In June, NASA revealed two mind-boggling facts: there is organic matter on Mars, and the level of methane in the planet's atmosphere changes over time. This is amazing news that shook our understanding of astrobiology. And while they definitely don't prove the existence of aliens, most of the methane on Earth is still produced by living things. And even a child will tell you that if you sensed it, it means that someone should have done it.
The latest methane finds "have surprised us with robust data that warrants interpretation," a group of international scientists wrote in a study published earlier this month in Astrobiology. The authors of the study, in fact, backed up this thesis with their work - they figured out which measurements, experiments and missions NASA and other aerospace organizations should put in the forefront in order to find more evidence that Mars supports (or supported) life.
In short, scientists want to investigate the geological activity of Mars. They want to understand what is the connection between newly discovered organic compounds and fluctuations in methane in the atmosphere. Their goal is to find traces of other molecules and gases that could allow some primitive microscopic life form to survive below the planet's surface. This is what they are looking for.
First: redox gradient
When we eat, our bodies draw energy from our food through chemical reactions that create a flow of electrons and oxygen atoms between molecules. This swing is necessary to feed our bodies - all living beings need it. But due to the extreme atmosphere of Mars, this balance does not exist. The atmosphere is so strongly oxidized that these reactions only take place in one direction. Any living creature on Mars will react so strongly with air that it will not be able to survive. Researchers are looking for components in the Martian atmosphere that could balance this reaction, thereby giving life a chance to develop.
Second: source of methane
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The next step towards understanding whether Mars can support life, according to scientists, is to excavate the surface of Mars and find out where all this methane comes from. While living things on Earth produce methane as they digest food, this is not the only way to create this gas in the atmosphere. NASA's future InSight mission will look beneath the surface of Mars. Its main task is to understand the seismic activity of the planet, but who knows what it will find along with it.
Why does the methane level on Mars fluctuate? Seasonal freezing and melting of ice that gradually captures and releases methane (we know this from the Curiosity rover). But there is no easy way to check how much of this methane is there and whether it gets more over time. And that means finding the source of Martian methane is much more difficult than grabbing a little green man by the finger.
By examining the chemical composition of underground samples and the atmosphere, scientists could find out where this methane comes from - from biological processes or complex chemical reactions that do not imply life at all.
Scientists who are considering all this, however, do not believe that we have convincing evidence for the existence of life on Mars. In fact, as Caleb Scharf once said, it is far more reasonable to assume that she does not exist anywhere other than Earth. After all, this is the only place we know for sure.
But if, by some weird chance, microbes lurked beneath the surface, or if there was another form of life on Mars, the strategy of the authors of this study probably represents our best chance of finding them.
Ilya Khel