Spacecraft nutational instability prediction by energy-dissipation measurements

Abstract

Nutational divergence of a spinning spacecraft was studied experimentally and later compard with flight data. Laboratory measurements of liquid energy dissipation in model tanks, with and without propellant management devices, were performed during forced precession of the tanks. Results were used to predict divergence time constants via the energy sink approach and were compared to time constants obtained from flight data. Agreement within 21% was obtained, considered very good since the energy sink approach was used for an exceptionally high liquid-fraction spacecaft. By contrast, analytical estimates were in error by one to three orders of magnitude. Time constants were also compared to drop tests with excellent agreement. Data encompass three designs of propellant management devices and several parameter variations for each design.