AOPP Seminar - Cosmic dust in the laboratory, from terrestrial collections to space missions

Since pioneering works in the 90s, large number of micrometeorites, interplanetary dust reaching Earth surface, are recovered from many locations including polar regions (Greenland and Antarctica). For the past twenty years, thanks to the support of the French polar Institute (IPEV), we performed collections of micrometeorites with sizes from a few tens to hundreds µm, at the vicinity of the CONCORDIA Antarctic Station. Thanks to the unique conditions of central Antarctic regions, the micrometeorites from CONCORDIA collection exhibit a minimal terrestrial weathering. The low terrestrial contamination allows to identify in such collections Ultra-Carbonaceous Antarctic MicroMeteorites (UCAMMs) with extreme concentration in organic matter, about a factor of 10 larger than that in carbonaceous chondrites. The UCAMMs organic matter exhibits a Nitrogen-rich component and its isotopic composition have a wide variation range, including components with extreme D/H ratios (up to 10-20 times that of terrestrial oceans). Both the chemical and isotopic compositions of UCAMMs indicate that they most probably originate from comets.
We performed experiments to show that the UCAMMs N-rich organic component can be formed at the surface of icy bodies by Galactic Cosmic Rays irradiation of cometary ices. Recent instrumental developments allow to perform IR nano-spectroscopy analyses on such complex samples and reveal their organics components at the sub-µm scale. The characterisation such cosmic dust opens a window on the composition the surface of small icy bodies from the outer Solar System currently not reachable by sample return space missions.
We will discuss the different components present in the cosmic dust flux reaching Earth’s surface and their comparison with samples returned by present and future space missions.