Abstract:
Objective Maintaining high-precision orbits for low earth orbit satellites is essential for advanced Earth observation and navigation systems. This study investigated real-time precise orbit determination using gravity recovery and climate experiment follow-on (GRACE-FO) satellite data based on global navigation satellite system (GNSS) and accelerometer, specifically focusing on precise orbit determination and orbit maintenance during GNSS-denied conditions (signal degradation or loss). The key aim was to evaluate the improvement in orbit accuracy from integrating onboard accelerometer data, particularly during geomagnetic storms.
Methods Following an initial study of orbit determination accuracy during geomagnetically quiet periods, this paper assesses the precision gain from using accelerometer data over conventional empirical models for real-time orbit determination. When both strategies showed comparable accuracy, we then investigated their performance differences during geomagnetic storms. This included evaluating both real-time orbit determination and orbit maintenance accuracy under different denial lengths in navigation-denied scenarios.
Results During quiet periods with unimpeded GNSS signals, both strategies delivered similar real-time orbit determination accuracy, better than 30 cm. Under geomagnetic storm conditions, the accelerometer-assisted strategy achieved orbit determination accuracy better than 40 cm, outperforming the conventional strategy by an average of 31%. In simulated GNSS-denied conditions during storms, accelerometer data significantly improved orbit maintenance accuracy: 30 minute and 60 minute accuracies were better than 50 cm, and 200 minute accuracy was better than 150 cm (by an average of 87% improvement) compared to conditions without accelerometer data.
Conclusions Integrating on-board GNSS and accelerometer data for real-time orbit determination and maintenance during GNSS-denied conditions effectively maintains orbit accuracy during geomagnetic storms. This strategy sustains precision levels comparable to those achieved in quiet periods, demonstrating a strong capability for robust orbit accuracy maintenance under disturbed space weather conditions.
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