A new paper published by Sean McMahon from Yale University and colleagues suggests that crushed rocks and marsquakes might make good guideposts in the search for life on Mars.
The researchers studied active fault lines in rock formations off the coast of Scotland and found that many of the rocks contained enough hydrogen gas in their fluids to support small populations of microbes. Hydrogen gas concentrations varied between 0.1 and 2 percent—high enough to serve as the basic nutrient for life’s methanogenesis reaction. Scientists already know that in hydrothermal vents on Earth’s ocean floor, microbes combine hydrogen gas and carbon dioxide to make methane and water.
McMahon’s team also found that hydrogen concentrations are particularly high in active fault lines where rocks grind against each other. Earthquakes occur when the shifting rocks suddenly get “unstuck” after being stuck against each other. Similar environments are thought to exist on Mars, but would be rarer there, because internal activity on Mars is thought to occur at a much lower level.
We’ll have a better picture of internal activity on the Red Planet after the Mars InSight lander conducts its first seismic experiments. That mission had been planned for launch this year, but has been delayed to 2018. It will be the first lander to drill into the Martian subsurface, down to a depth of a few meters.
If active fault zones are identified on Mars, they could be potential habitats for microbes to make a living. Ulrich Schreiber and colleagues from the University of Duisburg-Essen in Germany even suggested a few years ago that life could have originated in tectonic fault systems. Most faults are deep within the rock, and so would be protected from the otherwise detrimental radiation, low temperatures, and lack of water and organic molecules on the surface. So if we do find active faults, astrobiologists will surely want to take a peek.