Orbit Control of an Earth Orbiting Solar Sail Satellite

A concept for the utilization of solar sail satellite's propellant-free thrust capability at Low earth orbit (LEO) is proposed and its orbit control strategy is analyzed. Thrust vector control of the sail's normal direction is used to harvest the solar radiation pressure for generating the necessary acceleration to change the orbital elements. The required control vector direction is determined with two approaches. The first approach is realized by approximating the Gaussian Variational Equations at the employed orbit properties and deriving the optimal force direction in the orbital frame as a function of true anomaly. The second approach is accomplished by implementing a Lyapunov-based nonlinear feedback controller that continuously gives solar thrust in the orbital frame. The simulation results for the orbit control methods are given and discussed to show the solar sail satellite's capability for altering the orbital elements at LEO are stated. It is demonstrated that both approaches give satisfactory results.