Organic Carbon Found on Mars Rocks Is Not Life, New Study Says

By Rebecca Boyle Posted 05.24.2012 at 2:30 pm 8 Comments

Mars Phoenix Lander and Rocks The Phoenix lander prepares to grate some Martian rocks. NASA

Since the Viking landers’ footpads touched down on Mars, scientists have been searching for complex carbon molecules there, which on this planet are the building blocks of all life. They’ve found some examples in meteorites purported to come from the Red Planet, but debate persists about the origin of those rocks, let alone the carbon signatures inside them, which some have (controversially) argued could indicate life. Now a new study says the rocks in question are from Mars, but the carbon molecules are not relics of extraterrestrial life.

This new study sheds more light on Mars’ carbon cycle, suggesting that abiotic (not-life) sources of reduced carbon are actually pretty common. This will help set baselines for future life-hunting experiments.

Scientists led by Andrew Steele at the Carnegie Institution studied 11 meteorites from Mars, whose ages span 4.2 billion years. They even looked at the very recent Tissint meteorite, which fell in Morocco last summer and chunks of which were up for sale recently.

Steele and colleagues from four other countries examined the rocks with a suite of methods, including Raman spectroscopy, to determine the molecular structures. Ten of the rocks contained large carbon molecules, and at least some of those are indigenous to the rocks, meaning they didn’t come from Earth or other possible sources of contamination. It turns out the compounds originated in volcanic processes on our neighbor planet, not ancient microbes or other forms of life.

As silicate lava flows crystallized, carbon compounds interacted with oxide compounds and solidified. These compounds, which in one case included polycyclic aromatic hydrocarbons, are distributed throughout the rocks, Steele and colleagues report. This indicates that Mars has been completing organic chemistry on its own, probably for most of its existence.

There’s some indication that abiogenic hydrocarbons could form on Earth, too, although it would be very deep within and very uncommon. Most of our hydrocarbons come from long-dead life forms. “These findings show that the storage of reduced carbon molecules on Mars occurred throughout the planet’s history and might have been similar to processes that occurred on the ancient Earth,” Steele said in a statement.

Allan Hills Meteorite: The Allan Hills meteorite, named for the hills where it was found in Antarctica, is thought to be one of the oldest relics of the solar system. Scientists believe it coalesced 4.091 billion years ago and is thought to be from Mars. Wikipedia

In a separate but related paper, Steele also reports on the Allan Hills meteorite, which was once thought to contain fossil evidence of Martian microbial life. The meteorite, named for the site where it was found in Antarctica, is thought to be 4.1 billion years old. Back in 1996, a team of scientists at NASA and other institutions claimed it contained evidence of ancient microbial life, because it contains a unique pattern of organic carbon compounds. But Steele’s studies say that this, too, is not biologically based — rather, the chemical reactions involve the graphite form of carbon. That paper appears in American Mineralogist.

While it may seem disappointing to confirm that Mars is a native organic chemistry lab, this is useful information for future Martian life hunters. Scientists will be able to use these studies to compare and contrast carbon-bearing formations and determine whether they’re of abiotic or biological origin. The meteorite paper appears today in Science Express.

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8 Comments

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Charles R. Kiss

05/24/12 at 6:36 pm

I'm not sure that this proves that life had never existed before. I learned in chemistry 101, that reactions go backwards, as well. Isn't possible, plausible, that these carbon forms are decay products, or soups? We're talking billions of years!

Charles

"Everything not forbidden is mandatory." Murray Gell-Mann

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rlb2

05/24/12 at 10:50 pm

It's just a matter of time, the Mars soil from the Viking and Phoenix Landers tricked the scientist looking for organics. They cooked the soil at very high temperature to look for organics when they did they couldn't find any. They didn't find any because there were very high oxidizers in the soil, perchlorates. In 2010, thanks to NASA astrobiologist Christopher McKay and colleagues that tested Atacama Desert soil from Chile they found that perchlorates rapidly destroys organics.

"Perchlorates could set there in the Martian soil with organics around it for billions of years and not break them down" McKay said "But when you heat the soil to check for organics the perchlorates destroys them rapidly"

People seriously looking for life on Mars may find this new video very interesting.

http://youtu.be/M223QDCMWLY

Ron Bennett

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rlb2

05/24/12 at 11:04 pm

Another added tidbit from my statement above. Any Martian meteorite which had perchlorates in them entering the Earth's atmosphere would destroy most of the organics in the meteorite from the intense heat of re-entry because of oxidizing perchlorates.

Ron Bennett

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Charles R. Kiss

05/25/12 at 12:23 am

Thanks RLb2,

Is there a balanced redox (chemical) equation for this action of perchlorates on organics? Sure would be interesting, especially with some endothermic quantity and bibliography (if there is any)!

Wouldn't it then render the story moot?

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rlb2

05/25/12 at 2:51 am

Charles R. Kiss - In 2010 University of Mexico research chemist Dr Rafael Navarro Gonzalez and NASA astrobiologist Dr Christopher McKay tested if perchlorates skewed the Viking Landers results by testing Atacama Desert soil from Chile

As a result McKay claims that perchlorate will destroy organics when heated producing chloromethane and dichloromethane, the same chlorine compounds discovered by both Viking Landers when they performed the same tests on Mars.

What McKay was doing was showing although Viking didn't find perchlorates in the soil, Viking wasn't looking for them, the Phoenix Lander did find it in abundance. The two chemical produced by heating perchlorates to a high temperature was chloromethane and dichloromethane that were found at both Viking sites which strongly infers that perchlorates was in the soil at the Viking Landers site. I say soil because I believe it is soil, soil on earth has organics in them where on Mars they call it regolith instead of soil because no organics were found, but that may soon change...

Ron Bennett

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roboninjosh

05/25/12 at 8:45 am

I do not like the self-contradictory title and I am surprised no one noticed that the statement "is not life" is used to describe carbon that is also described as "organic"

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JediMindset

05/25/12 at 5:16 pm

i bet that when we excavate there we will dig up bones of many different species similar to those found on earth. maybe even find dinosaur bones. we have only dug like less than a feet. maybe eve find buried alien technology from another race similar to ours. maybe even similar languages. "ghost of mars" tells us this.

"religion is like a prison for the seekers of wisdom"

-Killah Priest

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S B Park

05/29/12 at 4:24 am

I can't believe this article yet. But if it is real, I am very disappointed with it. Personally, I hope that Alien has exist in space.

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