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Life Support > Temperature Control |
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Although space can be extremely cold, excess heat can also be a problem. A spacecraft uses heaters to generate heat, insulating materials to conserve heat, transfer systems to manage heat, and radiators to expel excess heat. Materials that can not reasonably be kept at certain temperatures must be specially made to prevent them from shrinking or expanding.
Analysis
Different parts of the spacecraft require cold or warm environments. Electric heaters electrically-heated wires to generate heat, and electronic equipment used give off heat as well. The insides of different spacecraft have different operating temperatures, such as 10°-30° Celsius. This means that the parts of the spacecraft have been tested and will function in those temperatures. If, for example, rocket thrusters use hydrazine as the rocket fuel, the fact that hydrazine freezes at 2°C (35°F) and boils at 113°C (236.3°F) must be taken into account. If the temperature in the spacecraft reaches or exceeds those temperatures, the spacecraft would be in critical condition. The operating temperature is maintained by covering the spacecraft with insulating materials such as thermal blankets, surface coatings, and paints.
Most materials need to be kept at room temperature, but instruments such as those with infrared detectors need to be kept at extremely cold temperatures of -180° Celsius (-292° Fahrenheit). The temperature control system first distributes the excess heat where it is needed, using cold plates to collect the heat or pumps and valves to transport the heat to another area. If there is still excess heat, the system gets rid of it through radiators, which radiate collected heat to outer space.
Some equipment that are not insulated, such as the solar array and the high-gain antenna, can be exposed to temperatures as cold as -100° Celsius (-148° Fahrenheit) or as hot as 150° Celsius (302° Fahrenheit). They are composed of materials that can withstand wide temperature variations to prevent them from shrinking or expanding, since it would require too much energy to keep them at room temperature.
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