Dynamic characterization and sail angle control of electric solar wind sail by high-fidelity tether dynamics

Abstract

This paper investigates the spin rate bounds, the configuration stability subject to the solar wind fluctuations, and sail angle control of an electric solar wind sail (E-sail) by a high-fidelity tether dynamic model. This model describes the elastic deformation of tethers with inter-connected 2-noded tensile elements discretized by the nodal position finite element method. The E-sail is assumed to be an axisymmetric system spinning in the plane normal to the heliocentric ecliptic plane. The upper and lower spin rate bounds are revisited to reveal the physics that dictates these bounds and analytic expressions are provided to ensure the proper operation of E-sail. Then, the influences of the solar wind fluctuations on the configuration stability of the E-sail are investigated by parametric analysis with different E-sail configurations, sail angles, and spin rates. Finally, an alternative sail angle control strategy for the E-sail is proposed by applying control force at the remote units with a simple PD control. Numerical analysis demonstrates that the sail angle of E-sail can be controlled quickly by the control law at the remote units with a high-precision.