Curiosity Rover Finds Organics Hidden In Mars’ Mudstones And Methane In Its Atmosphere

By Eric Betz | June 7, 2018 1:00 pm
A selfie of the Curiosity Rover taken on Vera Rubin Ridge. (Credit: NASA/JPL-Caltech/MSSS)

A selfie of the Curiosity Rover taken on Vera Rubin Ridge. (Credit: NASA/JPL-Caltech/MSSS)

In a much-hyped press conference held on Thursday, NASA announced its Curiosity rover had uncovered new evidence of methane — a potential sign of life — as well as signs of organic compounds buried in ancient mudstone.

The space agency did not say it had found evidence of alien life. However, these new results are still tantalizing.

Curiosity landed on Mars back in 2012 and it’s been slowly climbing up Mount Sharp, a large hill formed when an asteroid impact created Gale Crater, simultaneously exposing multi-billion year old sedimentary rocks laid down in an ancient lakebed. The rover came equipped with a suite of instruments known as Sample Analysis at Mars, or SAM. And its main goal was to find organic molecules. These commonly form in non-biological processes, but they’re also the building blocks of life.

And mysteriously, the VW Beetle-sized rover succeeded in finding organics even though past Mars missions, like 1976’s Viking landers, did not.

This latest announcement was tied to two scientific papers published simultaneously in the prestigious journal Science. One study focused on the methane and the other looked at the organics.

In the first paper, a team analyzed three Mars years worth (55 Earth months) of atmospheric data from Curiosity. In that time, the rover caught methane levels spiking as the seasons changed, growing several times stronger at the height of summer in the northern hemisphere.

Based on the chemical make-up, the scientists suspect this methane was heated up and released from sub-surface reservoirs where it was likely trapped in permafrost. They suspect large amount of the gas may be frozen in such underground reservoirs. But its exact origin remains a mystery.

The other study, led by NASA biogeochemist Jennifer Eigenbrode, examined drill samples of three-billion year old mudstones that Curiosity collected from two different sites in Gale Crater. The rover dropped these samples into an onboard laboratory and cooked them in order to analyze the gasses they threw out.

The drill bit of NASA's Curiosity Mars rover over one of the sample inlets on the rover's deck. The inlets lead to Curiosity's onboard laboratories. (Credit: NASA/JPL-Caltech/MSSS)

The drill bit of NASA’s Curiosity Mars rover over one of the sample inlets on the rover’s deck. The inlets lead to Curiosity’s onboard laboratories. (Credit: NASA/JPL-Caltech/MSSS)

According to Eigenbrode’s team, the rocks released organic molecules much like those found in organic-rich rocks on Earth. And intriguingly, these molecules seem to have broken off of bigger and more complex molecules — the kinds found in coal and shale on Earth.

This is far from the first time Mars researchers have claimed to find methane. Curiosity itself made headlines in recent years after seeing faint methane signals. But scientists have been chasing this gas for decades.

In 1966, a pair of astronomers made a startling announcement during a conference at San Francisco’s Jack Tar Hotel. They’d used a special kind of ground-based telescope to study the atmosphere of Mars, and in the process, they’d deduced the presence of methane. Headlines heralded the significance: Life could exist on Mars.

In the half-century since then, many teams of scientists have published potential signs of methane in Mars’ atmosphere. And each of those sparked hope for finding life, only to fade away without further proof.

“Every chapter in the story of methane on Mars has been a surprise,” says JPL’s Chris Webster, who led the methane study. But each of those signals was sporadic, and “none of them were repeatable.”

This time, they were able to watch the signal come and go. So the find looks destined to stick. What’s far less certain is exactly what it means.

Meaning Of Methane

To understand why methane matters so much, you first have to understand what it is.

Methane is a simple molecule — a so-called hydrocarbon — composed of four hydrogen atoms stuck to one carbon atom. It has no natural smell or color. And it’s also common because hydrogen is the most abundant element in the cosmos, and carbon is the third most abundant.

