Newly Discovered Carbon on Mars: Origin May Be Biologically Produced Methane

Curiosity Rock Hall Selfie

A selfie taken by NASA’s Curiosity Mars rover on Sol 2291 at the “Rock Hall” drill site, located on Vera Rubin Ridge. Reduced carbon released from powder from this drill hole was strongly depleted in carbon 13, the surprising carbon isotopic signature reported by the team. The selfie is composed of 57 individual images taken by the rover’s Mars Hand Lens Imager (MAHLI), a camera on the end of the rover’s robotic arm. Credit: NASA/Caltech-JPL/MSSS

NASA’s Curiosity rover landed on Mars on August 6, 2012, and since then has roamed Gale Crater taking samples and sending the results back home for researchers to interpret. Analysis of carbon isotopes in sediment samples taken from half a dozen exposed locations, including an exposed cliff, leave researchers with three plausible explanations for the carbon’s origin — cosmic dust, ultraviolet degradation of carbon dioxide, or ultraviolet degradation of biologically produced methane.

The researchers note today (January 17, 2022) in Proceedings of the National Academy of Sciences that “All three of these scenarios are unconventional, unlike processes common on Earth.”

Carbon has two stable isotopes, 12 and 13. By looking at the amounts of each in a substance, researchers can determine specifics about the carbon cycle that occurred, even if it happened a very long time ago.

“The amounts of carbon 12 and carbon 13 in our solar system are the amounts that existed at the formation of the solar system,” said Christopher H. House, professor of geosciences, Penn State. “Both exist in everything, but because carbon 12 reacts more quickly than carbon 13, looking at the relative amounts of each in samples can reveal the carbon cycle.”

Highfield Drill Hole on Vera Rubin Ridge

The image shows the Highfield drill hole on Vera Rubin Ridge. Drill powder from this hole showed carbon isotope values indicating a carbon cycle that includes either subsurface life, intense UV radiation penetrating the atmosphere, or Interstellar dust. The image was taken by the Mars Hand Lens Imager on sol 2247. Credit: NASA/Caltech-JPL/MSSS

Curiosity, which is led by NASA’s Jet Propulsion Laboratory in Southern California, has spent the last nine years exploring an area of Gale Crater that has exposed layers of ancient rock. The rover drilled into the surface of these layers and recovered samples from buried sedimentary layers. Curiosity heated the samples in the absence of oxygen to separate any chemicals. Spectrographic analysis of a portion of the reduced carbon produced by this pyrolysis showed a wide range of carbon 12 and carbon 13 amounts depending on where or when the original sample formed. Some carbon was exceptionally depleted in carbon 13 while other carbon samples where enriched. 

“The samples extremely depleted in carbon 13 are a little like samples from Australia taken from sediment that was 2.7 billion years old,” said House. “Those samples were caused by biological activity when methane was consumed by ancient microbial mats, but we can’t necessarily say that on Mars because it’s a planet that may have formed out of different materials and processes than Earth.”

The researchers propose three explanations for the severely depleted samples: a cosmic dust cloud, UV radiation breaking down carbon dioxide, or ultraviolet degradation of biologically generated methane.

According to House, every couple of hundred million years the solar system passes through a galactic molecular cloud.

“It doesn’t deposit a lot of dust,” said House. “It is hard to see any of these deposition events in the Earth record.”

To build a layer that Curiosity could sample, the cosmic dust cloud would have first decreased the temperature of a Mars that still had water and formed glaciers. The dust would have accumulated on top of the ice and would have had to stay in place until the glacier melted, leaving behind a layer of soil containing carbon.

So far, there is limited evidence of past glaciers at Gale Crater on Mars. According to the researchers, “this explanation is plausible, but it requires additional research.”

A second possible explanation for lower amounts of carbon 13 is the ultraviolet conversion of carbon dioxide to organic compounds like formaldehyde.

“There are papers that predict that UV could cause this type of fractionation,” said House. “However, we need more experimental results showing this size fractionation so we can rule in or rule out this explanation.”

The third possible method of producing carbon 13 depleted samples has a biological basis. 

