Abstract: To solve the problem in recovering the normal attitude from high spin speed for a threeaxis stabilized satellite under actuator failure, underactuated methods of despinning and precession control are proposed. The selection principle of thrusters is introduced, as well as the despinning control via integral multiple spin period duration firing mode and symmetry phase littlepulse firing mode. The precession control based on pulse modulation is also proposed. Moreover, the implementation steps and ways in engineering are presented. The numerical simulation and onorbit results indicate that the methods are efficient and practicable in engineering application. Besides, the methods can be used in both onboard autonomous control and remote control.

Key words: underactuated, threeaxis stabilized satellite, despinning, precession control