The variable electromagnetic environment in geospace plays a crucial role in influencing the occurrence probability of satellite anomalies. FORMOSAT-3 (FS3) is a Low-Earth-Orbit (LEO) mission, which consists of six identical microsatellites that orbit in the altitude of 700–800 km and with an inclination of 72°. The dependences of the FS3 satellite anomalies on space weather conditions have not been investigated in the past. With an exception of a small number of extremely high geomagnetic events, we find that the occurrence rate of the FS3 anomalies is negatively correlated with the level of geomagnetic activity. Moreover, the relationship between numbers of anomalies and sunspots is also anti-correlated. A superposed epoch analysis demonstrates that the intensity of galactic cosmic rays (GCR) is relatively high at the times of the anomalies. All these results infer that the FS3 anomalies predominantly occurred under the conditions associated with low solar activity. The possible main cause for the FS3 anomalies is high-energy trapped protons or GCR. In summary, this paper presents a statistical result that a satellite can be prone to suffer an anomaly under low solar or geomagnetic activity. [Figure not available: see fulltext.]
Bibliographical noteFunding Information:
This work was supported by the grant MOST 109-2111-M-008-007 to National Central University.
The authors gratefully acknowledge National Space Organization for using the list of the FS3 satellite anomalies to analyze. In addition, we would thank to GFZ German Research Centre for Geosciences for the use of the Kp data in this study.
© 2021, The Author(s).
- Galactic cosmic rays
- Geomagnetic activity
- Low earth orbit
- Satellite anomaly
- Solar cycle
- Space weather