Ultra-lightweight mirrors with high solar reflectivity and high infrared emissivity for sun-facing radiative thermal management in space

Abstract

We report the design, fabrication, and characterization of ultralight coatings that employ Salisbury screen principles and the unique nature of ITO to achieve frequency selective broadband emissivity. Our coating comprises 60 nm SiO2, 10 nm ITO, 2.3 µm NeXolv LaRC CP1 polyimide and 300 nm Ag, and achieves an aerial mass of 4.07 gm-2. It has a calculated and measured visible spectrum reflectivity of R = 0.893 and R = 0.896 respectively when weighted against AM0 from 300 nm to 1800nm; and a calculated and measured IR spectrum emissivity of e = 0.574 and e = 0.554 weighted against a 300 K blackbody respectively. This simple coating design, fabricated on the centimeter scale, achieves broadband frequency selectivity, with the highest reported thermal performance for an ultralight sun-facing radiative energy management structure.