Curiosity finds organics but where do they come from?

Yesterday, at the meeting of the American Geophysical Union in San Francisco, NASA announced first results from soil analysis performed by Curiosity. Indeed, initially there was an eager expectation about this announcement as some rumors leaked out and somebody told about historical results. Then, all this was teased by NASA but what they announced yesterday was all but disappointing. I followed a real-time chronicle on twitter by Emily Lakdawalla (@elakdawalla and check her blog) that was there in San Francisco and it was really exciting. The main point is that Curiosity indeed has found organics but that people at NASA cannot be sure yet that carbon was not from Earth. Anyhow, the analysis of the soil displayed a rich content and this is indeed a riverbed. Some further analysis are required before to give definitive conclusions about the presence of organics. If you need a short summary you can read this article on The Guardian but Emily should provide a complete account shortly.

I would like to spend a few words here to let my readers know what is at stake here. On 1975, NASA launched the Viking probes on Mars. One of the aims of this mission was to perform some experiments that should give evidence of life on Mars. A pair of these experiments turned out  to give favorable results giving such an evidence but the probes failed at finding any organic molecules and so these results were interpreted as due to some other chemical process at work. Indeed, the question is open yet. Should Curiosity find any evidence of organic molecular, the original findings of Viking probes would be vindicated but, more important, one should have a first evidence of life, even if bacterial, on another planet. This is for historical book indeed!