- NASA’s Curiosity rover found complex organic molecules on Mars. Scientists think they are the remains of fatty acids. Could ancient life have produced them?
- The organics were surprisingly abundant in the mudstone before radiation began to destroy them, a new NASA-led study shows.
- Non-biological sources don’t fully explain the abundance and complexity of the organics, the study says. But more work is needed to understand their origin.
EarthSky’s 2026 lunar calendar is available now. Get yours today! Makes a great gift.
Complex organics on Mars: A sign of life?
Almost a year ago, NASA’s Curiosity rover found something quite intriguing: long-chain organic molecules that scientists said could have come from fatty acids and/or alkanes. Fatty acids are common in life on Earth. Could they be evidence for ancient martian life? That possibility just got another boost from an international team of researchers led by NASA’s Goddard Space Flight Center in Maryland. The researchers said on February 6, 2026, that additional studies of the data from Curiosity show that non-biological sources they had considered don’t fully explain the organics. They conclude, therefore, that a biological source is a reasonable hypothesis.
The paper proposes two possible explanations: hydrothermal synthesis of the molecules or an ancient biosphere of microorganisms.
Curiosity found the complex organics – long-chain fatty acids and/or alkanes – in mudstone rocks in Gale Crater. Curiosity has been exploring this crater since 2012. The crater used to hold a lake or series of lakes billions of years ago.
This still isn’t proof of past life on Mars. But it certainly adds to the growing hints that Mars might have once been home to microbial life (and still could be).
The researchers published their peer-reviewed findings in a new hypothesis paper in the journal Astrobiology on February 4, 2026.
NASA Study: Non-biologic Processes Don't Fully Explain Mars Organicsastrobiology.com/2026/02/nasa… #astrobiology #Mars
— Astrobiology (@astrobiology.bsky.social) 2026-02-09T19:42:34.417Z
Organics in Gale Crater
NASA first reported the tantalizing finding back in March 2025. The rover found small amounts of the long-chain organic molecules decane, undecane and dodecane in the mudstone samples it analyzed. The samples came from a fine-grained sedimentary mudstone rock nicknamed Cumberland. They were the largest organics that any Mars mission had discovered so far. The rover’s onboard lab analysis suggested they were likely the remains of fatty acids and/or alkanes.
That’s significant, because on Earth, fatty acids are mostly produced by living organisms. Geological process can create them too, though.
NASA’s Curiosity rover found the largest organic molecules on Mars yet. Did ancient life produce them? Video via NASA Goddard.
Rewinding the clock
The researchers wanted to know how much organic material was present in the rock before radiation from the sun destroyed it while hitting the surface. That would provide clues as to whether it was small amounts from sources such as meteorites or dust or larger amounts that would be more difficult to explain without biology.
The researchers used a combination of lab radiation experiments, mathematical modeling and data from Curiosity itself. This allowed them to “rewind the clock” about 80 million years. That’s how long the rock would have been exposed on the martian surface.
An abundance of organics on Mars
Intriguingly, the results showed the rock had an abundance of the organic molecules before radiation began to destroy them. That is difficult to explain without biology. The press release said:
As the non-biological sources they considered could not fully explain the abundance of organic compounds, it is therefore reasonable to hypothesize that living things could have formed them.
As the paper explains:
The measured abundance of long-chain alkanes and their possible carboxylic acid precursors found in the ancient Cumberland mudstone in Gale Crater would have been substantially higher before the onset of exposure to ionizing radiation approximately 80 million years ago. Based on recent radiolysis experiments, we estimate conservatively that the Cumberland mudstone would have contained 120–7700 ppm of long-chain alkanes and/or fatty acids before ionizing radiation exposure. Such a high concentration of large organic molecules in martian sedimentary rocks cannot be readily explained by the accretion of organics from carbon-rich interplanetary dust particles and meteorites, nor by the deposition of hypothetical haze-derived organics from an ancient martian atmosphere.
Hydrothermal activity or biology?
The study focuses on two primary possibilities. One is that the organics were formed by hydrothermal activity. However, analysis of the mudstone rock itself showed it had not experienced the high temperatures associated with hydrothermal activity. The researchers also considered serpentinization, a low-temperature metamorphic and hydration process where water reacts with ultramafic, olivine- and pyroxene-rich rocks from the Earth’s mantle, transforming them into serpentinite. But the rover didn’t find any telltale serpentine minerals in the rock. Also, if either of those two processes formed the organics, it must have occurred elsewhere, with water later transporting the organics to the Cumberland location.
