Martian methane and other in-situ resources for sustaining human exploration of Mars and outer solar system

The transient detection of atmospheric methane on Mars suggests episodic venting from a subsurface source, whether the product of biogenic or abiogenic processes. In either instance, the production of methane requires the presence of groundwater, saturating the crust at depth. The most favorable conditions for the existence of groundwater on Mars occurred early in the planet's history, when the climate was warmer and the geothermal heat flow higher. However, as the climate cooled and the geothermal heat flow declined, a freezing front developed in the crust that propagated downward with time to form a compound water ice - methane hydrate stability zone. The natural buoyancy of any methane produced at depth would drive it toward the Martian surface. At least some of each vent episode would have reacted with water and ice to form methane hydrate -- a solid crystalline substance that is currently the subject of exploration on Earth as a major source of natural gas. We propose that, as on Earth, considerable concentration of methane may reside within and below the Martian permafrost, as both a gas and gas hydrate that would form an indigenous resource. Shallow deposits of hydrate may be readily accessible by drilling. The availability of such an in-situ resource would completely change the current model for the human exploration of Mars by making a Mars-sustainable human presence far more achievable. Methane can provide the basis for the production of liquid fuels and as a feedstock for the production of polymers that can be used in the manufacture of a wide variety of items, including vehicles, habitats, and other everyday items that would not have to be brought from Earth. Specialized drilling and water and gas handling apparatus, miniaturized chemical engineering plant, and 3D printing will be required. In combination with the additional availability of H₂O, CO₂, and minerals, the utilization of indigenous methane resources would make Mars and its moons not only sustainable for human habitation but would make Mars an ideal stepping stone for human exploration of the outer Solar System.