Optimal 3D orbit corrections in curvilinear coordinates

The minimum-time, constant-thrust orbit correction between two close non-coplanar circular orbits is studied using a relative motion formulation in curvilinear coordinates. The associated optimal control problem in the thrust orientation is tackled using the direct method to numerically solve a diverse set of problems for varying orbital radius and inclination. Additionally, an analytical estimate for the minimum-time inclination change maneuver is obtained. Fundamental changes in the structure of the solution and objective function are high-lighted depending on the relation between the required radial displacement, inclination change and available thrust.