Test-derived effective emittance for cassini mli blankets and heat loss characteristics in the vicinity of seams

摘要

Thermal performance of Cassini 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 19percent higher effective emittance than the hybrid Kapton-Mylar 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 deg 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.