Predicting temperature increases on the GOES imager and sounder radiant coolers

Jack T. Sanders Jr.; Robert R. Gorman; Michael S. Woronowicz

doi:10.1117/12.366704

25 October 1999 Predicting temperature increases on the GOES imager and sounder radiant coolers

Jack T. Sanders Jr., Robert R. Gorman, Michael S. Woronowicz

Proceedings Volume 3784, Rough Surface Scattering and Contamination; (1999) https://doi.org/10.1117/12.366704
Event: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1999, Denver, CO, United States

Abstract

Contaminants degrade the thermal properties of spacecraft systems. This paper describes a method of quantified visual inspection, which assumes a minimum visible particle size that can be easily evaluated for any observer. It also assumes a log-normal particle size distribution, but not the slope of it. By counting the particles visible in a convenient unit area, the fractional area coverage can be calculated. The method can be applied to real systems during ground inspection. This paper discusses methods for assessing the radiant cooler sunshields of the Imager and Sounder instruments on the Geostationary Operational Environmental Satellite (GOES) spacecraft. Then the method for converting the percent area coverage to the amount of solar power, which is scattered, to the cooler patch is explained. The essence of this conversion is based on careful consideration of the paths of specularly reflected and scattered solar light within the sunshield enclosure. A three-dimensional Bidirectional Reflectance Distribution Function (BRDF) model of the radiant cooler sunshield was constructed in order to estimate the illumination of a contaminated spot on a sunshield wall based on relative sun orientation, direct illumination, and specularly-reflected illumination from other walls. Radiant energy reflected from the contaminated spot to the radiant cooler was estimated using a BRDF model based on data reported by Young in previous studies.

Citation Download Citation

Jack T. Sanders Jr., Robert R. Gorman, and Michael S. Woronowicz "Predicting temperature increases on the GOES imager and sounder radiant coolers", Proc. SPIE 3784, Rough Surface Scattering and Contamination, (25 October 1999); https://doi.org/10.1117/12.366704

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