NASA’s Curiosity Mars Rover Finds Large Organic Molecules

HOUSTON—Samples of pulverized rock from the Martian surface gathered and analyzed by NASA’s Curiosity rover have found the largest collection of organic samples to date on the red planet.

Findings published March 24 in the Proceedings of the National Academy of Sciences identifies the organics as molecular compounds of decane, undecane and dodecane, which are respectively comprised of 10, 11 and 12 carbon.

They are believed to be fragments of fatty acids preserved in the analyzed sample. Fatty acids are among the organic molecules that on Earth are recognized as the building blocks of life, according to a March 24 update provided by NASA’s Goddard Space Flight Center.

But the update notes there could be a non-biological explanation.

“Living things produce fatty acids to help form cell membranes and perform various other functions. But fatty acids also can be made without life, through chemical reactions triggered by various geological processes, including the interaction of water with minerals in hydrothermal vents,” the update says. “While there’s no way to confirm the source of the molecules identified, finding them at all is exciting for Curiosity’s science team for a couple of reasons.”

While Curiosity mission scientists have previously identified small, simple organic molecules on the red planet, the discovery of the larger molecular compounds offers the first evidence that organic chemistry on Mars evolved toward a complexity necessary to become an origin for life on the planet, the Goddard update notes.

The findings suggest the prospect that large organic molecules made only in the presence of life, also known as “biosignatures,” could be preserved on Mars and not destroyed by the planet’s cold, desert-like environment over tens of millions of years of exposure to intense radiation and oxidation from harsh surface chemicals.

“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 lead study author and research scientist at the French National Center for Scientific Research in the Laboratory for Atmospheres and Space Observations in Guyancourt, France.

NASA is currently evaluating options for a timely, less costly Mars Sample Return mission strategy to obtain and return to Earth samples of the Martian surface gathered by the agency’s Perseverance rover in Jezero Crater, site of an ancient crater lake and river delta on Mars.

Perseverance soft landed at Jezero on Feb. 18, 2021.

Launched on Nov. 26, 2011, Curiosity touched down at Gale Crater on Mars on Aug. 5, 2012, equipped with a robot arm and drill to acquire samples with potential evidence of a past habitable environment as the rover made its way up Mount Sharp, which rises about 3.4 mi. (5.5 km) above the crater floor.