The futuristic spacecraft drawn by excited artists in the 1950s may not have arrived as imagined, but those artists did get one thing right: spacecraft are shiny, and always will be. This is all to do with temperature. Take the International Space Station: full sunlight can raise its surface temperature to 121°C, while spending an hour in Earth’s shade can drop the same surface to -157°C. The only way to keep the occupants safe is to reflect away as much sunlight as possible, using a shiny, silvery mesh made from aluminised mylar that blocks all solar radiation.
Full sunlight can raise the ISS’s temperature to dangerous levels, but a reflective coating keeps things comfortable