The presence of oxygen in an exoplanet’s atmosphere does not guarantee the existence of life

We have scrutinized the universe for decades, hoping to find a world comparable to ours, that is, favorable to life. Water is considered the ultimate requirement for making a planet habitable. In order for it to exist in a liquid state and favor the growth of living organisms, the star on which it is present must be at a reasonable distance from its star.

In fact, the surface temperature is also a criterion of great importance. As if that weren’t enough, scientists sometimes rely on data from studying the atmosphere to find traces of gases identical to those on Earth, particularly oxygen, carbon dioxide and nitrogen.

Gaseous oxygen, an important part of life on earth

With regard to oxygen in particular, it makes up about 21% of all gaseous components in the earth’s atmosphere and was created as a result of photosynthesis, which led to a large supply of oxygen about 2.45 billion years ago. Due to its importance for the development of life on our planet, this gas is considered to be one of the most important biosignatures in the search for extraterrestrial life.

A study by scientists at Johns Hopkins University raises these doubts. The study in question is titled “Gas-Phase Chemistry of Cool Exoplanet Atmospheres: Insights from Laboratory Simulations” – Gas-Phase Chemistry of Cold Exoplanet Atmospheres: An Overview of Laboratory Simulations – and was published in the journal ACS Earth. And published space chemistry.

Simulations with Sarah Hörst’s Planetary HAZE chamber

As the title suggests, the document records laboratory tests to determine whether the presence of certain gases in an exoplanet’s atmosphere could mean that there is life there. Specifically, the team focused on oxygen.

The presence of certain gases in an exoplanet’s atmosphere could mean that there is life there. Photo credit: Shutterstock / Dotted Yeti

For this purpose, she performed simulations with the Planetary HAZE Chamber (PHAZER) in the laboratory of Sarah Hörst, a planetary scientist and one of the lead authors of the study. The researchers began creating nine different gas mixtures to simulate exoplanet atmospheres, reports Each mixture was then injected into the PHAZER chamber after being heated to temperatures between 27 and 370 ° C.

Can be generated by simple chemical reactions

Using this approach, scientists were able to demonstrate that gaseous oxygen and most of the materials known to be the source of life can be created through simple chemical reactions.

“It used to be assumed that the simultaneous presence of oxygen and organic matter was a sign of the existence of life, but we have generated them abiotic in many simulations. This suggests that even the simultaneous presence of generally accepted biosignatures could be false positive for life, ”concluded Chao He, lead author of the study.

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