By Sid Perkins
Radiation-tolerant microbes might be able to live beneath Mars’ surface for hundreds of millions of years and may yet persist today, thanks in part — counterintuitively — to the Red Planet’s frigid, arid conditions.
In addition to being cold and dry, the Martian surface is constantly bombarded by cosmic rays, charged particles and other radiation from space. Previous studies have shown that desiccation vastly extends a microbe’s potential for surviving by limiting the production of highly reactive oxygen-bearing chemicals that can damage proteins and DNA, among other vital molecules within its tissues. To see how long microbes might survive such an onslaught on Mars, researchers desiccated five species of bacteria and one type of yeast, stored them at −80° Celsius and then irradiated them.