NASA’s Curiosity rover has detected more than 20 carbon-containing compounds — including seven never before seen on Mars — in a sample collected from 3.5-billion-year-old clay-bearing sandstones in Gale Crater.
A close-up of three holes Curiosity drilled into Martian rock at a location nicknamed Mary Anning in October 2020. Image credit: NASA / JPL-Caltech / MSSS.
Nicknamed Mary Anning 3 after an English fossil collector and paleontologist, the rock sample was collected by Curiosity on a part of Mount Sharp covered by lakes and streams billions of years ago.
This oasis surged and dried up multiple times in the planet’s ancient past, eventually enriching the area with clay minerals, which are especially good at preserving organic compounds.
Among the newly-identified molecules is a nitrogen heterocycle, a ring of carbon atoms that includes nitrogen.
This kind of molecular structure is considered a predecessor to RNA and DNA, two nucleic acids that are key to genetic information.
“That detection is pretty profound because these structures can be chemical precursors to more complex nitrogen-bearing molecules,” said Dr. Amy Williams, a researcher at the University of Florida.
“Nitrogen heterorcycles have never been found before on the Martian surface or confirmed in Martian meteorites.”
Another exciting discovery was benzothiophene, a carbon- and sulfur-bearing molecule that’s been found in many meteorites.
These meteorites, along with the organic molecules within them, are thought by some scientists to have seeded prebiotic chemistry across the early Solar System.
“It took dozens of scientists and engineers to locate this site, drill the sample, and make these discoveries with our awesome robot,” said Dr. Ashwin Vasavada, a researcher at NASA’s Jet Propulsion Laboratory.
“This collection of organic molecules once again increases the prospect that Mars offered a home for life in the ancient past.”
The analysis of the Mary Anning 3 sample was made with a sophisticated minilab called Sample Analysis at Mars (SAM), located in Curiosity’s belly.
A drill on the end of the rover’s robotic arm pulverizes a carefully selected rock sample into powder and then trickles it into SAM, where a high-temperature oven heats the material, releasing gases that instruments in the lab analyze to reveal the rock’s composition.
In addition, SAM can perform ‘wet chemistry,’ dropping samples into a small cup of solvent.
The resulting reactions can break apart larger molecules that would be difficult to detect and identify otherwise.
While the instrument has several such cups, only two contain tetramethylammonium hydroxide (TMAH), a powerful solution reserved for the highest-value samples.
The Mary Anning 3 sample was the first to be exposed to TMAH.
To verify TMAH’s reactions with otherworldly materials, the researchers also tested the technique on Earth with a piece of the Murchison meteorite, one of the most studied meteorites of all time.
More than 4 billion years old, Murchison contains organic molecules that were seeded throughout the early Solar System.
A Murchison sample exposed to TMAH was found to break much larger molecules into some of the ones seen in Mary Anning 3, including benzothiophene.
That result verifies that the Martian molecules found in the sample could have been generated from the breakdown of even more complex compounds relevant to life.
“Analysis of the spatial distribution of the organic matter is not possible with SAM, therefore the origin of this material as being introduced from meteorites, abiotically produced via aqueous processing such as serpentinization or electrochemical production, is currently unknown,” the scientists said.
“Regardless, confirmation of macromolecular organic matter supports the possibility that future optimized TMAH thermochemolysis experiments can liberate ancient biosignatures preserved in macromolecules on Mars (if present).”
“The broad structural variety of organic molecules observed in situ from surface materials suggests some chemical diversity is preserved in ancient Martian sediments despite over 3.5 billion years of diagenesis and radiation exposure.”
“These results expand the library of confirmed and suggested organic molecules preserved over deep eologic time in the Martian near-surface and confirm the presence of macromolecular carbon on Mars.”
The findings were published April 21, 2026 in the journal Nature Communications.
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A.J. Williams et al. 2026. Diverse organic molecules on Mars revealed by the first SAM TMAH experiment. Nat Commun 17, 2748; doi: 10.1038/s41467-026-70656-0
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