NASA’s Curiosity rover has discovered over 20 carbon-containing compounds, including seven previously unseen on Mars, from 3.5 billion-year-old clay-rich sandstone in Gale Crater.
A close-up of three holes drilled by Curiosity into Martian rock in October 2020 at a site named after Mary Anning. Image credit: NASA/JPL-Caltech/MSSS.
The drilled rock sample, named Mary Anning 3 in honor of the British fossil collector and paleontologist, comes from a region of Mount Sharp that was once abundant in lakes and streams billions of years ago.
This ancient environment underwent cycles of flooding and drying, which eventually enriched the area with clay minerals adept at preserving organic matter.
Among the newly identified compounds are nitrogen heterocycles—a type of ring structure containing carbon and nitrogen—believed to be precursors to crucial nucleic acids like RNA and DNA.
Dr. Amy Williams from the University of Florida stated, “This discovery is significant as these structures could be chemical precursors to more complex nitrogenous molecules.” She further explained that nitrogen heterocycles have never been recorded on Mars until now, nor have they been identified in Martian meteorites.
Another fascinating finding is benzothiophene, a molecule composed of carbon and sulfur, commonly found in many meteorites. Some scientists think that these meteorites, along with their organic compounds, may have contributed to prebiotic chemistry across the early solar system.
Dr. Ashwin Vasavada from NASA’s Jet Propulsion Laboratory emphasized the teamwork involved: “It required dozens of scientists and engineers to identify this site, drill samples, and achieve these remarkable discoveries with our advanced robotic technologies.”
This collection of organic molecules ignites the possibility that Mars may have harbored life in the distant past.
The analysis of the Mary Anning 3 sample was conducted in a sophisticated mini-lab known as Sample Analysis of Mars (SAM), housed within Curiosity’s body.
A drill at the end of the rover’s robotic arm carefully grinds selected rock samples into powder, which is then deposited into the SAM. Here, the samples are heated in a high-temperature oven that liberates gases, enabling laboratory equipment to analyze the rock’s chemical composition.
Moreover, SAM is capable of performing “wet chemistry,” where samples are mixed with a solvent in small cups, allowing large complex molecules to break down for easier detection.
Among the cups, only two are filled with tetramethylammonium hydroxide (TMAH), a powerful solution earmarked for the most significant samples. The Mary Anning 3 sample was the first to undergo TMAH treatment.
To verify TMAH’s reactions with extraterrestrial materials, researchers also tested this method on Earth with a fraction of the Murchison meteorite—one of the most studied meteorites, aged over 4 billion years, containing vital organic molecules from the early solar system.
Tests revealed that Murchison samples reacted with TMAH to break down larger molecules into smaller ones, including the benzothiophene found in Mary Anning 3, reinforcing the idea that these Martian compounds may originate from more complex molecules linked to life.
The spatial distribution analysis of organic materials is currently limited within SAM, leaving unclear whether the identified compounds stem from meteorite deposits or were formed abiotically through processes like serpentinization or electrochemical reactions. Nevertheless, the verification of macromolecular organics suggests that future optimized TMAH thermochemical experiments may unlock ancient biosignatures preserved within Martian macromolecules.
The diverse structural characteristics of organic molecules observed directly from surface materials indicate that some chemical diversity has been maintained in ancient Martian sediments, even after more than 3.5 billion years of geological changes and radiation exposure.
“These findings expand the inventory of organic molecules recognized as preserved at the Martian surface over deep geological time, supporting the existence of polymeric carbon on Mars,” the scientists concluded.
For further information, refer to the findings published in the Journal on April 21, 2026, in Nature Communications.
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AJ Williams et al. 2026. The first SAM TMAH experiment reveals a diverse array of organic molecules on Mars. Nat Commune 17, 2748; doi: 10.1038/s41467-026-70656-0
Source: www.sci.news
