Tethered aerobraking design for repeatable maneuvers

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Tethered aerobraking design for repeatable maneuvers

Tragesser, Steven G. / Umbert, Lluis

Abstract An aerobraking maneuver performed with a tethered system has the benefit of increasing the drag for a given center of mass orbit by dropping the lower subsatellite into the denser atmosphere. While this concept has received significant attention in the literature, the exact means of controlling the attitude prior to the aerobraking fly-through has not been adequately treated. In particular, a scheme for repeated passes in elliptical orbits has not been developed, which would be required, for example, in a debris elimination system. This work uses tether reeling during the exoatmospheric flight in order to control the tether libration to target a desired state prior to the aerobraking trajectory. The design of the control law requires numerical solution of nonlinear equations, but newly developed analytics provide an estimate that reduces computational time and increases the robustness of the algorithm. The results show that the nearly periodic state that is required for successive passes can be achieved for practical tether lengths and power requirements.

Highlights • Analytic solutions for tether dynamics in an elliptical orbit. • Efficient, robust computational algorithm for targeting tether libration angle and angular rate via tether length control. • Demonstrates that repeated aerobraking maneuvers are possible with practical power requirements.