Thermochromics with Very Low Transition Temperature

Triton Systems is developing an unpowered, self-switching variable thermal radiance technology we call the Phase Change Thermochromic Radiator (PCTR) for active temperature control of spacecraft surfaces. PCTR automatically changes from low to high infrared emissivity above a designed temperature setpoint, causing a surface in space to radiate heat only when it exceeds a critical temperature. The principle of operation involves a phase change compound integrated into a thin film multilayer less than 2 µm thick. Whereas previous demonstrations of PCTR have shown transition temperatures only down to 30°C, the proposed program will reach temperatures of -10°C and possibly as low as -25°C. The new generation of PCTR will be capable of meeting the demands of manned space vehicles, planetary probes and landers, including manufacturability in areas of 10's of square meters