An image of the Martian surface from NASA’s Viking 2
To eke out even the barest subsistence on Mars, a living thing would have to adapt to a formidable set of environmental challenges: an arid, often extremely cold landscape with miniscule amounts of oxygen in the atmosphere and no organic matter to eat. During a recent foray into a similarly inhospitable part of our own planet, scientists have discovered several species of bacteria that hint at what life on Mars, if it exists, might look like. These microbes survive on minerals in the surrounding rocks—minerals also found in the Martian surface.
The bacteria were living beneath a thin layer of ice coating a lava tube, a subterranean tunnel lava once flowed through, high in the Cascade Mountains. These frigid, dry conditions—an environment similar to Mars, albeit less extreme—are devoid of typical food sources, and the layer of ice blocks out much of the oxygen from the atmosphere. Rather than breaking down sugars and other nutrients, the bacteria have evolved to get by on what’s available: lots and lots of rock. They glean energy from a simple chemical reaction with the iron in olivine, a mineral abundant in the basalt rock of the lava tube and present in rocks on Mars as well. If olivine can sustain life in a milder proxy of the Martian environment, that gives researchers something to look for when searching for life on the red planet.
Scientists frequently look to the extremophile microbes living in Earth’s coldest, hottest, driest, most acidic, or least aerobic environments when exploring the possibility of extraterrestrial life. In 2009, another research team found a hundred bacterial species living miles deep in the dry, low-oxygen vents of an Andean volcano—another environment to analogous to Mars, and more possible blueprints on which to base the search for Martian life.
Image courtesy of NASA