By Becky Oskin
To find evidence of life on Mars, scientists from UC Davis and the U.S. Geological Survey are chasing clues in Mars-like environments on Earth.
The researchers hope to find rock patterns and textures that are uniquely linked to microscopic life such as bacteria and algae. “It’s challenging to prove that a mineral was made by a living organism,” said lead study author Amy Williams, an assistant professor at Towson University in Towson, Maryland. Williams led the research as a graduate student at UC Davis. Finding similar textures in Mars rocks could bolster confidence that microscopic shapes in Red Planet rocks were formed by living creatures.
Williams’ search centered on an extreme environment — the polluted water and soil at Iron Mountain, a shuttered mine near Redding, California. Originally a copper mine, the water and soil at Iron Mountain are stained red by iron, creating a landscape much like the one on Mars today.
“Iron Mountain is a sensational Mars analog site,” Williams said.
At Iron Mountain, the research team has discovered tiny filaments made of a form of iron oxide, or rust, surrounding microscopic organisms. The structures form around bacteria as the microbes munch on iron, leaving behind thread-like tubes that preserve the creature’s shapes. The tiny tubes could help narrow down the search for remnants of ancient life. For instance, similar microbial filaments could be preserved on Mars in an environment similar to Iron Mountain, with the Hematite Ridge in Gale Crater as tentative possibilities, the researchers said.
“This research is a step forward in understanding how to search for fossil life on Mars,” Williams said.
Other study authors include UC Davis professor Dawn Sumner, a member of NASA’s Mars Science Laboratory team, and USGS scientists Charles Alpers and Kate Campbell.
The findings were published March 2017 in the Geomicrobiology Journal.