📘 Definition
The thermal control system (TCS) manages heat on a spacecraft to keep all components within their operational temperature ranges. In space, there is no air for convection — heat transfer is only by conduction and radiation. Passive methods include multi-layer insulation (MLI) blankets, radiator panels, thermal coatings, and heat pipes. Active methods include heaters, louvers, and pumped fluid loops. The sunlit side of a satellite can reach 120°C+ while the shaded side drops below −150°C, so TCS design balances heat absorption, internal generation (from electronics), and radiation to space.
120°C+
Sunlit Surface
−150°C
Shadow Surface
MLI, radiators, heat pipes
Passive Methods
Heaters, louvers, fluid loops
Active Methods