A Method to Measure Absorptivity and Emissivity of Temperature-Controlling Coatings of Spacecraft Using Radiation Flux of Variable Intensity

A new method of determining the absorptivity and emissivity of surfaces with the use of a radiation flux of variable intensity is described. It is expedient to use this method in order to control the variations of integral optical coefficients of temperature-controlling coatings in the course of a long-term spacecraft flight. The method is developed on the basis of solving the inverse problem for a mathematical model of thermal balance for a thin metal plate. The stability of the algorithm of processing the results of measurements is analyzed for various levels of random errors. Some recommendations concerning the technical implementation of the method in the laboratory and space conditions are given. The method suggested has a number of advantages in comparison with methods used before, especially if it is used in space conditions. The main advantage is the possibility of varying the radiation flux incident on the surface of a specimen under study from an external source according to any smooth law.