Attitude acquisiton of a satellite with partially filled liquid tank

Attitude acquisition based on angular momentum exchange has been studied for a long time and implemented widely for geostationary communications satellites. In this technique, the spacecraft body is initially spin-stabilized at :a certain rate and despun by accelerating the wheel fixed in the body frame. Finally the wheel spin axis is reoriented to the angular momentum vector. In this paper, a similar technique is applied for a bias momentum stabilized satellite, which is equipped with a spherical fuel tank, and the effect of liquid slosh on the attitude acquisition by momentum transfer is investigated. In order to represent the slosh motion of liquid an equivalent mechanical model is adopted and full nonlinear equations of motion for three-body system are derived. Computer simulations are performed for several cases, which use the viscosity of liquid and the center location of the tank as control parameters, mainly in order to observe how the viscosity and the center location of the tank influence the attitude acquisition of the satellite. The investigation includes observing time-variations of moment of inertia, especially presence of components of product of inertia during the maneuver. Simulation results demonstrate that both the viscosity and the center location affect the attitude of the spacecraft during the maneuver but the center location of the tank has more effect on the stabilization than the viscosity.