Effective emittance for Cassini multilayer insulation blankets and heat loss near seams

Abstract

Thermal performance of Cassini multilayer insulation (MLI) blankets was characterized in thermal vacuum tests. Effective emittance was derived for the standard and high-temperature layups, with or without micrometeoroid protection standoffs, and for a high-performance duo-layup with staggered seams. The all-Kapton® layup was shown to have a 19% higher effective emittance than the hybrid KaptonMylar® layup, and the duo-layup exhibited a dramatic capability of reducing heat dissipation by 2.6-fold. Several different definitions of effective emittance are discussed, and their relations to distinct hardware-MLI configurations and corresponding modeling techniques clarified. Large temperature differences (up to 70°C) were observed between the center and seam of a blanket. Heat losses in the vicinity of seams are quantified, and a major MLI heat loss mechanism elucidated.