Satellite Anomalies from Galactic Cosmic Rays

TLDR

Satellite communication anomalies arise from unexpected triggering of digital circuits. The study examined whether galactic cosmic rays trigger these satellite anomalies. The authors modeled the charging of transistor base‑emitter capacitances to turn‑on voltage, estimating event rates from transistor parameters, charge collection efficiencies, and the number of sensitive devices identified by SEM analysis. Calculated iron‑cosmic‑ray event rates of 3.1×10⁻³ per transistor per year matched the observed 1.5×10⁻³, supporting the hypothesis.

Abstract

Anomalies in communication satellite operation have been caused by the unexpected triggering of digital circuits. Interactions with galactic cosmic rays were investigated as a mechanism for a number of these events. The mechanism assumed was the charging of the base-emitter capacitance of sensitive transistors to the turn-on voltage. The calculation of the cosmic ray event rate required the determination of transistor parameters, charge collection efficiencies, and the number of sensitive transistors. The sensitive transistors were determined by analyzing the results of a scanning electron microscope experiment. Calculations with iron cosmic rays resulted in an event rate of 3.1 × 10-3 per transistor per year, in reasonable agreement with the observed rate of 1.5 × 10-3.