High-precision Orbit Synthesis of Two-line Elements Based on Long Short-term Memory Network

To improve the accuracy of TLE (Two Line Elements) in orbit prediction and solve the problem of traditional polynomial fitting and physical modeling methods being difficult to handle the nonlinear evolution trend of orbits, a high-precision TLE orbit parameter fitting method based on Long Short Term Memory (LSTM) network is proposed. TLEs are widely applied in orbit prediction and space situational awareness because of their simplicity and accessibility, yet their accuracy deteriorates quickly when propagated forward due to perturbations such as atmospheric drag, solar activity, and Earth’s nonspherical gravity field. Therefore, developing a data-driven strategy that can capture the hidden dynamics and extend the validity of TLE prediction has significant practical value. Historical TLE data is used for high-precision time series fitting and orbit synthesis of orbit elements. LSTM neural network is used to model the time series of TLE orbit parameters, and a mixed modeling strategy is formed by combining polynomial fitting. Based on the TLE data of 87 Iridium 33 fragments, a fitting model was constructed and a synthetic TLE was generated using SGP4 (Simplified General Perturbations 4) propagator to propagate position error in the forward direction. The experimental results show that the proportion of the target for improving the position error of 81 fragments in the synthesized TLE propagation for 7 days during the conventional period is 65.43%～88.89%, and the error distribution is more concentrated and stable. The proportion of the target for improving the position error of the synthesized TLE propagation of 65 fragments during a geomagnetic storm for 3 days is 70.77%～80.00%, and the error fluctuation range is lower than that of the original TLE. The TLE orbital synthesis method based on LSTM performs excellently in capturing the nonlinear evolution of orbital parameters. By combining angle linearization and smooth filtering strategies, the accuracy and stability of orbital parameter fitting are improved.