Mars rocks may harbor signs of life from four billion years ago

May 25, 2018, University of Edinburgh
Mars
Credit: NASA

Iron-rich rocks near ancient lake sites on Mars could hold vital clues that show life once existed there, research suggests.

These rocks—which formed in lake beds—are the best place to seek evidence of life from billions of years ago, researchers say.

A new study that sheds light on where fossils might be preserved could aid the search for traces of tiny creatures—known as microbes—on Mars, which it is thought may have supported primitive life forms around four billion years ago.

A team of scientists has determined that made of compacted mud or clay are the most likely to contain fossils. These rocks are rich in iron and a mineral called silica, which helps preserve fossils.

They formed during the Noachian and Hesperian Periods of Martian history between three and four billion years ago. At that time, the planet's surface was abundant in water, which could have supported life.

The rocks are much better preserved than those of the same age on Earth, researchers say. This is because Mars is not subject to plate tectonics—the movement of huge rocky slabs that form the crust of some planets—which over time can destroy rocks and fossils inside them.

The team reviewed studies of fossils on Earth and assessed the results of lab experiments replicating Martian conditions to identify the most promising sites on the planet to explore for traces of ancient life.

Their findings could help inform NASA's next rover mission to the Red Planet, which will focus on searching for evidence of past . The US space agency's Mars 2020 rover will collect to be returned to Earth for analysis by a future mission.

A similar mission led by the European Space Agency is also planned in coming years.

The latest study of Mars rocks—led by a researcher from the University of Edinburgh—could aid in the selection of landing sites for both missions. It could also help to identify the best places to gather samples.

The study, published in Journal of Geophysical Research, also involved researchers at NASA's Jet Propulsion Laboratory, Brown University, California Institute of Technology, Massachusetts Institute of Technology and Yale University in the US.

Dr. Sean McMahon, a Marie Sklodowska-Curie fellow in the University of Edinburgh's School of Physics and Astronomy, said: "There are many interesting rock and mineral outcrops on Mars where we would like to search for fossils, but since we can't send rovers to all of them we have tried to prioritise the most promising deposits based on the best available information."

Explore further: Scientists use Dorset, UK, as model to help find traces of life on Mars

More information: S. McMahon et al. A Field Guide to Finding Fossils on Mars, Journal of Geophysical Research: Planets (2018). DOI: 10.1029/2017JE005478

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donaldsauter
2 / 5 (3) May 26, 2018
All very exciting, but be forewarned: once we've shown that life is common throughout the galaxy, we'll have explain why only on earth it advanced to a technological stage.

If they were out there, we would know it.

We don't.

They're not.
Valfreyja
5 / 5 (1) May 26, 2018
@ donaldsauter

While I tend to agree with you, I'd be careful how certain you are of that. There's no reason to assume any extant, equally intelligent beings are aware of us. Our electromagnetic "pollution" has barely escaped our local neighborhood. The chemical composition of planets as we've been able to determine via spectroscopy varies wildly to the point you can't really form any meaningful atmospheric signature of one inhabited by an intelligent species from one that just has a similar naturally occurring chemistry. Their industrial impact on their planet may differ dramatically from ours, so we don't even know what we're looking for. It could just be that we're at or near the height of what is possible, technologically speaking. We like to dream of a demigod-like future, but there may be significant, even insurmountable "laws of the universe" hurdles between us and our dreams. There's no good reason to assume that just because we don't notice them, that means they don't exis
rrwillsj
1 / 5 (3) May 28, 2018
Don & Val, I have to disagree with all your assumptions. First, wanting the Galaxy to be thriving with Living Worlds and star-faring sophonts? Doesn't make it true.

So far the evidence is tilting towards my guesstimate that there were billions of lotto tickets sold but only one winner, Earth.

Even here in our own solar system, out of a half-dozen possibilities? Only the Earth has a proven sustained biosphere. In the goldilocks zone there are four planets and only one is known to be habitable. You're standing on it.

Sure, aliens could have super-duper technology but not all of their history. And not all aliens would be many more advanced than a couple of centuries +/- of ours and thus detectable by our abilities.

If sentient aliens exist? It is much more likely they are trapped without the capability of tool use or fire. Consider how many intelligent species exist on Earth without hands. And the odds are highly stacked against them ever developing tool use.
andyf
4.6 / 5 (5) May 28, 2018
donaldsauter said:
If they were out there, we would know it.

We don't.

They're not.


This is an argument from ignorance.

Absence of evidence is not evidence of absence.

See https://en.wikipe...gnorance

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