BREM-SAT Attitude Control at Low Altitudes

The German University satellite BREM-SAT (scheduled for launch in early 1993) carries two experiments which require attitude control down to 150 km altitude and aerodynamic stabilization between 150 and 100 km altitude. These contradicting requirements and new ways to change the satellite's attitude and to keep it stable and controlled at very high disturbance torque levels. Complex numerical attitude simulation has shown the feasibility to maintain the required attitude with a momentum wheel and a single torque coil down to 150 km when optimized algorithms are used. To achieve the aerodynamic stabilization, the momentum wheel has to be ejected and flaps must be deployed just before loosing attitude control.