Dynamics and Aerodynamic Control of a Cross-Track Tether Satellite System

The objective of this paper is to analyze the dynamics and control strategy of a new type of formation flying architecture, enabling unprecedented space mission capabilities. We propose a tether satellite system composed of two satellites, flying in LEO, connected by a linear tether, maintained in tension along the cross-track direction (perpendicular to the motion and radial directions). A three-dimensional multibody model was developed, by writing the equations of relative dynamics in an orbiting reference frame. The dynamic model was linearized and an optimal LQR controller was introduced. The linear control law was validated by simulating its application on the full system model, demonstrating the possibility of stabilizing the system by using a unidirectional and constant force. Aerodynamic surfaces were then inserted into the model so as to generate the required force. Finally, the proposed aerodynamic stabilization approach was compared to a gyroscopic stabilization alternative strategy.