Understanding Organic Carbon on Mars
Scientists are gaining new insights into the organic carbon found on Mars, thanks to NASA’s Perseverance rover. This carbon, which forms the molecular backbone for all known life, is being studied to determine if it could indicate past microbial life on the Red Planet.
The research focuses on organic carbon detected in sedimentary rock within Jezero Crater, a region that once held a body of water billions of years ago. The mudstone in this area formed between 3.2 and 3.8 billion years ago, offering a potential glimpse into Mars’ ancient environment.
Organic carbon can be a key indicator of past life because it is essential for building DNA, cells, and proteins. However, its presence alone does not confirm life, as it can also form through nonbiological processes like chemical interactions between rock and water.
In 2022, the Perseverance rover identified organic carbon in two rocks named Cheyava Falls and Walhalla Glades. These rocks were sampled at locations approximately 330 feet (100 meters) apart. Planetary scientist Ashley Murphy from the Planetary Science Institute in Arizona, who co-led the research, highlighted the significance of these findings.
NASA released an image of the Cheyava Falls rock, showing a fine-grained, rusty-red mudstone with ring-shaped features resembling leopard spots and dark marks similar to poppy seeds. On Earth, such features can be linked to microbial activity, making them potential biosignatures — substances or structures that may have a biological origin but require further study to confirm.
A Closer Look for Signs of Life
Using the Perseverance rover’s SHERLOC instrument, researchers examined the complex carbon, known as macromolecular carbon, present in the two rocks. They found that this carbon resembles carbon formed through both biotic and abiotic processes on Earth, as well as carbon found in meteorites.
This discovery marks the first time macromolecular carbon has been found in mudstones in Jezero Crater, where Perseverance landed in 2021. Previously, NASA’s Curiosity rover detected similar carbon in Gale Crater, located about 2,300 miles (3,700 km) away.
Kyle Uckert, a planetary scientist at NASA’s Jet Propulsion Laboratory and co-leader of the study, emphasized the implications of these findings. “These results suggest that Mars’ habitability and the availability of organic materials may have been widespread across the planet billions of years ago,” he said.
While the findings strengthen the evidence that ancient Mars had conditions suitable for life, they do not provide definitive proof of life. Uckert noted that the rover’s instruments cannot determine whether the carbon originated from biological processes involving microbes.
“We need to return these samples to Earth for more detailed analysis using advanced laboratory equipment,” Uckert added.
Mars’ Ancient Environment
Today, Mars is cold and desolate, but it may have had a thicker atmosphere and warmer climate during its early history, allowing liquid water to exist on its surface. Like Earth and other planets in the solar system, Mars formed roughly 4.5 billion years ago.
Water is considered essential for life, which is why Perseverance has been exploring Jezero Crater since 2021. This region was once filled with water and contained an ancient lake basin. Scientists believe river channels may have spilled over the crater wall, creating a lake that could have supported microbial life.
Uckert reflected on the broader implications of the research. “The only place in the universe where we know life has emerged is Earth,” he said. “If life is discovered on Mars, it could mean that life’s emergence is not limited to Earth, assuming the right conditions and ingredients are available. That would be a groundbreaking discovery.”
