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December 3rd, 2012

Mars Curiosity discovery revealed: complex chemistry in soil with possibility to form organic materials

Published on December 3rd, 2012 | By: pwray@ceramics.org

Image of Martian surface, likely an ancient riverbed, where Curiosity’s SAM instruments scooped samples that NASA scientists believe they have found signs of organic materials. Credit: NASA.

This isn’t really ceramics or glass related, but a follow up to a story I wrote last week about the Curiosity’s “SAM” soil analysis lab (which, as NASA aptly describes, is a CSI-like unit). This morning NASA revealed what “remarkable” thing it found already in its two-year exploratory effort.

Highlights from SAM: The rover apparently landed in what NASA still believes is an ancient river bed and the unit found water and sulfur, chlorine-containing substances, common volcanic minerals, and about half of the samples’ contents were noncrystalline materials such as glass. The presence of the chlorine was particularly intriguing, and SAM was able to detect clorinated organic compounds (CH3Cl, CH2Cl2, CHCl3) that NASA scientists believe are the results of the breakdown of perchlorate salt or perchlorate-like compounds when heated in SAM ovens. SAM also found water, CO2, O2, SO2 in the vapors of the heated material.

Gases found in SAM analysis. Credit: NASA.

Somewhat surprisingly, the rover determined that the deuterium-to-hydrogen ratio is five times what it is on earth but varies with the Martian season. They also say it appears that, in general, there are higher amounts of heavier isotopes in sulfur and nitrogen, and probably other elements (they say the lighter ones likely were lost via the atmosphere to space).

Going back to the issue of the perchlorate and organic compounds, NASA acknowledges that perchlorate had previously been found on Mars’ arctic region. However, if I understand NASA correctly, the new findings suggest an abundance of perchlorate and the ability to form chlorinated organics. NASA says the results need to be greeted with caution because it still needs to confirm that carbon in the compounds is Martian in origin and not from Earth.

NASA’s John Grotzinger, whose interview with NPR touched off the hype about this discovery, was asked in a live press conference what he believed was the most important discovery. He said that, for him, the importance lies in several things: the apparent finding organic or pre-organic compounds in “globally representative material,” the ability of all of the analytical instruments to feed into results and then seeing the experiments repeatedly provide the same results.

Another reporter asked Grotzinger about his reaction to the the hype around the discovery. Grotzinger admits, “I learned that you have to be careful about what you say and how you say it… perhaps the enthusiasm we are having for this project is just misunderstood.”

Regarding next steps, the NASA reps say that if they determine that carbon is of Martian origin, they next will be looking at isotope ratios of the carbon in the compounds to determine whether it is of a biotic origin.

Here is a link to NASA’s news release on the announcements today.


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