Cold and wet early Mars: Proposing and testing a new theory to understand the early Martian environments
Geologic evidence indicative of flowing and ponding liquid water on the surface of ancient Mars appears abundantly across most of the Martian landscape, indicating that liquid water was present in variable amounts and for long periods of time on and/or near the surface at different moments of Mars’ early history, the Noachian era. Early Mars appears to have been “wet”. However, the presence of liquid water on the surface of early Mars is difficult to reconcile with the reduced solar luminosity at 3.8 Ga. and before, which would have imposed mean temperatures below freezing all over the planet. Atmospheric greenhouse gases and carbon dioxide ice clouds in the upper troposphere are suggested to provide over freezing temperatures, explaining some of this discrepancy, but these solutions have been probed to face numerous unsolved problems. So, it is difficult to explain the early Martian hydrology invoking global “warm” conditions. Here I propose to conduct interdisciplinary investigations in order to define and test a new hypothesis to understand the early environmental traits on Mars: that the young Martian surface was characterized by global mean freezing conditions, as predicted by climate models, and at the same time a vigorous hydrogeological cycle was active during hundreds of millions of years, as confirmed by geomorphological and mineralogical analyses. The aim of this investigation is to comprehensively analyze the triggers, traits and consequences of a cold aqueous environment dominating the Noachian, studying the geomorphological, mineralogical and geochemical evidences that such a hydrological cycle would have left behind, and also proposing new paths for the astrobiological exploration of Mars on the basis of geochemical and geomicrobiological studies in cold aqueous environments. Mission-derived datasets will be used to test hypotheses through paleogeomorphological reconstructions, theoretical modeling and experiments in the laboratory.