SPACECRAFT CHARGING ANOMALY ON A LOW-ALTITUDE SATELLITE IN AN AURORA

On May 5, 1995, the microwave imager instrument aboard the Defense Met eorological Satellite Program F13 spacecraft experienced a lockup of i ts microprocessor unit. The anomaly is attributed to an electrical mal function caused by an electrostatic discharge on the vehicle. It occur red during an intense energetic electron precipitation event within a region of very low plasma density in the auroral zone. Plasma measurem ents indicate that the spacecraft frame charged to a voltage near 459 V within a few seconds. Calculations of the capacitance of the ungroun ded thermal blankets covering the surface of the spacecraft are consis tent with a surface charging time of a few seconds to reach several ki lovolts. Subsequent electrostatic discharge led to the lockup.