Comparison of Control Moment Gyros and Reaction Wheels for Small Earth-Observing Satellites

Abstract

Multi-ton Earth-observing spacecraft have traditionally used control moment gyros (CMGs) to store momentum and to generate the large torques required for fast slew maneuvers. Small 3-axis controlled satellites, by contrast, will typically use cheaper and simpler reaction wheels to perform the same functions. The question then arises: which actuator is better suited for an Earth-observing mission? This paper compares the performance of each actuator subject to identical agile pointing requirements, and identifies the operating conditions in which one actuator outperforms the other.