Gravity gradient torque control for Earth-orbiting satellites using time-varying systems analysis

The controlled pointing of Earth-orbiting objects (e.g. astronomical telescopes) in the presence of time-dependent gravity-gradient torques is studied using recent techniques for the analysis and synthesis of time-varying linear scalar dynamical systems. The authors present results which show that effective adaptive control of unstable motions due to gravity gradient torques can straightforwardly be accomplished, resulting in high pointing accuracy and stability in both circular and elliptical orbits