Abstract: According to the mission requirements and planning of the first China mission exploration, the gravity gradient torque and solar pressure torque are investigated by considering the orbiter mass property, configurations, and the highly eccentric orbit. The accumulation of the disturbance torques can increase the rotational speed of the flywheels and finally decrease the attitude maneuver capability. Therefore, the momentum unloading utilizing active thrust forces are usually required. To reduce the number of the momentum unloading, a method based on attitude bias is developed to achieve the canceling effect of gravity gradient torque and solar pressure torque. The numerical simulation results indicate that the accumulation of the disturbance torques can reduce to 70 percent, making a contribution to saving on fuel and promoting longer life of the spacecraft.

Key words: Mars rover, space moment, angular momentum