However, it’s also fragile. It can’t handle things too hot. And the oxygen and carbon dioxide in Earth’s atmosphere can break its bonds. So, on Earth, methane doesn’t last long in our atmosphere.

And most of the methane that we do have is produced by biology. Things die and their hydrocarbons get trapped in stores deep underground or in permafrost, where it’s known as a clathrate.

Living things also churn out methane, too. Cows and other livestock produce enormous amounts of the greenhouse gas. And simple lifeforms, known as methanogens, also produce methane.

All this means that, on Earth, methane is a sign of life. That’s given astronomers good reason to see methane as a potential signal of microbes on Mars.

Like Earth, it also has methane-destroying conditions. The Red Planet’s atmosphere is almost completely made of carbon dioxide. And even the ultraviolet light that penetrates Mars’ weak atmosphere could destroy it.

So, any methane we do see must have been released into the atmosphere very recently.

But life isn’t the only process that makes methane. We know that because it’s abundant on Uranus and Neptune. And there’s enough of the stuff to create bizarre landscapes on the surfaces of Pluto and Titan. And even on Earth, a small amount of methane is made in specific sorts of volcanic reactions, even if it doesn’t stick around long.

But Mars has no active volcanoes. And it doesn’t have ways of replenishing methane like those outer solar system worlds.

To truly find out what’s causing these seasonal surges of methane, we’ll need new Mars missions capable of better searching for definitive signs of life. And, thankfully, those spacecraft are already in the works. NASA’s Mars 2020 rover, which will launch in a couple years, is custom-built for this purpose. And the European Space Agency’s ExoMars rover should soon follow with similar aims.

Whatever the final cause — whether microbes or natural chemistry — we’re now closer to finding the source of Mars’ methane than ever before.

CATEGORIZED UNDER: Space & Physics
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  • John C

    That’s something.

    If they confirm life exists or existed on Mars – the first place we looked – it’s safe to say it’s everywhere in the universe. Remarkable

    How much would be advanced and intelligent? Who knows? But it really makes you wonder about those F-18 gun camera videos the DoD released.

    • StanChaz

      What I wonder about is whether we truly have intelligent life on earth – with examples such as twittering traitor Trump being evidence to the contrary. So sad, so sad….

      • Lorie Franceschi

        Why does everything have to turn political. Why can’t we talk about about the discoveries instead of trying to be idiots about who we support in the political arena.

        • DogmanII

          Exactly. It’s a small response to make to much broader issues. Sad…

      • John C

        Ugh

        Does every single thing have to be a game of 6 Degrees of Donald Trump?

  • Lorie Franceschi

    What I find interesting in this article, is the discussion about how methane is produced. Life, dead things and volcanic action.

    • OWilson

      It is also, according to Scientific American, “a product of chemical processing of primordial solar nebula material”.

      Neptune’s atmosphere, they tell us is 80% methane!

      • John C

        Methane is the simplest organic molucule and so not surprisingly widespread. But gas giant Neptune is a different story from solid rock Mars. Neptune’s methane is the product of the reaction between C and H from the primordial material that congealed to form that planet. Mars’ methane is more of a mystery. If it the result of volcanic chemistry why so much methane still several billion years after volcanic activity ceased? If the methane is a byproduct of chemistry involving water likewise why so much if there’s been minimal water for eons, present water being in solid form making a chemical pathway to methane difficult or minimal. Methane is difficult to produce in bare cold non-organic rock especially in the absence of vulcanism or liquid water.

        My guess is it’s microbial life being stimulated seasonally. Only because the other chemical explanations seem even less likely.

