Life on Mars? Bacteria may have survived under its surface for 280 million years

Is there life on Mars? This question has been bugging scientists and commoners alike for ages. Well, there just might be, because a new study says microorganisms may be able to survive just beneath the Martian surface, shielded from the harsh radiation of space, much longer than previously thought.

The journal Astrobiology on Tuesday published the findings of the study carried out by researchers at Illinois’s Northwestern University. The team simulated the conditions on Mars in a lab to see how bacteria and fungi could survive.

The results showed that dried-up bacteria could survive for 280 million years in Mars-like conditions, buried under the surface, and protected from the ionizing radiation and solar particles that bombard the planet’s surface. This finding improves our chances of finding out if Mars ever hosted extra-terrestrial life. Even if it did, the evidence might be buried under the subsurface.

A question of survival

Mars, today, is like a frozen desert. The planet’s midlatitudes record an average temperature of minus 62 degrees Celsius (minus 80 degrees Fahrenheit). The planet has a thin atmosphere, which exposes it to the constant threat of radiation.

Also read: Scientists find new evidence for liquid water beneath south pole of Mars

“There is no flowing water or significant water in the Martian atmosphere, so cells and spores would dry out,” said co-author of the study, Brian Hoffman, in a statement. “It also is known that the surface temperature on Mars is roughly similar to dry ice, so it is indeed deeply frozen,” he added.

However, billions of years ago, Mars may have had a more hospitable environment for life, including a denser atmosphere and water on its surface. But the question was whether they could have survived Mars’s harsh conditions and, if so, for how long.

A different path

To answer that question, most previous experiments used hydrated bacteria at room temperature. The toughest of microbes were thought to be able to survive for about 1.2 million years in Mars-like conditions.

However, Hoffman and his colleagues took a different path. They took six types of bacteria and fungi found on Earth and placed them in a simulated Martian surface environment. They froze these microorganisms and subjected them to radiation like what they would experience buried on Mars.

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“There’s this phenomenal multiplication of the resistance when you get rid of the water and you cool everything down,” Hoffman said in the statement. It is like freeze-drying food to make it last longer. The samples were damaged so little by the radiation that they estimated the bacteria could survive for up to about 280 million years.

No longer zero probability

The exciting bit is that if the freeze-dried bacteria were warmed up and exposed to water, they would emerge from their dormant state. “It opens some possibilities that you could get revitalisation if a meteor with some water comes down and splashes on the surface, it could regenerate,” Hoffman stated.

“The probability that it’s still alive now has increased from zero to the tiniest thing you could imagine—it’s non-zero, but it sure as hell ain’t big,” he added.

However, since it is estimated that Mars dried up about 3 billion years ago, the chances of any bacteria being alive is slim.

Implications of the findings

The findings have implications for both returning Martian samples to Earth and landing crewed missions on Mars. The Mars Sample Return program, an ambitious joint project of the NASA and the European Space Agency, will launch multiple missions to Mars to collect and return samples gathered by the Perseverance rover.

Also read: NASA’s Perseverance rover spots a shiny piece of foil on Mars

The rover team hopes that the rock and soil samples could help determine if life ever existed on the red planet. The samples might contain microfossils of ancient microbial life.

Another concern is that astronauts may accidentally deliver bacteria from Earth when they land on Mars. “We concluded that terrestrial contamination on Mars would essentially be permanent—over timeframes of thousands of years,” Hoffman said.

“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.”