Thermal control of spaceborne experiments

Heat calculation methods and applied thermal control principles are presented. The specificity of thermal control problems in a space environment, especially the absence of atmosphere, is emphasized. Convection is of very minor importance. The roles of conduction and radiation are discussed. Radiation laws are given and radiative exchange equations are derived for the exchange between two gray bodies. As a dimensional exercise, convective and radiative exchange are compared. Thermal control equipment is reviewed with relation to thermo-optic coefficients. Cooling systems are also covered. A grating spectrometer is described as a typical thermal control problem. Cooling of the detectors and difficulties due to the solar flux are treated. Space environment simulation for thermal tests is depicted and data analysis is explained. Results show the delicate balance of thermal control system parameters.