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Curiosity finds signs of chlorine in Mars' soil; carbon iffy

December 03, 2012|By Amina Khan
  • JPL's Curiosity rover has sampled what appear to be chlorinated organic molecules at a site called Rocknest, but scientists are not yet sure if the part that makes them organic is native to Mars or is a molecular hitchhiker from Earth.
JPL's Curiosity rover has sampled what appear to be chlorinated organic… (AP Photo / NASA )

After much hype, NASA's Curiosity rover just may have found signs of organic compounds on the Red Planet. But not so fast, Mars Science Laboratory researchers said Monday.

The rover has scooped and sampled what appear to be chlorinated organic molecules at a site called Rocknest, but scientists are not yet sure if the part that makes them organic is native to Mars or is a molecular hitchhiker from Earth, said Paul Mahaffy, lead investigator for Sample Analysis at Mars, one of the lab instruments in Curiosity’s belly.

Since touching down in Gale Crater on Aug. 5, Curiosity has zapped minerals with lasers, scooped and photographed soil, and tasted rocks with X-rays. But the rover’s internal laboratory is what sets it apart from other Martian expeditions in the scientists’ eyes.

“We really consider this a terrific milestone, the two instruments buried deep inside Curiosity getting their first gulp of Mars material,” Mahaffy said.

The announcement at the American Geophysical Union meeting in San Francisco capped about two weeks of speculation that the Mars Science Laboratory rover’s internal laboratory had discovered some sure sign of the precursors to life on the planet.

Mahaffy put the kibosh on those hopes: “SAM has no definitive detection to report of organic compounds with this first set of experiments.”

But he went on to explain that the rover had picked up what appeared to be chlorine-rich carbon compounds. The scientists aren’t certain yet, however.

Although measured chlorine levels are far too high to have originated from Earth, the same can’t be said about the measured levels of carbon. It’s possible that the carbon hitchhiked on the spacecraft and tainted the sample.

That kind of contamination is something the researchers are very wary of, particularly after an initial signal of methane raised their hopes several weeks ago. It was a false alarm: The methane had snuck aboard from Earth.

In any case, the complex compounds they’ve found may well have been formed while baking in Curiosity’s oven, Mahaffy said. And it will be a while before they can run another test to confirm that the results were real, said the mission’s lead scientist, John Grotzinger. In all likelihood, that test will have to wait until after they’ve tested out the drill at the end of the rover’s robotic arm.

Once they do, it will still take some time to determine whether any carbon-based compounds could be biologic in nature, the Caltech geologist said. First they’ll have to see if they find a similar signal in soils they sample down the road to Mount Sharp, the 3-mile-high mound in the middle of Gale Crater.

“We’re doing science at the speed of science,” Grotzinger said.

Return to the Science Now blog.

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