Retrieval strategy for failed satellite on tether’s optimal balance swing angle

A retrieval control strategy for failed satellite, which is connected to a servicing spacecraft by a tether, is studied. The Lagrange analytical mechanics based dynamics modeling for the system composed of a servicing spacecraft, a tether and a failed satellite, is presented under the earth center inertia coordinate system, then model simplification is conducted under the assump-tion that the failed satellite’s mass is far smaller than the servicing spacecraft’s, meanwhile the tether’s length is far smaller than the size of the servicing spacecraft’s orbit. Analysis shows that the retrieval process is intrinsically unstable as the Coriolis force func-tions is a negative damping. A retrieval strategy based on only the tether’s tension is designed, resulting in the fastest retrieval speed. ln the proposed strategy, firstly, the tether’s swing angle amplitude is adjusted to 45○by deploying/retrieving the tether; then the tether swings freely with fixed length until it reaches negative maximum angle –45○; finally, the tether is retrieved by the pre-assigned exponential law. For simplicity, only the coplanar situation, that the tether swings in the plane of the servicing spacecraft’s orbit, is studied. Numerical simulation verifies the effectiveness of the strategy proposed.