LEO satellite formation flying via differential atmospheric drag

Formation flying involves multiple spacecraft flying with pre-defined relation to each other. This allows a number of individual, smaller satellites to work together and accomplish tasks extraneous to single satellite systems. However, the required precision of orbital positioning and control makes the maintenance of such formations quite challenging. This is particularly true for space systems without propulsive controls; even for systems equipped with active control, propellant consumption can be quite high. To facilitate orbital control, this study investigates formation flying in low earth orbit (LEO), focusing primarily on propulsion-free methods of control for micro and nano-class satellites such as aerodynamic differential drag. A fuzzy logic control algorithm was developed to control the satellites' position by manipulating the drag configuration of each satellite in the formation. The outcome of this study shows that successful formation control can be achieved using drag forces alone. The time taken for each formation control and by-products, including altitude loss are evaluated. The orbital modelling presented here can be used as the baseline for a control algorithm developed for station keeping of satellites in low earth orbit.