Martian Nahkla meteorite yields more evidence of Life

The finding of a 'cell-like' structure, which investigators now know once held water, came about as a result of collaboration between scientists in the UK and Greece.

Their findings are published in the latest edition of the journal Astrobiology.

While investigating the Martian meteorite, known as Nakhla, Dr Elias Chatzitheodoridis of the National Technical University of Athens found an unusual feature embedded deep within the rock.

In a bid to understand what it might be, he teamed up with long-time friend and collaborator Professor Ian Lyon at the University of Manchester.

Professor Lyon, based in Manchester's School of Earth, Atmospheric and Environmental Sciences (SEAES) explains: "In many ways it resembled a fossilized biological cell from Earth but it was intriguing because it was undoubtedly from Mars.

Our research found that it probably wasn't a cell but that it did once hold water, water that had been heated, probably as a result of an asteroid impact."

Elias Chatzitheodoridis

These findings are significant because they add to increasing evidence that beneath the surface, Mars does provide all the conditions for life to have formed and evolved.

It also adds to a body of evidence suggesting that large asteroids hit Mars in the past and produce long-lasting hydrothermal fields that could sustain life on Mars, even in later epochs, if life ever emerged there.

Sarah Haigh

As part of the research, the feature was imaged in unprecedented detail by Dr Sarah Haigh of The University of Manchester whose work usually involves high resolution imaging for next generation electronic devices, which are made by stacking together single atomic layers of graphene and other materials with the aim of making faster, lighter and bendable mobile phones and tablets.

A similar imaging approach was able to reveal the atomic layers of materials inside the meteorite.

Together their combined experimental approach has revealed new insights into the geological origins of this fascinating structure.

Ian Lyon

Professor Lyon said: "We have been able to show the setting is there to provide life. It's not too cold, it's not too harsh. Life as we know it, in the form of bacteria, for example, could be there, although we haven't found it yet."

"It's about piecing together the case for life on Mars, it may have existed and in some form could exist still."

Now, the team is using these and other state-of-the-art techniques to investigate new secondary materials in this meteorite and search for possible bio signatures which provide scientific evidence of life, past or present.

Professor Lyon concluded: "Before we return samples from Mars, we must examine them further, but in more delicate ways. We must carefully search for further evidence."

More information: "A Conspicuous Clay Ovoid in Nakhla: Evidence for Subsurface Hydrothermal Alteration on Mars with Implications for Astrobiology." Elias Chatzitheodoridis, Sarah Haigh, Ian Lyon. Astrobiology. August 2014, 14(8): 651-693. online.liebertpub.com/doi/pdfp… 0.1089/ast.2013.1069

What Is Odd Cell-Like Structure in Mars Nakhla Meteorite?

Scanning electron microscope image of a mysterious oval structure in the Nakhla Mars meteorite.

Credit: Elias Chatzitheodoridis, Sarah Haigh and Ian Lyon

Scientists have found a strange structure resembling a microbial cell inside a Martian meteorite, but they're not claiming that it's evidence of Red Planet life.

The researchers discovered the microscopic oval object within the Nakhla Mars meteorite, which fell to Earth in Egypt in 1911.

While the structure's appearance is intriguing, it most likely formed as a result of geological rather than biological processes, team members said.

"The consideration of possible biotic scenarios for the origin of the ovoid structure in Nakhla currently lacks any sort of compelling evidence," the scientists write in a new study published this month in the journal Astrobiology.

"Therefore, based on the available data that we have obtained on the nature of this conspicuous ovoid structure in Nakhla, we conclude that the most reasonable explanation for its origin is that it formed through abiotic processes."

Cell-Like Structure
The hollow ovoid is about 80 microns long by 60 microns wide, researchers said, far larger than most terrestrial bacteria but in the normal size range for eukaryotic Earth microbes (single-celled organisms that possess nuclei and other membrane-bound interior "organelles").

The study team is confident that the object is native to the sample and not the result of terrestrial contamination.

The scientists studied the structure using a number of different techniques, including electron microscopy, X-ray analysis and mass spectrometry.

This work revealed that the ovoid is composed of iron-rich clay and contains a number of other minerals.

The researchers run through a number of possible formation scenarios in the new study, eventually concluding that the ovoid most likely formed when materials partially filled in a pre-existing vesicle, a vapour bubble, for example, in the rock.

Transmitted light photomicrograph of an oval structure (center) in the Mars meteorite known as Nakhla. 

There is no evidence that the ovoid is a sign of Martian life, researchers say.

Credit: Elias Chatzitheodoridis, Sarah Haigh and Ian Lyon

But this supposition doesn't rule out the possibility that Martian lifeforms had something to do with the structure, team members said.

"Despite the extremely biomorphic overall shape of the ovoid, it is highly unlikely that it itself was an organism," said lead author Elias Chatzitheodoridis, of the National Technical University (NTUA) of Athens in Greece.

"However, it could have been formed directly by micro-organisms, or it could trap organic material that came from elsewhere," Chatzitheodoridis told reporters.

"That the ovoid is hollow means that there is enough space to accommodate colonies of microorganisms."

Making a firm link to Mars life would require further study and further discoveries, he added.