A team of astrobiologists from the University of Arkansas conducted a year-long experiment that proved that, despite the harsh conditions, microbes can survive on Mars. This means that once upon a time life on the red planet could well exist - even microscopic.
The impetus for the experiment was methane found on Mars by the Curiosity rover. The fact is that on Earth, most methane is produced by living organisms, methanogens, and scientists from Arkansas decided to investigate this possibility.
On Earth, methanogenic microbes live in swamps and in the intestinal tract of cattle. They don't need oxygen or photosynthesis to live. In the conditions of Mars, they could inhabit the soil of the planet, which would protect them from the harsh ultraviolet radiation on its surface.
For the experiment, scientists have grown a culture of methanogens in a liquid medium that mimics the one that could exist under the surface of Mars many years ago. They also recreated the conditions of extremely low pressure and extremely low Martian temperature.
After a year of observing four different types of microbes, the researchers concluded that each species managed to survive in such harsh conditions from 3 to 21 days. However, warning of possible speculations, team leader Rebecca Micol emphasizes that methane on Mars could have been formed as a result of other, non-biological processes - for example, volcanic ones.