Why Satellites Are Wrapped In Gold?

You cannot see them with naked eyes, but the reality is that there are hundreds of satellites orbiting the earth. Not everyone may be functional, but that does not mean they do not exist. Here on earth, we often come across images and videos of satellites being prepped up for launch.

One thing that is common across most satellites is the yellow-colored layer that is used to cover these satellites. It makes us wonder why satellites are wrapped in gold. For answers, here are some important things to understand.

Are satellites wrapped in gold?

The gold-colored wrapping seen on satellites appears exactly like gold foil. And given the general perception that these satellites have highly sensitive equipment, one tends to believe that the golden colored wrapping is actually gold. But the golden colored wrapping used on satellites is usually not gold. And even the appearance of foil is deceptive, because the material is not a foil at all.

What we see as golden colored wrapping on satellites is actually multi-layer insulation. It is referred to in short as MLI. It comprises multiple layers of reflective films that are combined together as one. Most commonly used materials for making the layers are polyimide or polyester films. These are a type of plastic that are coated with thin layers of aluminium. Their exact chemical composition and thickness depends on various factors such as the orbiting area of the satellite, what components are being protected and the level of exposure to sun.

On the one side, the polyimide has a silver shade that is actually the aluminium coating. This layer is usually placed on the inside. The outer side of the polyimide has a yellow shade, which is usually mistaken for gold. However, it is just the color and not actually gold.

Although not gold, multi-layer insulation is necessary for a satellite. Without MLI, the satellite will be exposed to extreme temperatures of the space. Such exposure can damage the satellite within seconds. MLI can protect the internal components of a satellite from extreme cold and heat of space. In near earth orbit, temperatures can vary from -200°F to 300°F. MLI works by deflecting solar radiation, thereby keeping internal components cool. Another crucial role played by MLI is protection from dust and debris.

Why is gold used in satellites?

As is evident from above, the gold wrapping seen on satellites is not usually real gold. But that does not mean that satellites do not use gold. As a matter of fact, satellites have a significant amount of gold. Much more than one would find in electronic items used on earth. Real gold in satellites is used on electrical and electronic contacts, radars, sensors and solar panels.

Gold reduces corrosion and protects equipment from x-rays and ultraviolet light. With use of gold, satellites can be more reliable and function for longer periods in space. Even the astronauts’ visors are coated with a thin layer of gold to filter out harmful rays coming from the sun.