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

Kurzfassung

The Rosetta spacecraft has been orbiting the comet 67P from August 2014 to September 2016 with the aim to understand better the activity, the evolution and the surface processes of the nucleus. The VIRTIS spectrometer [1] has acquired reflectance spectra from two channels: VIRTIS-M, an imaging-spectrometer, ranging from 0.25 μm to 5.1 μm with ~2 nm and ~10 nm resolution (resp. in the VIS and IR) and VIRTIS-H, a point spectrometer ranging from 1.9 μm to 5.1 μm with a ~10 times higher spectral resolution than VIRTIS-M. The goal of this study is to reproduce the spectral behavior of the surface as observed by VIRTIS in the range 0.4 μm - 2.7 μm. For this purpose, we measured reflectance spectra of cometary analogs produced in the lab from iron sulphides, coal and silicates.