A Dual Multilayer Insulation Blanket Concept to Radically Reduce Heat Loss From Thermally Controlled Spacecraft and Instruments
At large distances from the Sun (e.g. Jupiter/Saturn), the solar flux is less than 4% that at Earth. This requires very large solar arrays to meet the power demands of a typical new mission concept. Heat loss through Multi-Layer Insulation (MLI) blankets typically constitutes the vast majority of the total heat loss. Hence, improvements to MLI blankets that reduce heat loss are advantageous to the spacecraft design. The overall effective emittance (ε*) of MLI is usually a range dependent on the number of layers, size of blanket, seams, feedthroughs, layer density and operating temperatures of the heat source and heat sink. A concept has been developed at JPL to reduce the ε* by as much as a factor of two, which produces a corresponding reduction in heat losses. This concept utilizes two MLI blankets physically separated by traditional bumpers or spacers used for micrometeoroid protection. The outer surface of the inner blanket and the inner surface of the outer blanket are low emissivity surfaces to further minimize the total ε* of the overall dual MLI system. Analytical predictions of a dual MLI concept have been made using test data based ε* correlations. A development test has been conducted to validate the dual blanket design’s performance. This paper will describe the dual blanket design concept, schemes for its implementation, and the corresponding test results to validate its performance.