Starlink TLE Accuracy: Empirical Comparison of Propagation Methods

This paper characterizes the position-error behavior of Two-Line Element (TLE) propagation against operator-updated truth on Starlink satellites. The study sweeps 24,641 next-TLE-truth pairs across 501 satellites, stratified by altitude shell and platform generation, over April 2026. The researchers compared SGP4 and high-fidelity propagation methods (using GMAT with EGM2008, NRLMSISE-00 drag, Sun and Moon third-body gravity, and conical-shadow SRP) against the operator's next TLE as a proxy for truth. The findings indicate that position error follows a per-cell power law with fitted exponents in (1,2) on every v2-mini cell and on the high-fidelity v1.x cells at 540 and 560 km. Surprisingly, high-fidelity propagation from public-TLE inputs does not improve over SGP4 at any of the four staleness horizons. SGP4 outperforms high-fidelity propagation on approximately 65-75% of pairs. This negative result is attributed to operator-OD residual dominance at epoch, SGP4-vs-SGP4 truth-construction kernel alignment, and spacecraft-property bias amplification on the high-fidelity arm. The per-satellite SGP4 staleness coefficient regressed against F10.7 returns a positive slope clearing conventional significance at one shell (560 km) on the 30-day, ~17 sfu window, consistent with the LEO density-gradient expectation. The implications for the space sector are significant, as the accuracy of TLEs is crucial for space situational awareness, collision avoidance, and space traffic management. The findings suggest that relying solely on public TLEs for high-precision orbit determination may be insufficient, particularly for megaconstellations like Starlink.

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