Largest organic molecules ever found on Mars confirm that life can form there

NASA’s Curiosity rover has made another remarkable discovery on Mars – the largest organic compounds ever detected on the Red Planet.

These molecules, discovered in a rock sample drilled in 2013, offer fresh insights into the potential of Mars to support life.

The findings suggest that Mars might have hosted more advanced prebiotic chemistry than scientists had assumed.

Complex molecules in Martian rock

Inside Curiosity’s onboard mini-lab called SAM, scientists identified three organic molecules: decane, undecane, and dodecane.

These compounds contain 10, 11, and 12 carbon atoms, respectively. The researchers believe they are remnants of fatty acids.

On Earth, fatty acids help form cell membranes. They can be produced through both biological and geological processes.

For example, water interacting with rocks in hydrothermal vents can create fatty acids without the influence of living cells.

Still, detecting these molecules on Mars is a thrilling step. It shows that complex chemistry did occur there.

Long-awaited sample yields new surprises

Curiosity drilled into the rock target “Cumberland” on May 19, 2013. The sample came from a location called Yellowknife Bay inside Gale Crater.

At the time, scientists believed the area resembled an ancient lakebed. That guess turned out to be correct.

The rock was rich in clay, sulfur, and nitrates. All three materials help preserve organic compounds. Also present was methane with a carbon signature that, on Earth, often points to the presence of life.

“There is evidence that liquid water existed in Gale Crater for millions of years and probably much longer, which means there was enough time for life-forming chemistry to happen in these crater-lake environments on Mars,” said Daniel Glavin, senior scientist at NASA’s Goddard Space Flight Center.

Serendipitous discovery of molecules

The discovery came during an unrelated experiment. Scientists were searching for amino acids in the Cumberland sample. They heated the sample and measured released gases.

No amino acids were present. But instead, the experts found small amounts of decane, undecane, and dodecane.

These molecules could have broken off from longer ones during heating. Scientists traced them back to possible parent compounds: undecanoic acid, dodecanoic acid, and tridecanoic acid.

To confirm their findings, the researchers recreated the process in labs on Earth. They added undecanoic acid to Mars-like clay and heated it. It released decane, just like the Martian sample had.

Martian molecules may hint at past life

One interesting detail emerged. The detected fatty acids seem longer than those usually formed by geological activity. Non-biological processes tend to produce shorter chains – usually with fewer than 12 carbon atoms.

Cumberland’s molecules had 11 to 13 carbon atoms. That suggests either a unique chemical process or possible signs of past biology. However, SAM’s tools cannot detect the longest chains reliably.

“Our study proves that, even today, by analyzing Mars samples we could detect chemical signatures of past life, if it ever existed on Mars,” said Caroline Freissinet, the study’s lead author.

Why this matters for future missions

The research supports the idea that organic molecules can survive Mars’s harsh conditions. Radiation and oxidation often destroy organic molecules over time. The preservation in Cumberland gives scientists hope for future discoveries.

Curiosity’s instruments can only do so much. That’s why scientists are eager to return Mars samples to Earth.

“We are ready to take the next big step and bring Mars samples home to our labs to settle the debate about life on Mars,” stated Glavin.

Search for life-linked molecules

​NASA’s Curiosity rover continues its mission inside Gale Crater, exploring rock layers to better understand Mars’s ancient environments. The Sample Analysis at Mars (SAM) tool remains key to these investigations.

Every new sample adds another clue to a much larger puzzle.

With each discovery, scientists move one step closer to exploring one of the oldest and most profound questions we’ve ever asked: Did life ever exist on Mars, and if so, what traces of it remain locked beneath the planet’s surface?

Watch NASA’s video about this discovery here…

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This research was supported by NASA’s Mars Exploration Program. Curiosity is managed by NASA’s Jet Propulsion Laboratory (JPL) in Southern California. The Centre National d’Études Spatiales (CNES), the French Space Agency, contributed to SAM’s gas chromatograph system.​

The study is published in the journal Proceedings of the National Academy of Sciences.

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