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Astrobiologist says we may have already discovered life on Mars

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Astrobiologist says we may have already discovered life on Mars

In all our explorations of Mars to date, no evidence has been found that meets the rigorous standards of claiming that we have finally discovered life.

But decades ago, in the 1970s, when the Viking landers became the first American mission to safely land and explore the Red Planet, we may have come close.

One researcher raises the possibility of life in a Martian soil sample. And then, trying to smell it, we extinguished it. Just like that.

According to astrobiologist Dirk Schulze-Makuch of the Technical University of Berlin in Germany, an experiment to detect signs of microbial life on Mars could have been fatal. In his Big Think column, he speculates that our methods themselves may have been destructive.

It therefore behooves us to carefully consider the ecology of Mars when designing future experiments. And precisely for these reasons, advises Schulze-Makuch, humanity should send another mission, devoted primarily to the search for life.

When both Viking landers landed on Mars in 1976, they had a list of targets. One of them was to conduct a set of experiments to check Martian dirt for biosignatures – traces of molecules that indicate the presence of life.

So far, these were the only dedicated biological experiments conducted on Mars.

1976 Viking 1 image of Mars, showing craters, mountains, and the planet’s thin atmosphere. (NASA)

In one of these experiments, a gas chromatograph mass spectrometer (GCMS) detected chlorinated organics. At the time, this result was interpreted as contamination with cleaning agents intended for humans, and thus zero detection of signs of biology.

We now know that chlorinated organics occur naturally on Mars, although it is not known whether they are formed by biological or non-biological processes.

In recent years, there has been speculation about the destructiveness of the Vikings’ biological experiments. GCMS had to heat the samples to separate the different materials they contained. As later analysis showed, this may have burned up the same organics that the researchers hoped to find.

Schulze-Makuch suggests that other experiments may have destroyed the evidence as well; namely, the labeled release and pyrolytic release experiments, which involved flooding Martian samples with liquid and then checking the results for evidence of metabolism and photosynthesis, respectively.

An artist’s impression of what Mars might once have looked like with oceans, billions of years ago. (ESO/M. Kornmesser)

The results suggested a positive signal that seemed to contradict the null results of the fourth experiment, gas exchange. It was and remains confusing, writes Schulze-Makuch.

However, looking back, the release experiments were probably ill-conceived. At that time, we assumed that life on Mars would be similar to life on Earth and would develop in the presence of water – the more, the merrier. However, as we recently learned, life can optimize itself to thrive in very dry conditions. And Mars is very dry.

Change these conditions, and development may end.

“Now let’s ask ourselves what would happen if these dry-accustomed microbes were flooded with water. Could it overwhelm them? Technically, we would say we over-hydrated them, but to put it simply, it would be more like drowning them,” explains Schulze-Makuch.

“It would be as if an alien spaceship found you wandering half-dead in the desert, and your would-be saviors decided, ‘People need water. Let’s put the man in the middle of the ocean to save him! » That wouldn’t work either.”

Blue sunset on the red planet. (NASA/JPL/Texas A&M/Cornell)

Interestingly, it indicates that the signs of life identified in the pyrolytic release experiment were much stronger in the dry control, which did not add water to the sample. So it seems natural that we ask ourselves, as do others: Did these experiments detect signs of life that we rejected?

These signals, of course, are still contradictory and far from conclusive. However, they may require further investigation.

In 2007, Schulze-Makuch proposed that dry-adapted life could exist on Mars, containing hydrogen peroxide. The results of Viking’s study, he and his co-author Joop Houtkooper say, do not contradict this hypothesis.

“As I have argued before, we need a new mission to Mars, dedicated primarily to the detection of life, to test this and other hypotheses,” concludes Schulze-Makuch. “I can’t wait for such a mission to begin.”

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