If you've just been perusing the science headlines this week, you might be under the impression
NASA found evidence of life on
Mars but accidentally destroyed it.
This is absolutely untrue.
To understand the real story, we have to briefly go back to 1976 when NASA's twin Viking landers arrived on the Red Planet and scooped up some Martian dirt. The soil was then heated in the landers' special ovens to allow for an on-board Gas Chromatograph Mass Spectrometer (GCMS) to detect any organic molecules within. To the surprise of many at the time, the results showed the samples appeared to be devoid of any such organics, which are often referred to as the building blocks of life.
It would be more than three decades until the Curiosity rover would finally confirm the presence of those important molecules on Mars. Just last month, we learned more about evidence of organics found by the rover in both the soil and atmosphere of the fourth planet.
Those most recent findings inspired a team of scientists to go back and check that old Viking data. They then published a paper in the Journal of Geophysical Research that suggests one explanation for why no organic molecules were found with Viking is because they were accidentally burned up in the ovens.
That's a very brief summary of the story.
And yet a number of headlines attached to stories covering the new research say NASA accidentally destroyed "evidence for life on Mars" or even worse: "proof of life on Mars."
To be clear: the building blocks of life and life itself are very, very different things. The building blocks of life are pretty widespread throughout the universe. In fact, they're flying around on comets right now. Does that mean there's life on comets? Not that we've seen. (If you've seen life on comets, firsthand -- not on YouTube -- please contact me.)
What's bizarre, but not totally surprising for the internet, is that if you click through these headlines and read the stories attached to them, many do a pretty good job drawing the distinction between inanimate organics that we know are on Mars and actual living, breathing, swimming things that they can support, but which we have yet to find on other worlds.
In the process, these stories completely contradict their own headlines. And unfortunately, we're all guilty of sometimes never reading beyond the headline, 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 he was also baffled by the editorial dissonance between the hyperbolic headlines and the relatively accurate stories beneath them.
"For example, we see organics in meteorites and they are not evidence of life. Not sure how the mistake got propagated. It is certainly not in our paper," McKay said.
Seems there's some confusion somewhere. 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 carbon compound.
And while pretty much all life as we know it requires certain organic molecules to survive, it doesn't work in reverse. In other words, where ever there's life there's organic molecules, but that doesn't mean that wherever there's organic molecules there's life.
"I think it's interesting that life is mentioned in the title with no allusion to the life detection Viking did try to do," lead author Melissa Guzman told me via email.
There were experiments on Viking that looked for evidence of actual life, and through the decades Viking's principal investigator Gilbert Levin has suggested, including in peer-reviewed papers, that one of those experiments did find evidence of Martian microbes. This notion has been easily dismissed, however, by pointing to Viking's failure to find organic molecules on Mars.
"It was the lack of organics detected by the GCMS that made it impossible for scientists to imagine life was there," Guzman told me.
So the real story is not that NASA may have burned up evidence of life, but rather that it may have torched evidence of the prerequisites for life to exist, thereby negating another experiment, which may have really found indications of actual life.
This may seem like nitpicking, but it's a critical distinction and -- somewhat ironically -- the actual story is more encouraging for those hoping to find signs of Martian life.
Guzman says we may begin to get a more clear picture of what is really happening in Martian soil in just a few years, when the ExoMars 2020 rover will perform its own set of experiments looking for evidence of life.
Hope this clears things up, and perhaps most important: remember to always read past the headlines.