According to Rebecca Mickol, a graduate student at the University of Arkansas, some Earth organisms could survive on Mars. In particular, she means methanogens, anaerobic microorganisms responsible for creating methane.
Methanogens do not require oxygen, that’s what anaerobic means, and use hydrogen as an energy source and carbon dioxide as a carbon source. They basically eat hydrogen and secrete methane. They are usually found in swamps and marshes, but also live within cattle and termites, and they’re part of the decomposition process, so they live in dead animals too. In addition to not needing oxygen, they don’t need sunlight either, so they could survive underground on Mars, if put to the test.
They can also survive in extremely low pressure, so they can continue to life after moving through such regions, or even within them. This means they could survive on planets with lower pressure than Earth, and maybe even survive the vacuum of space, if they had an energy source. Previously, Mickol even found two species that could survive the Martian freeze-thaw cycle.
Mickol, who works with professor Timothy Kral, presented her work in New Orleans at the General Meeting of the American Society for Microbiology. Professor Kral has been working on methanogens, and their ability to survive on Mars, since the 1990s.
Why methanogens, and why Mars? Scientists have been eying the Red Planet for generations, and many suggest that we could land humans on Mars in the near future. Visiting Mars and actually making a go of living there are two different things though. Being able to grow plants on Mars, much less terraform the planet, requires an understanding of what it would take for Earth organisms to survive there. Figuring out if, and how, microorganisms like methanogens could do that is a start.