Complex Organics on Mars

Leak in Mars Rover Curiosity’s Wet Chemistry Test Finds Organics 


Credit: ASA/JPL-Caltech/MSSS 

This image from NASA’s Curiosity rover shows the first sample of powdered rock extracted by the rover’s drill from the Yellowknife study site. Curiosity used its Mastcam on Sol 193 (Feb. 20, 2013) of its mission to capture this photo.  An unexpected leak of a chemical designed to tag complex organic molecules in samples collected by NASA’s Mars rover Curiosity appears to have serendipitously done its job,

Curiosity’s onboard laboratory includes seven so-called “wet ” experiments designed to preserve and identify suspect carbon-containing components in samples drilled out from rocks.

None of the foil-capped metal cups has been punctured yet, but vapors of the fluid, known as N-methyl-N-tert-butyldimethylsilyl-trifluoroacetamide, or MTBSTFA, leaked into the gas-sniffing analysis instrument early in the mission.

Curiosity landed in a 96-mile wide impact basin known as Gale Crater in August 2012 to determine if the planet most like Earth in the solar system has or ever had the chemistry and environments to support microbial life. Scientists quickly fulfilled the primary goal of the mission, discovering sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon in powder Curiosity drilled out of an ancient mudstone in an area known as Yellowknife Bay.  That paved the way for a more ambitious hunt for complex organic , an effort complicated by the MTBSTFA leak. “This caused us a lot of headache in the beginning, frankly, because it has a lot of carbon in it and other fragments that can break apart,” Curiosity scientist Danny Glavin, with NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said on Tuesday at the Lunar and Planetary Science conference in Houston, Texas. “We’ve turned this sort of bad thing into a good thing because we’ve learned how to work around this leak. We’ve actually used this vapor from this leak to carry out derivitization,” he said, referring to the to tag organics. Samples drilled out from Yellowknife Bay were stored inside the Sample Analysis at Mars, or SAM instrument, as the rover made its way over the next two years to Mount Sharp, a three-mile high mound of sediments rising from the floor of Gale Crater. “These samples were just reacting with this MTBSTFA vapor, reacting with all that good organic stuff. That turned out to be a good thing,” Glavin said.

In addition to analyzing the doggy-bagged sample that had been reacting with the MTBSTFA vapors for two years, scientists also were able to compare the results with residue from a sample that had been heated twice, effectively killing off any volatiles, but which also had been exposed to the vapors for two years. Initial results show indigenous Mars complex organics in the fresh sample, though more work is needed to definitely peg the compounds.  “It’s probably going to be years of work trying to disentangle this story,” said Glavin. “This is really exciting stuff. We’ve got a mudstone on Mars in a habitable environment. There was a lake there at one point. We’ve got organic molecules, possibly some interesting ones, of astrobiological interest. Bottom line, this sample has an even more diverse set of organic compounds than we previously thought. “Million dollar question? Is this or not. I wish I had an answer I can’t tell you. We’ve got basically a few compounds that we’re dealing with here. You probably need a lot more before you can start discriminating between biological and non-biological origin,” Glavin added.

This article was provided by Discovery News. MeasureMeasure


Curiosity Finds a Once-Habitable Mars

On the floor of Gale crater, NASA’s newest rover is finding that ancient Mars seems to have had an environment quite conducive to microbial life.

The researchers coordinating NASA’s $2.5 billion Mars Science Laboratory have always been careful to note that their beefy Curiosity rover is not searching for life on the Red Planet. Rather, it’s designed to find out whether Mars was ever suitable for life.

After a year of zapping, scratching, sniffing, and tasting rocks and sand near the rover’s landing site, the answer is “yes.” A flurry of findings published in the December 9th issue of Sciencesimultaneously announced at December’s meeting of the American Geophysical Society, provide the best evidence yet that ancient Mars was indeed habitable.

Yellowknife Bay on Mars

Curiosity’s Mast Camera recorded this view of sedimentary deposits inside Gale crater in February 2013. The mudstone ledge at lower right is about 20 cm (8 inches) high. Click here for a larger view.
NASA / JPL-Caltech / MSSS

Curiosity dropped onto the broad floor of Gale crater on August 6, 2012, then spent many months exploring intriguing rocky outcrops in a nearby expanse dubbed Yellowknife Bay. Mission scientists soon realized that much of the terrain was covered in mudstone, silty sediments that settled onto the bottom of an ancient lake.

What’s now clear, as reported by one research team led by project scientist John Grotzinger (Caltech) and a second by David Vaniman (Planetary Science Institute), is that the sediments contain an iron- and sulfur-rich clay called smectite. Moreover, this clay formed in water with a neutral pH and low salinity — just the kind of benign habitat that primitive life forms called chemolithoautotrophs would want. Such microbes derive their energy from the oxidation of inorganic compounds and their carbon from atmospheric carbon dioxide.

A separate analysis by Kenneth Farley (Caltech) and others used isotopic ratios — never measured before by a Martian lander — to estimate the age of a mudstone slab nicknamed Cumberland. It’s between 3.86 and 4.56 million years old, confirming that Gale crater formed very early in Martian history.

But Farley and his team also tested for elemental isotopes produced by the potent cosmic rays that constantly bombard the Martian surface. Cumberland’s “exposure age” is comparatively young, only 60 to 100 million years. Apparently the sediments in Yellowknife Bay spent eons buried under the protective cover of overlying material, which eventually was stripped away by the planet’s incessant winds only in the recent geologic past.

Biologically speaking, this is great news. It means the rover has at least a chance to detect organic matter that might have become trapped in these ancient sediments. In fact, a research team led by Douglas Ming (NASA Johnson Space Center) reports that Curiosity continues to detect chlorinated hydrocarbons in samples of the Martian surface – and that it can’t all be contaminants brought from Earth. Instead, these simple organics might be indigenous to Mars or else hitchhiked there inside meteorites.

In an unusual move for Science, all six of its just-published Curiosity articles are freely available online. You can also watch a press briefingheld during the AGU meeting.