In a new study, researchers say that non-biological sources they considered could not fully account for the abundance of organic compounds in a sample collected on Mars by NASA’s Curiosity rover.
A self-portrait of NASA’s Curiosity rover taken on
June 15, 2018, when a Martian dust storm had reduced sunlight and visibility at
the rover’s location in Gale Crater.
NASA/JPL-Caltech/MSSS
In March 2025, scientists reported
identifying small amounts of decane, undecane, and dodecane in a rock sample
analyzed in the chemistry lab aboard Curiosity. These were the largest organic
compounds found on Mars, with researchers hypothesizing that they could be
fragments of fatty acids preserved in the ancient mudstone in Gale Crater. On
Earth, fatty acids are produced mostly by life, though they can be made through
geologic processes, too.
It was not possible to determine from
Curiosity’s data alone whether
or not the molecules they found were made by living things, which led to a follow-on study that evaluated known non-biological
sources of these organic molecules — such as delivery by meteorites smashing
into the Martian surface — to see if they could account for the amounts
previously found.
Reporting
on Feb. 4 in the journal Astrobiology,
researchers say that 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.
To reach their conclusion, scientists
combined lab radiation experiments, mathematical modeling, and Curiosity data
to “rewind the clock” about 80 million years — the length of time the rock
would have been exposed on the Martian surface. This allowed them to estimate
how much organic material would have been present before being destroyed by
long-term exposure to cosmic radiation: far more than typical non-biological
processes could produce.
The team says more study is needed to
better understand how quickly organic molecules break down in Mars-like rock
under Mars-like conditions — and before any conclusions can be reached about
the absence or presence of life.
By Lonnie Shekhtman
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Source: NASA Study: Non-biologic Processes Don’t Fully Explain Mars Organics - NASA Science

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