Orbit maintenance strategy integrated with power management for ultra low Earth orbit satellites

Overcoming limitations in payload performance, ultra low Earth orbit (ULEO) satellites operating at altitudes of 120–300 km can significantly enhance sensor resolution and geospatial accuracy. However, these spacecraft experience dissipative atmospheric drag, necessitating frequent orbit maintenance via low-thrust electric propulsion (EP) systems. Such recurrent EP operation induces high-frequency charge–discharge cycles, leading to accelerated battery degradation and even over-discharge risks. Additionally, thrusting intervals for orbit maintenance often conflict with communication and payload operation windows, resulting in resource redundancy. Consequently, a propulsion-power integrated maintenance strategy is proposed in this study, to enable long-term operations of ULEO spacecraft. Firstly, a perturbed orbital dynamics model under low-thrust control and a fundamental lithium-ion battery state-of-charge (SoC) model are established, followed by analysis of the ULEO propagator accuracy. The depth of discharge (DoD) and temperature are further incorporated to capture their impacts on both battery lifetime cycle (BLC) and thrust availability, forming a combined optimization indicator that balances propellant consumption with BLC degradation. Furthermore, the maintenance problem is formulated as a low-thrust control optimization problem. And a pre-selection and re-optimization dual-layer framework with power management is proposed to minimize the combined propulsion-power indicator. The feasibility of on-board algorithm implementation is also discussed. Numerical simulations demonstrate that the proposed strategy effectively maintains control accuracy in both orbital altitude and shape while ensuring the SoC remains above safe threshold of 10%, which is also robust during solar activity bursts. This approach prevents the over-discharge events, and achieves an in-orbit balance among orbital dynamics, power management, and battery lifetime.