AN OPEN-ACCESS VISIBLE NEAR-INFRARED SPECTRAL REFLECTANCE LIBRARY OF SPACECRAFT MATERIALS

摘要

The task of identifying specific material types in reflectance spectra of artificial Earth-orbiting objects is difficult in part because there are no open-access spectral bidirectional reflectance distribution function (BRDF) libraries of spacecraft materials. Moreover, the limited number of published spectra of some spacecraft materials provide very little or no information as to the illumination and observational geometry that was used to acquire the measurements which severely limits their utility when attempting to compare these with reflectance spectra of artificial Earth-orbiting objects. In response to this problem, a goniospec-tromcter was designed and built to measure the spectral scattering characteristics, between 350 and 1100 nm, of materials that are commonly found on the surfaces of spacecraft. Four types of material samples were characterized over a wide range of illumination and observational geometries, namely triple-junction photovoltaic cells, aluminum surfaces, white-coated metallic surfaces and aluminized polyimide films. The results show that all samples exhibit distinct spectral BRDFs which clearly points to the requirement for a spectral BRDF libraiy of commonly used spacecraft materials to interpret reflectance spectra of artificial Earth-orbiting objects.