Nested Autonomous Orbit Determination and Control for Distributed Satellite Systems: A General Case Study on Constellation of Formations for Earth Observation

Distributed Satellite Systems (DSS) require new advanced navigation and control functionalities to meet the ever more stringent mission requirements of Earth Observation (EO) missions. In particular, Autonomous Orbit Determination and Control (AODC) can significantly reduce operational costs and enable continuous feedback without being limited by ground station link availability. Recent advancements in Global Navigation Satellite System (GNSS) navigation in space, coupled with high-efficiency low-thrust electric propulsion, have made it possible to leverage autonomous and continuous operations to optimise propellant mass and thruster power, improve orbital accuracy, reduce collision risks, and develop new services through distributed operations. Within this framework, we propose a novel concept for a DSS that implements a Constellation of Formations (COF) architecture for EO missions, offering the advantage of combining single-pass multiple acquisitions with high revisit frequencies. However, maintaining the formation geometry and constellation parameters may conflict with each other. To address this challenge, we propose a control architecture that incorporates suitable loops for the (absolute) constellation orbit control and the (relative) formation orbit control using inter-satellite communication links within each formation.