Space blanket

A space blanket (also known as a Mylar blanket, first aid blanket, safety blanket, thermal blanket or weather blanket) is an especially low-weight, low-bulk blanket made of heat-reflective thin plastic sheeting. Their design reduces the heat loss in a person's body which would otherwise occur due to thermal radiation, water evaporation, or convection. Their compact size before unfurling and light weight makes them ideal when space is at a premium. They may be included in first aid kits and also in camping equipment. Lost campers and hikers have an additional possible benefit: the metallic surface appearance flashes in the sun, allowing use as an improvised distress beacon for searchers.

First developed by NASA's Marshall Space Flight Center in 1964 for the US space program, the material consists of a thin sheet of plastic (often PET film) that is coated with a metallic reflecting agent, making it metallized polyethylene terephthalate (MPET), usually gold or silver in colour, which reflects up to 97% of radiated heat.

For use in space, polyimide (e.g. kapton, UPILEX) substrate is usually employed due to its resistance to the hostile space environment, large temperature range (cryogenic to −260 °C and for short excursions up to over 480 °C), low outgassing (making it suitable for vacuum use) and resistance to ultraviolet radiation. Aluminized kapton, with foil thickness of 50 and 125 µm, was used e.g. on the Apollo Lunar Module. The polyimide gives the foils their distinctive amber-gold color.

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