For the last twenty million years, Chile's Atacama Desert has been the driest, most inhospitable place on Earth. But deep below the surface of this unimaginably arid world, microbes are flourishing without even oxygen or sunlight. Meet the extremest extremophiles.
Researchers from Spain's Center of Astrobiology and Chile's Catholic University of the North discovered microbes more than six feet below the surface of Atacama's hypersaline substrates. These formations trap in both salt and moisture, providing the bacteria and archaea microorganisms living beneath them with all the food and water they need to survive.
But what makes this finding particularly striking is how far underground the microbes are, leaving without any oxygen or sunlight. Those sorts of conditions are very much like what microbes would have to deal with on Mars today. The Atacama has long served as an experimental - and sometimes cinematic - stand-in for the red planet, and the researchers discovered these microbes while testing out SOLID, or Signs of Life Detector, which they hope to see used on future Mars missions.
SOLID uses a biochip loaded with as many as 450 antibodies that can be used to identify various different kinds of biological material, including DNA and sugars. Researcher Vincent Parro explains the importance of this particular find:
"We have named it a 'microbial oasis' because we found microorganisms developing in a habitat that was rich in halite (rock salt) and other highly hygroscopic compounds (anhydrite and perchlorate) that absorb water. If there are similar microbes on Mars or remains in similar conditions to the ones we have found in Atacama, we could detect them with instruments like SOLID."
According to Parro, we already know that saline deposits exist on Mars, so it's not unreasonable to think that hypersaline environments could be found deep underground. These substrates could trap water just like their counterparts in the Atacama desert, and even better the makeup of the substrates could solve one major impediment to Martian life: the low temperature. Because of the ridiculously high salt concentration, the substrates could lower the freezing point of water to -20 degrees Celsius, allowing microbes to maintain access to water even in the colder conditions of the red planet.