A Dual Multilayer Insulation Blanket Concept to Radically Reduce Heat Loss From Thermally Controlled Spacecraft and Instruments
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Deep space missions typically utilize solar arrays as their power source. 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 the spacecraft. Heat loss through Multi-Layer Insulation (MLI) blankets typically constitutes the vast majority of the total losses. Hence, improvements to MLI blankets that reduce heat loss are advantageous to the spacecraft design. The overall effective emissivity (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 that cover the controlled component, and are 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. Detailed thermal models of a dual MLI concept have been made using test data based ε* correlations to show the significant advantage of this concept over traditional single blanket designs. A development test is planned to validate the dual blanket design performance. This paper will describe the dual blanket design concept, schemes for its implementation and test results that are available at the time of its publication.