It would also imply that there were abundant organics in the surrounding early Noachian (early Mars) rocks of Gale Crater. But only trace amounts have ever been detected so far.
The other, more exciting, possibility is that the organics, such as the former fatty acids, were the products of life, just as most of them on Earth are. The long-chain molecules are suggestive of an ancient martian biosphere of microorganisms. It is hard to assess that, however, because the parameters of the experiments with the Sample Analysis at Mars (SAM) instrument on Curiosity made it difficult to detect both shorter and even longer-chain molecules. Scientists would need to compare them to the known long-chain molecules to more accurately assess their abundance.
More study needed
A lot more study is required to further determine whether these organics really could be evidence of past life. For now, the paper concludes:
We agree with Carl Sagan’s claim that extraordinary claims require extraordinary evidence and understand that any purported detection of life on Mars will necessarily be met with intense scrutiny. In addition, in practice with established norms in the field of astrobiology, we note that the certainty of a life detection beyond Earth will require multiple lines of evidence. Nevertheless, our approach has led us to estimate that the Cumberland mudstone conservatively contained 120–7700 ppm of long-chain alkanes and/or fatty acids before exposure to ionizing radiation. We argue that such high concentrations of long-chain alkanes are inconsistent with a few known abiotic sources of organic molecules on ancient Mars.
To improve the ability to predict the types and concentrations of organic molecules that could have been preserved in ancient sedimentary rocks exposed to ionizing radiation at the martian surface – regardless of their origin – we recommend experimental studies that determine the radiolytic degradation rates of kerogens, alkanes and fatty acids in Cumberland-like Mars analogs under Mars-like conditions.
Bottom line: NASA’s Curiosity rover found complex organics on Mars, possibly remains of fatty acids. A new NASA study suggests they are difficult to explain without life.
Read more: Surprisingly big organic molecules on Mars: A hint of life?
Read more: Life on Mars? Odd rings and spots tantalize scientists
The post NASA says organics on Mars are hard to explain without life first appeared on EarthSky.
from EarthSky https://ift.tt/uUNYr1R
- NASA’s Curiosity rover found complex organic molecules on Mars. Scientists think they are the remains of fatty acids. Could ancient life have produced them?
- The organics were surprisingly abundant in the mudstone before radiation began to destroy them, a new NASA-led study shows.
- Non-biological sources don’t fully explain the abundance and complexity of the organics, the study says. But more work is needed to understand their origin.
EarthSky’s 2026 lunar calendar is available now. Get yours today! Makes a great gift.
Complex organics on Mars: A sign of life?
Almost a year ago, NASA’s Curiosity rover found something quite intriguing: long-chain organic molecules that scientists said could have come from fatty acids and/or alkanes. Fatty acids are common in life on Earth. Could they be evidence for ancient martian life? That possibility just got another boost from an international team of researchers led by NASA’s Goddard Space Flight Center in Maryland. The researchers said on February 6, 2026, that additional studies of the data from Curiosity show that non-biological sources they had considered don’t fully explain the organics. They conclude, therefore, that a biological source is a reasonable hypothesis.
The paper proposes two possible explanations: hydrothermal synthesis of the molecules or an ancient biosphere of microorganisms.
Curiosity found the complex organics – long-chain fatty acids and/or alkanes – in mudstone rocks in Gale Crater. Curiosity has been exploring this crater since 2012. The crater used to hold a lake or series of lakes billions of years ago.
This still isn’t proof of past life on Mars. But it certainly adds to the growing hints that Mars might have once been home to microbial life (and still could be).
The researchers published their peer-reviewed findings in a new hypothesis paper in the journal Astrobiology on February 4, 2026.
NASA Study: Non-biologic Processes Don't Fully Explain Mars Organicsastrobiology.com/2026/02/nasa… #astrobiology #Mars
— Astrobiology (@astrobiology.bsky.social) 2026-02-09T19:42:34.417Z
Organics in Gale Crater
NASA first reported the tantalizing finding back in March 2025. The rover found small amounts of the long-chain organic molecules decane, undecane and dodecane in the mudstone samples it analyzed. The samples came from a fine-grained sedimentary mudstone rock nicknamed Cumberland. They were the largest organics that any Mars mission had discovered so far. The rover’s onboard lab analysis suggested they were likely the remains of fatty acids and/or alkanes.
