Passive thermal control systems in spacecrafts

A spacecraft is a vehicle designed for accomplishing a mission for military, scientific and commercial purposes. While designing a spacecraft, scientists face some challenges, one of which is the design of a thermal subsystem. A spacecraft is exposed to internal and external thermal loads during its lifetime. External heat loads are solar flux, Earth IR radiation, and albedo flux. The significance of these external loads varies depending on the orbit type. Internal loads are heat dissipation induced by the electrical and mechanical equipment. Thermal control systems must be developed carefully to keep spacecraft subsystems within operating temperatures until the end of their operating life. Thermal control can be performed with two methods: passive and active. This article mainly focuses on passive thermal control systems that have been designed and tested before. This type of thermal systems do not exert any power from a system, and they are more robust. Typical passive control hardware are thermal control coatings, multilayer insulation systems, radiators, louvers, thermal interface materials, and passive heat pipes. Here, we summarize some of the most recent developments in passive thermal protection system testing and design.