Could Martian mudstones be holding evidence of ancient microbes? New findings strengthen the case that the Red Planet once held life.
New data from NASA’s Perseverance rover has revealed complex carbon in two Martian mudstones found in Mars’ Jezero crater, the same location where previous evidence of possible ancient life has been found. Scientists think this macromolecular (meaning large) complex carbon, could hold evidence that ancient microbial life once existed in the same sedimentary material, according to one new paper describing these observations. “Measurements of two mudstones show hundreds of organic detections, making this the most robust organic detection in Jezero crater,” the paper reads.
This comes soon after the news last year that Perseverance found what has been dubbed the strongest evidence of potential biosignatures, or hints of life, on Mars.
“Carbon is the primary building block for life on Earth, and all living things are made up of complex organic macromolecules,” lead author Ashley Murphy, a researcher at the Planetary Science Institute, told Space.com. “On Earth, [macromolecular carbon] is often found in extremely old rocks and in some cases it is the only organic evidence of past microbial life.
“Since early Mars may have been more similar to Earth,” Murphy added, “we may anticipate finding [macromolecular carbon] in old Martian rocks too, so we are searching for these organic macromolecules on Mars and other planetary bodies to determine whether the necessary chemical ingredients and environmental conditions to support life have ever existed there.”
Perseverance landed on Mars in 2021 in Jezero Crater, an expansive crater thought to once be a lake that could have possibly harbored life. This landing site was in fact chosen because scientists thought it could have some of the best evidence for possible ancient life on the planet. And so far, in Perseverance’s extensive explorations — which have now officially taken the rover the distance of a marathon on Mars — that prediction seems like it’s turning out to be true.
In this new research, a team of scientists led by Murphy used Perseverance’s spectrometer SHERLOC (the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals), which uses lasers to identify an area or object’s chemical and mineral makeup, to map the distribution of organic matter in the individual mudstones. The crew found organic carbon inside two mudstones.
Furthermore, these carbon-filled mudstones were found in the same location as the last year’s discovery of a potential biosignature found in a sedimentary rock on the Red Planet, which scientists say is still the strongest evidence that life could have once existed on early Mars. In this discovery, Perseverance found a rock now-named “Cheyava Falls” with distinctive “leopard spots.”
These types of rock marking can be created in high heat or extremely acidic temperatures, but neither of these conditions are thought to have existed in the area. However, the markings can also be formed by the presence of life. So, while this rock wasn’t conclusive evidence of past life on Mars, it certainly provided significant evidence that is now supported by this new data.
With these observations, the rover has made two main findings.
First, Perseverance has found organic, large, complex carbon in mudstones in Bright Angel, a rocky area on the northern and southern edges of Neretva Vallis, which is an ancient river valley in the Jezero area. And not only did Perseverance make hundreds of detections of organic carbon in these rocks, but the researchers also state that this is “the only detection of macromolecular carbon on a natural rock surface on Mars.”
“This is also the first detection of MMC in a mudstone on Mars outside of Gale Crater, suggesting that the availability of organics may have been widespread across the planet billions of years ago,” co-author Kyle Uckert, the SHERLOC deputy principal investigator at NASA’s Jet Propulsion Laboratory, told Space.com.
While both studied mudstones have organic carbon in their interiors, according to these observations from Perseverance, there were some differences between the two rocks. The carbon in one mudstone was found mixed with primarily silicate minerals, while the other was filled with carbon mixed with secondary carbonate and sulfate minerals. The team also found that the carbon in both rocks was relatively intact, meaning the specimens might be resistant to radiation and oxidation or that it may have been recently exposed to the Martian surface.
Secondly, the team found that, in this identified carbon, Perseverance has detected evidence of potential biochemical interactions. These interactions left behind features in the two mudstones that look just like features created by microscopic life in sediments on Earth. This begs the question: Did ancient microbes on Mars really live in the sediments in this once-flowing river?
Maybe, maybe not. While that would certainly be one explanation, it’s also possible that the carbon could have been created without life.
“There are multiple potential pathways to form abiotic organics on Mars,” the authors state in this paper, clarifying that this, even compounded with other existing data, cannot conclusively say whether or not life created what Perseverance has observed.
“The science payload of the Perseverance rover was not designed to distinguish between abiotic and biotic processes, but was instead selected to identify compelling rocks to be collected for possible return to Earth for more rigorous testing,” Ukert told Space.com. Ukert added that there could be many non-life reasons behind the presence of this complex carbon, “for example, it may have been delivered to the surface via meteoritic infall, or formed through hydrothermal geologic processes,” he said.
For now, we can only wait until the next juicy bit of evidence about ancient life on Mars reveals itself.
This work was described in a paper published June 24 in the journal Science Advances.