Hello,

We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Intelligent Machines

Mars Rover Finds Puzzling Organic Traces in First Soil Sample

Curiosity sees tantalizing hints of compounds needed for life, but further analysis is needed to make sure it’s not contamination from Earth.

Finding organic compounds on Mars would help scientists determine whether life has ever existed on the Red Planet.

NASA announced yesterday that the Curiosity Mars rover has found small amounts of simple organic compounds—the building blocks of life—in three samples of Martian soil, but cautioned it is too soon to say whether the carbon in that material came from the Red Planet or hitchhiked there from Earth. Experiments on both the rover and in labs around the world will attempt to find the answer over the coming weeks.

Double dip: Two scoops of Martian soil made by Curiosity.

Organic material is not evidence for life—it is found on comets, for example—but it does make up the building blocks of life, and has never been found on Mars, leading to a frenzy of excitement over its possible discovery by Curiosity.

SAM—or the Sample Analysis at Mars—is the instrument capable of finding organic, or carbon-containing, material in Martian soil or rock samples. Rover scientists discussing SAM’s finds at the American Geophysical Union meeting in San Francisco yesterday said they had no definitive evidence for organics on Mars. Simple organic compounds called chloromethanes were produced in small amounts when SAM heated soil taken from a sandy area called “Rocknest.”

If the carbon is from Mars, it might have come from minerals—such as magnesium carbonate—or organic compounds that fell to the planet on meteorites or, just maybe, formed there by life.

The problem, says SAM scientist Michel Cabane of the Pierre and Marie Curie University in Paris, is that the carbon might have come from Earth, perhaps left over from when organic material was used to put the instrument through its paces before launch.

So how will the team test for terrestrial contamination?

SAM’s chief scientist, Paul Mahaffy of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, says one way is to drill into one of five pieces of specially doped glass carried onboard Curiosity and run that material through the sample analysis system. “If we see the same stuff” that was thought to come from Mars, Mahaffy said at the briefing, “we gotta say, ‘hold the show—this might be terrestrial stuff.’ “

And even if the carbon did come from Mars, it might not have formed there. Dozens, if not hundreds, of metric tons of organic material are thought to fall on the Red Planet every year in the form of meteorites. Studying the ratio of different isotopes of carbon—something SAM can do—could help distinguish between a meteorite and a terrestrial source of carbon, says Cabane.

Planet rover: Curiosity captured this image of itself by snapping 55 separate photographs. The resulting mosaic was created in a way that hides from view the arm used to capture the images.

Isotopes might also provide some clues about whether or not any carbon came from life itself. On Earth, life uses more carbon-12 than carbon-13, so seeing a similar signature on Mars could hint at a biological source.

The rover’s other instruments will also provide helpful context for figuring out whether Martian carbon formed on the planet itself—by geochemical processes or life—or fell from space via meteorites. That’s because measuring the exact mineral makeup of a sample of rock, something an instrument called CheMin can do, shows the conditions under which it formed. “As you can see, it’s a complicated decision pathway there, and we have to explore each one systematically,” John Grotzinger of Caltech, the mission’s principal scientist, said at the briefing.

“We have a lot of work to do,” agrees Cabane, adding that the SAM team plans to run different mixtures of chemicals through SAM-like instruments at Goddard and in Paris, to see which combinations best match SAM’s actual results.

SAM will also continue taking samples on Mars. The instrument has only analyzed samples from sandy soil—taking its first soil sample on November 9. The samples came from just below the surface, a place where solar radiation and particles from space, along with reactive gases in the atmosphere such as hydrogen peroxide, should destroy organic molecules. “It’s not unexpected necessarily that this sandpile would not be rich in organics,” Mahaffy said at the briefing. “It’s been exposed to the harsh Martian environment.”

Rover scientists will spend the next few weeks scouting for a rock to drill into. If they are present, “organic molecules in the rock should be more pristine” than in porous soil, says Cabane, since they should be more shielded from radiation and cosmic rays.

Tech Obsessive?
Become an Insider to get the story behind the story — and before anyone else.

Subscribe today

Uh oh–you've read all of your free articles for this month.

Insider Premium
$179.95/yr US PRICE

More from Intelligent Machines

Artificial intelligence and robots are transforming how we work and live.

Want more award-winning journalism? Subscribe and become an Insider.
  • Insider Plus {! insider.prices.plus !}* Best Value

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus the digital magazine, extensive archive, ad-free web experience, and discounts to partner offerings and MIT Technology Review events.

    See details+

    What's Included

    Unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

    Bimonthly print magazine (6 issues per year)

    Bimonthly digital/PDF edition

    Access to the magazine PDF archive—thousands of articles going back to 1899 at your fingertips

    Special interest publications

    Discount to MIT Technology Review events

    Special discounts to select partner offerings

    Ad-free web experience

  • Insider Basic {! insider.prices.basic !}*

    {! insider.display.menuOptionsLabel !}

    Six issues of our award winning print magazine, unlimited online access plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    What's Included

    Unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

    Bimonthly print magazine (6 issues per year)

  • Insider Online Only {! insider.prices.online !}*

    {! insider.display.menuOptionsLabel !}

    Unlimited online access including articles and video, plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    What's Included

    Unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

/
You've read all of your free articles this month. This is your last free article this month. You've read of free articles this month. or  for unlimited online access.