We still don't know if there's life on Mars—but if there is, these researchers have some thoughts on where we might find it.
Much like on Earth, it's very much possible that certain types of rocks formed within the red planet's crust are capable of supporting life, according to a new paper published in the journal Nature Communications on Tuesday.
"Our study supports that if life is to be found on Mars then it would likely be in the martian subsurface whereby the methane could potentially be an energy source to support microbial activity," wrote Nigel Blamey, an assistant professor at Brock University, and the study's lead author, in an email.
Whether life will actually be found in practice, of course, is another matter entirely.
"It is important for the public to understand that we have not found life on Mars"
The study was conducted by an international team of researchers from Canada, the US, and the UK. They performed their tests, not on Mars, but using Martian meteorites that had fallen to earth, using what is referred to as a crush scan technique where the meteorites are literally crushed to release the gasses that are trapped within. Each crush yielded a burst of gas that was measured with a mass spectrometer—and the gas contained within was deemed similar to what is found in analogous, life-bearing rocks on earth.
"It is important for the public to understand that we have not found life on Mars," Blamey wrote. "Instead we have found hydrogen and methane in martian meteorites that were blasted off the martian surface by impacts."
On earth, basalt rocks under the sea support a rich microbial population that feed on the release of methane trapped within the rocks. The researchers note that similar rocks exist on Mars, and that based on the composition of the Martian meteorites they've obtained, the planet's subsurface could similarly generate methane–and, in theory, have the ability to support life.
"Methane supports the deep biosphere on Earth, including in basalt where, critically for a Martian analogue, the methane is used by anaerobic microbes," the paper reads. "The evidence presented here indicates that a methane-bearing subsurface habitat is similarly available on Mars," and that gasses "would be most concentrated in subsurface environments such as fracture systems and basalt lava vesicles."
"Whether or not the habitat has been occupied remains to be determined."