Could Life Still Be Hiding Beneath Mars?
Mars is a rough place to be alive. Its surface is cold and dry, with little protection from harmful radiation. But below ground, rock could offer shelter. If there's water and a source of energy down there too, tiny living things called microbes might have a chance.
Life on Mars hasn't been confirmed. Still, scientists have reasons to keep looking beneath the surface. And one of those reasons starts with gas above a volcano.
Gas Escaping from Below?
In November 2026, the European Space Agency reported an unusual gas pattern over Alba Mons, a Martian volcano. Its Trace Gas Orbiter spacecraft had detected a gas called hydrogen chloride there in early summer. That was different from the wider seasonal pattern, which peaked in winter.
Images of the same area showed narrow cracks that looked fresh. Now researchers had two clues to work with: gas in the air and possible routes out of the ground.
The team suspects gas is leaking from magma, or melted rock, beneath the volcano. Winter ice could hold it back, then release it as the ice disappeared. That could explain the early-summer signal.
Hydrogen chloride isn't a sign of life, and the observations showed no new lava flows or eruptions. But if magma is down there, it could warm water underground and create a sheltered, wet place for microbes.
How Volcanic Gas Could Escape From Beneath Mars
Getting By Without Sunlight
Shelter would help. But anything living deep underground would also need a way to get energy in the dark.
Some microbes on Earth already do that. Natural radiation from rock can break water molecules apart. The chemicals produced can then react and release energy. Certain microbes use that energy to stay alive.
In a 2021 study of Martian rocks, researchers asked whether Mars could offer a similar fuel supply. They examined rocks from Mars that had reached Earth as meteorites, and found the ingredients they were looking for in several kinds.
This process doesn't depend on magma heating the water.
Water is still the catch. The rocks would have to stay in contact with liquid water for that fuel supply to work.
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The Water Problem
Far from Alba Mons, NASA's InSight lander recorded vibrations moving through Mars. These travel at different speeds through different materials, giving researchers a way to study rock they can't see.
In a 2024 study of InSight's measurements, a team compared the evidence with models of the underground rock. Of the possibilities they tested, cracked rock holding liquid water was the best match. That would put the water about 11.5 to 20 kilometers down, or roughly 7 to 12 miles.
This would be water filling small spaces in rock. No one had drilled down and found it, or photographed an underground lake. The team had worked backward from the measurements to a possible explanation.
The result concerned the area beneath InSight. It couldn't establish water beneath Alba Mons, where the gas was found.
How InSight Probed the Hidden Interior of Mars
Then other researchers tested models with something else filling the cracks.
In a 2025 challenge to the water study, they found that solid minerals could also fit the measurements. A good match wasn't enough to show that the filling was water.
A separate critique questioned the amount of water. The original model allowed a wide range of amounts, so its most likely answer wasn't the only one the evidence allowed.
The original team acknowledged that wet and dry rock could both fit the observations. Water remains possible, but these measurements haven't settled whether it's there or how much there might be.
A Clue to Life Long Ago
Meanwhile, Perseverance has been investigating a different kind of clue in Jezero Crater.
The rover sampled a rock called Cheyava Falls in 2024. A year later, NASA reported possible traces of ancient life in the rock. Its mineral patterns and chemistry could fit changes made by microbes long ago.
Chemical reactions without living things could also have made those patterns. Scientists still have to work out which explanation fits.
That's a different prize from finding something alive today. Ancient traces could show that Mars once supported life. They wouldn't tell us whether anything still lives beneath the ground.
Cheyava Falls gives scientists something the rover can examine up close. The possible water below InSight remains miles out of reach. Both are useful leads, but they answer different questions about different parts of Mars.
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Following the Gas
At Alba Mons, the next step is to find out where the gas comes from and how it reaches the air. If it leads to underground heat, researchers will still need to establish whether water is there too.
A place where microbes could survive would be worth finding. Whether anything actually lives there is the question waiting beyond it.
