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Introduction:

The use of the Thermal Control System is controlled by the technical or functional limitations and compatible sources of all the devices used for a spacecraft and, in the case of controlled missions, by the need to supply the crew with suitable working surroundings. Almost all complicated equipment has specified temperature ranges in which it will function rightly. Thermal Control System is to maintain the temperature and stability of temperature of every item in the spacecraft within those predefined limits for all mission parts and it using a small amount of spacecraft resources.

The environmental Interaction:

The outer layer of a spacecraft need secure from the local environment and improved interaction with it, it involves:

·         The increment of reduction absorbed by environmental fluxes.

·         The increment or reduction of heat losses to the environment.

Heat provision and storage:
In some of cases, to maintain the good temperature level and it has to be supplied AND/OR a proper storage capability of heat has to be informed.

Heat collection:
In many of cases, dispersed the heat has to be removed from the device in which it is generated to avoid an unwanted increment in the unit's, AND/OR the spacecraft's temperature.

Heat transport:
In general, it is impossible to avoid the heat directly where it is generated, and right means have to be used to pass the heat from the collection equipment to the radiating equipment.

Heat rejection:
The collection and transportation of heat has to be avoided at a suitable temperature to a heat sink, which is usually the surrounding of the space environment. The avoidable temperature depends on the amount of heat involved, the temperature to be controlled and the temperature of the environment into which the device send outs the heat.