Published: Fri, June 08, 2018
Research | By Raquel Erickson

Rocks on Mars still harbour organic molecules after billions of years

Rocks on Mars still harbour organic molecules after billions of years

"We found organic molecules in rocks from an ancient lakebed", said Jen Eigenbrode, a research scientist and astrobiologist at NASA's Goddard Space Flight Center in Greenbelt, Md.

At this point, there's simply no way of knowing whether the organic molecules and the methane findings point to potential life on Mars. One of NASA's aims with the Curiosity Rover is to search for signs of ancient life on the red planet.

In a second, potentially more significant finding announced Thursday, scientists reported detection of a seasonal variation in methane levels in the martian atmosphere.

Researchers say they can't rule out a biological source. Most of Earth's atmospheric methane comes from animal and plant life, and the environment itself. Both discoveries were made possible by NASA's Mars Curiosity rover and have been detailed in a pair of new studies.

The space agency has not divulged specific information about what it may have found, leaving many to wonder what intriguing details will be learned about the red planet.

The full findings will also appear in the 8 June edition of the journal Science. Here on Earth, we associate methane with life, but it's a mystery what could be causing it on Mars.

But it's getting easier to hypothesise that Mars once harboured life, because Curiosity's extended trundling on Mars has shown evidence of liquid water on the surface and found plenty of the chemicals that you'd expect as pre-cursors to, or by-products of, life.

Kirsten Siebach, a Rice University geologist said: "The big takeaway is that we can find evidence".

"And maybe we can find something better preserved than that, that has signatures of life in it", she told AFP.


For the first time, scientists say they have clear evidence that the chemical building blocks of life exist on Mars.

"These clathrates lock the methane inside a water-ice crystal structure and are incredibly stable for millions of years until environmental conditions change and suddenly they can release that gas", says Duffy. The methane concentrations peak near the end of the northern hemisphere's summer, then dwindle in the winter.

"For the first time we have something that we can get a handle on", said Dr Webster of NASA's Jet Propulsion Laboratory.

"Even nowadays on Earth, we see a large influx of extraterrestrial [organic] material in the form of interplanetary dust and meteorites", ten Kate said. "It's tripling ... that's a huge, huge difference". The changes were detected by the rover's Sample Analysis at Mars instrument suite, more commonly called SAM. The diameter is slightly smaller than a US dime.

He and his colleagues think the methane is coming from underground.

The team picked up a welter of closely related organic signals reflecting dozens or hundreds of types of small carbon molecules, probably short rings and strands called aromatics and aliphatics, respectively. So they looked elsewhere.

They hit pay dirt about 6.5 kilometres away, at two sites near Pahrump Hills at the base of Mt Sharp. This new discovery builds on the inventory of molecules detected in the ancient lake sediments on Mars and helps explains why they were preserved.

"With these new findings, Mars is telling us to stay the course and keep searching for evidence of life", NASA science mission chief Thomas Zurbuchen told USA Today.

Ever since the twin Viking landers touched down in 1976, scientists have hunted for signs of organic molecules on Mars.

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