A novel framework for experimental validation of X-ray pulsar navigation using NICER observations

Haifeng SUN

doi:10.1016/j.cja.2025.104032

A novel framework for experimental validation of X-ray pulsar navigation using NICER observations

10.1016/j.cja.2025.104032

2025-12-22

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X-ray Pulsar-Based NAVigation (XPNAV) faces significant computational challenges due to intensive Two-Dimensional (2-D) phase-frequency grid searches, limiting its real-time implementation for autonomous spacecraft navigation. To address this issue, we propose an integrated XPNAV framework that unites a Reduced-dimension Phase Delay Estimation (RPDE) module with an Extended Kalman Filter (EKF), demonstrated on four days of Neutron star Interior Composition ExploreR (NICER) observations of PSR B0531+21 (the Crab Pulsar). By optimizing the measurement model, our method replaces the conventional 2-D phase-frequency grid search with a one-dimensional phase-only search, resolving the computational bottleneck. We derive a theoretical velocity bound that ensures the validity of this dimensionality reduction, and verify it experimentally. For statistical rigor, we employ bootstrap-enhanced navigation validation with 20 resamples. Experimental results show that RPDE delivers a 5 080× speedup over the 2-D grid search and a 4.8× acceleration relative to X-ray pulsar-based navigaTion usIng on-orbiT pulsAr timiNg (XTITAN), while improving phase-estimation accuracy by roughly one order of magnitude. The full framework mitigates orbital propagation errors and achieves 5.3 km position accuracy over four days of continuous tracking, with phase-estimation uncertainty (≈3 km) as the dominant error source. Photon-level simulation cross-validation exhibits less than 23.3% discrepancy against NICER’s benchmarks, confirming framework fidelity.

Keywords:

pulsar-based navigation

NICER observations

extended Kalman filter (EKF)

Crab pulsar

orbit determination

A novel framework for experimental validation of X-ray pulsar navigation using NICER observations

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