NASA accidentally destroyed evidence of life on Mars

Is searching for life through traces of water an outdated path?

So far, we have not found any convincing evidence to prove that life once existed on Mars.

Decades ago, in the 1970s, when the Viking lander became the first American spacecraft to safely land and explore the Red Planet, we came very close to answering the question of life there.

Sunrise on Mars (Photo: NASA/JPL-Caltech).

However, according to astrobiologist Dirk Schulze-Makuch at the Technical University of Berlin, Germany, humans conducted an experiment to detect signs of microbial life on Mars and accidentally killed off those tiny clues.

When the two landers landed on Mars in 1976, they had a number of missions. One was to conduct a series of experiments to test the Martian soil for biosignatures, or traces of molecules that indicate life might have existed there.

So far, humans have not conducted any similar experiments directly on Mars.

This photo taken by the Viking 1 spacecraft of Mars in 1976 shows the impact craters, mountain ranges and very thin atmosphere of the Red Planet (Photo: NASA).

One of the aforementioned experiments, performed with a gas chromatograph-mass spectrometer (GCMS), found chlorinated organic matter. At the time, this result was interpreted as contamination from cleaning products used by humans, and therefore did not indicate any biological signature.

We know that chlorinated organics are present on Mars, although whether they are produced by biological or abiotic processes remains uncertain.

In recent years, some scientists have speculated that the Viking biological experiments themselves were destructive. GCMS requires heating samples to separate the materials in them, which could have destroyed the very organic matter we were hoping to find in the experiment.

Other experiments could also inadvertently destroy similar evidence, namely experiments designed to search for the presence of microbial life on planets and pyrolysis experiments, which infuse Martian samples with liquid to look for evidence of metabolism and photosynthesis.

Illustration of Mars billions of years ago, it may have had oceans (Image: ESO/M.Kornmesser).

Although the results showed a positive sign of gas exchange, it was not taken seriously because at that time we thought that life on Mars was like life on Earth in that it only developed when there was water, and the more water, the more life.

But we learned later that life can arise in extremely dry environments. And Mars is an extremely dry place. If those conditions were changed, life on Mars would very likely end as well.

"Let's ask the question, what happens if you pour water on these dry-loving bacteria? Does that suffocate them? Technically, we're giving them too much water, but in simple terms, we're drowning them," says astrobiologist Schulze - Makuch.

It's like an alien spaceship finds you half dead in the desert and decides "humans need water, let's take them to the middle of the ocean to save them!" but ends up drowning them in the middle of the ocean.

Blue sunset on the Red Planet (Image: NASA/JPL/Texas A&M/Cornell).

Interestingly, the pyrolysis experiment detected more signs of life than the dry control experiment, which did not add water to the sample. So it is easy to wonder whether these experiments might have detected signs of life that we were inadvertently rejecting?

Clearly there are still many contradictions here and nothing can be concluded, but further research and investigation is necessary.

In 2007, biologist Schulze-Makuch suggested that life on Mars might have adapted to a dry environment containing hydrogen peroxide. He and his team confirmed that the results of the Viking probe's experiments were consistent with this hypothesis.

If life does exist in the dry conditions of Mars, then instead of "following the water" as NASA has long considered the guiding principle in the search for life there, we should be following the hydrated and hygroscopic compounds, i.e. salts, to search for life.

"Nearly 50 years after the Viking experiments, it is time for a new mission to search for life. We now know a lot more about the environment on Mars," he said .