WASHINGTON: Scientists using NASA’s Perseverance rover have gained new insight into the nature of organic carbon found in ancient Martian rocks, strengthening evidence that early Mars possessed the chemical ingredients and environmental conditions that may have supported life.
The study, published in the journal Science Advances, examined the structure of complex organic carbon discovered in sedimentary rocks inside Jezero Crater, where Perseverance has been exploring since landing on Mars in 2021.
Researchers cautioned that while the findings add to evidence that ancient Mars may once have been habitable, they do not constitute proof that life ever existed on the planet.
The organic carbon was identified in two rocks, named Cheyava Falls and Walhalla Glades, which were sampled about 100 metres apart in Jezero Crater in the planet’s northern hemisphere.
According to planetary scientist Ashley Murphy of the Planetary Science Institute in Arizona, a co-leader of the study, the rocks are ancient mudstones that likely formed beneath a body of water between 3.2 billion and 3.8 billion years ago.
The discovery follows last year’s announcement by researchers that one of the rocks, Cheyava Falls, contained a potential biosignature—a possible indication of ancient microbial life requiring further investigation.
NASA previously released images showing the fine-grained, rust-coloured mudstone containing ring-shaped features resembling leopard spots and dark markings similar to poppy seeds.
Scientists noted that comparable features on Earth can be associated with microbial activity, although they stressed that additional evidence is required before any biological origin can be confirmed.
Using Perseverance’s SHERLOC instrument, researchers carried out a detailed analysis of the complex organic material, known as macromolecular carbon, found within the rocks.
The team said the carbon shares characteristics with material produced through both biological and non-biological processes on Earth, as well as carbon created through abiotic processes found in meteorites.
Organic carbon forms the chemical backbone of DNA, proteins and cells in all known living organisms. However, scientists emphasised that its presence alone does not indicate life because it can also form through purely chemical interactions between rocks and water.
The study marks the first detection of macromolecular carbon in mudstones at Jezero Crater. NASA’s Curiosity rover had previously identified similar carbon compounds in Gale Crater, about 3,700 kilometres away.
Kyle Uckert, a planetary scientist at NASA’s Jet Propulsion Laboratory and co-leader of the study, said the findings suggested that habitable environments and organic materials may once have been widespread across Mars.
“These findings indicate that the habitability of Mars and the availability of organic materials may have been widespread across the planet billions of years ago,” Uckert said.
“This strengthens evidence that ancient Mars had chemical ingredients and environmental conditions that could have supported life, but does not provide proof of life nor does it push the needle any further towards biotic or abiotic origins,” he added.
Researchers said Perseverance’s scientific instruments are not capable of determining whether the carbon originated from biological activity involving ancient microbes or from non-biological chemical processes.
“We need the return of these samples to Earth for more rigorous testing with higher sensitivity and higher resolution laboratory instruments,” Uckert said.
