Sign of life in the clouds of Venus? Maybe, but there is no evidence

Astronomers believe they have discovered a gas in the clouds of Venus that may indicate life high in the planet’s atmosphere. Their research has appeared in the professional magazine Nature Astronomy.

The observation is certainly not proof of life, the scientists emphasize. They speak of “abnormal and inexplicable chemistry” and say that the gas can be created by unknown chemical processes or – like on Earth – by life.

Venus is a hellish world. On the surface, the temperature is about 500 degrees, the air pressure is crushing and the atmosphere consists almost entirely of carbon dioxide. Russian landers who descended into the atmosphere last century only lasted two hours at the most.

It is about 30 degrees high above the surface, but there are clouds full of caustic sulfuric acid. They make the conditions for potential life difficult; few terrestrial microbes would tolerate those conditions.

Phosphine

An international team of astronomers thinks they have discovered a rare substance in those sulfuric acid clouds: the molecule phosphine. On Earth, that molecule is only made in industrial processes and by bacteria that thrive in an oxygen-free environment.

When the astronomers pointed a telescope in Hawaii at the cloud cover of Venus and processed the data, they were completely surprised. “It was a shock when we got the first glimpse of phosphine,” said team leader Jane Greaves of Cardiff University, UK.

To be more sure of the observation, 45 large dishes from the ALMA telescope in Chile were aimed at the Venusian cloud cover. That measurement also pointed to the presence of phosphine in Venus’ high atmosphere.

The researchers estimate that it concerns about 20 phosphine molecules per billion molecules. In theory, sunlight, volcanoes or lightning can influence chemical processes that produce phosphine. In addition, the molecule can also originate on the surface.

However, according to the researchers, such non-biological processes cannot produce more phosphine than one ten thousandth of the estimated amount found. So they suspect that the phosphine on Venus is produced by unknown chemical processes or by life.

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