by a sequence of mathematical programming problems. After introducingg KS-variables and piecewise-constant thrust accelerations, all necessary trajectory integrations are performed in closed form. This optimization procedure leads to a considerable reduction in computing time and allows the solution of a wide class of problems: The propulsion system may be thrust-limited or power-limited, one may consider rendezvous or transfer maneuvers with fixed or free final time. A numerical example for a 3-dimensional maneuver is included.