What is Multilayer insulation (MLI)?

Multilayer insulation is a special blanket for space tools that stops heat from escaping or entering.

Imagine you are sleeping in a very cold tent. You might put on three thick wool blankets to stay warm. Multilayer insulation works the same way, but for rockets and satellites. It is made of many thin sheets of shiny metal or plastic stacked together, like pages in a very thin book. Each sheet reflects heat away, just like a silver lunchbox keeps food hot or cold. The spaces between the sheets are empty, which means no air can move to carry heat. This stops warmth from leaking out into the freezing dark of space.

Think of a thermos bottle. The shiny inside reflects heat back to your coffee. Multilayer insulation does this many times over. If you have five layers, heat bounces off the first sheet, then the second, and so on. It is like a game of catch where the ball (heat) gets stuck bouncing back and forth instead of flying away. This keeps sensitive electronics safe from extreme cold or hot sun. Without it, a satellite would freeze or overheat very quickly. It is simple physics, not magic, just smart stacking of reflective sheets.

It is the space equivalent of wearing ten t-shirts when it is freezing outside.