NASA’s Curiosity Rover Detects Largest Organic Molecules On Mars, Offering Clues To Potential Ancient Life

 

NASA’s Curiosity rover has uncovered the largest organic molecules ever detected on Mars, providing new insights into the planet’s past and its potential to support life. The discovery of these complex compounds suggests that Mars once hosted the necessary chemistry for life to emerge, according to recent research.

The newly identified molecules—decane, undecane, and dodecane—were found in a 3.7-billion-year-old rock sample analyzed by Curiosity’s onboard laboratory, the Sample Analysis at Mars (SAM). Scientists believe these long-chain molecules could be remnants of fatty acids, which are key building blocks of life on Earth, though they can also form through non-biological processes, such as interactions between water and minerals in hydrothermal vents.

While the molecules cannot yet be confirmed as evidence of past life, their presence adds to the growing list of organic compounds found on Mars in recent years. A study detailing these findings was published in the journal Proceedings of the National Academy of Sciences.

Preserving Clues to Ancient Life

The detection of these fragile molecules excites astrobiologists because it suggests that if biosignatures—chemical signs of past life—ever existed on Mars, they may still be detectable despite billions of years of exposure to harsh radiation.

“Ancient life, if it happened on Mars, would have released complex and fragile molecules,” said Dr. Caroline Freissinet, the study’s lead author and a research scientist at the French National Centre for Scientific Research. “Now that we know Mars can preserve these molecules, it means we could detect ancient life on Mars.”

This discovery strengthens the case for returning Martian samples to Earth, where more advanced tools could analyze them to determine if life ever existed beyond our planet.

A Decade-Long Mission Uncovers a Breakthrough

Since landing in Gale Crater in 2012, Curiosity has traveled over 21 miles (34 kilometers), climbing Mount Sharp and studying its many layers, which hold a record of Mars’ transition from a wet to a dry world.

One of the most valuable samples Curiosity collected was drilled in May 2013 from Yellowknife Bay, an ancient lakebed. This sample, called Cumberland, revealed that Mars once had water-rich environments where clay minerals formed—conditions that could have supported life. The fine-grained sedimentary rock preserved organic molecules, allowing scientists to analyze them years later.

Freissinet and her team first identified organic molecules in the Cumberland sample in 2015. They detected sulfur, which can help preserve organic compounds, as well as nitrates and methane, which are associated with biological processes on Earth.

“There is evidence that liquid water existed in Gale Crater for millions of years—possibly much longer—providing enough time for life-forming chemistry to occur,” said study coauthor Daniel Glavin, a senior scientist at NASA’s Goddard Space Flight Center.

Unexpected Organic Molecules

Curiosity has preserved portions of the Cumberland sample, allowing scientists to revisit it with new experiments. In a recent attempt to detect amino acids—the building blocks of proteins—the team heated the sample twice in SAM’s oven. Instead of amino acids, they found decane, undecane, and dodecane.

To verify whether these compounds were remnants of fatty acids, scientists conducted lab experiments on Earth, mimicking the conditions inside SAM. They found that heating undecanoic acid—a type of fatty acid—produced decane, just like what Curiosity detected on Mars.

The molecules found in Cumberland contain 11 to 13 carbon atoms, making them more complex than previous organic detections on Mars, which were smaller and simpler.

“Non-biological processes typically create shorter fatty acids with fewer than 12 carbon atoms,” explained study coauthor Dr. Amy Williams, a planetary geologist at the University of Florida. “Larger and more complex molecules are likely required for an origin of life—if it ever occurred on Mars.”

While Curiosity cannot directly detect longer-chain fatty acids, SAM’s ability to identify these molecules suggests it could potentially recognize chemical signatures of past life.

Closer Than Ever to Answering the Life on Mars Question

Curiosity’s mission is not designed to detect life, but rather to determine whether Mars had the right conditions to support it. Even so, this discovery pushes the rover’s capabilities beyond expectations.

“Before Curiosity, scientists doubted organic molecules could survive on Mars due to its intense radiation exposure,” Glavin said. “Now, we know otherwise.”

While Curiosity won’t return to Yellowknife Bay, it still holds pristine Cumberland samples for future tests. The team is now working on new experiments to extract more information from them.

“That’s the most precious sample we have on board,” Freissinet said. “It holds secrets, and we need to decipher them.”

The Next Steps: Bringing Martian Samples to Earth

The European Space Agency’s Rosalind Franklin rover, set to launch in 2028, will carry instruments capable of drilling deeper into Mars’ surface, potentially uncovering even better-preserved organic molecules.

Meanwhile, NASA’s Perseverance rover is actively collecting samples from Jezero Crater—another ancient lakebed—aiming to return them to Earth in the 2030s as part of the Mars Sample Return mission. These efforts will allow scientists to analyze Martian material in ways that Curiosity and Perseverance cannot, hopefully resolving the long-standing question of whether life ever existed on the red planet.

“This detection confirms that sediments from ancient Martian lakes could preserve organic molecules, offering clues about prebiotic chemistry and even potential biosignatures from ancient organisms,” said planetary scientist Dr. Briony Horgan.

While organic compounds alone are not proof of life, some scientists believe that fatty acids like those found in the Cumberland sample could have played a role in forming early cell membranes on Earth.

“This is the closest we’ve come to detecting a major biomolecule-related signal,” said Dr. Ben Pearce, a planetary scientist at Purdue University. “Finding biomolecules such as amino acids, nucleotides, and sugars would be groundbreaking.”

With each discovery, the possibility of past life on Mars becomes more compelling. But until samples can be studied in Earth-based laboratories, the debate will continue.

“I’m more optimistic than ever that we’re finally getting closer to answering the age-old question: Was there ever life on Mars?” Glavin said.