That’s significant, because on Earth, fatty acids are mostly produced by living organisms. Geological process can create them too, though.
NASA’s Curiosity rover found the largest organic molecules on Mars yet. Did ancient life produce them? Video via NASA Goddard.
Rewinding the clock
The researchers wanted to know how much organic material was present in the rock before radiation from the sun destroyed it while hitting the surface. That would provide clues as to whether it was small amounts from sources such as meteorites or dust or larger amounts that would be more difficult to explain without biology.
The researchers used a combination of lab radiation experiments, mathematical modeling and data from Curiosity itself. This allowed them to “rewind the clock” about 80 million years. That’s how long the rock would have been exposed on the martian surface.
An abundance of organics on Mars
Intriguingly, the results showed the rock had an abundance of the organic molecules before radiation began to destroy them. That is difficult to explain without biology. The press release said:
As the non-biological sources they considered could not fully explain the abundance of organic compounds, it is therefore reasonable to hypothesize that living things could have formed them.
As the paper explains:
The measured abundance of long-chain alkanes and their possible carboxylic acid precursors found in the ancient Cumberland mudstone in Gale Crater would have been substantially higher before the onset of exposure to ionizing radiation approximately 80 million years ago. Based on recent radiolysis experiments, we estimate conservatively that the Cumberland mudstone would have contained 120–7700 ppm of long-chain alkanes and/or fatty acids before ionizing radiation exposure. Such a high concentration of large organic molecules in martian sedimentary rocks cannot be readily explained by the accretion of organics from carbon-rich interplanetary dust particles and meteorites, nor by the deposition of hypothetical haze-derived organics from an ancient martian atmosphere.
Hydrothermal activity or biology?
The study focuses on two primary possibilities. One is that the organics were formed by hydrothermal activity. However, analysis of the mudstone rock itself showed it had not experienced the high temperatures associated with hydrothermal activity. The researchers also considered serpentinization, a low-temperature metamorphic and hydration process where water reacts with ultramafic, olivine- and pyroxene-rich rocks from the Earth’s mantle, transforming them into serpentinite. But the rover didn’t find any telltale serpentine minerals in the rock. Also, if either of those two processes formed the organics, it must have occurred elsewhere, with water later transporting the organics to the Cumberland location.
It would also imply that there were abundant organics in the surrounding early Noachian (early Mars) rocks of Gale Crater. But only trace amounts have ever been detected so far.
The other, more exciting, possibility is that the organics, such as the former fatty acids, were the products of life, just as most of them on Earth are. The long-chain molecules are suggestive of an ancient martian biosphere of microorganisms. It is hard to assess that, however, because the parameters of the experiments with the Sample Analysis at Mars (SAM) instrument on Curiosity made it difficult to detect both shorter and even longer-chain molecules. Scientists would need to compare them to the known long-chain molecules to more accurately assess their abundance.
More study needed
A lot more study is required to further determine whether these organics really could be evidence of past life. For now, the paper concludes:
We agree with Carl Sagan’s claim that extraordinary claims require extraordinary evidence and understand that any purported detection of life on Mars will necessarily be met with intense scrutiny. In addition, in practice with established norms in the field of astrobiology, we note that the certainty of a life detection beyond Earth will require multiple lines of evidence. Nevertheless, our approach has led us to estimate that the Cumberland mudstone conservatively contained 120–7700 ppm of long-chain alkanes and/or fatty acids before exposure to ionizing radiation. We argue that such high concentrations of long-chain alkanes are inconsistent with a few known abiotic sources of organic molecules on ancient Mars.
To improve the ability to predict the types and concentrations of organic molecules that could have been preserved in ancient sedimentary rocks exposed to ionizing radiation at the martian surface – regardless of their origin – we recommend experimental studies that determine the radiolytic degradation rates of kerogens, alkanes and fatty acids in Cumberland-like Mars analogs under Mars-like conditions.
Bottom line: NASA’s Curiosity rover found complex organics on Mars, possibly remains of fatty acids. A new NASA study suggests they are difficult to explain without life.
Read more: Surprisingly big organic molecules on Mars: A hint of life?
Read more: Life on Mars? Odd rings and spots tantalize scientists
The post NASA says organics on Mars are hard to explain without life first appeared on EarthSky.
from EarthSky https://ift.tt/uUNYr1R
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