In recent years, Mars has looked more and more like a place where past life might have flourished. Now, some researchers believe the Red Planet may have the ingredients for life to exist in the present. You just have to go underground.
In published today in Nature Geoscience, a JPL-led team looked at the amount of oxygen in Martian soil, and their findings were influenced by two key recent discoveries. First, the had found rocks on Mars that were heavily oxidized, possibly the result of water permeating into the rocks. Second is the recent research that revealed sources of briny water on Mars. Looking deeply into the abundance of oxygen in the rocks and the potential oxygen in subsurface reservoirs of briny water, the scientists found there was enough oxygen to sustain simple kinds of subsurface life.
"We found something very surprising: Many brines can exist in different places on Mars," says Vlada Stamenkovic, a JPL scientist and lead author on the paper. "They fully suffice to allow the aerobic breathing for microbes and even sponges, which are the simplest animals."
This opens up the possibility of life throughout various pockets on the Red Planet—though, make no mistake, this study doesn't prove there is life. And if life is there, it may be hard to test for. NASA tends to avoid any area on Mars that may have water deposits for fear of contaminating any life there with hardy Earth bacteria. This means that most rovers, including the upcoming Mars 2020 rover, are left looking for evidence of past life.
But there is evidence of these kind of underground brine lakes, including at the South Pole of Mars. These would be the best spots to look for such life. That's especially true because the breakdown of oxygen would give any microbes—or even smaller macrobes—something to breath. "Oxygen matters for mars more than we ever dreamt of, and it allows a new way of looking at life on Mars," Stamenkovic says.
It also changes the view of Mars we've held since the 1960s, where the Mariner missions discovered a seemingly dry, desolate world. We've since looked for evidence of past water on Mars, which we have in abundance. That meant past life, and maybe an outside chance of extremely hardy present day microbes, a minority view.
But these findings mean that there may be a few places where life forms need not be so extreme—and that even after the surface of a planet becomes inhospitable, there may be more than meets the eye going on just below the surface.
"The last 40 years, people didn’t think oxygen would matter at all for life on Mars," Stamenkovic says. "We wanted to change that dogma."