Analytical Control Laws for Planet-Centered Solar Sailing

With increased interest in solar sailing from both ESA and NASA for future science missions comes the requirement to assess potential planet-centered orbits and generate algorithms for effective orbit maneuvering and control. Previous planet-centered solar-sail trajectory work has been limited mostly to Earth-escape or lunar flyby trajectories as a result of the difficulties of fully optimizing multirevolution orbits. A new method of blending locally optimal control laws is introduced, where each control law is prioritized by consideration of how efficiently it will use the solar sail and how far each orbital element is from its target value. The blended, locally optimal sail thrust vector is thus defined to use the sail as efficiently as possible, allowing the rapid generation of near-optimal trajectories. The blending method introduced is demonstrated for a complex orbit transfer and for two stationkeeping applications. Furthermore, the algorithms developed are explicitly independent of time, and as such the control system is demonstrated suitable as a potential future onboard sail controller.