Permanent magnet as passive stabilization and magnetorquer with solid core as active stabilization has been used over the year in satellites.But the would have magnetic field lines, wouldn't they affect the reading of magnetometer. The magnetometer is used for taking the reading of earth magnetic field.
There is possibility of switching off the magnetorquer with air core while taking reading of magnetometer, but what about the other two case of actuator one with permanent magnets and second with the solid core (Ferrite) magnetorquer ?
Is placement of magnetometer important? If yes, where should one put the magnetometer ideally? Can one take reading of Permanent magnet and solid core, and subtract it from overall reading of magnetometer? but how reliable would be that, as the earth magnetic field magnitude would be quite less than that of permanent magnet.