A space blanket (also known as a
Mylar
BoPET (biaxially-oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aro ...
blanket, emergency blanket, first aid blanket, safety blanket, thermal blanket, weather blanket, heat sheet, foil blanket, or shock blanket) is an especially low-weight, low-bulk
blanket
A blanket is a swath of soft cloth large enough either to cover or to enfold most of the user's body and thick enough to keep the body warm by trapping radiant body heat that otherwise would be lost through convection.
Etymology
The term ...
made of
heat-reflective, thin, plastic sheeting. They are used on the exterior surfaces of spacecraft for thermal control, as well as by people. Their design reduces the heat loss in a person's body, which would otherwise occur due to thermal radiation, water evaporation, or convection. Their low weight and compact size before unfurling make them ideal when space or weight are at a premium. They may be included in
first aid kit
A first aid kit or medical kit is a collection of supplies and equipment used to give immediate medical treatment, primarily to treat injuries and other mild or moderate medical conditions. There is a wide variation in the contents of first aid ...
s and with camping equipment. Lost campers and hikers have an additional possible benefit: the shiny surface flashes in the sun, allowing its use as an improvised
distress beacon
An Emergency Position-Indicating Radio Beacon (EPIRB) is a type of emergency locator beacon for commercial and recreational boats, a portable, battery-powered radio transmitter used in emergencies to locate boaters in distress and in need of i ...
for
searchers and as a method of signalling over long distances to other people.
Manufacturing
![Myla32rp](https://upload.wikimedia.org/wikipedia/commons/5/56/Myla32rp.jpg)
First developed by
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
s
Marshall Space Flight Center
The George C. Marshall Space Flight Center (MSFC), located in Redstone Arsenal, Alabama (Huntsville postal address), is the U.S. government's civilian rocketry and spacecraft propulsion research center. As the largest NASA center, MSFC's first ...
in 1964 for the US space program,
the material comprises a thin sheet of
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
(often
PET film) that is coated with a
metal
A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...
lic,
reflecting agent, making it
metallized polyethylene terephthalate Metallised films (or metallized films) are polymer films coated with a thin layer of metal, usually aluminium. They offer the glossy metallic appearance of an aluminium foil at a reduced weight and cost. Metallised films are widely used for decorat ...
(MPET) that is usually gold or silver in color, which reflects up to 97% of
radiated heat.
For use in space,
polyimide (e.g.
Kapton
Structure of poly-oxydiphenylene-pyromellitimide
Kapton insulating pads for mounting electronic parts on a heat sink
Kapton is a polyimide film used in flexible printed circuits (flexible electronics) and space blankets, which are used on spac ...
,
UPILEX
Upilex is a heat-resistant polyimide film that is the product of the polycondensation reaction between biphenyl tetracarboxylic dianhydride ( BPDA) monomers and a diamine. Its properties include dimensional stability, low water absorption, high c ...
) substrate is usually chosen due to its resistance to the hostile
space environment
Space environment is a branch of astronautics, aerospace engineering and space physics that seeks to understand and address conditions existing in space that affect the design and operation of spacecraft. A related subject, space weather, deals ...
, large temperature range (cryogenic to −260 °C and for short excursions over 480 °C), low
outgassing
Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen, or absorbed in some material. Outgassing can include sublimation and evaporation (which a ...
(making it suitable for
vacuum use), and resistance to
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
radiation. Aluminized
Kapton
Structure of poly-oxydiphenylene-pyromellitimide
Kapton insulating pads for mounting electronic parts on a heat sink
Kapton is a polyimide film used in flexible printed circuits (flexible electronics) and space blankets, which are used on spac ...
, with foil thickness of 50 and 125 µm, was used on the
Apollo Lunar Module
The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed ...
. The polyimide gives the foils their distinctive amber-gold color.
Space blankets are made by
vacuum-depositing a very precise amount of pure
aluminum
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
vapor onto a very thin, durable film substrate.
