Alien civilizations may fill the atmospheres of planets with greenhouse gases and this could be a technosignature for their detection.
With the help of modern telescopes, it is possible to detect the existence of an alien civilization on other planets, if the aliens, like humans, emit greenhouse gases into the atmosphere.
If there are many such gases, this can serve as a kind of signal about the existence of highly developed life. This is the opinion of the authors of a study published in The Astrophysical Journal Room.
On Earth, gases including fluorinated versions of methane, ethane and propane are known to be among the gases that retain heat best. These greenhouse gases are released during various production processes.
Because these substances are not naturally formed in large quantities based on Earth’s chemical conditions, their presence in the atmosphere of another planet could indicate that an advanced alien civilization lives there. The authors of the study think so.
According to scientists, these gases are very dangerous for the inhabitants of the Earth, because they cause global warming. Perhaps potential aliens would like to terraform an uninhabitable planet. In this case, there may be many greenhouse gases in the atmosphere.
For example, aliens have decided to warm up a very cold planet like Mars, in which case they will have to change the climate. If aliens were to form such a planet, scientists found that the Webb Space Telescope could detect five greenhouse gases in this world’s atmosphere.
One of these, sulfur hexafluoride, contributes 23.5 thousand times more to planetary warming than carbon dioxide. A small amount of this gas, which lasts for at least a thousand years, is enough to melt an ice-cold planet so much that liquid water flows over its surface.
According to scientists, their long lifespan makes these gases excellent technosignatures for the systematic search for extraterrestrial intelligence.
The most interesting thing is that these gases can remain in the atmosphere even if the experiment to form the planet is unsuccessful. Other similar fluorinated gases can linger in the atmosphere for up to 50,000 years.
This means that if an alien civilization on cold planets outside the solar system pumps a lot of greenhouse gases into the atmosphere, it can be detected.
The study authors say that even if just one in a million gas molecules were to absorb infrared radiation from its parent star, it would create a distinctive signature that could be detected by the Webb telescope.
