NASA finds more evidence that Mars could have once supported life

Cristina Cross
June 8, 2018

Big news from Mars today: NASA's Curiosity rover found ancient traces of organic matter embedded in Martian rocks and detected a "seasonal variation" in atmospheric methane on the Red Planet - an annual pulse of the gas, nearly as if something out there were breathing.

The Mars Curiosity rover is sniffing methane in the Martian air but NASA researchers suspect that the distinctive gas-often a sign of life on Earth-may be leaking from buried deposits and not from microbes living on the Red Planet today, space agency scientists said Thursday.

"We can find organic matter preserved in mudstones that are more than 3 billion years old".

"The closer we look, the more we see that Mars is a complex, dynamic planet that - particularly early in its history - was more conducive to life than we might have previously imagined", said Williford, who was not involved in either study.

This diagram shows how methane beneath the Martian ground might find its way to the surface, where its uptake and release could produce the large seasonal variation in the atmosphere that was observed by the Curiosity rover. "Short of taking a picture of a fossil in a rock on Mars, [finding life there] is extremely hard to do scientifically", says Chris Webster, a chemist at the Jet Propulsion Laboratory and lead author of the methane study. Alas, still no aliens: the rover found some rocks-some billion-year-old rocks-containing "ancient organic material". Organic molecules pop up frequently in space, but it's neat that Mars had life's building blocks during a time when many think it was more habitable.

Neither paper can say whether past life ever existed on Mars, the scientists said.

The results revealed a wealth of organics, Eigenbrode said - including some that had carbons linked in ring structures (such as benzenes) and others that include carbon chains (such as propane).

That Mars possesses organic molecules is not surprising. Yet when NASA's twin Viking probes landed on Mars in 1976, their studies suggested something startling: Martian soil, it seemed, contained less carbon than lifeless lunar rocks.

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"We don't know if that methane is ancient or modern", Webster said in a press conference.

The mudstone rock was drilled from the top five centimeters (two inches) of the Martian surface and heated in a miniature analysis lab located on board the rover. What the authors have found is a systematic variation in methane concentration with season, with the highest concentrations occurring at the Gale Crater towards the end of the northern summer. Or it could be ancient, belched out billions of years ago by geologic or biological processes and then trapped in matrices of ice and rock that unfreeze when warmed by the sun.

"All sorts of big questions could be answered by finding life on Mars or by not finding life on Mars", says David Weintraub, a professor of astronomy at Vanderbilt University in Nashville and author of the book "Life on Mars: What to Know Before We Go".

In the first study, a team led by Christopher Webster, a chemist at NASA's Jet Propulsion Laboratory in California, describes how Mars' atmosphere appears to have low levels of fluctuating methane. "Now we have data to confirm that there's a seasonal cycle, suggesting the methane is being generated by something".

This does not mean life was discovered on Mars... yet.

In 2013, SAM detected some organic molecules containing chlorine in rocks at the deepest point in the crater.

In December 2012, the rover's two-year mission was extended indefinitely.

Webster theorizes the methane created either now or long ago is seeping from deep underground reservoirs up through cracks and fissures in the crust. This doesn't constitute proof that life existed on Mars, though.

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