NASA rover discovers possible ancient life in Martian rocks

Table of Contents

A Potential Biosignature on Mars

A sample collected by NASA's Perseverance rover from a reddish rock formed billions of years ago from sediment at the bottom of a lake has sparked excitement among scientists. The findings suggest the possibility of ancient microbial life on Mars, though some of the minerals found in the sample could also form through nonbiological processes.

The discovery, made in Jezero Crater, is considered one of the most compelling pieces of evidence to date regarding the potential for life on Mars. Joel Hurowitz, a Perseverance scientist from Stony Brook University and lead author of the study published in the journal Nature, highlighted the presence of a "potential biosignature" in the rock. This rock was formed during a time when Jezero Crater was believed to have been a watery environment, between 3.2 and 3.8 billion years ago.

Acting NASA Administrator Sean Duffy emphasized that the agency's scientists spent a year examining the data before concluding that "we can't find another explanation, so this very well could be the clearest sign of life that we've ever found on Mars."

NASA released an image of the rock, a fine-grained, rusty-red mudstone with ring-shaped features resembling leopard spots and dark marks like poppy seeds. These features may have resulted from chemical reactions involving microbes during the rock’s formation, according to researchers.

A potential biosignature refers to a substance or structure that might have a biological origin but requires further study to confirm whether it indicates the presence of life. Nicky Fox, associate administrator for NASA's Science Mission Directorate, clarified that the scientists were not announcing the discovery of a living organism. "It's not life itself," she said.

Since 2021, the Perseverance rover has been exploring Jezero Crater, a region in Mars' northern hemisphere that once contained water and an ancient lake basin. Scientists believe river channels spilled over the crater wall, creating a lake. The rover has been analyzing rocks and regolith using its onboard instruments, collecting samples and sealing them in tubes stored inside the rover.

In July 2024, the rover collected a sample named Sapphire Canyon from a rock called Cheyava Falls in the Bright Angel rock formation. The sample came from rocky outcrops on the edges of Neretva Vallis, an ancient river valley about a quarter of a mile wide.

Telltale Minerals

Two minerals were detected in the sample that appear to have formed as a result of chemical reactions between the mud of the Bright Angel formation and organic matter present in that mud. These minerals are vivianite, which contains iron and phosphorus, and greigite, which contains iron and sulfur.

On Earth, similar reactions that combine organic matter and chemical compounds in mud to form new minerals like vivianite and greigite are often driven by microbial activity. "The microbes are consuming the organic matter in these settings and producing these new minerals as a byproduct of their metabolism," Hurowitz explained.

The rover's instruments found that the rock was rich in organic carbon, sulfur, phosphorus, and iron in its oxidized form, rust. This combination of chemical compounds could have provided a rich source of energy for microbial metabolisms, according to Hurowitz.

However, Hurowitz cautioned that the findings cannot yet be confirmed as definitive evidence of life. "The reason we cannot claim this is more than a potential biosignature is that there are chemical processes that can cause similar reactions in the absence of biology, and we cannot rule those processes out completely based on rover data alone."

Mars was not always the inhospitable planet it is today. Liquid water existed on its surface in the distant past. The sample collected and analyzed by Perseverance provides a new example of a potential biosignature that the research community can explore to determine whether these features were formed by life or if natural processes mimicked life-like activity.

"We can make a lot of progress on this question with laboratory experiments and fieldwork here on Earth to understand the various pathways that might create features like the ones we observe in the Bright Angel formation. But the ultimate tests can only be performed on the Sapphire Canyon core sample if and when it is brought back to Earth for study," Hurowitz added.

NASA faces challenges in its Mars Sample Return mission, as U.S. President Donald Trump's current budget proposal would cancel the existing mission. Duffy stated that NASA is exploring various options for potential sample retrieval or sending equipment to Mars for further analysis.

"We're going to look at our budgets and our timing, and how we spend money better and what technology do we have to get samples back more quickly," Duffy said.