An exciting new study has shown that life may have once existed on Mars — and that, at one point, the planet would have held more than enough chemical energy to have allowed microbes to flourish underground.
As Phys.org reports, lead author Jesse Tarnas of Brown University explains that below the surface of ancient Mars there would have been plenty of hydrogen, creating a habitable zone for some forms of life.
“We showed, based on basic physics and chemistry calculations, that the ancient Martian subsurface likely had enough dissolved hydrogen to power a global subsurface biosphere. Conditions in this habitable zone would have been similar to places on Earth where underground life exists.”
One example of life that may have once existed on Mars — which can also be found on Earth — are subsurface lithotrophic microbial ecosystems, or SliMEs. Because these microbes are unable to receive sunlight, they subsist on energy that they take from the electrons of molecules around them.
Dissolved molecular hydrogen, in particular, is known to feed these SliMEs with plenty of electrons on our planet — and it is highly probable that the same thing would also have occurred on Mars.
In a new study, scientists were able to demonstrate that radiolysis would have helped to create hydrogen below the surface of Mars — and that hydrogen levels in the crust of Mars four billion years ago would have easily equaled the amount that is currently present on Earth. The hydrogen levels in the relevant strata of the Earth’s crust where SliMEs are said to congregate is abundantly adequate to fuel said microbes currently present.
While this new research is certainly not intended to be definitive proof that there was life on Mars, it does demonstrate that the building blocks of life were once present underground and could have kept microbes alive and healthy for hundreds of millions of years.
As co-author Professor Jack Mustard — of Brown Department of Earth, Environmental and Planetary Sciences — explained, “The question then becomes: What was the nature of that subsurface life, if it existed, and where did it get its energy? We know that radiolysis helps to provide energy for underground microbes on Earth, so what Jesse did here was to pursue the radiolysis story on Mars.”
Fortunately for us, NASA’s Mars 2020 rover may be able to answer some of these questions, as part of its mission will be to search for evidence of ancient life on the red planet, as Professor Mustard noted.
“The mission of the 2020 rover is to look for the signs of past life. Areas where you may have remnants of this underground habitable zone — which may have been the largest habitable zone on the planet — seem like a good place to target.”
The new study which demonstrates that life may have once thrived underground on Mars has been published in Earth and Planetary Science Letters.