An experimental study of a smart radiator device (SRD) for enhanced passive thermal control of satellites
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This thesis is an investigation of the performance, benefi ts, and commercial viability of a new satellite thermal control technology called a Smart Radiator Device, or SRD, developed by MPB Communications. The SRD is proposed as a replacement for traditional radiators in certain spacecraft applications, speci fically for components with a wide variation in thermal loads. These variations can be due to external conditions, such as the extended eclipse periods for lunar landers, or internal conditions resulting from a high power low duty cycle component. The SRD provides improved thermal control over a radiator as it exhibits a temperature dependent emissivity profi le, resulting in high heat rejection rates at high temperatures and low heat rejection rates at low temperatures. These variations in heat rejection are expected to affect both the survival heater power required for components and the variations in component temperature throughout a given orbit/cycle. For this study, I fi rst performed thermal vacuum chamber (TVAC) testing of a set of sample SRDs, and correlated this test data with the results of simulations I created in NX Space Systems Thermal software. I was able to correlate the data within my required 10C error margin, with maximum and average deviations of 7.21C and 3.57C respectively. The testing experience also led me to develop a set of best practices for TVAC testing small satellite components. To evaluate the SRD performance I created thermal math models and simulations of small spacecraft in three test case conditions: a Low Earth Orbit satellite, a Geostationary Orbit satellite, and a lunar lander. Using these simulations to compare the SRD performance with a traditional radiator I found that the SRDs resulted in survival heater power savings of 24% to 219% for the test cases considered. The SRDs also result in slightly higher temperature variations, with temperature swing increases of 1.19C to 2.90C compared to the traditional radiator. Overall, these results indicate that the SRDs are a feasible and benefi cial replacement for a traditional radiator, provided that MPB Communications can make the necessary improvements to the SRD properties and manufacturing processes to make the technology commercially viable.