COSmoMatériaux du Milieu Interstellaire au Système solaire : Multi-diagnostics Expérimentaux

    The origin and evolution of carbonaceous solid extraterrestrial matter are the central objectives of this ANR. Interstellar dust originates in cool late type stars envelopes, passes through the interstellar medium (ISM), enters in molecular clouds, where collapse of the clouds is responsible for the formation of the stars (Sun), circumstellar disks, primitive nebulae (solar nebula) and planets. At each of these events, a wide number of physical and chemical processes do alter the solid materials: interaction with radiation, energetic particles, gas to surface reactions, formation and photochemistry of ices, evaporation/recondensation of grains from volatiles and/or refractories, and build-up of complex molecular entities of organic nature. These are observed in astrophysics from the visible (space weathering modifying composition and thus reflectance of minor bodies surfaces), the vibrational infrared (giving access to the molecular and structural composition of surfaces), to the millimetre tracing the cold dust peak emission together with the detection of gas phase molecules. To these observations, one must include in this life cycle the analyses of extraterrestrial, possibly pristine, collected materials from the proto-solar nebula when various bodies, comets, asteroids, planetesimals and up to telluric planets were formed in a rather short time.

    Fully primitive interstellar matter, unaffected by any alteration process may have pervaded in the solar nebula and incorporated in some part of the material collected or observed today. However, results of the Stardust mission confirmed that the solar nebula has been subjected to a strong radial mixing. Some material has been brought close to the young sun, subjected to violent irradiation or thermal alterations and may have been partly reset to an atomic phase and then re-condensed. Moreover, various processes in the parent bodies can have modified to various extent the structure and chemical composition of carbonaceous solid matter. It is thus a difficult task to draw an historical filiation between the different materials accessible to the astronomers, although such a task must be considered as a high priority to understand the formation of our today solar system.

    Simulations on ISM and proto-nebular solid phase analogues of these materials and their evolution can be performed in the laboratory. These simulations, through different methods of characterisation (UV/Vis/IR spectroscopy, Raman spectroscopy, mass spectrometry, HRTEM, elemental composition, GCMS…), help to understand and shed light on the complex interplay between physical and chemical processes occurring in the diffuse interstellar medium phase, during the early primitive solar nebula phase and later on the processes affecting the matter released by contemporary parent bodies.

    We wish, in this proposal, to push the full characterisation of dust analogues using a broad range of complementary spectroscopic techniques, to ultimately decipher the relations between structural and physico-chemical possible formation and evolution routes. We will, in synergy between the different partners and collaborations, prepare and analyse genuine extraterrestrial Antarctic collected micro meteorites, focusing on their organic contents. Our multi-analyses techniques combined to the inter-comparison of the measurements will help to understand what can be learned from our laboratory analogues simulations and investigations and which past record of the solar system (ISM, radial mixing, alteration) they may hold. One of the key goals in this topic is to identify, in the diversity of the encountered physico-chemical structures, the ones that would be specific or unique to some degree to a process occurring in this complex scenario, or alternatively that could be opposed to invalidate a proposed scenario. No need to say that this huge and interdisciplinary effort is very competitive on an international basis.