Estimation of residual accelerations on board a spacecraft in the mode of a single-axis solar orientation

We investigate the mode of a single-axis solar orientation of the projected spacecraft that will be used for microgravity experiments. The normal to the plane of spacecraft solar arrays is constantly directed to the Sun in this mode, the absolute angular rate of the spacecraft is practically equal to zero. The mode is realized by means of reaction wheels (RW). We obtain the acceleration estimates by mathematical modeling of the spacecraft attitude motion taking into account the gravitational and the aerodynamic torques acted upon the spacecraft, as well as the control torque produced by the RW system. We consider two models of the spacecraft attitude motion. One of them is rather simple and idealized. The other is more realistic. Using both models, we analyzed two control laws for the RW system. The first law provides only a stabilization of the spacecraft in the prescribed attitude. The second one provides additionally a ecrease of the angular momentum of RW system due to the special choice of the spacecraft turning about the normal to the solar arrays.