Statistical analysis of one Chinese sun-synchronous satellite anomalies

Based on the data from the Medium-Energy Proton and Electron Detector （MEPED） onboard NOAA-17, 141 anomalies of a Chinese Sun-Synchronous satellite （SSO-X） that occurred between 02/01/2010 and 09/31/2012 were studied statistically. About 26 out of the 52 anomalies that occurred outside the South Atlantic Anomaly （SAA） were accompanied by energetic electron storms. Superposed Epoch Analysis （SEA） was used to analyze the properties of the anomalies and the dynamics of the space environments during these 26 events. Then, a Monte Carlo method was utilized to simulate the electron deposition and the interactions of the injected electrons with an aluminum shield and polyethylene dielectric. The average, median, and 75tb percentile values of the maximum electric field strength inside the dielectric were calculated. The results showed the tbl- lowing. （1） SSO-X anomalies are more likely to occur within the SAA, as 89 out of 141 anomalies （63%） occurred there. （2） Twenty-six of the anomalies that occurred outside the SAA during energetic electron storms were located near the outer boundaries of the outer radiation belts, and these were more frequent in the Southern Hemisphere than in the Northern Hemi- sphere. （3） Electron flux enhancements occurred around the failure time at all energy levels but were more profound in the lower energy channels. The maximum fluxes of electrons 〉30 keV, 〉100 keV, and 〉300 keV were 106, 3.5x10s, and 1.2×10^6 cm 2 s^-1 · sr ^-1, respectively. （4） The average, median, and 75th percentile values of the maximum electric field strengths inside the dielectric for the aforementioned 26 events remained in the range from 106 to 107 V/m for long time periods, which sug- gests that the ＇potential hazards＇ of internal discharges cause SSO-X anomalies. The above results can provide useful infor- mation for the design and protection of sun-synchronous spacecraft.