Possible current sheet flapping motion and periodic particle flux enhancements observed during the Galaxy 15 spacecraft anomaly

Abstract:

On 5 April 2010, the Galaxy 15 spacecraft, orbiting at geosynchronous altitudes experienced an anomaly near local midnight when it stopped responding to any ground commands. Galaxy 15 spacecraft encountered severe plasma conditions while it was in eclipse and during the subsequent anomaly interval and these conditions included a massive magnetic field dipolarization that injected energetic particles from the magnetotail during a substorm. The GOES and THEMIS satellites were well located in the nightside to observe the substorm. At the time of the field line stretching and dipolarization some of the satellites observed magnetic variations together with particle flux enhancements with periodicities of a few minutes. In this study, we detail characteristics of the perturbation in the magnetic field and particle fluxes that may be an indication of current sheet flapping motion. The exact origin of this flapping motion, particularly the frequency of the variations, is an open question as is the connection between the motion and substorm progression especially particle injection. We will also discuss the wave properties in relation to the kink mode and any evidence of bifurcated structures.