Surface Materials Analysis Of Space Debris Based On BRDF Spectrum

With the development of space technology, the human’s passion for developing space resources has been promoted. More and more satellites were sent up into space, which made the outer space quite crowded.Space debris larger than a centimeter level can smash the spacecraft,which have been a great threaten to the orbital spacecraft, especially manned spacecrafts. Therefore, it is necessary to fully understand the physical properties of on-orbit space debris, and then detect, analyze the space debris in the catalogue.This paper mainly shows the surface materials analysis of space debris based on BRDF spectrum. At first, the BRDF spectrums of common surface materials were measured in laboratory environment, and the shapes of the visible band were analyzed.Then, the grounded-observed spectral data were decomposed and thecomposition of the surface materials were gotten.In the laboratory, there are many materials for this experiment:xenon lamp, used as the light source, optical fiber spectrometer, used to analyze the BRDF spectral of insulation polyester film(MLI) samples,OSR sample and solar cell samples of BRDF spectral. The reflectance spectrals were normalized in 550 nm and the reflectance spectral shapes of the materials were analyzed in the visual band(420nm-700nm). Then, the data of the spectrum characteristics with those of laboratory measured common space materials were compared and the surface materials composition of space debris were analyzed by correlation method,constrained least squares method and linear spectral unmixing method based on selective endmemble, which provided basic data for the identification of space debris.The results show that in the diffuse reflection condition, the reflection zenith angle of insulation polyester film samples, OSR samples and solar cell samples though the reflectivity will be different, the spectral shape is basically coincident in visible light band. Therefore,when the space debris spectrum were decomposed in visible light band,it is available to use spectrum shape to compare and analyze.Correlation method, constrained least squares method and linear spectral unmixing method based on selective endmemble were used to decompose the grounded-observed data, and then the materials can be obtained.Furthermore, the result of linear spectral unmixing model based on selective endmemble is closer to the original spectrum than this based on the calculated correlation coefficient.