Fig. 1. A schematic diagram of the experimental apparatus (a) and photograph of the apparatus (b)

Fig. 2. (a) Red, green, yellow, and blue materials in the ratio of 1:1:1:1; (b) red, green, yellow, and blue materials in the ratio of 3:2:1:2

Fig. 3. Illuminance fluctuations of in light source over time

Fig. 4. Photographs of the scattering spectra measurements for single-material samples

Fig. 5. Scatter and reflectance spectra of the four single-material samples

Fig. 6. Scattering spectrum of the equiproportional combination (combination 1)

Fig. 7. Scattering spectrum of the non-equiproportional combination (combination 2)

Fig. 8. Scattering spectra of a piece of space debris and the inversion fitting of its material proportions
(a): Measured raw spectral data; (b): Denoised scattering spectrum and the inversion fitting of its materials