Preventing heat escape through gold paint
To help prevent heat from escaping out of the rover body and cold air from coming inside during landing operations, the outside of the rover body is painted with a gold coating. Using the same technique that many jewelers use, engineers lightly "sputter" or spray on the gold metal. The gold coating helps reduce energy that is radiated (energy spread outward) from the rover body.
The highly reflective gold finish effectively isolates the rover body from emitting heat energy out to the cold, sky temperature. This technique is similar to that used in a thermos bottle, where the reflective coating on the inner vacuum bottle helps keep coffee hot by minimizing radiation heat transfer across the bottle.