Interpretation of VIRTIS/Rosetta surface spectra of comet 67P from laboratory reflectance measurements of cometary analogues, including iron sulfides

International audienceThis work provides clues about the interpretation of the surface spectrum of 67P as acquired by VIRTIS/Rosetta imaging-spectrometer. Fine powders (<0.4µm) of coal, iron sulphide and silicates have been produced and measured in reflectance. Grain sizes effects, mixing modalities and various compositions have been tested in order to reproduce the VIRTIS spectrum