Life that fell between the cracks: mining the fingerprints of alien life

The north east of England might seem to be a strange place to search for alien life but, more than a kilometre beneath the surface, at Boulby Underground Laboratory, scientists are refining techniques that could help the next generation of rovers find evidence of life on Mars hiding in the cracks.

Ok, so Martian life won’t have eyeballs and tentacles, but evidence of microbial life might still be hiding in the cracks. Mars surface image: NASA (we may have added a bit of an artist flourish ourselves)

Is there life out there? That is one of humanity’s most enduring questions. From almost the moment we recognised that the stars and planets were more than just pin pricks of light in the curtain of night, we asked whether someone, or something, might call them home.

This speculation only increased when, with the invention of the telescope in 1609, we were finally able to see details on the very surfaces of these distant worlds. Less than 30 years later, in his book ‘The Discovery of the World in the Moone’, John Wilkins would speculate that it “may be probable there are inhabitants in this world.”

And, when in 1877, the Italian astronomer, Giovanni Schiaparelli, published a series maps of the Martian surface, that seemed to be covered in criss-crossing lines that almost looked to straight to be natural. This lead to speculation that these lines must be canals constructed by an advanced Martian civilisation — the fact that Schiaparelli called them ‘canali’, which is Italian for ‘channels’, but which looks to non-Italian eyes to be ‘canals’, didn’t help the matter.

Giovanni Schiaparelli’s map of the Martian surface seemed to show a network of canals. Later, people would speculate that they were built by an advanced Martian civilisation as irrigation channels to carry water from the planet’s poles

Rovers & landers & orbiters, oh my!

It wasn’t until the first robotic probes reached the Red Planet that those canals were revealed to be nothing more than streaks of dust brushed from the shoulders of mountains by thin Martian winds. The dream of an alien civilisation may have died but there was still hope that something smaller might still be crawling through the planet’s red dust.

Then, in the 1970s, Nasa’s Viking landers dropped on the Martian surface with the mission of finding direct evidence of life beyond our planet and they came up with precisely nothing. Decades of subsequent landers, rovers and orbiters have roved around the surface, dug beneath it, and spectroscopically analysed it from space — we’ve even flown above it — and what evidence of life all of these efforts have yielded?

Nothing.

Not a thing.

The first ever close up image of the surface of Mars was transmitted back to Earth by Nasa’s Viking 1 lander in 1976. It showed a lot rocks, but scientists hoped that signs of life would be found in the surface. They were going to be disappointed. Image: NASA

So surely this must mean that Mars is currently, and always was, bereft of life?

Not necessarily — it just might be that we’ve been looking for it all wrong. But how do you refine methods of searching for life on a near-sterile, inhospitable alien world? You can’t just find a suitable analogue here on Earth where you could try things out and see what works… can you?

It’s life Jim, but not where you’d expect it

More than a kilometre beneath the surface of Earth, in an alien world called the ’north of England’, is a place that fits the bill perfectly. Boulby Underground Laboratory is located 1.1 kilometres underground in an inactive section of a giant salt and polyhalite mine. The salt being mined just happened to have been laid down by the ebbs and flows of an ancient sea about 250 million years ago.

This sea, known as the Zechstein Sea, once covered an area stretching from England to Norway and all the way over Poland. This isolated inland sea on the surface of ancient Pangea was far more shallow that the current North Sea and filled a rift valley — created as the supercontinent’s tectonic plates pulled apart to form the continents we know today.

This process of expansion and evaporation would cause the sea levels to rise and fall in repeated cycles over millions of years. Expansion would create cracks that would fill with water, minerals and organic material and evaporation would dry the material within. This happened again and again, creating vast seams of deposited material in what are known as desiccation cracks.

For our story, the crucial component of these desiccation cracks is the organic material. This material is made up of microorganisms and plant life — meaning that the evidence of life in the oceans of ancient Pangea literally fell through the cracks where it has remained locked away for a quarter of a billion years.

A cracking way to search for life

On ancient Mars, one of the last places that could have sustained life would have been the planet’s oceans. It is thought that, as they evaporated to their own oblivion, a similar process might have taken place on the Red Planet as that which happened in the Zechstein Sea on Earth — meaning that life’s fingerprints may have been locked away in the Martian equivalent of desiccation cracks.

Nasa’s Curiosity Rover found evidence of desiccation cracks on the Red Planet’s surface. Could evidence of ancient Martian life be hiding within? Image: NASA

Fortunately for today’s Earth-bound life-hunting scientists, these desiccation cracks are relatively easy to spot as they form long dark streaks that stand out from surrounding salt mineral layers. All you need is access to them, which the salt mining process conveniently allowed.

So now, 1.1 kilometres beneath the North of England, scientists are experimenting with ways to identify the fingerprints of life locked away in those dark streaks with hope such methods could be applied to other worlds, such as Mars.

One such scientist is Dr Jens Holtvoeth, a geologist and lecturer from Teesside University, who is leading a team at Boulby Underground Lab currently collecting core samples from the desiccation cracks.

Taking core samples from a desiccation crack at Boulby Underground Laboratory. Image: STFC

Jens hopes that by, analysing the sample material and determining the chemical composition, they can identify the geochemical finger print of ancient microbial life. This would potentially tell scientists what sort of biochemical traces of organic life they would have to look for on other planets.

As well as evidence of microbial life, the core samples contain leaf waxes that can tell scientists about the sort of plant life that thrived in the area 250 million years ago, which, in turn, can tell them about the local climate. Image: STFC

Building the next generation of life hunters

As part of Boulby’s Mine Analogue Research Programme (MINAR), the team is working with NASA to help the space agency develops its next-generation of life-hunting robotic probes.

The aim is to create a biogeochemical fingerprint of the organic matter found in the remains of the Zechstein Sea and compare this with modern microbial systems. This would allow NASA to design extremely compact detectors that are designed to detect very specific chemical signs of life — rather than the far larger, less-targeted systems used to date.

All of which would mean that future rovers could spend more energy roving and excavating samples and less energy hauling around huge experiments. It would also mean they will be better equipped to finally answer that eternal question: is there life out there?

Story by: Ben Gilliland & Ky Trickett. Video by: Ky Trickett