Named substance that may be the first sign of extraterrestrial life

(ORDO NEWS) — A group of scientists from the University of California at Santa Cruz conducted a study and found out the circumstances that allow us to talk about the biological origin of methane in the atmosphere of a rocky exoplanet.

Methane may be a sign of life on the planet, but until now, scientists had no criteria to judge this. Now they’ve appeared

Despite some previous studies of methane biosignatures, until now scientists have not assessed the conditions on exoplanets necessary for methane to be highly likely to indicate the presence of life.

Therefore, the observation of methane in the atmosphere of a rocky planet today can be interpreted in different ways – and not necessarily that life is present on it.

In a study published in Proceedings of the National Academy of Sciences, the authors looked at various non-biological sources of methane and assessed their potential to support a methane-rich atmosphere.

Such sources include volcanoes, mid-ocean ridges, hydrothermal vents, and tectonic subduction zones. Potentially, the cause of the appearance of methane in the atmosphere can be collisions with comets or asteroids.

How to define “biological” methane

The fact is that methane as a biosignature stems from its instability in the atmosphere. Since photochemical reactions destroy atmospheric methane, it must be continuously generated to maintain high concentrations.

Non-biological sources would not be able to produce this amount of methane while remaining invisible. For example, the release of gases from volcanoes will add both methane and carbon monoxide to the atmosphere, while biological organisms tend to easily absorb carbon monoxide.

Researchers have found that non-biological processes cannot easily create a habitable planetary atmosphere rich in both methane and carbon dioxide and virtually free of carbon monoxide.

The researchers also concluded that for a rocky planet orbiting a sun-like star, atmospheric methane is more likely to be considered a strong sign of life if there is also carbon dioxide in the atmosphere, more methane than carbon monoxide, and not as much water ( it can absorb methane and carbon dioxide).


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