An ancient Martian system of canyons and valleys could be home to archaic life forms, a ground-breaking scientific paper has found.
Scientists investigating the Red Planet’s mind-boggling cave system believe they’ve discovered something new – eight karst caves sculpted by extinct watercourses.
The paper, published in the highly-respected Astrophysical Journal Letters, suggests these caves could be alien-hunters’ best bet.
Until now, scientists believed that Mars’ skylights – pits in the surface of mars – were formed by volcanic activity.
But data from Nasa’s orbiters suggests there are karst caves – underground bunkers created when a river diverts down through a planet’s surface.
The discovery has got scientists’ chins wagging.
Why do these caves matter?
Karst caves provide two vital things for sustaining life – shelter from Mars’ intense radioactive rays, and water.
If life on Mars ever existed, it may have needed protection from hostile surface conditions like solar radiation, dust storms, and wild temperature fluctuations.
And we already know that water provides the building blocks for life.
Karst caves may well have provided water and shelter a the same time – roughly 3.5 billion years ago.
The paper’s authors are now urging future Martian ventures to ensure robots head down into these caves.
They hope they will be able to find ‘preserved biosignatures’ – scientific evidence of past or present life in geological materials like rocks, ice, or minerals.
Scientists believe these are water-formed caves for numerous reasons – especially the composition of its surrounding rock.
Data from Nasa’s Thermal Emission Spectrometer (TES) suggests the presence of carbonates and sulfates – probably caused by water flow dissolving soluble bedrock.
What sort of aliens are we looking for?
There is scientific consensus that Mars has had, at a point in its history, the conditions to host organic life.
But what this life looked like, or how complex it may have been, remains hotly discussed,
Some 19th and 20th century astronomers believed modern Mars was teeming with intelligent aliens with nefarious plans to invade Earth.
They mistakenly thought dark linear features on Mars were ‘canals’ and that seasonal colour changes were vegetation.
Better telescopes and the development of probes proved them wrong – but scientific discussion of historic life continued.
It led to eminent astronomers like Carl Sagan speculating that, billions of years ago, Martians would have looked like ‘a man dressed up in a turtle suit’ with tentacles protruding out.
Sagan reasoned that ‘the creature’s spindly limbs suit Mars’s low gravity; its glass-like shield blocks ultraviolet radiation’.
Nowadays, scientists have lowered their expectations – and are looking for signs of life, either historic or present, of small microbial life.
One of the ‘clearest signs yet’ came in September when Nasa found ‘leopard spots on Mars’ surface’.
Microbes, as they wriggle around on rocks, can create minerals as they gobble up chemicals, leaving behind these mysterious patches.
The findings are noteworthy enough to meet Nasa’s criteria for a sign of ancient life.
And in March, a scientific paper said Nasa’s Curiosity rover had found the largest organic compounds ever seen on the planet.
The material was found inside a 3.7 billion-year-old rock in Yellowknife Bay, which may have once been a habitable freshwater lake.
Onboard tests detected molecules suspected to be remnants of fatty acids, which are produced by living creatures to form cell membranes.
Researchers did however stress that these molecules, though described as organic, could have also formed in chemical reactions that did not involve life.
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