Over the past few years, evidence that water once flowed on Mars has been pilling up, and with it the idea that the Red Planet might have been able, at one point in its history, to sustain at least basic forms of life. Now, following a new scientific study, researchers believe they are very close to identifying portions of our neighboring planet where water could still exist today. They are referring to the Olympus Mons volcano, the largest one in the solar system, which extends over more than 15 miles (24 km) above the surface.

What's so interesting about it is its shape, which is very asymmetrical and closely resembles volcanoes on Earth that spilled, in the past, their ash and lava, forming layers of clay. And there's only one possibility for this type of clay to form, namely when incandescent materials reach large bodies of water. Also, because the volcano's cone and dejection areas spread around 150 miles in all directions, astronomers and geologists think that it's only on a layer of clay that the volcanic material could have traveled so far.

During previous Martian missions, NASA's Phoenix lander discovered frozen water just under the surface of the planet's North Pole, suggesting that harsh conditions on it might have driven all existing water underground. But researchers are now wondering if it's possible that at least some pockets of liquid still remain under the lava layers near the Olympus Mons. They argue that, isolated from the surface by molten rock and a thick layer of clay, water may endure for countless years.

And they also believe that these pockets of liquid may host even now microscopic organisms, bacteria and microbes adapted to such extreme conditions. Similar creatures are known to exist on Earth as well, where even the most inhospitable places, such as the underwater hydrothermal vents, volcanic mountain tops, or abandoned gold mines, hold the most amazing diversity of beings.

“This deep reservoir, warmed by geothermal gradients and magmatic heat and protected from adverse surface conditions, would be a favored environment for the development and maintenance of thermophilic organisms,” geophysicist Patrick McGovern, from the NASA-affiliated Lunar and Planetary Institute in Houston, and Rice University geologist Julia Morgan argue in a paper published in the latest issue of the journal Geology.