Pulse Width Modulating Low Power Magnetic Torquers for Precise Spacecraft Attitude Stabilization

Abstract This article describes a spacecraft attitude stabilization system that uses a set of 12 low power magnetic torquers. The low power magnetic torquer consists of a hard magnetic material rod inside a solenoid. Discharging a capacitor through the solenoid winding generates a current pulse that changes the magnetic dipole moment of the rod when required. The interaction of this magnetic dipole moment with the Earth's magnetic field creates a torque on the rod that is used to stabilize the attitude of a spacecraft in low Earth orbit to a local vertical orientation. Pulse width modulating the low power magnetic torquers is shown to improve significantly the precision with which the spacecraft can be aligned with the local vertical. This system is compared by means of computer simulation to a similar one that uses conventional electromagnet torquers and is shown to use about two orders of magnitude less power and energy.