Martian microbes could survive millions of years underground
Ancient microbes on Mars could survive millions of years if they are resistant to radiation and left buried underneath the ground in frozen, moist conditions, according to a study published on Tuesday.
Mars is a difficult planet to survive. Lacking a magnetic field, it cannot shield its surface from harsh cosmic radiation or prevent liquid water evaporating from its surface.
If Mars did harbor life in the past, it would be nothing short of a miracle for astronauts to discover live samples. The best chance of finding these hypothetical microbes would be to look below the planet’s surface.
Buried beneath the Martian regolith, these alien microorganisms are protected from radiation and could lie dormant and survive for hundreds of millions of years if they are anything like Deinococcus radiodurans (pictured), one of the hardiest species of bacteria found on Earth.
Nicknamed “Conan the Bacterium,” the microbe is particularly resistant to radiation and can survive with little oxygen under cold, dry temperatures.
A team of scientists performed radiation experiments on six different types of frozen bacteria and fungi, zapping the samples with gamma rays to mimic conditions on Mars. They discovered Conan the Bacterium could withstand 140,000 grays of radiation, an amount 28,000 times more than the lethal dose for a human.
If the bacterium lurks just ten centimeters below the surface, it could survive up to 1.5 million years and if it is pushed down to ten meters, it could survive up to 280 million years, the researchers estimated. The results were published in the Astrobiology journal.
Other environmental constraints like moisture are also required to keep microbes alive. Liquid water is believed to have disappeared from Mars billions of years ago. Other processes like meteorite impacts could melt water ice in its soil to keep the cells hydrated, explained Michael Daly, a professor of pathology at Uniformed Services University of the Health Sciences (USU), who led the study.
“Although D. radiodurans buried in the Martian subsurface could not survive dormant for the estimated 2 to 2.5 billion years since flowing water disappeared on Mars, such Martian environments are regularly altered and melted by meteorite impacts,” he said in a statement.
“We suggest that periodic melting could allow intermittent repopulation and dispersal. Also, if Martian life ever existed, even if viable lifeforms are not now present on Mars, their macromolecules and viruses would survive much, much longer. That strengthens the probability that, if life ever evolved on Mars, this will be revealed in future missions.”
The study’s results, however, also show that if astronauts or spacecraft were to contaminate Mars with Earth’s bacteria or fungi, these samples could, in theory, survive and lurk on Mars for up to hundreds millions of years.
“We concluded that terrestrial contamination on Mars would essentially be permanent – over timeframes of thousands of years,” said Brian Hoffman, a senior co-author of the paper and a professor of chemistry and molecular sciences at Northwestern University.
“This could complicate scientific efforts to look for Martian life. Likewise, if microbes evolved on Mars, they could be capable of surviving until present day. That means returning Mars samples could contaminate Earth.”
See more here theregister.com
Header image: Michael Daly / USU
Editor’s note: we already have ancient Martian microbes on Earth, in the form of the ‘microfossil’ discovered on the ALH84001 meteorite found in Antarctica, and there is no evidence it ‘contaminated’ Earth.
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Tom
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Life on Mars? Probably much more intelligent than life on earth. While I believe their are thousands or perhaps millions of other beings and entities in the universe, the search for extraterrestrial life is comical to me. Until we get our affairs settled here on earth, it is rather pointless.
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Kevin Doyle
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Katyana Quach,
Really?
I am astonished anyone would pay you salary? Your entire article is prefaced by the words ‘could’ or ‘might’.
Jimmy Hoffa might also still be alive having waffles with Elvis in Vegas…
You are an embarrassment to the world of science.
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lloyd
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Talking about possibilities is part of scientific research. Next, is trying to prove the mentioned possibilities.
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Jerry Krause
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Hi Lloyd,
When you wrote, “Next, is trying to prove the mentioned possibilities.”, you provided evidence that you do understand that experimentation (observation and measurement) can only absolutely prove WHAT IS NOT. The data cannot prove anything to be true.
Sir Arthur Conan Doyle had his fictional character, Sherlock Holmes, make the following two statements (which I believe to be historical fact; believe because I have never read his original copies which he submitted for publication.)
“It is a capital mistake to theorize before you have all the evidence; it biases the judgment.” And: “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.”
These two statements are not compatible (consistent with one another). For one only has to ask the question: How can one ever know IF one has considered ALL THE EVIDENCE???
Have a good day, Jerry.
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Jerry Krause
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And I have just proven how easy it is to make a mistake by not typing the word “NOT” which I intended to type. No, I did not purposefully do this to make a point.
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