View on a muddy Mars, with a wet atmosphere. © Getty Images

Mars may have enough oxygen to support subterranean life

It’s theoretically possible that microbial life could exist in pools of liquid water present beneath the Martian surface.

If there is life on Mars, it seems the best place to look for it may be beneath the surface. According to calculations by a team at NASA’s Jet Propulsion Laboratory, the salty water that is thought to exist under the Red Planet’s surface could contain enough oxygen to support microbial life.

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Recent studies have suggested that liquid water could exist in subsurface pools despite temperatures on the surface being as low as -70°C, as salt present in the water lowers its freezing point. Also, back in 2016, the Curiosity mission discovered that Mars may once have had an oxygen-rich atmosphere, but the loss of the planet’s magnetic field led to most of it escaping.

However, according to the team’s calculations, this subsurface water could potentially absorb enough oxygen from the thin Martian atmosphere to sustain basic forms of life at low enough elevations where the atmosphere is thickest. In the best-case scenario, the team found that an unexpectedly high amount of oxygen could exist in the water – much more than the minimum amount needed for aerobic respiration in Earth’s oceans.

“Nobody ever thought that the concentrations of dissolved oxygen needed for aerobic respiration could theoretically exist on Mars,” said researcher Dr Vlada Stamenković.

The researchers say these findings could inform future missions to Mars by providing better targets to sample and investigate for rovers searching for signs of past or present habitable environments.

This is an extract from issue 329 of BBC Focus magazine.

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Inside Mars: What will we uncover beneath the Red Planet's surface? © Andy Potts, NASA

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