A Heat Switch for Space Applications

Various planned NASA missions require heat switches for active thermal control. As an example cryocoolers, including redundant coolers are incorporated on select missions. The redundant coolers operate when deteriorating or defunct coolers are deactivated. However, integration of redundant coolers may cause substantial parasitic heat loads unless the cold regions are thermally connected to the active cryocooler only. The overall system efficiency will depend in part on the efficacy of the intervening heat switches. We propose to develop a highly effective, innovative prototype heat switch that combines two recently developed technologies. First, it employs a highly conductive thermal contact at a low applied force. Secondly, the heat switch employs an innovative bi-stable actuator. The actuator requires little energy to switch between states and can achieve motion on the order of millimeters. This available motion exceeds the tens to hundreds of microns needed to engage the contact, enabling complete separation, and thus, excellent thermal isolation in the off state. Combining the inherently high on- and low off-conductance of the contacts with the bi-stable actuator positioning provides for a highly effective, innovative heat switch, potentially enabling significant performance enhancement of NASA missions.