One of the most commonly utilized insulation systems for National Aeronautics and Space Administration spacecraft is multilayer insulation (MLI). The problem of predicting performance of MLI blankets containing discontinuities is described. Design data and test techniques are required which allow correlation of heat leaks through discontinuities with measurable parameters. Some of these design data are obtained using the Jet Propulsion Laboratory's calorimetric testing program.

New materials and testing approaches will be required for more extreme environments of future spacecraft. Both higher and lower environmental temperatures are anticipated. Insulation performance must meet these demands, at the same time avoiding excessive weight.