Colloquium

Thu, October 03, 2019

The inventory and history of CO2 and H2O on Mars – past, present, and future

The evidence for liquid water on ancient Mars is compelling, yet the climate today is too cold and dry to allow it. The availability and abundance of CO2 as a greenhouse gas, and of H2O in all of its forms, are fundamental to understanding the history of the climate, the evolution of the surface, and the habitability of the planet by microbes. We examine the “sinks” for the early CO2 as a way of determining how much might have been present; key new information has been provided by the MAVEN spacecraft mission on the role of loss of gas from the atmosphere to space. We also examine the sinks for H2O, to constrain how much might have been present. In both instances, ratios of the isotopes of the light stable gases (particularly D/H, 13C/12C, and 38Ar/36Ar) provide valuable constraints. I’ll also discuss the potential to “terraform” Mars by putting gases currently locked up in the crust back into the atmosphere.