The 5 Nms Variable Speed Control Moment Gyroscope (VSCMG) is a single gimbal Control Moment Gyroscope (CMG), which has variable rotor angular speed. A VSCMG is considered to be a hybrid device comprised of a CMG and a momentum (or reaction) wheel, with advantages on both large torque output as a single gimbal CMG, and accurate output torque magnitude as a wheel. The VSCMG acts like a regular CMG during rapid attitude reorientation period, and alternates to the flywheel control mode, when approaching the demand position for high pointing allocation.
The 5Nms VSCMG is designed for mini satellites (mass between 300 kg and 500 kg). With 5 Nms VSCMGs onboard, the satellite angular rates can reach up to 5 deg/s, and angular acceleration up to 1 deg/s^2, which are dedicated to high resolution earth observation and environment monitoring.