Advances in Reaction Wheel Design for Magnetic Cleanliness

Scientific spacecraft that measure the local magnetic environment in which they fly need to minimize any disturbance caused by the spacecraft itself. Attitude control reaction wheels, often accommodated to meet pointing requirements, are a known source of disturbance to both the DC and AC magnetic fields. Previous missions (such as on Cassini and MESSENGER) have typically reduced the disturbance effect by using a shield applied externally on standard commercial wheels. We present a reaction wheel assembly that applies a broader strategy of both internal and external disturbance field reductions within the context of the Solar Orbiter mission. Compared to standard commercial wheels with no mitigation, a resulting improvement of the magnetic field generated at the fundamental rotation rate of the reaction wheel by approximately 100dB is predicted.