What is the function of the golden foil that covers space probes?

Without its shimmering sheath, the probe would boil – or is that freeze…?

11th March 2016
What is the function of the golden foil that covers space probes? © NASA

Asked by: Wail Alsallami, Yemen

Some people think that the gold foil is there to block electromagnetic radiation and to protect the electronics on the spacecraft, but the function is actually thermal. Without the foil, heat would readily escape from the space probe into the coldness of space. In return, the Sun’s heat would fry the equipment. The foil consists of several aluminium sheets, each contributing to better insulation. Sandwiched between the thin metal sheets is thermally opaque plastic spacer.