Mars was once home to flowing rivers and vast oceans and perhaps even life.
These days, the red planet is a dry, dusty orb and, for the most part, lacking in green or grey Martians.
Yet volcanic rifts belching a particular gas suggest our planetary neighbour isn’t dead inside but merely sleeping.
The discovery, published today in the journal Science Advances, was detected by a European Space Agency (ESA) orbiter.
‘Hydrothermal systems are known on Earth for being the main, or one of the main environments where life emerged,’ Professor Daniel Mège, a Mars researcher at Poland’s Academy of Sciences and study’s co-author, tells .
‘On Mars it could be the same.’
Hydrothermal what now?
Mars is a very quiet place. It’s pocked with some of the largest volcanoes in the solar system that have been silent for millions of years.
Still, in 2021, scientists discovered tiny traces of hydrogen chloride swirling in Mars’ atmosphere.
While the gas doesn’t sound conducive to life – it corrodes and irritates human skin – it is coughed out by magmatic vents on Earth.
We already know that Mars might have been warmed by the magmatic gassy burps of active volcanoes, heating and warming its atmosphere.
How the hydrogen chloride is still floating around hints that molten rock is still churning within Mars, despite the planet being barren and cold.
Professor Mège and his team said the gas is released in seasonal bursts.
It reaches its gassy peak during the Northern Hemisphere’s winter, which lasts 154 Martian days, or sols, and almost vanishes during the summer.
For the most part, this is because of Mars’ dust and water cycles, as crusty salt from evaporated Martian oceans is whipped by the wind.
Yet hydrogen chloride was consistently near volcanic fissures on the flanks of Alba Mons, a volcano in Mars’ Northern Hemisphere, in the summer.
His team used a powerful camera on ExoMars Trace Gas Orbiter, called CasSSIS, to spot fresh and narrow fissures, some hundreds of metres long.
Something must be generating the gas, Professor Mège says, and if magmatic gas is about, it could be a sign of hydrothermal systems.
On Earth, these systems see hot fluids sloshing under the ground, revved by magmatic gas, produce chemical reactions that could make the ingredients for life.
It’s within these that Martian life, likely bacteria, could have once been wriggling inside. Or still is, in the case of the leaky fissures in Alba Mons.
‘The big unknown is time,’ Professor Mège says.
‘To obtain life from the existing materials, a lot of chemistry is needed, and this chemistry takes time, perhaps hundreds of thousands of years, or perhaps tens of millions of years.’
The planet’s crust – split into two or three layers – also needs to have been stable long enough to give it a chance to form.
Colin Wilson, a planetary scientist at the ESA, tells that the magma could melt ice and make habitable ‘niches’.
‘If these gas emissions are occurring until the present day, perhaps Mars may have been habitable more recently than previously thought.’
Professor Mège stresses that the findings need to be double-checked with more observations. Life on Mars isn’t guaranteed.
But a bucket and spade might help find it.
‘One would probably need to dig a bit,’ he adds, ‘perhaps 20cm, perhaps 100m.’
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