On the Impact of Attitude Data Deviations for GNSS Precise Orbit Determination

Precise Orbit Determination (POD) of Global Navigation Satellite Systems (GNSS) satellites relies on precise satellite attitude data to accurately model satellite dynamics and observation geometry. Errors in the attitude control, such as biases, and periodic signals, have the potential to propagate into orbit estimates and derived geodetic parameters, thereby influencing the accuracy required for high-precision geodetic applications. Furthermore, accurate attitude determination plays a critical role in Next-Generation GNSS, particularly for the implementation of inter-satellite range links. This study presents a simulation framework to analyse the impact of such effects on GNSS attitude data and their implications for POD.

A Galileo-like constellation is simulated over a three-year period, employing state-of-the-art methods and datasets, including ITRF2020. The basis of the simulation are realistic assumptions concerning satellite geometry and attitude control. Systematic orientation biases and periodic signals, such as misalignments in solar panel orientation or inaccuracies in yaw steering, are applied to the attitude data to emulate potential errors in real systems. The simulation then examines the propagation of these errors into POD solutions, including their effects on orbit errors and clock estimates.

Particular attention is given to systematic effects arising from solar radiation pressure (SRP) modelling in combination with systematic attitude errors. The results obtained demonstrate the sensitivity of GNSS POD to precise attitude knowledge, thereby providing valuable insights for the design and calibration of future GNSS. This study emphasises the critical role of attitude control in achieving the accuracy objectives outlined by the Global Geodetic Observing System (GGOS) for subsequent reference frame determination.