Passive Magnetic Attitude Control for CubeSat Spacecraft

CubeSats are a growing and increasingly valuable asset specifically to the space sciences community. However, due to their small size CubeSats provide limited mass (\u3c 4 kg) and power (typically \u3c 6W insolated) which must be judiciously allocated between bus and instrumentation. There are a class of science missions that have pointing requirements of 10-20 degrees. Passive Magnetic Attitude Control (PMAC) is a wise choice for such a mission class, as it can be used to align a CubeSat within f10f of the earth\u27s magnetic field at a cost of zero power and \u3c 50g mass. One example is the Colorado Student Space Weather Experiment (CSSWE), a 3U CubeSat for space weather investigation. The design of a PMAC system is presented for a general 3U CubeSat with CSSWE as an example. Design aspects considered include: external torques acting on the craft, magnetic parametric resonance for polar orbits, and the effect of hysteresis rod dimensions on dampening supplied by the rod. Next, the development of a PMAC simulation is discussed, including the equations of motion, a model of the earth\u27s magnetic field, and hysteresis rod response. Key steps of the simulation are outlined in sufficient detail to recreate the simulation. Finally, the simulation is used to verify the PMAC system design, finding that CSSWE settles to within 10f of magnetic field lines after 6.5 days