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Posted on: Tuesday 25 October 2022 – 22:07 | Last update: Tuesday 25 October 2022 – 10:07 pm
In a one-of-a-kind study, a research team found that ancient bacteria could live near the surface of Mars longer than previously thought.
According to the study, when the bacteria are buried they are protected from galactic cosmic radiation and solar protons and can survive longer, so when the first Martian samples return to Earth, scientists should be on the lookout for ancient dormant bacteria.
These findings, published Tuesday in the journal Astrobiology, raise the possibility that future missions including ExoMars and Mars Life Explorer, which will carry tools to extract material from two meters below the surface, will return bacterial samples.
As scientists have shown that certain strains of bacteria can survive Mars’s harsh environment, future astronauts and space tourists could inadvertently contaminate Mars with hiking bacteria.
“Importantly, these findings also have biological defense implications, because the threat of biological agents such as anthrax remains a military defense problem,” says Michael Daley, professor of pathology at Northwestern University and member of the National Academies Committee for Planetary. Protection, who led the study. and internal. “
He adds: “We have found that Earth’s pollution on Mars will be permanent for thousands of years, this could complicate scientific efforts to search for Martian life and, likewise, if microbes have evolved on Mars, they can survive, and this means that the return of Mars samples may be to pollute the earth.
The environment on Mars is harsh and unforgiving, and the arid and freezing conditions, averaging -80 degrees Fahrenheit (-63 degrees Celsius) in mid-latitudes, make the Red Planet seem inhospitable to life and, worse still, even Mars is constantly bombarded with intense radiation from cosmic and solar galactic protons.
To explore whether life is possible, the researchers first determined the survival limits of ionizing radiation for microbial life, then exposed six terrestrial bacteria and fungi to mimic the surface of Mars – frozen and dry – and contaminated it with gamma rays or protons (to mimic radiation in space).
Researchers have found that some terrestrial microorganisms can live on Mars on geological time scales of hundreds of millions of years.
Indeed, the researchers found that a powerful microbe, the ‘radiation-resistant peculiar cocci’, is particularly well suited to survive the harsh conditions on Mars. In new experiments, the bacteria survived astronomical amounts of radiation in the freezing, arid environment.
To test the effects of radiation, the research team exposed the samples to large doses of gamma radiation and protons, which are typical of what Mars receives in the nearby subsurface, and to much smaller doses, which would occur if a microorganism were buried. deep.
Next, Northwestern’s Hoffman team used advanced spectroscopy technology to measure the accumulation of the antioxidant manganese in the cells of the radioactive microorganisms.
According to Hoffman, the size of the radiation dose that microorganisms or their spores can survive is related to the amount of antioxidants contained in manganese, so more antioxidants from manganese mean greater radiation resistance and greater survival.
In previous studies, previous researchers found that “exotic radiation resistant cocci” bacteria, when suspended in a liquid, could survive 25,000 units of radiation, the equivalent of about 1.2 million years below the surface of Mars.
