(Georgia Institute of Technology, 2018-04-27)
Heron, Matthew R.
Traditionally, Earth-pointing CubeSats have Attitude Control Systems (ACS) that consist
of two primary types of actuators – reaction wheels and magnetorquers. Reaction wheels
provide the fine attitude control while the magnetorquers prevent reaction wheel saturation.
This control scheme may not always meet CubeSat mission requirements, however, for some
missions require a spacecraft with a large angular momentum (e.g. CubeSats with spinning
instruments). In this case, the gyroscopic stiffness induced by the angular momentum will
impose large torque requirements on the ACS to maintain Earth-pointing. This torque
requirement on the reaction wheels may cause the wheels to spin up to saturation before the
magnetorquers can unload the reaction wheel momenta. This paper analyzes the ACS
feasibility and design of a 12U dual-spinning, nadir-pointing satellite. Two distinct ACS
schemes are considered. In the first control scheme, the embedded angular momentum of the
satellite is offset by a momentum wheel. In the second scheme, the use of an aerotorquer (i.e.
drag panel) to provide the required torque is considered.