Usage
In their principal usage, space blankets are included in many emergency,
first aid
First aid is the first and immediate assistance given to any person with either a minor or serious illness or injury, with care provided to preserve life, prevent the condition from worsening, or to promote recovery. It includes initial in ...
, and survival kits because they are usually waterproof and windproof. That, along with their low weight and ability to pack into a small space, has made them popular among outdoor enthusiasts and emergency workers. Space blankets are often given to
marathon
The marathon is a long-distance foot race with a distance of , usually run as a road race, but the distance can be covered on trail routes. The marathon can be completed by running or with a run/walk strategy. There are also wheelchair div ...
ers and other endurance athletes at the end of races, or while waiting before races if the weather is chilly. The material may be used in conjunction with conductive insulation material and may be formed into a bag for use as a
bivouac sack
A bivouac shelter is any of a variety of improvised camp site, or shelter that is usually of a temporary nature, used especially by soldiers, or people engaged in backpacking (hiking), backpacking, bikepacking, scouting, or Mountaineering, mount ...
(
survival bag).
In
first aid
First aid is the first and immediate assistance given to any person with either a minor or serious illness or injury, with care provided to preserve life, prevent the condition from worsening, or to promote recovery. It includes initial in ...
, the blankets are used to prevent or counter
hypothermia
Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
. A threefold action facilitates this:
* The airtight foil reduces
convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...
* Heat loss caused by
evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
of
perspiration
Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals.
Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distr ...
is reduced
* The
reflective
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The ' ...
surface inhibits losses caused by
thermal radiation
Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is ...
In a hot environment, they can be used to provide shade or protection against radiated heat, but using them to wrap a person would be counterproductive, because
body heat
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
would get trapped by the airtight foil. This effect would exceed any benefit gained from heat reflection to the outside. Wearing a space blanket produces an insignificantly slower cooling rate after running in hot, humid conditions.
Space blankets are used to reduce heat loss from a person's body, but as they are constructed of
PET film, they can be used for other applications for which this material is useful, such as insulating containers (e.g. DIY solar concentrators) and other applications.
In addition to the space blanket, the
United States military
The United States Armed Forces are the military forces of the United States. The armed forces consists of six service branches: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. The president of the United States is the ...
also uses a similar blanket called the "casualty blanket". It uses a thermal reflective layer similar to the space blanket, backed by an
olive drab
Olive is a dark yellowish-green color, like that of unripe or green olives.
As a color word in the English language, it appears in late Middle English. Shaded toward gray, it becomes olive drab.
Variations
Olivine
Olivine is the typical ...
-colored, reinforcing, outer layer. It provides greater durability and warmth than a basic space blanket at the cost of greater bulk and weight. It is also used as a partial liner inside the layers of bivouac sacks in very cold weather climates. Space blankets were also used by the
Taliban
The Taliban (; ps, طالبان, ṭālibān, lit=students or 'seekers'), which also refers to itself by its state (polity), state name, the Islamic Emirate of Afghanistan, is a Deobandi Islamic fundamentalism, Islamic fundamentalist, m ...
to hide their heat signature from NATO forces.
[Smucker, Philip]
"U.S. soldiers' options limited to protect Afghans from Taliban."
The State. Jun. 2, 2009.
See also
*
Emergency shelter
*
Emissivity
The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation that most commonly includes both visible radiation (light) and infrared radiation, which is n ...
*
R-value (insulation)
In the context of construction, the R-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat. R-value is the temperature difference per ...
*
Radiant barrier
A radiant barrier is a type of building material that reflects thermal radiation and reduces heat transfer. Because thermal energy is also transferred by conduction and convection, in addition radiation, radiant barriers are often supplemented wit ...
*
Reflectivity
The reflectance of the surface of a material is its effectiveness in Reflection (physics), reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the respon ...
*
Thermal insulation
Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...
*
Thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
*
Thin-film deposition
A thin film is a layer of material ranging from fractions of a nanometer ( monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many a ...
References
External links
*
{{DEFAULTSORT:space blanket
Blankets
First aid
Materials
Technical fabrics
NASA spin-off technologies
American inventions
1964 introductions