Thermo-mechanical design and analysis of a multispectral imaging payload using phase change material

CubeSats have been on the rise during the last decade and have the potential to substitute large, expensive satellites in many commercial and scientific applications. A reasonable commercial application of these standardized small satellites are Earth Observation constellations with medium spatial and high temporal resolution. The company Orbital Oracle Technologies GmbH (OroraTech) works on such a constellation of CubeSats to detect and monitor wildfires and other high-temperature events. One of the design challenges for any small satellite with high power instruments is thermal design and its thermal stability. The changing thermal environment of the Low Earth Orbit (LEO), the varying power consumption and thereby thermal activity of sensors and processing units combined with the low thermal inertias of small satellites create a challenging task for the design and simulation of small satellites. In the case of OroraTech, each 3-unit (U) CubeSat is equipped with an inf rared sensor ensuring a resolution of 200m/pixel. The thermal stability of the sensor is a main driver of the design of the satellite, to achieve a reasonable measurement quality. Furthermore mass, volume, and power restrictions of 3U CubeSats, but also the design for robustness of the satellite, limit the application of active thermal control for this use case. Thus, in a research collaboration between OroraTech, the TUM, and Fraunhofer IGCV this problem was addressed investigating different thermal control systems (TCS). The use of phase change material (PCM) was chosen as the most appropriate solution to achieve the desired stability and robustness. This paper will evaluate different PCM design aspects, namely material, containment, and conduction enhancement. The final design and its validation through thermal analysis in COMSOL and ESATAN-TMS are addressed.