With his three-year, $600,000 grant, Wehmeyer will investigate novel approaches to thermal-control materials for spacecraft. His proposal is titled “High Turndown Ratio Heat Switch Using Temperature-Dependent Magnetic Forces.”
Wehmeyer earned his Ph.D. in MECH from the University of California, Berkeley, in 2018, and joined the Rice faculty the same year. His Nanoscale Heat Transfer Lab includes two doctoral students and an undergraduate.
“Spacecraft experience extreme temperature swings at different times of the mission,” he said. “Engineers also have to efficiently manage the heat generated by instruments onboard. Thermal control systems keep components at just the right temperature over a wide range of conditions.
“NASA now uses a phase-change heat switch based on paraffin wax to regulate the temperature. When the wax melts, it expands and pushes metal surfaces into thermal contact to keep electronics from overheating. When the system cools down, the wax solidifies, and the gap between surfaces keeps the spacecraft insulated.”
Wehmeyer proposes an alternative strategy: a passive magnetic heat switch. Unlike the paraffin wax heat switches used today, the proposed magnetic switch would employ the mechanism of temperature-dependent magnetic repulsion to control the heat flow between surfaces.
“The system now in use is bulky and heavy, and NASA like to make everything as compact and light as possible. We propose using a magnetized thin film system for thermal control,” he said.
The Early Career Faculty initiative is administered by NASA’s Space Technology Research Grants Program, funded by its Space Technology Mission Directorate.