Optical Measurement of the Reflectance Behavior of Z93, the Thermal Coating on the International Space Station

Space-based construction materials must meet a range of requirements: mechanical robustness, lightweight characteristics, and tolerance to heat (due to extreme exposure to solar radiation). There are three optical requirements for heat management: the solar reflectance must be sufficiently high, the thermal emissivity must be sufficiently high, and the surface must be diffuse. These properties ensure that the spacecraft will remain cool, and the thermal control material will perform over a wide range of exposure angles. Here, we examine a ceramic material, Z93, which is in current use on the International Space Station (!SS). Measurements of the optical properties reveal why Z93 is successful in the ISS’s implementation, and also point to potential future material improvements.