A Primitive solar Atmosphere around The young Earth?

ongoing

The existence of an atmosphere enriched in H and He around the Earth as it formed has often been proposed. One hypothesis suggests that it could have been captured from the gas present in the proto-planetary disk, before its evaporation. Subsequently, a secondary atmosphere would have been degassed or brought in by a late veneer of chondritic/cometary material. Although this model is regularly evoked using giant planets for comparison, there is no geological proof for its existence, except possibly for the neon in the Earth's mantle. While the model has a flaw (mainly relating to chronology, as the gas from the disk is lost in <6 My while the Earth formed over a period of more than 30My), the solar-type neon in the Earth's mantle is an argument for the existence of such a captured atmosphere, which partially dissolved into a magma ocean. A second scenario for a primordial H2/He-rich atmosphere is the degassing of a mantle that contained implanted solar wind. The APATE project aims to study the isotopic composition of neon in the Earth's mantle in order to determine if this composition is the same as that of the nebula or the solar wind material. I will investigate the degassing processes of magmas experimentally and numerically in order to study the isotopic fractionation that occurs during bubble formation and to determine whether the measured neon isotopic composition can provide an accurate composition for the original mantle. The project aims to calculate the amount of neon that can be incorporated into a magma ocean by establishing the atmospheric pressure of the captured atmosphere and by studying the dynamics of the magma ocean. I will also explore the hypothesis involving solar wind irradiation. Using simulations of irradiation, I will identify those conditions under which this model is realistic and its implications for the Earth’s (isotopic/chemical) composition. The origin of light solar volatiles will then be explored by the APATE project.