        • John Thompson

          Or the Methane simply condenses to liquid in one season (thereby reducing the amount in the atmosphere) and becomes gaseous in another season.
          That would be purely thermal.
          There are deeper places and possible caverns at the polar regions that may have the temps low enough combined with enough pressure (by being deep) to allow methane to condensate.
          I have no specific data, but the point where it condensates seems to be in the same ballpark as possible underground Martian conditions.
          We know for sure that CO2 forms snow based on the seasons, and that changes the amount of CO2 in the atmosphere.
          Granted Methane requires much colder temps to liquefy.

          • John C

            I don’t think solar radiation would break down CO2, although I’m not sure. If not, you could imagine a fixed reservoir of ancient origin going between frozen and gaseous states during seasonal change. Methane apparently is easily degraded by solar radiation so an ancient reservoir would shrink after billions of seasonal cycles.

  • Welshmartian

    Gil Levin (look up the name) discovered life with his experiment on Viking 76. His results were dismissed because another experiment failed to find organics. His experiment was far more sensitive. Similar tests were performed in dry desert area on Earth where the other experiment also failed where life is known albeit minimal.. At the very least you would expect NASA to double-check because of the ambiguous result but they have avoided further tests for life ever since. Despite spending vast amounts of money on many repeat visits with opportunities for further tests they haven’t done so – It doesn’t make sense.

  • Mike Richardson

    It is interesting that the methane waxes and wanes with the seasons. If it isn’t a biological process, it certainly mimics one in that regard.

    • John C

      If its not life that’s some inorganic reservoir. Especially considering Mars has been a bone dry geologically inactive irradiated rock for several billion years, not condusive to methane production. You would think whatever methane was produced when Mars was wet or volcanic would have been outgassed long ago.

  • Madmustang

    I just wonder why wasting time on a planet where extra terrestrials were abandoning it far long ago? Are we searching for life or a dead life or perhaps just unwritten historical events to put colors on it. Dont get it wrong but it seems too much to way out over far from what it seemed planned and happen. Just a critique.

  • http://www.mazepath.com/uncleal/EquivPrinFail.pdf Uncle Al

    Primordial biogenesis could have slimed Mars with racemic biochemistry. Absent proven homochiral discrimination, this is NASA funding-loosening wackadoodlery.

    • OWilson

      The term “building blocks of life” is always put forward as a teaser.

      Truth is building blocks of life, hydrogen/carbon compounds are relatively common, even on Pluto, given that hydrogen and carbon are the most common elements in the universe.

      Uranus and Neptune are considered to owe their blue visual appearance to methane.

      Nothing really new here citizen, move along! :)

      • John Thompson

        Methane is pretty common.
        CH4 is common because it’s easy to make in a variety of ways – Hydrogen and Carbon being readily available in the Universe.
        And then there is this part:
        “as well as signs of organic compounds buried in ancient mudstone.”
        “signs” of organic compounds is not the same as the stated find of organic compounds themselves.
        NASA has a history of hype, and the media obliges.
        They tried to grab a headline by saying Voyager had left the solar system, and the media obliged them – even as on NASA’s own website it still stated that there were objects much further away that were in our solar system.
        The media didn’t even ask them to explain the discrepancy.
        In tens of thousands of years Voyager will actually leave our solar system.
        NASA has yet to say that the comets that are far past Voyager actually leave our solar system in their orbits of our sun.
        So I simply do not trust them with their claims at this point. They have proven to choose a false headline over hard facts in the past.

        • OWilson

          This article describes “organics” found, and the major Breaking News at that Cable News Network, breathlessly announces “Organic Matter Found in the Soil of Mars.

          You can see the problem! :)

  • PhishPhace

    Once humans step foot on Mars you can kiss the hunt for life goodbye.
    if we ever found anything alive the question would remain as if to it is native or something we introduced. About the only way we could tell the difference is if Martian life happened to have evolved with the opposite isomer of chemistry

    • OWilson

      There’s probably contaimation already.

      Mars has become a literal junk yard of abandoned and crashed probes over the last 50 years or so!

      Aliens with powerful telescopes would definitely see “signs of life” on Mars!

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