I have the Curiosity rover in my Twitter contacts and last Thursday it had some great news to share, organic material found at last! The research done it had its colleagues on Earth write it all up in an article in Science. (DOI). Here are the key findings. The soil drill site was on a mudstone surface of what once was an ancient lake. The instrument involved was the SAM Suite, a combination of a gas chromatograph, a mass spectrometer and a tunable laser spectrometer. Samples were heated up to a temperature of 860 degrees and among the volatiles were organic compounds benzene, toluene, thiophene and benzothiophene. Only the volatiles formed above 500 degrees were considered, making the discovery consistent with the presence of organic macromolecules, carbonaceous chondrite or kerogen.
The article next explains how these macromolecules could have survived given the harsh Martian conditions. Mechanisms mentioned are inclusion in inorganic material, the presence of nearby oxygen sinks but most importantly a naturally occurring vulcanisation process with sulfur inserting itself in organic molecules. Three billion years ago the Martian atmosphere was rife with reactive sulfur. That could have done the job. The final question then where the organic material came from in the first place (life?, meteorites?) is raised but not answered. The article concludes that the detection of organic molecules did not concern the compounds as the were formed billion of years ago and that the amount of material analysed was simply too low.