No, NASA did not find any "proof of life" on Mars, and then accidentally destroyed it

If you have just gone through the headlines of science this week, you may have the impression that NASA has found evidence of life on Mars but has accidentally destroyed it.

This is absolutely false.

To understand the real story, we must return briefly to 1976 when the two NASA Viking landers arrived on the red planet and picked up Martian land. The soil was then heated in the special kilns of the undercarriage to allow a gas chromatograph mass spectrometer (GCMS) to detect any organic molecule in the interior. To the surprise of many at the time, the results showed that the samples seemed devoid of such organic compounds, which are often called the building blocks of life.

It would take more than three decades before the Curiosity rover finally confirmed the presence of these important molecules on Mars . Last month, we learned about the biological evidence found by the robot in the ground and the atmosphere of the fourth planet.

These most recent discoveries prompted a team of scientists to go back and check the old Viking data. They then published an article in the Journal of Geophysical Research that suggests an explanation for which no organic molecule was found with Viking because they were accidentally burned in the ovens.

Here is a very brief summary of the story.

Still, a number of headlines on new research say that NASA has accidentally destroyed "evidence of life on Mars" or worse: "proof of life on Mars."

To be clear: the building blocks of life and life are very, very different things. The building blocks of life are quite common throughout the universe. In fact, they fly on comets right now. Does this mean that there is life on comets? Not that we have seen. (If you've seen life on comets, first hand – not on YouTube – contact me.)

What's weird, but not totally surprising for the Internet, is that if you click on these titles and read the attached stories for them, many do a very good job in distinguishing between inanimate organic matter that we know about Mars and real life, breathing, swimming things that they can bear but we have not yet found it on other worlds.

In the process, these stories completely contradict their own titles. And unfortunately, we are all guilty of never reading beyond the title, which is a real problem in this case.

I contacted the study's authors, including Chris McKay from NASA's Ames Research Center in California, and he told me that he was also puzzled by the editorial dissonance between hyperbolic titles and the relatively accurate underlying stories. We do not see how the error has spread, it's certainly not in our paper, "said McKay.

It seems that there is some confusion some In order to be clear, in chemistry, "organic" does not mean something that comes from living plant or animal sources, even though that is another definition of the word.Rather, an organic molecule typically refers to a compound

And while practically all of life, as we know, requires some organic molecules to survive, it does not work in the opposite direction: in other words, wherever there is life, There are organic molecules, but that does not mean that wherever there are organic molecules, there is life.

"I think it's interesting that life is mentioned in the title without any hint of life detection that Viking has been trying to make, "he said. Lead author Melissa Guzman by e-mail.

There were experiments on Viking that were looking for evidence of real life, and through the decades, Viking's principal investigator, Gilbert Levin has suggested, including in scientific articles, that one of these experiments had found Martian microbes. This idea was easily rejected, highlighting Viking's failure to find organic molecules on Mars. "It's the lack of organic substances detected by the GCMS that has prevented scientists from imagining that life was there," Guzman said. me.

The real story is not that NASA has burned evidence of life, but rather that it has highlighted the prerequisites for existence, thus negating another experience, which may have found indications of real life.

This may seem like a punch, but it's a critical distinction and – ironically – the real story is more encouraging for those hoping to find signs of Martian life.

Guzman says we can start having a clearer picture of what's really going on in Martian soil in a few years, when the ExoMars 2020 rover will conduct his own set of experiments looking for evidence of life .

I hope this will clear things up, and perhaps most importantly: do not forget to always read beyond headlines.

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