Optimized Performance of a Semipassive Aerodynamic Controller

A semipassive, aerodynamic attitude controller is proposed for spacecrafts in arbitrary near-Earth orbits. The analysis suggests that a system of flaps, operating in the free molecular environment, can efficiently damp the librational motion and provide a mechanism for imparting to the satellite any arbitrary orientation in space. The control performance is optimized, numerically, on the basis of the damping time in circular orbits and the maximum pointing error due to steady state limit cycles in elliptic trajectories. A parametric analysis yields the operating region for quick damping (<| orbit) and small pointing errors (< 1°). The controller promises to be economical, efficient, and would extend the useful life of near-Earth space vehicles.