How Astronauts Will Survive In Space

Protection from the Cold and Heat of Space

Temperatures in space fluctuate drastically depending on whether a surface is in sunlight or in darkness. For instance, the International Space Station can be as hot as 250 degrees Fahrenheit on the sunny side and negative 250 degrees Fahrenheit on the dark side. Insulation must keep the internal temperature relatively stable in fluctuating conditions and also shield the cabin from radiation and microwaves. Currently, space craft is insulated with MLI or multilayer insulation. This insulation has multiple layers that serve to insulate and shield spacecraft and satellites from extreme temperatures and radiation. The insulation is composed of Mylar and Dacron. Mylar or Melinex is used for electrical insulation and performance boat sails. It is extremely tough material and has a high tensile strength. Dacron is a thermoplastic polymer used to insulate materials. It has many industrial insulation uses. Mylar and Dacron are layered to create a strong supple insulating fabric. The Mylar also prevents electrical conduction and radiation penetration. The Mylar and Dacron are covered with Kapton – the silver copper colored paper remembered from the first lunar lander. Kapton also composes the outer layer of space suits. Water is then pumped inside the craft via a duct-way of heat exchanges and cold plates to regulate the internal and external temperatures of the craft. Convection heating and cooling is used internally for the air temperature and conduction is used for mechanical parts, engines, and external temperature regulation. Spacecraft have always been well insulated – so much that radiators are required to expel excess heat out into space.

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The insulating and cooling mechanisms on spacecraft have remained roughly the same since early Apollo missions. Solar technology along with gas cooling and thermoelectric cooling has not been widely used. Peltier units combined with a solar collection grid may be an interesting experiment for future spacecraft temperature regulation. Peltier units are solid state, have no moving parts, and function as a heat pump with both a hot and cold side. Eliminating the use of moving parts and reliance on water or liquid/gas cooling could be a large step in improving the reliability and reducing the size and weight of spacecraft survival systems and machinery cooling apparatus.