The study of solar cycle 24 effect on THEOS

摘要

THEOS (Thailand Earth Observation Satellite) is the low earth orbit satellite at 822 km and is the first earth observation satellite of Thailand. It has been launched since October 2008, which is, in fact, the beginning of solar cycle 24. The satellite condition is still in nominal mode even after more than four years of operation. However, some anomalies did occur over the period of four years and the study shall take a detailed look into the cases of these anomalies. Almost 50 % of the cases of anomalies on THEOS satellite are investigated to be due to Single Event Upset (SEU) on mission plan execution. The only remedy has been to increase the complexity of telecommands to bypass error and run system check so as to reduce the risk of satellite anomaly. Around 20% of cases of anomalies are due to the error unknown satellite equipment errors and internal communication errors of which the root causes cannot be defined. This paper shall concentrate about the effect of the solar flare in solar cycle 24 on THEOS satellite by using top 20 solar flare phenomena and the anomalies that have caused THEOS satellite to enter safe mode.