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Influence of Spacecraft Surface Spectral Radiation Characteristics on the Accuracy of Thermal Load Simulations in Infrared Simulators

Relying on the data on the spectral absorptivity of materials and coatings used in space engineering, we estimated the level of possible errors in simulating the given external thermal loads on the spacecraft surface in infrared simulators with emitters of grey radiation characteristics. We used an assumption, which is introduced in the known methods for determining the optimal mode of the operation, that the outer spacecraft surface elements' spectral absorptivity does not depend on the wavelength of the incident radiation in the spectral bandwidth of the simulator. Findings of the research show that errors depend on the emitter temperature, especially for those coatings having spectral characteristics of radiation in the near infrared region of spectrum which cardinally differ from these characteristics in the middle and far regions of spectrum. For some coatings, the errors are unacceptably large. We arrived at a conclusion that it is necessary to adjust the known techniques to solve the problem of choosing the operating modes of infrared simulators. The technique is based on the iteration process of searching for a solution of the problem including repeated determination of radiation intensity vector of the simulator modules by minimization of the target function ψ with simultaneous specification, at each iteration, of coefficient values characterizing the absorptivity of the spacecraft outer surface elements with respect to radiation arriving from the simulator modules