## 4 Conclusions  
This paper presents an orbit determination (OD) method for non-cooperative Starlink satellites performing continuous low-thrust maneuvers under sparse ground-based observations. The adopted reduced orbital dynamics model includes only the perturbations from the Earth's non-spherical gravity field and the combined effects of low-thrust propulsion and atmospheric drag, which are represented as a net along-track acceleration. This simplification provides a physically consistent yet computationally efficient representation of the satellite's motion. The OD algorithm is constructed within a batch estimation framework using an unscented transformation based on an optimized rho-minimum sigma points strategy. Numerical simulations under different levels of measurement noise and initial state uncertainty demonstrate that the proposed method achieves reliable convergence and favorable precision of OD and OP. Statistical analysis across a range of satellites shows that, with a measurement noise level of (100 m, 100 arcsec,100 arcsec), the algorithm converges within 10 iterations and produces 24 h OP results with three-dimensional position RMS errors below 3 km. To further evaluate the proposed OD method, a higher-fidelity orbital dynamics model was used for comparison, where the effects of atmospheric drag are treated as an independent perturbation. The results indicate that adopting the high-fidelity model results in a notable improvement in 24 h OP accuracy and enhances the robustness of OD to the initial state uncertainty within a certain range.  
However, several limitations remain. The state covariance initialization is still challenging. Our findings reveal that increased initial uncertainties in position and velocity can help improve the stability of orbit determination. However, this benefit is dependent on maintaining proper scaling with acceleration uncertainty--mismatches here degrade orbit prediction accuracy by 13-49% in our test cases. Further work is still needed on proper state covariance initialization. Moreover, the current dynamics model is limited by the assumption of constant along-track acceleration, which makes it unsuitable for situations where the change rate of orbital altitude varies significantly, such as during large variations in thrust or atmospheric drag. Future efforts will focus on the development of orbital anomaly detection and thrust mode transition schemes to extend the applicability of the method to more general mission profiles.  
A.L.: Conceptualization, methodology, software, validation, formal analysis, investigation, data curation, writing--original draft, writing--review and editing, visualization, funding acquisition. Y.J.: Conceptualization, validation, formal analysis, investigation, writing--review and editing. All authors have read and agreed to the published version of the manuscript.  
This work was funded by the National Natural Science Foundation of China with No. 11902238, and the China Postdoctoral Science Foundation funded project with No. 2020M673373.  
Not applicable.  
Data Availability Statement: Data will be made available upon request.  
The authors declare no conflicts of interest.