On The Habitability Of An Impacted Young Earth: The effects of a post-impact, reducing atmosphere on Hadean Earth’s habitability

Abstract

Atmospheres have an important role in determining whether a planet can both form and sustain life. In the case of early Earth under the faint young Sun, a heavy hydrogen- dominant atmosphere would have allowed for a temperate surface and the production of biomolecules necessary for life to form, such as HCN and H2CO. This heavy atmosphere is thought to have been delivered to Earth by a large impact or series of large impacts on Earth’s surface. In this work, we use a 1D radiative-convective equilibrium modelling code to obtain the thermal profiles for various post-impact atmospheres outlined by Zahnle et al. (2020). Our current results suggest that, in the work of Zahnle et al. (2020), early post-impact HCN yields were computed for atmospheres that are too hot for the necessary liquid surface water.