Dynamics of double-pyramid satellite formations interconnected by tethers and coulomb forces

The tethered formation and the coulomb formation are two important concepts in constructing satellite formation architecture, and they have the advantage that the relative motion between satellites can be maintained quite accurately with minimal active control. In this study, a formation termed the "coulomb tether double-pyramid" is proposed to combine the best features of the tethered formation and the coulomb formation. Chief and deputy satellites are charged bodies and located in the Earth-facing plane normal to the geostationary orbit, with the chief at the center. Each deputy is connected with two anchor satellites via a massless, straight tether, such that the Earth-facing plane can be maintained by using gravity-gradient torques. First, the equations of motion are obtained via Lagrange equations. Then, the charges and tether extensions necessary to support a Hill-frame stationary formation are analytically determined. Finally, open-loop charge control strategies are designed to maintain the spinning formation or carry out reconfiguration. The proposed coulomb tether double-pyramid formation has great potential to enhance the surveillance and imaging of Earth objects in future missions.