TABLE OF CONTENTS Insulation is used to minimize the thermal interaction of a system with its surroundings and, hence, reduce the expenditure in the energy needed to maintain it at a selected temperature. The thermal design of most satellite canisters is based on the principle of maximizing coverage by insulation while directing waste heat to thermally controlled radiators for disposal into space.
Insulating from surrounding space is generally accomplished with fluffy stacks of very thin (from ?7.5 ?m) sheets of Kapton or Mylar that are made reflective by vapor-deposited aluminum (gold has also been used) on one or both surfaces. Fluffiness is seen to improve when using crinkled or embossed sheets separated by nonmetallic material such as a Dacron mesh. A somewhat thicker ( ?25 ?m) end sheet and still heavier ( ?50 ?m to ?125 ?m) aluminized Kapton or silvered Teflon outer cover enclose the stack to form what is known as a thermal blanket (or MLI blanket or insulation blanket), which is held together by stitching with non-metallic thread or intermittent taping along the edges (every 10 15 cm for large blankets) and sometimes by using nonmetallic snap buttons (say, one for every 25 25 cm 2 of surface area.) Outer covers also serve as a substrate for preferred surface coatings that may be electrically conductive and resistant to the effects of atomic oxygen (Sec. II.E of this chapter).
A schematic of a typical lay-up is shown in Fig.
