Perseverance Rover Finds Complex Organic Carbon on Mars, Potentially Evidence of Ancient Life

NASA's Perseverance rover has discovered complex organic carbon in mudstone rocks within Mars' Jezero Crater, a finding researchers say could be evidence that microbial life existed on the Red Planet 3.5 billion years ago. The study was published June 24 in the journal Science Advances.

Discovery Location and Process

The discovery was made at a rocky outcrop called "Bright Angel," located on the northern and southern edges of Neretva Vallis, an ancient river valley within Jezero Crater.

The research team used Perseverance's SHERLOC instrument (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) to analyze two mudstone samples in detail. SHERLOC uses lasers to identify the chemical and mineral composition of target areas, mapping the distribution of organic matter within the rocks.

The results showed organic carbon in both mudstones, generating hundreds of organic detection signals total. The research paper states this is "the most robust organic detection in Jezero Crater."

Connection to Previous Findings

Notably, the carbon-bearing mudstones are located at the same site where a potential biosignature was discovered last year. At that time, Perseverance found distinctive "leopard spots" on a rock now named "Cheyava Falls." While such markings on Earth are typically formed in high-heat or extremely acidic conditions—neither of which scientists believe existed in this area—they can also be produced by biological activity.

Ashley Murphy, a researcher at the Planetary Science Institute and co-lead author of the study, told Space.com: "Carbon is the primary building block for life on Earth, and all living things are made up of complex organic macromolecules. 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."

Differences Between the Two Mudstones

The research team found differences between the carbon in the two mudstones: one contained carbon mixed primarily with silicate minerals, while the other had carbon mixed with secondary carbonate and sulfate minerals. The carbon in both rocks was relatively intact, suggesting the specimens might be resistant to radiation and oxidation or may have been recently exposed to the Martian surface.

Kyle Uckert, SHERLOC deputy principal investigator at NASA's Jet Propulsion Laboratory and co-lead author, noted: "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."

Cautious Interpretation

Despite the exciting findings, the research team urges caution. Uckert told Space.com: "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."

He added that the complex carbon could have multiple non-biological explanations: "For example, it may have been delivered to the surface via meteoritic infall, or formed through hydrothermal geologic processes."

Perseverance landed in Jezero Crater in 2021, chosen because scientists believed the ancient lake site could harbor some of the best evidence for possible ancient life on Mars. The rover has now traveled the equivalent of a marathon on Mars, and the evidence it has found appears to be increasingly supporting that initial assessment.

Further Reading

Original article: Did NASA just find evidence of ancient life on Mars? Perseverance rover spots complex carbon in Red Planet rocks

Research paper: Science Advances