Observation of Sustained Arc Circuit Failure on Solar Array Backside in Low Earth Orbit

On March 12, 2010, two anomalies occurred simultaneously on NASA’s Aura spacecraft, both lasting under 1 min. There was a momentum buildup due to a persistent disturbance torque lasting 40–50 s. A system anomaly in the current and voltage telemetry of one of the power subsystem array regulator electronic modules lasted for the same duration and ended with six strings (one array group) of solar cell current loss. This paper presents the evidence gathered by the joint NASA/GSFC–Northrop Grumman investigation team that concluded that both anomalies were caused by a sustained vacuum arc on the array backside. The primary cause that triggered the sustained arc was not conclusively established.