Universe Today
Over the past few decades, our ongoing studies of Mars have revealed some very fascinating things about the planet. In the 1960s and early 70s, the
Mariner
probes revealed that Mars was a dry, frigid planet that was most likely devoid of life. But as our understanding of the planet has deepened, it has come to be known that Mars once had a warmer, wetter environment that could have supported life.
This in turn has inspired multiple missions whose purpose it has been to find evidence of this past life. The key questions in this search, however, are where to look and what to look for? In a
new study
led by researchers from the
University of Kansas
, a team of international scientists recommended that future missions should look for vanadium. This rare element, they claim, could point the way towards fossilized evidence of life.
Their study, titled "
Imaging of Vanadium in Microfossils: A New Potential Biosignature
", recently appeared in the scientific journal
Astrobiology.
Led by Craig P. Marshall, an associate professor of geology at the University of Kansas, the international team included members from the
Argonne National Laboratory
, the
Geological Technical Services Division of Saudi Aramco, the
University of Liege
, and the
University of Sydney
.
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The microphone for the upcoming Mars mission will be attached to the SuperCam, seen here in this illustration zapping a rock with its laser. Credit: NASA/JPL-Caltech
[/caption]
To be clear, finding signs of life on a planet like Mars is no easy task. As Craig Marshall indicated in a University of Kansas
press release
:
In their paper, Marshall and his colleagues recommend that missions like NASA's
Mars 2020
rover, the ESA's
ExoMars 2020
rover, and other proposed surface missions could combine Raman spectroscopy with the search for vanadium to find evidence of fossilized life. On Earth, this element has been found in crude oils, asphalts, and black shales that have been formed by the slow decay of biological organic material.
In addition, paleontologists and astrobiologists have used Raman spectroscopy - a technique that reveals the cellular compositions of samples - on Mars for some time to search for signs of life. In this respect, the addition of vanadium would provide material that would act as a biosignature to confirm the existence of organic life in samples under study. As Marshall
explained
:
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Artist's impression of the Mars 2020 with its sky crane landing system deployed. Credit: NASA/JPL
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This is not the first time that Marshall and his co-authors have advocated using vanadium to search for signs of life. Such was the subject of a presentation they made at the A
strobiology Science Conference in 2015
. What's more, Marshall and his team emphasize that it would be possible to perform this technique using instruments that are already part of NASA's
Mars 2020
mission.
Their proposed method also involves new technique known as X-ray fluorescence microscopy, which looks at elemental composition. To test this technique, the team examined thermally altered organic-walled microfossils which were once organic materials )called acritarchs). From their data, they confirmed that traces of vanadium are present within microfossils that were indisputably organic in origin.
"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."
These microfossilized bit of life, they argue, are probably not very distinct from the kinds of life that could have existed on Mars billions of years ago. Other scientific research has also indicated that vanadium is the result of organic compounds (like chlorophyll) from living organisms undergoing a transformation process caused by heat and pressure (i.e. diagenetic alteration).
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Artist's impression of ESA's ExoMars rover (foreground) and Russia's stationary surface science platform (background) on the surface of Mars. Credit: ESA/ATG medialab
[/caption]
In other words, after living creatures die and become buried in sediment, vanadium forms in their remains as a result of being buried under more and more layers of rock - i.e. fossilization. Or, as Marshall explained it:
The work was supported by an ARC
International Research Grant
(IREX) - which sponsors research that seeks to find biosignatures for extracellular life - with additional support from the
Australian Synchrotron
and the
Advanced Photon Source at the Argonne National Laboratory
. Looking forward, Marshall and his colleagues hope to conduct further research that will involve using Raman spectroscopy to study carbonaceous materials.
At present, their research appears to have attracted the interesting of the European Space Agency. Howell Edwards, who also conducts research using Raman spectroscopy (and who's work has been supported by an ARC grant), is part of the ESA's Mars Explorer team, where he is responsible for instrumentation on the
ExoMars 2020
rover. But, as Marshall indicated, the team also hopes that NASA will consider their study:
The next decade is expected to be a very auspicious time for exploration missions to Mars. Multiple rovers will be exploring the surface, hoping to find the elusive evidence of life. These missions will also help pave the way for NASA's crewed mission to Mars by the 2030s, which will see astronauts landing on the surface of the Red Planet for the first time in history.
If, in fact, these missions find evidence of life, it will have a profound effect on all future mission to Mars. It will also have an immeasurable impact on humanity's perception of itself, knowing at long last that billions of years ago, life did not emerge on Earth alone!
Further Reading: University of Kansas, Astrobiology
