Views:118 Author:Site Editor Publish Time: 2017-03-22 Origin:Site
Have you ever been at the finish line of a marathon? Did you wonder why, as the runners cross the line,
they wrap themselves in what looks like thin blankets of aluminum foil?
These blankets help the athletes regulate their body temperatures,
which tend to drop drastically once they stop running.
These sheets aren't made of the typical foil you pick up at the grocery store, though.
Derived from NASA technology, the common name for these sheets of foil is space blankets.
Everyone from mountaineers to astronauts to surgeons use them.
Even though space blankets are mass produced and cheaply available today, they had their start
in the space program in the 1970s. In 1973, the Skylab space station began overheating while in orbit.
Because of a broken heat shield, the temperature inside the station approached temperatures of
130 degrees Fahrenheit (54 degrees Celsius). As temperatures continued to rise, NASA personnel
worried about the decay of equipment and food inside the station. The possibility of toxic gases was
also a threat.
Engineers contacted a New Jersey company called National Metallizing to assist them in the
creation of an emergency sunshield for Skylab. Up until this point, manufacturers used the metallizing
process mostly for the toy industry and the making of tinsel for Christmas trees. But NASA realized the
potential of these shiny, thin metallic sheets to deflect heat. Working together, the two organizations
created a reflective parasol that a space crew placed on top of Skylab. It worked, deflecting the heat
and allowing the spacecraft to remain at a normal temperature.
As they work to keep heat out, space blankets also work to keep heat in. Because they could reflect the
wearer's body heat back toward the wearer, these blankets had potential for a multitude of uses.
They/ve become invaluable to marathon runners to help stay warm at the end of a race. Hospitals
find them useful to keep patients warm during surgery, as anesthesia tends to make people shiver.
Campers, climbers and mountaineers -- anyone who may find themselves stranded in cold weather
-- discover space blankets are an extremely lightweight and cheap addition to their first-aid kits.
In 2005, after an earthquake devastated parts of Pakistan, charitable organizations delivered
space blankets to the victims. People used them as both ground cover and warming blankets.
So, how exactly can a paper-thin sheet help hold in heat? How could you use a space blanket in
a survival or emergency situation? Keep reading to find out.
The Science of Space Blankets
How can something so thin keep you warm? Even though it sounds cliché, it's space age technology.
Manufacturers created the material by depositing vaporized aluminum onto a very thin plastic film.
The resulting material is thin, flexible and thermal-reflective -- meaning it reflects heat.
The aluminum helps redirect infrared energy, which is just a fancy word for heat. Depending on how
the blanket is made, it can reflect heat away (that's how NASA used it to cool down Skylab),
or it can reflect heat in (that's how it regulates body temperature). Sometimes called a passive
warming system, space blankets assist the body in conserving that infrared energy.
Let's focus on how space blankets work to keep a person warm. First, we need to understand how
a body loses heat in the first place. Excessive heat loss leads to hypothermia, an extremely
dangerous condition. Space blankets stop both evaporative and convective heat loss.
Evaporation is the process of water changing from a liquid to a gas. In the case of a person,
the liquid can be sweat or wet clothing. Evaporation uses a lot of energy and lowers the body temperature.
This is why you need to be careful not to get too sweaty in cold weather. Your body temperature will
drop quickly once you stop exerting yourself -- and the evaporation of sweat will make you even colder.
To prevent evaporative heat loss, you should try to stay as dry as possible. A space blanket helps
slow down the process of evaporative heat loss by increasing the humidity of the air next to the skin.
Convection is a lot like conduction. Conduction is the transfer of heat or cold between two objects.
For example, if you sit down on a pile of snow, your backside will get colder, and the snow will get warmer.
With convective heat loss, however, the cold object is moving -- like a cold wind. The wind takes the
warmth away from whatever it touches. The faster the object is traveling, the colder you'll get.
You can help reduce convective heat loss by wearing layers of clothing as insulation.
A space blanket forms a barrier between the wearer and the wind, providing insulation.
Lastly, we also lose body heat through radiation -- it simply radiates off our body. The reflective
agent on space blankets -- usually silver or gold -- reflects about 80 percent of our body heat back to us.
Next up, we'll talk about the many ways you can use a space blanket for survival.