HeatTransfer is the study of the movement of thermal energy from one object toanother object of different temperature. When considering heat transfertechnologies, many may consider examples such as battery cooling, soldering,brazing, solar panels and turbines. However, the study of heat transfer andheat transfer design heavily contributes to the design of spacesuits.Spacesuits are required to keep an astronaut safe in the harsh environments ofspace; an environment that is completely lethal to human beings without properengineering. With the help of heat transfer technology, such as heat sinks, anastronaut in space can be safely exposed to the dangerous conditions.
Toregulate heat, heat syncs are incorporated into three primary components of thespacesuit that allow the astronaut to maintain homeostasis in the spacesuitcomfortably: extravehicular activity,coolant through various tubing, and layered insulation. Tounderstand the critical components of a spacesuit, one must first understand whatmakes the space environment dangerous for life. Space is a vacuum, meaningthere is no air and no pressure, and this kind of environment allows electromagnetic radiation to travel greatdistances without being scattered, which is about 3.
0 x 108 metersper second through a vacuum.Withthe combination of vacuums and electromagnetic waves, space is subjected toextremely hot and cold temperatures. Understanding how these varyingtemperatures interact with objects in space, the concept of “empty space” iscritical. Empty space, is known as the space between the stars, and iscomprised of 99.9% of atoms. Empty space has a cosmic background temperaturewhich is negative 270 degrees Celsius, and this is the temperature of themajority of space.
Temperatures onlyincrease when next to stars, like the Sun, which generate heat through radiation.However, heat can still travel through the vacuum of space by infraredradiation. In space, the UV radiation generated is mostly due to the sun.Radiation can also be generated from particles trapped in the Earth’s magneticfield; particles shot into space during solar flares (solar particle events);and galactic cosmic rays, which are high-energy protons and heavy ions fromoutside the Milky Way solar system. Due to the frigid nature of the cosmicbackground temperature, the various gasses and molecules that do exist in emptyspace do not have the energy to bounce around, and heat is sparse despiteradiation heat transfer existing.
This combination of the natural frigid stateof space and the heat generated from various stars, such as Earth’s Sun,essentially means that most of the gas that exists in empty space is too farand few in between. There are not enough energized particles to bump into eachother, and transfer heat in empty space, despite having numerous starts thatgenerate heat.Therefore,heat transfer boils down to two extremes in space: whether an object isshielded by the sun or not.
If an object is in space, but shielded from the sun,essentially all heat is radiated away to the cooler cosmic backgroundtemperature. If not shielded by the sun, that same object is exposed to extremeradiation that would kill any living organism in space that is not properlyprotected. Even on earth where 95% of UV radiation is absorbed bythe atmosphere, problems such as sunburns and increasing the risk of DNA andother cellular damage in living organisms exists. When considering a spacesuit that must protect an astronaut,these extreme conditions must be taken into consideration. In addition toprotecting the astronaut from extreme temperatures, the spacesuit has othercomponents that are necessary for the astronaut to function in space. The suitis capable of supplying the astronaut with oxygen, since there is no air inspace. The spacesuit contains water for the astronauts to drink and the suitprotects the astronaut from getting injured by small space debris, which havethe potential to travel faster than a bullet.
The spacesuit has several pats.The chest is protected by the Hard Upper torso, made from fiberglass. There is also a helmet, which is made from apolycarbonate material, and has a large plastic pressurized bubble that has ventilationdistribution pad. There is a straw for drinking, a camera for recording and amicrophone for keeping communication. The Lower torso includes pants boots layers of synthetic polymers suchas nylon, Teflon, Kevar and Nomex. There is a backpack worn called the PrimaryLife Support Subsystem, which holds the oxygen for astronauts. A small fanmoves the oxygen from the life support subsystem, through the spacesuit and life supportsystems. The subsystem also provides electricity for the suit.
In addition tothis there is the Liquid Cooling and Ventilation and Garment, which cools theastronauts down. A schematic of the spacesuit can be found below in Figure 1: insert figure of spacesuit Inaddition to considering design features of the space suit, such as stabilizinginternal pressure, mobility, adequate supply of oxygen; the design of a spacesuit is largely a heat regulation and heat transfer design accomplishment. For example, just in Earth’s orbit, conditions can beas cold as minus 156 degrees Celsius. In the sunlight, they can be as hot as 121degrees Celsius. If an astronaut’s back is facing the sun and the front is not,the temperature difference can be as much as 135°C. The vacuum in spaceincreases the temperature too, as heat cannot escape into the surrounding airas it does on Earth.
The vacuum can also free trapped pollutants such as watervapor, and deposit this water on cool parts of the space suit where it cancause problems such as shorting electronics. Spacesuits are speciallydesigned to protect astronauts from the cold, radiation and low pressure inspace. To regulate heat, heat syncs are incorporated into three primarycomponents of the spacesuit that allow the astronaut to maintain homeostasis inthe spacesuit comfortably: extravehicularactivity, coolant through various tubing, and layered insulation.