Spin stability of dual-spin spacecrafts.

The spin-axis attitude stability in torque-free environment of dual-spin spacecrafts with energy losses in both bodies is studied by analytical means. A new mathematical model, which assumes the high speed rotor to be symmetrical, is introduced and analyzed. The linearized variational system of equations for the model with periodic coefficients is transformed to a kinematically similar autonomous system (according to Floquet and Liapunov) which can be analyzed routinely using established procedure. As an example, this technique is used on a recent mathematical model of the SAS-A spacecraft to establish steady state stability over a wide range of speeds.