"If we find life on another planet, it's likely going to be microbial," said Ashley Manning-Berg, assistant professor in geology at The University of Tennessee in Chattanooga.
"So a lot of the focus for evidence for life is not just to learn about the ecosystems on early Earth, it's a way of telling us that if life evolved and then died on Mars, what do we look for?
Manning-Berg is studying how billion-year-old fossils of microorganisms were preserved on Earth, so we can know what to look for on other planets.
“So if you have a microfossil that is torn and kind of just looks like maybe a little squiggle in a rock, how do we know that's a microfossil? So by looking at the morphologies of the rocks that we know have life, we can get a sense of whether or not that's a microbial morphology,” said Berg. “Looking at the chemistry, so is there carbon there? Is that carbon thermally altered? Has it been changed since its deposition?
Berg is also studying how the silica that preserves her billion-year-old microbes is formed. This helps her understand how quickly the microbes were preserved, and whether their specific chemical signatures are preserved.
"That's very important, especially with early life for astro-biological samples. You're going to have to show-- using more than one technique--that this is life," she said.