SURFACE CHARGING ANALYSIS OF HIGH-INCLINATION, HIGH-ALTITUDE SPACECRAFT - IDENTIFICATION AND PHYSICS OF THE PLASMA SOURCE REGION

We have identified surface charging as the probable cause of anomalies experienced by several high-inclination, high altitude spacecraft. Th ese spacecraft have no monitors of the local space particle environmen t. Thus a direct association of anomaly occurrence with surface discha rge is not possible. Rather, we use empirical magnetic-field models to map from a satellite's position, at the time of an anomaly, to the Ea rth's magnetospheric equatorial plane. We appeal to the well-establish ed occurrence distribution of spacecraft charging in the near-geostati onary orbit equatorial plane as a function of magnetic local time, rad ial distance, and geomagnetic activity to interpret the anomaly events . On the basis of the similarity between known surface charging distri butions and the anomaly distributions, we conclude that anomaly associ ated surface charging likely occurred owing to transient hot plasma an d medium-energy electrons associated with magnetospheric substorms. We believe that this technique will aid satellite operators in the asses sment of anomalies experienced by high-inclination spacecraft.