Evaluation of phase change material thermal control architectures for a WaferSatellite using integrated design and optimization techniques

Abstract

Small satellites such as CubeSats are changing the satellite industry by offering low-cost access to space. The concept of WaferSat - a satellite consisting of only a single silicon wafer - seeks to take this paradigm one step further, utilizing microelectromechanical systems processes to reliably enable mass-producible spacecraft with the potential to form large space sensor arrays. However, as a 200 mm diameter silicon wafer with only 250 grams of mass, WaferSat has little heat capacity. Therefore, temperatures on the spacecraft rapidly approach extremes in eclipse and sunlight. Moreover, the highly integrated nature of WaferSat couples the thermal design challenge to other subsystems. This thesis seeks to explore the potential application of phase change materials to efficiently increase effective heat capacity to reduce the temperature extremes attained on-orbit. An integrated design and optimization framework is utilized to optimize the selection of phase change materials and masses in the presence of severe system resource constraints. Two reference mission scenarios are explored. First, a minimum mass solution is obtained for a fixed-attitude case. Next, a scenario of varied WaferSat attitudes is shown to reduce the required phase change material mass. Finally, design implications and future work to improve implementation feasibility are presented.