Motion modeling and deployment control of a long tethered spacecraft system with an atmospheric sounder

The paper studies the deployment dynamics of a long tethered spacecraft system (TSS) with an atmospheric sounder. The tether (several ten kilometers) is deployed from the spacecraft by means of a mechanism that works only for braking. A dynamic nominal deployment control law is designed in an orbital moving coordinate system taking into account the aerodynamic forces acting on the end-bodies (the spacecraft and atmospheric sounder) and inextensible tether. The motion stability of the TSS is analyzed. The deployment process is studied in a geocentric coordinate system with consideration of the dynamics of control mechanism operation, tether elasticity, and other perturbations. The numerical simulations show that designing the nominal deployment control law taking into account the aerodynamic force reduces the system’s control error several times for the deployment process.