Applicability of controllable nanoparticle radiative properties for spacecraft heat rejection

A study was conducted to demonstrate the applicability of controllable nanoparticle radiative properties for spacecraft heat rejection. It was proposed to use thermoresponsive nanoparticle suspensions to achieve passively controlled high turndown ratio heat rejection. The study investigated the performance of the system, including the range of volumetric swelling needed to achieve different levels of turndown and the solar-weighted reflectance. The proposed system was based upon the design of phonon-resonant shell materials coupled with thermoresponsive core materials suspended in a base fluid operating in a single flow loop of the radiator. The optical properties of the base particles needed to be found to determine the system emittance to understand the performance of the device.