On Earth, a strongly carbon 13 depleted signature from a paleosurface would indicate past microbes consumed microbially produced methane. Ancient Mars may have had large plumes of methane being released from the subsurface where methane production would have been energetically favorable. Then, the released methane would either be consumed by surface microbes or react with ultraviolet light and be deposited directly on the surface.

However, according to the researchers, there is currently no sedimentary evidence of surface microbes on the past Mars landscape, and so the biological explanation highlighted in the paper relies on ultraviolet light to place the carbon 13 signal onto the ground.

“All three possibilities point to an unusual carbon cycle unlike anything on Earth today,” said House. “But we need more data to figure out which of these is the correct explanation. It would be nice if the rover would detect a large methane plume and measure the carbon isotopes from that, but while there are methane plumes, most are small, and no rover has sampled one large enough for the isotopes to be measured.”

House also notes that finding the remains of microbial mats or evidence of glacial deposits could also clear things up, a bit.

“We are being cautious with our interpretation, which is the best course when studying another world,” said House.

Curiosity is still collecting and analyzing samples and will be returning to the pediment where it found some of the samples in this study in about a month.

“This research accomplished a long-standing goal for Mars exploration,” said House. “To measure different carbon isotopes — one of the most important geology tools — from sediment on another habitable world, and it does so by looking at 9 years of exploration.”

Reference: “Depleted carbon isotope compositions observed at Gale crater, Mars” by Christopher H. House, Gregory M. Wong, Christopher R. Webster, Gregory J. Flesch, Heather B. Franz, Jennifer C. Stern, Alex Pavlov, Sushil K. Atreya, Jennifer L. Eigenbrode, Alexis Gilbert, Amy E. Hofmann, Maëva Millan, Andrew Steele, Daniel P. Glavin, Charles A. Malespin and Paul R. Mahaffy, 17 January 2022, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2115651119

Also working on the project from Penn State was Gregory M. Wong, recent doctoral recipient in geosciences.

Other participants in the research were, at NASA Jet Propulsion Laboratory: Christopher R. Webster, fellow and senior research scientist; Gregory J. Flesch, scientific applications software engineer; and Amy E. Hofmann, research scientist; at Solar System Exploration Division, NASA Goddard Space Flight Center: Heather B. Franz, research scientist; Jennifer C. Stern, research assistant; Alex Pavlov, space scientist; Jennifer L. Eigenbrode, research assistant; Daniel P. Glavin, associate director for strategic science; Charles A. Malespin, chief, Planetary Environments Laboratory; and Paul R. Mahaffy, Retired Solar System Exploration Division Director; at University of Michigan: Sushil K. Atreya, professor of climate and space sciences and engineering and director of the Planetary Science Laboratory; at Carnegie Institution for Science: Andrew Steele, scientist; and at Georgetown University and NASA Goddard Space Flight Center: Maëva Milan, postdoctoral fellow.

NASA supported this project.

5 Comments on "Newly Discovered Carbon on Mars: Origin May Be Biologically Produced Methane"

  1. It might be biologically produced. On the other hand, maybe not. It is an interesting question, but consider this: if, after much careful study and consideration we determine that the carbon detected was (most likely) biological in origin, we still haven’t found the life-form responsible, and a likely reason for that is that Mars is no longer suitable for hosting life, something we strongly suspected in the sixties. So following the pats on the back, where does that leave us?

    • It shows that life could arise independently on another planet on the solar system. Not every discovery has to be about “Ogg hungry. Ogg need food.”

  2. Babu G. Ranganathan | January 18, 2022 at 8:37 am | Reply

    Babu G. Ranganathan*
    (B.A. Bible/Biology)


    A Newsweek article of September 21, 1998, p.12 mentions the high possibility of Earth life on Mars because of millions of tons of Earth soil ejected into space from ancient volcanic explosions. “We think there’s about 7 million tons of earth soil sitting on Mars”, says USC scientist Kenneth Nealson. “You have to consider the possibility that if we find life on Mars, it could have come from the Earth” [Weingarten, T., Newsweek, September 21, 1998, p.12]. This may also explain why life forms may exist on Venus, again because they originated from Earth.

