Estimation of nutation divergence of spinning spacecraft with liquid tanks

An experimental method to estimate the nutation time constant of spacecraft is presented. When a spacecraft is spinning about its minimum moment of inertia, the energy dissipation at liquid tanks causes nutation divergence which may result in mission failure. This study gives a macroscopic investigation of nutation mechanism through hardware simulation using a spacecraft model with liquid tanks in it. The model spins freely in a vacuum chamber and growth of nutation angle is measured via optical camera. Through a series of hardware experiments, it was found that the nutation divergence time constant depends strongly on spin rate.