You've been on a long hike and despite your best efforts you've become lost. You followed the map, you marked your trail prior to leaving, but somewhere between the crawling over the rocks and being inspired by the natural beauty around you, you lost your way. It's getting dark. It's cold, and it's only going to get colder. There's no way you can make off the mountain in time, and you'll never find the trail in fading light. Your fire making skills are minimal. You didn't dress for a night out in the elements. Your thin long sleeved t-shirt and windbreaker will do little to stave hypothermia. What to do?
Suddenly, you remember the emergency kit in the bottom of your daypack. Beneath the emergency flares, gauze, and paracord, you find a small plastic bundle filled with what looks like silver foil. Ripping it open you begin to unfold it. It's surprisingly large. You find a large pile of leaves and spread the blanket over it. Climbing inside, you seal yourself up. You immediately begin to feel warmer as your body heat warms the space around you. Tonight won't be comfortable, but you will survive it. You fall asleep vowing to never get lost again.
A space blanket can save your life in an emergency situation. Also known as a Mylar blanket, first aid blanket, emergency blanket, thermal blanket or weather blanket, the space blanket was designed in 1964 by NASA for (you guessed it) space travel. It is essential a thin layer of plastic covered by a MPET (metalized polyethylene terephthalate) usually silver or gold in color.
The Space Blanket works by reducing heat loss due to convection, evaporation, and thermal radiation. It does not prevent heat loss due to conduction. A layer of insulation must be between the user and the ground. If the user is lying on snow, they will freeze to death. Used properly the Space Blanket can save lives.
Space blankets can also be used as:
Sun Shields: They are reflective
Signals: Once again using their reflective properties
Improvised shelters: They are waterproof
As insulation: If you are trapped in your car or a similar closed space. Cover the windows and openings with the blanket (shiny side) in to prevent heat loss due to thermal radiation.
Space blankets come in a variety of shapes and sizes but most commonly they are about the size of a deck of cards when folded and fold out to be about 5 feet by 7 feet. They are generally less than $4 and can be found many places online and at your local sporting goods store or camping outfitters. They are an essential part of any emergency kit or go-bag.