<h2>AAS 95-337</h2><h2>Parametric Excitation of Two-Rotor Gyrostats with Damping</h2><h4>C. D. Hall, Air Force Institute of Technology, Wright-Patterson AFB, OH</h4><h2> Abstract </h2>In 1974, Scher and Farrenkopf proposed a pulsing procedure to enable a spacecraft to "escape" from a trap state.  Here we study this problem with one of the rotors viscously damped and the other parametrically excited by a periodic torque.  The spacecraft is intended to operate with rotor 1, denoted R1, having a specified angular momentum, and R2, subject to a viscous torque, in an all-spun condition.  Normally this state is asymptotically stable.  It is possible that a different asymptotically stable state exists, with R1 having the same angular momentum.  Periodic excitation of R1 leads to "escape."<br><br>