The Inner Solar System's Habitability Through Time

TL;DR

This paper explores the divergent evolutionary paths of Earth, Mars, and Venus in terms of habitability, focusing on physical processes shaping their atmospheres and surfaces over time, to inform the search for extraterrestrial life.

Contribution

It provides a comparative analysis of the physical processes influencing habitability on the inner planets, highlighting their roles in atmospheric and surface evolution.

Findings

Early habitability of all three planets possible

Different atmospheric escape mechanisms shaped current conditions

Physical processes influenced divergent planetary evolutions

Abstract

Earth, Mars, and Venus, irradiated by an evolving Sun, have had fascinating but diverging histories of habitability. Although only Earth's surface is considered to be habitable today, all three planets might have simultaneously been habitable early in their histories. We consider how physical processes that have operated similarly or differently on these planets determined the creation and evolution of their atmospheres and surfaces over time. These include the geophysical and geochemical processes that determined the style of their interior dynamics and the presence or absence of a magnetic field; the surface-atmosphere exchange processes that acted as a source or sink for atmospheric mass and composition; the Sun-planet interactions that controlled escape of gases to space; and the atmospheric processes that interacted with these to determine climate and habitability. The divergent evolutions of the three planets provide an invaluable context for thinking about the search for life outside the Solar System.