    In the Earth’s past there was powerful volcanic activity which could have easily spewed dirt and rocks containing microbes and life into outer space which not only could have eventually reached Mars but also ended up traveling in orbit through space that we now know as meteors, comets, and asteroids. This would mean life forms found in meteorites originated from Earth in the first place.

    Secular scientists have a different explanation from creationist scientists on the volcanic eruptions of the Earth’s past. Creation scientists believe, as Genesis teaches, that as the fountains of the deep were opened to release water for the world-wide flood the force of the eruptions could have indeed spewed great amounts of earth soil into space.

    Life could not have evolved. A partially evolved cell would quickly disintegrate under the effects of random forces of the environment, especially without the protection of a complete and fully functioning cell membrane. A partially evolved cell cannot wait millions of years for chance to make it complete and living! In fact, it couldn’t have even reached the partially evolved state.

    Having the right conditions and raw material for life do not mean that life can originate or arise by chance. Stanley Miller, in his famous experiment in 1953, showed that individual amino acids (the building blocks of life) could come into existence by chance. But, it’s not enough just to have amino acids. The various amino acids that make-up life must link together in a precise sequence, just like the letters in a sentence, to form functioning protein molecules. If they’re not in the right sequence the protein molecules won’t work. It has never been shown that various amino acids can bind together into a sequence by chance to form protein molecules. Even the simplest cell is made up of many millions of various protein molecules.

    The probability of just an average size protein molecule arising by chance is 10 to the 65th power. Mathematicians have said any event in the universe with odds of 10 to 50th power or greater is impossible! The late great British scientist Sir Frederick Hoyle calculated that the odds of even the simplest cell coming into existence by chance is 10 to the 40,000th power! How large is this? Consider that the total number of atoms in our universe is 10 to the 82nd power.
    Also, what many don’t realize is that Miller had a laboratory apparatus that shielded and protected the individual amino acids the moment they were formed, otherwise the amino acids would have quickly disintegrated and been destroyed in the mix of random energy and forces involved in Miller’s experiment.

    Miller’s experiment produced equally both left-handed and right-handed amino acids, but all living things strictly require only left-handed amino acids. If a right-handed amino acid gets into the chain the protein won’t work.

    There is no innate chemical tendency for the various amino acids to bond with one another in a sequence. Any one amino acid can just as easily bond with any other. The only reason at all for why the various amino acids bond with one another in a precise sequence in the cells of our bodies is because they’re directed to do so by an already existing sequence of molecules found in our genetic code.

    Of course, once you have a complete and living cell then the genetic code and biological machinery exist to direct the formation of more cells, but how could life or the cell have naturally originated when no directing code and mechanisms existed in nature? Read my Internet article: HOW FORENSIC SCIENCE REFUTES ATHEISM.

    Visit my newest Internet site: THE SCIENCE SUPPORTING CREATION


    * I have had the privilege of being recognized in the 24th edition of Marquis “Who’s Who In The East” for my writings on religion and science, and I have given successful lectures (with question and answer time afterwards) defending creation from science before evolutionist science faculty and students at various colleges and universities.

    • Listen, you dumb “BA in Bible/biology ” (LOL) – Hoyle’s calculations were flawed and have been debunked ages ago, because of his misguided assumptions that any combination of amino acids were possible. In his days, we didn’t know how peptides fold (and that apparently wasn’t taught in bible biology class). Amino acid combinations are deterministic, and that drastically reduces the number of possible combinations. He also chose a very complex protein, whereas in hindsight the obvious choice would have been archean proteins, which happen to be much simpler.

      Of course, explaining this to a bible/biology buffoon, who prides himself on having “internet articles” is a waste of time.

  3. I can’t get excited about life on mars. Even if it exists today, which is unlikely, or at any time in the past, it’s highly probable to have originated on Earth and have landed on the planet following a meteor impact, spreading across the Martian surface. Not very interesting.

    On the other hand unique Martian life that spontaneously developed independently of life on Earth would be an amazing and profound discovery.

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