1. Attitude control. Earth observation

From application satellites in low circular orbits (Earth observation) and geostationary orbits (telecommunications), to scientific satellites in elliptical orbits, they all require a privileged orientation (attitude) in orbit.

• The purpose of the "attitude measurement and control" function, also known as stabilization, is to determine the satellite's attitude relative to external reference points, and to adjust and maintain this attitude despite external and internal disturbances.

  This attitude measurement is commonly performed using attitude sensors that detect and measure the instantaneous directions of fields produced by the surrounding stars: magnetic fields, gravity gradients and optical radiation. Whenever high angular accuracy is required (typically $⩽$...