Living microbes could be hanging out beneath the Martian surface, according to a new study of Mars rocks from Brown University. All life needs energy to survive. The life on Earth’s surface mostly gets that energy from the sun, but microbes can survive without light if they get their energy elsewhere. “To have sufficient chemical energy for life, you need both reducing compounds and oxidizing compounds,” says Jesse Tarnas, a planetary scientist at NASA’s Jet Propulsion Lab.
Microbes would need these basic chemical fuel types, along with liquid water, to survive. Where this underground water touches Martian rocks, certain chemical reactions can take place, producing the reduction and oxidation chemicals essential for life. When these nuclides emit radiation, it breaks up nearby water molecules into hydrogen gas and oxides, both highly reactive chemicals which go on to create other chemicals that can sustain life.
Testing the ingredients for life on Mars
They looked at the composition of the Mars rocks and calculated the amount of reducing and oxidizing chemicals those rocks could produce over time, then compared this to the rates that Earth microbes would chomp them up. They found that some types of Mars rocks could support life’s requirements long-term. The researchers then estimated how many microbes could survive in different rocky areas under Mars, assuming that these microbes would be similar to those deep underground or on the seafloor on Earth, which feed off of sulfates instead of oxygen. First, he says, “the source of energy, and second, the consistency of environments,” or how stable they are.
Though we haven’t found liquid water on Mars directly, he says, “it’s a pretty good guess that there is a lot of liquid water down there. This water most likely exists in pockets, Tarnas says. This water, along with the small amount of radiation coming off Mars rocks, could supply a steady stream of the chemical energy life needs for billions of years, the researchers found.
‘Nature’s drill’ on Mars could be another route to finding life
It may still be a while before rovers or astronauts dig that deep, but with technologies like transient electromagnetic sounding, Tarnas says, researchers can get an idea of where and how much water is hiding beneath the surface. And there’s another way to glimpse the deep down of Mars. Large impacts on the surface of Mars have ejected rocks from deep down under the surface. Exposed on the surface, the rocks wouldn’t still have living microbes on them. Treiman says his gut feeling all along has been that there isn’t life on Mars.