Innovative Wax-Filled Heat Sinks Enhance Cooling for Space Electronics

An interdisciplinary research team, led by Professor Mickey Clemon from the Grainger College of Engineering at the University of Illinois Urbana-Champaign, is pioneering advancements in thermal management systems for electronics in space. Their innovative approach involves the use of wax-filled heat sinks, which were tested aboard a satellite currently orbiting Earth, demonstrating significant potential for improving the longevity and performance of electronic components in extreme conditions.

The research team’s findings, published in the International Journal of Heat and Mass Transfer on July 3, 2025, highlight how the wax-based phase change material within these heat sinks operates effectively by absorbing excess heat. This mechanism allows the electronics to remain within safe temperature ranges for extended periods, crucial for maintaining functionality in the challenging environment of space. Professor Clemon stated, "We are testing different duty cycles and cooling regimes with the fixed heat sinks that we've put up there, aiming to inform the design and operating sequences for other electronics and computing in space."

Historically, managing heat in space has presented significant challenges due to the lack of convective cooling in a vacuum and the high waste heat generation from electronic devices. Traditional methods often necessitate limiting computing power to avoid overheating. However, the research team has developed a novel solution that circumvents these limitations by utilizing the melting wax to store energy more rapidly, thus cooling the electronics more efficiently.

The heat sinks were deployed on a CubeSat, a miniaturized satellite comprising cubic modules measuring 10 cm per side, launched as part of the Waratah Seed Mission in August 2024. This mission's success is noteworthy, as university-sponsored satellites have a historically low success rate in reaching orbit. According to Clemon, "We're very happy that we made it into space and that our system works."

The experimental setup aboard the CubeSat allows the team to alternate between their experiments and those of other research payloads, providing a collaborative environment for testing various technologies in microgravity. Preliminary results have been promising; notably, the melting wax significantly enhances the duration that electronics can function within a safe thermal range. Additionally, the microgravity environment has shown no adverse effects on the wax's orientation within the heat sinks, a crucial factor for the reliability of the cooling system.

Further developments in this research include the creation of simplified predictive models for heat sink performance. These models will enable designers to test their concepts without the need for immediate physical prototypes, thereby streamlining the development process for future space electronics. Clemon emphasized the importance of understanding the underlying heating profiles from solar exposure, stating, "Our orbit is about 90 minutes, and because of that, we have some sun exposure time and non-sun exposure time. We want to explore the effect of that on the computing time that's available for the electronics."

This groundbreaking research not only enhances the potential for more efficient electronics in space but may also have broader implications for various industries reliant on thermal management solutions. As the team continues its experiments, the data collected will contribute significantly to the design and operation of future electronic systems in aerospace and beyond.

The co-authors of the study include Laryssa Sueza Raffa, a Ph.D. student at the University of Technology Sydney; Matt Ryall from Mawson Rovers, the industry partner; as well as Professor Iver Cairns and Associate Professor Nick Bennett from the University of Sydney and the University of Technology Sydney, respectively. Their collaborative efforts underscore the interdisciplinary nature of this important research, which is set to influence the future of electronics in demanding environments.