It is possible that ancient bacteria may still exist beneath Mars’ surface
There might be hundreds of millions of years of radiation-tolerant microbes that can survive there.
Microbes that are radiation-tolerant may be able live below Mars’ surface for many millions of years. They might even persist today, contrary to popular belief. This is due in part to Mars’s cold, dry conditions.
The Martian surface is not only cold and dry but also constantly bombarded with cosmic rays, charged particle and other radiation from outer space. Studies have previously shown that dehydration can greatly increase a microbe’s survival potential by limiting its production of reactive oxygen-bearing chemicals, which can damage DNA and proteins. Researchers desiccated five types of bacteria and one yeast species to see how long they could survive such an assault on Mars. They then stored them at -80 degrees Celsius before irradiating them.
Experiments showed that some of these microbes may not be viable for more than a few thousands of years. One species, Deinococcus Radiodurans, which is a radiation-resistant greebly some scientists call “Conan” the bacterium — could survive up to 280 million years provided it is protected from radiation at soil depths below 10 meters or moree.
Even though microbes that developed on Mars eventually died, there may still be remnants of their macromolecules or proteins. This gives hope that future missions might be able, with the right equipment, to find these signs.