Is Searching for Life Through Water Signatures an Outdated Approach?
So far, we have not found any convincing evidence to prove that life ever existed on Mars.
Decades ago, in the 1970s, when the Viking landers 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 (Image: NASA/JPL-Caltech).
However, according to astrobiologist Dirk Schulze-Makuch at the Technical University of Berlin, Germany, human experiments aimed at detecting signs of microbial life on Mars may have inadvertently destroyed the faint evidence.
Upon landing on Mars in 1976, the two landers had many missions. One of these was to conduct a series of experiments to check for biosignatures in Martian soil, essentially looking for molecular traces indicating the presence of life.
To date, there have been no similar experiments conducted directly on Mars.
Image taken by Viking 1 of Mars in 1976 showing impact craters, mountain ranges, and the thin atmosphere of the Red Planet (Image: NASA).
One of the aforementioned experiments conducted with the Gas Chromatography-Mass Spectrometry (GCMS) did find chlorinated organic compounds. At that time, this result was interpreted as contamination from cleaning products used by humans, and thus, there were no biosignatures detected.
We know that chlorinated organic compounds are present on Mars, although it remains uncertain whether they are produced by biological or abiotic processes.
In recent years, some scientists have speculated that the biological experiments of the Viking missions were destructive. GCMS needed to heat samples to separate materials within them. This may have incinerated the very organic compounds we hoped to find with this experiment.
Other experiments may also have inadvertently destroyed similar evidence, specifically those designed to search for the presence of microbial life on planets and thermal decomposition experiments, which involved introducing liquids into Martian samples to look for evidence of metabolic processes and photosynthesis.
Illustration of Mars billions of years ago possibly having many oceans (Image: ESO/M.Kornmesser).
While the results showed a positive sign of gas exchange, they were not given much importance because at that time we believed that life on Mars, like life on Earth, could only thrive in the presence of water—more water meant more life.
However, we later learned that life could exist in extremely arid environments. Mars is an extremely dry place. If those conditions change, then Martian life could very well end as well.
Astrobiologist Schulze-Makuch states, “Ask yourself what happens if you pour water on these drought-resistant bacteria; does it suffocate them? Technically, you could say we are providing too much water for them, but simply put, we are drowning them.”
It’s like an alien spacecraft finding you barely alive in a desert and deciding, “Humans need water; let’s take them to the middle of the ocean to save them!” only to find that it ends up drowning them in the sea.
Green sunset on the Red Planet (Image: NASA/JPL/Texas A&M/Cornell).
Interestingly, the thermal decomposition experiments identified more signs of life compared to the dry control experiments that did not add water to the samples. Therefore, it raises the question of whether these experiments might have detected signs of life that we inadvertently dismissed.
Clearly, there are still many contradictions here, and no conclusions can be drawn yet, but further research and investigation are necessary.
In 2007, astrobiologist Schulze-Makuch suggested that there might be life on Mars adapted to the dry environment containing hydrogen peroxide. He and his research team affirmed that the Viking mission’s experimental results align with this hypothesis.
If it is true that organisms exist in the arid conditions of Mars, then instead of “following the trail of water” as NASA considers a guiding principle in the search for life here, we should look for hygroscopic and moisture-retaining compounds, namely salts, to search for life.
He stated, “Almost 50 years after the Viking experiments, it is time for us to undertake a new mission to search for life. Now we understand much more about the environment on Mars.”
