The magnetorquer is the executive component of a satellite attitude control system. Inside the magnetorquer are the soft alloy rods with high permeability, low residual magnetism and low loss. The outer layer is wound with enameled wire. The unit is orthogonally installed inside the satellite. A current supplied by the control computer passes through the magnetorquer and generates a proportional magnetic moment M. This magnetic moment then generates a reaction torque T with the Earth’s magnetic field B. T = M × B is the satellite control torque which is used for the reaction wheel to unload momentum and control satellite attitude.