NASA rover takes a closer look at organic carbon on Mars

Scientists using NASA's Perseverance rover have gained fresh insights into the nature of organic carbon discovered on Mars, advancing efforts to understand whether the Red Planet may once have supported life. The findings focus on organic carbon detected in ancient sedimentary rocks inside Jezero Crater, a site believed to have hosted a lake billions of years ago.

The organic carbon was identified in two rock samples, named Cheyava Falls and Walhalla Glades, located about 100 metres apart. These mudstones are estimated to have formed between 3.2 and 3.8 billion years ago beneath a body of water that has long since disappeared. Organic carbon is considered an important building block of life because it forms the basis of molecules such as DNA, proteins and cells.

However, scientists caution that its presence alone does not confirm past life, as similar compounds can also be produced through non-biological chemical reactions involving rocks and water.

Last year, researchers announced the discovery of a potential biosignature in the Cheyava Falls rock. NASA also released images showing fine-grained, reddish mudstone containing ring-shaped patterns resembling leopard spots and tiny dark specks. On Earth, such features can sometimes result from microbial activity, although they are not considered definitive evidence of life.

In the latest study, published in *Science Advances*, researchers used Perseverance's SHERLOC instrument to closely examine a complex form of organic carbon known as macromolecular carbon. Their analysis revealed similarities to carbon produced through both biological and non-biological processes on Earth, as well as carbon found in meteorites that formed through abiotic processes.

The discovery marks the first detection of macromolecular carbon in mudstones at Jezero Crater. NASA's Curiosity rover had previously identified similar material in Gale Crater, located about 3,700 kilometres away, suggesting that organic compounds may have been widespread across ancient Mars.

Researchers say the findings strengthen the case that early Mars possessed the chemical ingredients and environmental conditions necessary to support life. However, they emphasise that the evidence does not confirm whether the carbon originated from living organisms or natural geological processes.

Because Perseverance's onboard instruments cannot determine the carbon's origin with certainty, scientists say the rock samples must eventually be returned to Earth for detailed laboratory analysis using more advanced technology.

Mars, now cold and dry, is believed to have had a thicker atmosphere, a warmer climate and abundant liquid water during its early history. Scientists think Jezero Crater once contained a lake fed by rivers, creating conditions that may have been suitable for microbial life. Confirming evidence of past life on Mars would have profound implications, suggesting that life could emerge beyond Earth when the necessary conditions exist.