Synthesis of analogues of cometary organic matter: thermochemical evolution and preparation of in-situ observations

An organic residue is remaining at 300 K after the VUV photolysis of ices mixture and subsequent heating. This residue is thought to be representative of the organic matter contained in comets. Our experiments show that the thermal evolution is an important process. Indeed, the organic residue remaining at 300 K is not produced completely during the photolysis at low temperature but also during the heating. Furthermore, when heated at temperature higher than 300 K, the residue undergoes chemical evolution which has to be taken into account in astrophysical models. Furthermore, our work allows to propose observational strategy to maximize the chance to detect in-situ some compounds, such as POM and HMT, thanks to COSIMA which is one of the mass spectrometers on board of the Rosetta spacecraft.