Active Aerodynamic Pitch Control for Earth Observation Missions in Very Low Earth Orbits

This paper presents an attitude control system to exploit aerodynamic torques for the pitch control of Earth observation satellites in very low Earth orbits (altitude <450 km). Satellites are that are flying at these low altitudes can experience significant aerodynamic torques. The proposed pitch control system uses a pair of steerable fins, the surface area of which is subjected to the rarefied gas flow and are adjustable to produce a pitch torque. Moreover, then the pitch control system aims to damp the pitch rate by switching the fins to produce damping torques. Simulations are carried out for a CubeSat currently under development as an example in a 6-DoF nonlinear simulator with high fidelity environment models. The simulation results for a given case show that the accuracy of the proposed pitch control is about ±15° to ±6°, improved by implementing a more accurate attitude sensor. The pitch agility is about 0.016°/s with the maximum pitch control range of ±48°. Furthermore, an analysis of the energy consumption of the pitch control system is also included. Finally, the limitation of the pitch control system and potential implementation to improve the control performance are also discussed.