How we will find life on Mars

The search for life on other planets has captivated mankind for decades.

But the reality could be a little less like the Hollywood blockbusters, scientists have revealed.

They say if there was life on the Red Planet, it probably will present itself as fossilized bacteria – and have proposed a new way to look for it.

Is this what life on Mars will look like? Scientists say if there was life on the Red Planet, it probably will present itself as fossilized bacteria similar to these on Earth researchers used to develop e new way to test for evidence of martian life

MARS ON EARTH 

To test their theory, Marshall and his colleagues tried out their new test on microfossils with acknowledged biological origins on Earth – organic microfossils called acritarchs that might not be far from the kinds of traces of life possibly existing on the Red Planet. 

The age of this microfossil we think is Devonian, and they are aquatic microorganisms more advanced than bacterial. 

They say that finding evidence of life will almost certainly involve a rover, and admit it will be tough.

Astrobiologists likely will need to decode the chemical analysis of rock samples performed by a rover like the one NASA plans to send to Mars in 2020. 

In a new paper in the journal Astrobiology, researchers propose hunting for proof of Martian biology in the form of ‘microfossils’ could use the element vanadium in combination with Raman spectroscopy on organic material as biosignatures to confirm traces of extraterrestrial life.

‘You’ve got your work cut out if you’re looking at ancient sedimentary rock for microfossils here on Earth – and even more so on Mars,’ said Craig Marshall, the paper’s lead author and an associate professor of geology at the University of Kansas. 

‘On Earth, the rocks have been here for 3.5 billion years, and tectonic collisions and realignments have put a lot of stress and pressure on rocks. Also, these rocks can get buried, and temperature increases with depth.’

These pioneering techniques will allow experts to find 'biosignatures' of life - allowing them to make high-resolution maps of postage stamp-sized areas on the red planet. Pictured is an artist's impression of the Mars 2020 rover 

These pioneering techniques will allow experts to find ‘biosignatures’ of life – allowing them to make high-resolution maps of postage stamp-sized areas on the red planet. Pictured is an artist’s impression of the Mars 2020 rover 

Marshall says an ancient Martian microorganism would be similar a cut of steak from the supermarket in a pressure cooker.

‘You can see a steak looks biological – there’s blood dripping from it,’ he said. 

‘Then, you put it in a pressure cooker for very long time, and you end up with charcoal. 

‘It could be abiotic charcoal, or it could be made from heat and pressure on organic materials. 

‘A lot of biological compounds get destroyed and ripped apart from heat and pressure, and you’re left with carbon residue. 

‘We can see this carbon with Raman spectroscopy.’

Experts hunting for life on Mars have made use of Raman spectroscopy, a technique that can reveal the cellular composition of a sample.

Astrobiologists likely will need to decode the chemical analysis of rock samples performed by a rover like the one NASA plans to send to Mars in 2020.

Astrobiologists likely will need to decode the chemical analysis of rock samples performed by a rover like the one NASA plans to send to Mars in 2020.

‘People say, ‘If it looks like life and has a Raman signal of carbon, then we have life,” Marshall said. 

‘But, of course, we know there can be carbonaceous materials made in other processes – like in hydrothermal vents – consistent with looking like microfossils that also have some carbon signal. 

‘People also make wonderful carbon structures artificially that look like microfossils — exactly the same. So, we’re at a juncture now where it’s really hard to tell if there’s life only based on morphology and Raman spectroscopy.’

In the new paper, Marshall and his co-authors offer a path toward ironclad verification that microfossils once were alive. 

According to the researchers, the proposed technique could be possible to perform with instrumentation already planned for the NASA 2020 rover mission to explore areas of Mars where the ancient environment could have fostered microbial life. 

‘We applied a new technique called X-ray fluorescence microscopy — it looks at elemental composition,’ said Marshall.

‘Vanadium is an element in the periodic table, a transition metal. It’s been shown it can substitute into biological compounds. If you can’t unambiguously assign if something is biology or not with morphology and Raman spectroscopy in tandem — maybe we could look for a known biological element, like vanadium. 

‘Then, if the material that looked like a microfossil, and looked carbonaceous with Raman spectroscopy – and had vanadium – that’s a new way forward for finding out if something really was biology.’

Mars 2020 Rover’s equipment

Mastcam-Z: An advanced camera system with panoramic and stereoscopic imaging capability with the ability to zoom. The instrument will also establish the minerals found in Mars’ surface, and help with rover operations.

SuperCam: An instrument that provides imaging, chemical composition analysis, and mineralogy. It will also be able to locate organic compounds in rocks, from a distance.

Planetary Instrument for X-ray Lithochemistry (PIXL): An X-ray fluorescence spectrometer with a built-in high resolution imager than can determine the fine scale elemental composition of Martian surface materials. PIXL will make it possible to make detailed detection and analysis of chemical elements than ever before.

Scanning Habitable Environments with Raman & Luminescence for Organics and Chemicals (SHERLOC): A spectrometer that offers fine-scale imaging and uses an ultraviolet (UV) laser to determine detect minerals and compounds.

The rover will have a spectrometer that offers fine-scale imaging and uses an ultraviolet (UV) laser to determine detect minerals and compounds

The rover will have a spectrometer that offers fine-scale imaging and uses an ultraviolet (UV) laser to determine detect minerals and compounds

The Mars Oxygen ISRU Experiment (MOXIE): An exploration technology that will produce oxygen from carbon dioxide in the Martian atmosphere.

Mars Environmental Dynamics Analyser (MEDA): A set of sensors that provide measurements of temperature, wind speed and direction, pressure, relative humidity and dust size and shape.

The Radar Imager for Mars’ Subsurface Exploration (RIMFAX): A ground-penetrating radar that provides centimetre-scale resolution of the geologic structure of the subsurface.

According to the researchers, vanadium can be found in crude oil, asphalt and black shale, formed from acknowledged biological sources. 

Bright field photomicrograph image of the large leiosphaerid acritarch analyzed in this work, a microfossil found on Earth

Bright field photomicrograph image of the large leiosphaerid acritarch analyzed in this work, a microfossil found on Earth

Marshall and his colleagues proved the concept of testing for vanadium on known microfossils with acknowledged biological origins on Earth – organic microfossils called acritarchs that might not be far from the kinds of traces of life possibly existing on the Red Planet.

‘We tested acritarchs to do a proof-of-concept on a microfossil where there’s no shadow of a doubt that we’re looking at preserved ancient biology,’ Marshall said.

‘The age of this microfossil we think is Devonian. 

‘These guys are aquatic microorganisms — they’re thought to be microalgae, a eukaryotic cell, more advanced than bacterial. We found the vanadium content you’d expect in cyanobacterial material.’ 

Marshall said his research team’s vanadium-based verification technique deserves attention from NASA scientists planning for the Mars 2020 mission. Luckily, the KU researcher has good contacts at the space agency.

‘Hopefully someone at NASA reads the paper,’ said Marshall. 

‘Interestingly enough, the scientist who is lead primary investigator for the X-ray spectrometer for the space probe, they call it the PIXL, was his first graduate student from Macquarie University, before his KU times. I think I’ll email her the paper and say, ‘This might be of interest.”

 

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