Analysis of Nanosatellite Formation Establishment and Maintenance Using Electric Propulsion

Nanosatellite clusters are one of the current and future trends in space technology. To maintain a satellite cluster over a long period of time, the nanosatellites need to mitigate the alongtrack drift created by the initial orbit injection. In the mass range of 1–10 kg, CubeSats have strict constraints on allowed mass, volume, and electrical power; and they are equipped with only limited sensor and actuator capabilities. A state-of-the-art miniaturized electric propulsion system is one option to realize the required orbit control capability. Due to the low thrust provided by an electric propulsion system, long orbit control maneuvers are required. Therefore, mission design is highly affected by long-term attitude and power constraints. Assuming a cyclic thrust controller, four methods are developed to allocate the satellite power and attitude resources for orbit control. Two time division methods are presented that allocate dedicated time slots for each of the satellite’s main tasks. Alternatively, two cosine methods are presented that use an error cone, around the required attitude, as a criterion for selecting when to operate the thruster. It is demonstrated that the proposed methods are capable of maintaining a realistic CubeSat formation-flying mission using low-power electric propulsion. For a CubeSat with deployable solar panels, the double cosine method shows the best performance.