Correlation of GEO Comsat Anomalies and Space Weather Phenomena for Improved Satellite Performance and Risk Mitigation

Abstract

We correlate on-orbit component telemetry data from seven Inmarsat geostationary communications satellites from 1996 to 2012 with historical space weather information. We specifically utilize data from the Geostationary Operational Environment Satellites (GOES), the Advanced Composition Explorer (ACE) Satellite, the Royal Observatory of Belgium’s Solar Influences Data Analysis Center (SIDC), and the Kyoto Geomagnetic Equatorial Disturbance Storm Time (Dst) Index data service. In our analysis, we compare the Inmarsat solid-state power amplifier (SSPA) currents to energetic particle fluxes and space weather indices such as Dst, Kp (an index that describes disturbances in horizontal component of the Earth’s magnetic field), and solar flares. These space weather indices capture the severity of solar storms that can send energetic particles streaming towards Earth and magnetic storms that can impact the performance of GEO communication satellites. We find that seventeen out of twenty-six SSPA anomalies occurred within two weeks of prior severe space weather events. Two anomalies occurred during geomagnetic events, one occurred during a severe radiation event caused by solar energetic protons, and fifteen occurred within two weeks of severe radiation events caused by relativistic electrons. There was no apparent correlation between spacecraft eclipse periods and anomaly occurrence. Although the year with the most anomalies coincided with a sunspot cycle minimum, there were additional fleet transition factors that prevent a clear conclusion about this aspect. Additional findings include an interesting direct relationship between the GOES 2 MeV electron flux and SSPA current prior to an anomaly. Anomalies with on-board components such as SSPAs are expected and are managed by all satellite operators. An anomaly rate is factored into the design of geostationary satellites and is typically mitigated through the use of on-board unit redundancy and configuration options. The examples given have been handled without impacting the performance of any satellite. The current SSPA anomaly rate is significantly lower than that modeled as part of the design reliability analysis, hence both performance and lifetime have not been impacted adversely.