Development of Mechanical Heat Switch for Future Space Missions

The heat switch provides appropriate thermal switching (high or low thermal conductance) depending on the thermal environment around spacecraft. It has an advantage in terms of thermal control of spacecraft such as a lunar rover and planetary exploration spacecraft which have difficulty securing sufficient heater power to keep the spacecraft within its allowable temperature range. The authors have developed a paraffin-actuated heat switch. The required thermal performance is 1W/K as ON thermal conductance and 100 as ON/OFF thermal conductance ratio. The test model was fabricated and some activities to improve thermal performance were conducted, such as Au coating on the contact surfaces. A breadboard model (BBM) with the improved design was fabricated and its performance evaluated. Consequently, BBM achieved 1.6W/K as ON thermal conductance and 127 as ON/OFF ratio.