Effects of Giant Impacts on the Atmosphere Formation

Abstract

It is generally thought that the terrestrial planets experience the Mars-sized giant impacts. Such giant impacts modify the atmosphere obtained before the giant impact stage. Genda and Abe (2003) clarified that the significant atmosphere (35-90%) survived the giant impact blown-off event in the case of no ocean. In this study, we consider the case that an ocean exists at the planetary surface, which is likely in the Earth's orbit. The existence of an ocean greatly enhances the atmospheric loss due to evaporation of water. There is the possibility that the above escape mechanism explains the differences between the present Earth's and Venus' atmospheres.