Mars More Toxic to Life Than Previously Thought

By Nathaniel Scharping | July 6, 2017 2:32 pm
Mount Sharp on Mars, as imaged by the Curiosity rover. (Credit: NASA/JPL-Caltech/MSSS)

Mount Sharp on Mars, as imaged by the Curiosity rover. (Credit: NASA/JPL-Caltech/MSSS)

Life on Mars … does it exist? Depending on when you last checked in with news about the Red Planet, you could probably be convinced either way. As we discover more and more about the composition and planetary dynamics of Mars, there has been cause for both elation and disappointment regarding the likelihood that organic life could manage to eke out a living on the planet.

The pendulum swung back toward the “no” side today with the release of a study examining how a special kind of salt on Mars interacts with ultraviolet radiation there. Martian soil is laced with perchlorates, an ion composed of one chlorine and four oxygen atoms, and which binds to a number of different elements to form various compounds. It’s classified as a salt, and was initially cause for celebration among extraterrestrial hopefuls because it drastically lowers the freezing point of water, meaning that liquid H20 might conceivably exist on the surface. It can also be used to produce rocket fuel and oxygen, another plus for future settlers.

Salt of the Mars

It turns out that these perchlorates are actually highly toxic to life when bathed in UV radiation that pummels Mars. Researchers from the United Kingdom Centre for Astrobiology at the University of Edinburgh exposed a strain of bacteria commonly found on spacecraft to levels of perchlorates and UV light found on the Red Planet and found that nearly all of them were dead within a minute. They tried this with several different kinds of perchlorate, and found similar results every time. Adding in additional environmental factors found on Mars like low temperatures, additional minerals found on Mars and a lack of oxygen also failed to keep the bacteria alive.

This was a bit surprising for the researchers because the strain of bacteria used, Bacillus subtilis, belongs to a genus that actually does fine in the presence of perchlorates, as studies of the microbes in terrestrial environments have confirmed. These findings were initially good news for researchers looking for extraterrestrial life, as they suggested that some forms of life could survive in Martian analogue conditions.

It Takes More Than Salt

There’s more to Mars than just the soil though, and when the Edinburgh researchers added in a few more Mars-like factors — UV specifically — the bacteria died in short order. They think this happens because the UV light breaks apart the perchlorate molecules into more reactive ions that wreak havoc on living cells. This hypothesis was backed up by the observation that low temperatures, which slow down chemical reactions, extended the lifespan of the bacteria in the perchlorates but still resulted in them dying. If they can’t survive there, it significantly lowers our chances of finding life on Mars — life that looks similar to organisms on Earth at least. The researchers published their findings Thursday in Nature Scientific Reports.

While it’s a blow to the possibility of finding life on Mars, there is at least one upside to the news: NASA regularly worries about the possibility of contaminating other planets with Earthly bacteria, even going so far as to crash probes into Saturn so that they don’t hit the planet’s moons. If Mars is so hostile to bacteria that they can’t even make it a minute on the surface, our fears of contamination could be pretty much resolved.

CATEGORIZED UNDER: Space & Physics, top posts
  • Uncle Al

    Shall we spend a $trillion to personally verify Mars is a crap hole? Add surface 30 rad/year from cosmic radiation – no magnetosphere, no atmosphere. $ocial intent!

    The same feat was accomplished in Harlem, Baltimore, Camden, urban Washington, DC; Atlanta, Detroit, Chicago, Pacoima…- though it cost $10 trillion during the Obama administration.

    • OWilson

      Enough already!

      Take your Radio Shack toys home and play with them there!

      Let’s get back to classical Einsteinian “thought experiments”.

      It’s cheaper and more productive!

      • Uncle Al

        …The most dangerous and destructive person in an ivory tower is somebody with a testable original idea. They are broken by withholding funding. Wiser heads can only fear that idea being found in the gutter.

        • OWilson

          Now that they have maxed out all the “origin of life” theories, and terraforming potential of Mars, they are salivating at the thought of the infinite number of “Earth Like” planets in the universe to transfer their speculations to, and apply for new funding to do so.

          How do you get those jobs? :)

          • Uncle Al

            You Gore the ox yourself, then spread the wealth among your kind.

    • Janey Carter


    • Chuckiechan

      No oil, no methane, no wood. Nada. Just a bunch of dead space cadets.

  • Maia

    And astronaut/colonists would grow their food in toxic soil, and last how long??

    • OWilson

      Look up “Biosphere Project”.

      The New Agers tried to build a self contained sealed dome here on Earth.

      Didn’t work out too well, because, well, humans are humans. :)

      Wouldn’t help that all volunteers for such a project, would be, to be kind, “lacking” in certain areas. Community living communes tend attract lots of sheep, and the wolves that feed on them.

      As Groucho said wisely, “I would never join a club, that would have me as a member!” :)

  • jimgrot

    not all life is at the surface (Earth included). Mars does have a “below the surface” level, i.e. dig down a bit … AND lava tubes

  • Mike Richardson

    Well, we knew it wouldn’t be easy. On earth, there are bacteria that thrive in ultrasaline environments, at temperatures above the boiling point of water, inside the containment structure at Chernobyl, and feasting on petroleum. I’m sure we could genetically engineer bacteria to make the soil more hospitable for less hardy earth life. There are probably other ways of chemically treating and refining the soil to remove excess perchlorates, which I’m sure NASA (or Elon Musk) will be researching prior to sending humans to Mars.

  • m1ckDELTA

    We aren’t going to interstellar space. We aren’t going to deep space. We can’t even seem to get to outer space anymore. Humans haven’t left earth’s orbit in over a generation; since the last time we went to the moon. The ISS, contrary to popular belief, isn’t floating in outer space, it’s in orbit, LEO at that. We can’t live anywhere but here, it’s how we evolved over hundreds of thousands of years. We’re stuck here and we better get our act together soon.

    • Maia

      Since I was a kid, like most others, I was very excited about the possibility of space travel. BUT. Now I see that, overwhelmingly, what we need to do is, as you put it, “get our act together” right here on this planet that keeps us alive every moment, and we’ve messed up to a shocking extent. The fantasy of space travel distracts us from putting all possible efforts into making up for at least some of our blunders and ravages on Earth. “We can’t live anywhere but here”…and they way things are going, we won’t be able to live here, either…unless we wake up and give this situation as much energy, focus and money as we gave the moonshot and before that, building a nuclear bomb. But I disagree that “we are stuck here”. We have wrecked our oasis…the most beautiful and amazing planet. We need to wake up, be grateful for the life-support and companion creatures that are left, and work all out to restore as much as we can..before it’s too late.

  • Steven C. Moser

    If I am wrong but I thought UV light kills bacteria in the first place…


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