Early evolution of the solar system : The case of Mars

The early evolution of the solar system can be reconstructed through either geochemical analysis or physical modeling. These two approaches are often considered independently. In this talk, using Mars’ atmosphere as a case study, I will illustrate how combining both perspectives can yield very promising results. Mars finished forming while the solar nebula was still present, and acquired its primordial atmosphere from this reservoir. Following the dispersal of the nebula, a dynamical instability among the giant planets scattered comets into the inner solar system. The absence of a detectable cometary xenon signature in the present-day Martian atmosphere suggests that the capture of solar nebular gas was significant enough to dilute later cometary contributions. By quantifying the mass of cometary material efficiently retained on Mars, a robust lower bound can be placed for the mass of the primordial Martian atmosphere. This results holds important implications related to Mars’ accretion rate or pre-Noachian climate models.