Subscribe to CNN’s Wonder Theory science newsletter to stay updated on exciting discoveries, scientific progress, and more. The Curiosity rover has identified the largest organic molecules ever found on Mars, shedding light on the planet’s past. These newly discovered compounds hint at complex organic chemistry that might have occurred in Mars’ history — a crucial component for the potential origin of life, as per recent research.
Among the organic compounds detected by the rover are decane, undecane, and dodecane, unveiled through the analysis of a pulverized 3.7 billion-year-old rock sample by the rover’s onboard mini lab SAM (Sample Analysis at Mars). Scientists speculate that these molecular chains could be remnants of fatty acids, essential building blocks of life on Earth that contribute to cell membranes. While these compounds can also form without the presence of life, through interactions of water with minerals in hydrothermal vents, their discovery enhances the growing array of compounds unearthed by robotic explorers on Mars in recent times. A recent study detailing these findings was published in the Proceedings of the National Academy of Sciences on Monday.
The detection of these delicate molecules excites astrobiologists, hinting that potential biosignatures or remnants of past life on Mars could still be detectable despite the harsh solar radiation the planet has endured for millions of years. According to lead study author Dr. Caroline Freissinet, a research scientist at the French National Centre for Scientific Research, the discovery of these molecules indicates Mars’ capability to preserve complex and fragile compounds, raising the possibility of finding traces of ancient life on the planet.
Furthermore, this discovery highlights the urgency of retrieving samples from Mars for further analysis on Earth with advanced tools. This endeavor could potentially settle the question of whether life once thrived beyond our planet.
Curiosity’s journey began with its landing in Gale Crater on August 6, 2012. Over the course of more than 12 years, the rover has traveled over 21 miles (34 kilometers) to reach Mount Sharp within the crater. The layers of Mount Sharp preserve a wealth of geological history, showcasing the transformation of Mars from a wet to a dry environment.
In May 2013, Curiosity collected a crucial sample known as the Cumberland sample from the Yellowknife Bay crater, resembling an ancient lake bed. This sample piqued the interest of Curiosity’s science team, prompting a detour to gather more samples from the area prior to ascending Mount Sharp. The Cumberland sample has been a focal point of research for Curiosity, enabling in-depth studies using the SAM instrument.
Yellowknife Bay once hosted an ancient lake where clay minerals formed in water, creating an environment that could preserve organic molecules. In 2015, Freissinet and his research team identified organic molecules in the Cumberland sample, detecting sulfur, nitrates, and methane associated with biological processes on Earth. Daniel Glavin noted that liquid water existed in Gale Crater for millions of years, providing ample time for life-forming chemistry to occur on Mars. Curiosity holds pristine pieces of the Cumberland sample for further analysis, conducting experiments to explore the presence of amino acids. Unexpectedly, the team discovered small amounts of decane, undecane, and dodecane in the sample, prompting further investigation to determine their origins. Dr. Amy Williams highlighted the significance of detecting larger and more complex molecules, suggesting they could be crucial for the origin of life. Though SAM is not specifically designed to detect longer fatty acid chains, the discovery opens up possibilities for identifying chemical signatures of past life on Mars. The findings push the boundaries of Curiosity’s capabilities and enhance our understanding of Mars’ habitability potential.
“More organic molecules were discovered on Mars than initially anticipated by scientists before sending missions to the red planet. The intense radiation exposure on Mars led researchers to believe organic compounds would be scarce, but the findings proved otherwise, according to Glavin. During Curiosity’s mission, it will not revisit Yellowknife Bay, but remnants of the Cumberland sample remain for further analysis. The team is eager to conduct new experiments to identify additional long-chain molecules, which could provide insights into their origins, Freissinet mentioned.
Briony Horgan, a co-investigator on the Perseverance rover mission and a planetary science professor at Purdue University, hailed the discovery as a significant achievement for the team. The Sample Analysis at Mars (SAM) instrument played a crucial role in detecting organic compounds in Martian rock and soil samples.
Horgan expressed optimism that the discovery of organic molecules in ancient watery environments on Mars could yield valuable insights into prebiotic processes, the origins of life, and potential biosignatures from ancient organisms. Dr. Ben K.D. Pearce, an assistant professor at Purdue specializing in astrobiology research, described the findings as one of the most exciting organic detections on Mars to date.
The detection of fatty acids like decanoic acid and dodecanoic acid, believed to have been crucial for the formation of early cell structures on Earth, represents a significant step in understanding potential indications of life. Pearce emphasized the importance of biomolecules such as membranes, amino acids, and nucleotides in shaping the foundations of life.
Looking ahead, the European Space Agency is set to launch the ExoMars Rosalind Franklin rover in 2028, equipped with advanced instruments to drill beneath the Martian surface. The mission aims to retrieve larger and better-preserved organic molecules for further study. The ongoing Mars Sample Return project plans to bring back samples collected by the Perseverance rover from Jezero Crater to Earth in the 2030s.
While both Curiosity and Perseverance have uncovered a range of organic carbon molecules on Mars, the question of their origins remains a topic of ongoing research. Dr. Ashley Murphy, a postdoctoral research scientist at the Planetary Science Institute, highlighted the significance of these discoveries and the need for continued exploration to unravel the mysteries of organic matter on Mars.”
The organics previously studied by Perseverance, which were not involved in the recent research, will require thorough analysis in terrestrial labs to properly investigate the potential biosignatures. Bringing these samples back to Earth will enable high-resolution and high-sensitivity analyses, as stated by Murphy. If the molecules found in the Cumberland sample prove to be remnants of ancient microbial life from 3.7 billion years ago, it would correspond with the emergence of life on Earth during the same period, according to Glavin. While Curiosity’s discovery offers significant insight, Glavin believes that conclusive answers are more likely to be obtained through the study of samples on Earth. He expressed optimism about finally settling the ongoing debate regarding life on Mars.
