New reaction wheel reduces impact of electromagnetic fields on nearby instruments

Many scientific and earth observation satellites carry sensitive magnetic instruments which can be  disturbed by the electro-magnetic fields emitted by reaction wheels​ – an instrument onboard a spacecraft used to control the attitude and pointing direction.

Some missions, such as the currently flying Solar Orbiter, have demonstrated that it is very hard to reduce the levels of these fields and the available techniques to reduce them, and prevent them damaging surrounding equipment are not always sufficient.

A new activity with TDE and Astro Und Feinwerktechnik in Germany has developed a reaction wheel with an optimized magnetic structure and has demonstrated its effectiveness.

The consortium selected active magnetic shielding as the main technique to suppress the magnetic field emissions.​ This involved a set of Helmholtz-coils, located in the housing of the wheel, which counter-act the magnetic emissions coming from the motor, the electronics and the mechanical parts.​

Further design options to make it less magnetic were implemented, such as passive shielding around the motor and an optimised electronic circuit design. Compared to conventional techniques, i.e. passive shielding, there are several advantages: better attenuation, ability to re-calibrate in-flight, considerable mass savings.

Next, the activity intends to improve the mechanical and electronic design further, with a qualification model planned by 2026.

4000119937 completed in 2021.