Lawden's method of optimization in arbitrary central fields

In the present paper, some optimal orbital transfer trajectories in a central field of arbitrary structure are analyzed, by Lawden's basis vector method, on the basis of necessary optimality conditions. The field structure is assumed to be subjected only to some weak regularity and smoothness constraints. It is shown that the basic properties of optimal trajectories in a Newtonian gravitational field are retained for motions in an arbitrary central gravitational field.