On minimum time and fuel orbital transfer.

The problem of a maneuverable spacecraft, with limited thrust capability, moving between
two coplanar circular earth orbits is considered. Thrusting is performed in the plane defined by the circles, so that the nonlinear dynamics and subsequent optimization problem are simplified.
The approach used in this paper differs from the approaches of Edelbaum and Goetz in that the
equations of motion are not linearized before formulating the optimization problem. An averaging approximation is used to determine the structure of the significant co-state variables.