Launch Load Alleviation for Lightweight, Active Mirrors

Abstract

Lightweight, active, silicon carbide mirrors can increase the capability of space-based optical systems. However, launch survival is a serious concern for such systems, with the vibrations and acoustic from launch threatening to damage the optics. Therefore, this paper examines launch load alleviation techniques that may increase the probability of launch survival. A dynamic, state-space mirror model is developed to determine the launch stress and survival probability. Then, three launch load alleviation techniques are presented and analyzed: whole spacecraft isolation, passive shunt circuits using the existing embedded actuators, and active damping using the existing actuators. All of the techniques reduce the launch stress, but at the expense of mass and complexity. Shunting circuits and active damping can greatly reduce the launch stress and allow many designs that perform well on-orbit to survive launch, increasing the potential capabilities of lightweight, active mirrors.