Multi-layer insulation

Multi-layer insulation (MLI) is thermal insulation composed of multiple layers of thin sheets and is often used on spacecraft and cryogenics. Also referred to as superinsulation,^[1] MLI is one of the main items of the spacecraft thermal design, primarily intended to reduce heat loss by thermal radiation. In its basic form, it does not appreciably insulate against other thermal losses such as heat conduction or convection. It is therefore commonly used on satellites and other applications in vacuum where conduction and convection are much less significant and radiation dominates. MLI gives many satellites and other space probes the appearance of being covered with gold foil which is the effect of the amber-coloured Kapton layer deposited over the silver Aluminized mylar.

For non-spacecraft applications, MLI works only as part of a vacuum insulation system.^[1] For use in cryogenics, wrapped MLI can be installed inside the annulus of vacuum jacketed pipes.^[2] MLI may also be combined with advanced vacuum insulation for use in high temperature applications.^[3]