The lopsided nature of the solar system's biggest volcano, Olympus Mons, strengthens the case that life is hiding in the Martian surface, according to a new study.

Rising three times higher than Mount Everest, Olympus Mons was active at least 40 million years ago, and perhaps more recently.

Researchers believe magma may still be close enough to the surface to support heat-loving bacteria like those found near hydrothermal vents on Earth. But bacteria also need water.

Dr Patrick McGovern of the Universities Space Research Association and Assistant Professor Julia Morgan of Rice University at Houston, believe they may have found a source, locked in thick layers of clay-rich sediments beneath the mountain.

Spreading out over an area larger than the state of Victoria, Olympus Mons' massive lava flows are bunched up in the southeast, and stretched out in the northwest.

In a detailed computer simulation of the volcano, the researchers found the volcano would only assume its oblong shape if the erupted lava piled on top of layers of weak, water-laden sediments.
Trapped reservoir

Scientists aren't certain how old Olympus Mons is, but it's likely that its first eruptions were billions of years ago.

If so, it could've formed in a time when Mars was much warmer and wetter, and trapped a large reservoir beneath it.

Whether or not that reservoir is still warm - and whether it contains life - remains a uncertainty.

No heat signatures have yet been detected from satellites orbiting the planet, because their instruments can't penetrate into the subsurface.

"If we were to go there and shove a probe a metre below the surface, you'd get a very different picture of heat flow," says Dr Brian Hynek of the University of Colorado at Boulder, suggesting the mountain is probably still warm.
Buried deep

The blackest depths of a volcano might not seem like the best place to go alien-hunting.

But life on Earth has been found subsisting several kilometres down in the crust, and a kilometre beneath the ocean floor.

So finding life a kilometre or so below Olympus Mons' lava flows is well within the realm of possibility, says Hynek.

The flows may even act as a kind of insulating blanket, keeping water and heat in, and Mars' cold, corrosive surface conditions out.

"It's the natural place I'd go first on an astrobiological expedition to Mars, given that it's the place where volcanism is strongest and youngest on the planet," says McGovern. "And you want to be looking wherever it's hot."

by:ABC Science