Mars Perseverance rover data suggests presence of past microbial life
A new study co-authored by Texas A&M University geologist Dr. Michael Tice has revealed potential chemical signatures of ancient Martian microbial life in rocks examined by NASA’s Perseverance rover.
The findings, published by a large international team of scientists, focus on a region of Jezero Crater known as the Bright Angel formation—a name chosen from locations in Grand Canyon National Park because of the light-colored Martian rocks. This area in Mars’s Neretva Vallis channel contains fine-grained mudstones rich in oxidized iron (rust), phosphorus, sulfur and—most notably—organic carbon. Although organic carbon, potentially from non-living sources like meteorites, has been found on Mars before, this combination of materials could have been a rich source of energy for early microorganisms.
“When the rover entered Bright Angel and started measuring the compositions of the local rocks, the team was immediately struck by how different they were from what we had seen before,” said Tice, a geobiologist and astrobiologist in the Department of Geology and Geophysics.
“They showed evidence of chemical cycling that organisms on Earth can take advantage of to produce energy. And when we looked even closer, we saw things that are easy to explain with early Martian life but very difficult to explain with only geological processes.”
Tice went on to explain that “living things do chemistry that generally occurs in nature anyway given enough time and the right circumstances. To the best of our current knowledge, some of the chemistry that shaped these rocks required either high temperatures or life, and we do not see evidence of high temperatures here. However, these findings require experiments and ultimately laboratory study of the sample here on Earth in order to completely rule out explanations without life.”
The team published its findings in Nature.
A window into Mars’s watery past
The Bright Angel formation is composed of sedimentary rocks deposited by water, including mudstones (fine-grained sedimentary rocks made of silt and clay) and layered beds that suggest a dynamic environment of flowing rivers and standing water. Using Perseverance’s suite of instruments, including the SHERLOC and PIXL spectrometers, scientists detected organic molecules and small arrangements of minerals that appear to have formed through “redox reactions,” chemical processes involving the transfer of electrons. On Earth, those processes are often driven by biological activity.
Among the most striking features are tiny nodules and “reaction fronts”— nicknamed “poppy seeds” and “leopard spots” by the rover team—enriched in ferrous iron phosphate (likely vivianite) and iron sulfide (likely greigite). These minerals commonly form in low-temperature, water-rich environments and are often associated with microbial metabolisms.
“It’s not just the minerals, it’s how they are arranged in these structures that suggests that they formed through the redox cycling of iron and sulfur,” Tice said. “On Earth, things like these sometimes form in sediments where microbes are eating organic matter and ‘breathing’ rust and sulfate. Their presence on Mars raises the question: could similar processes have occurred there?”
Source: phys.org
Our Moon Is Drifting Away. Here’s What We Can Expect to Happen.
Mars Perseverance rover data suggests presence of past microbial life