The search for evidence of life on Mars just got a little more interesting with the discovery of large organic molecules in a rock sample.
The Mars Curiosity Rover, which is digging in the Martian rock beds as it goes along, tested pieces of its haul and found interesting organic compounds inside them.
To be specific, the sample contains three molecules called decane, undecane, and dodecane. They’re carbon-rich molecules and look like fragments of fatty acids – which are part of the chemical recipe for life.
Not only might these molecules indicate some interesting chemical mixing on ancient Mars, but their existence may also help fill in the history of Yellowknife Bay in Gale Crater on Mars.
That’s where the sampled rocks containing these fragments were found.
According to research scientist Caroline Freissinet, the fact that her team’s study of the rocks found the samples is a big step toward understanding the chemistry of early Mars.
“Our study proves that even today, by analyzing Mars samples we could detect chemical signatures of past life, if it ever existed on Mars,” she said.
The discovery of long-chain hydrocarbons is a big step toward bringing rock samples back to Earth for further study.
Finding hydrocarbon chains in rocks
The discovery stems from a rock sample called “Cumberland” drilled from an outcrop in Yellowknife Bay.
Scientists wanted to probe Cumberland for the presence of amino acids. The rover placed the material into the Sample Analysis Lab onboard Curiosity, where it was heated twice.
The instrument measured the mass of the molecules released during heating and the team looked for traces of materials to indicate the presence of those protein building blocks. They didn’t find any. However, they did notice that the heated sample released small amounts of decane, undecane, and dodecane. These are long-chain hydrocarbons found in life-relevant amino acids here on Earth.
Freissinet and her colleagues think these substances may have broken off from larger molecules during the SAM heating process.
If so, then they likely were part of fatty acids called undecanoic acid, dodecanoic acid, and tridecanoic acid. Fatty acids are an important component of lipids, which are themselves part of the structures of living cells in plants, animals, and – most importantly for Mars – microorganisms.
The discovery of these compounds are also strong evidence that Yellowknife Bay was the site of an ancient lake. It provided the right environment that allowed organic molecules to concentrate and be preserved in the mudstone that was eventually tested by the rover.
“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 for sample return at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a study co-author.
Do these organic compounds prove Mars life?
The mere presence of the fatty acid chains in the Cumberland Sample doesn’t prove Mars had life.
Sure, they’re part of the “soup” of life, but they can also be produced by geological processes.
Interactions between water and minerals in hydrothermal vents could also create these organic chains.
Coupled with previous discoveries of simple organic molecules on Mars, this discovery really points toward something even more ancient than the first life forms. It means that organic chemistry (on a Mars that was warmer and wetter in the past) had the same kind of complex chemistry that eventually led to life on Earth.
So, it’s not proof of life, but the existence of these complex chains of carbon-rich molecules shows that Mars had the proper ingredients for life’s primordial soup at some time in the past. Whether that life came to be – or still exists – is a separate question.
But, at least scientists know the chemistry existed. Further, if these fragments still exist in Mars rocks, then other large organic molecules that are evidence of life could survive on Mars up to the present time. Now all scientists have to do is find them.
Written by Carolyn Collins Petersen/Universe Today.
