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reThe press conference had not yet started when the news had already leaked and spread in a short time on the Internet: an international team of scientists discovered a substance in the clouds of Venus that could indicate extraterrestrial life. It is monophosphane gas, which is secreted by terrestrial microbes under certain conditions and which should actually decompose rapidly in the aggressive atmosphere of Venus.
Perhaps we are no longer alone in the universe? An answer to the great human question could come at least a little closer with work. Consequently, speculation on social media is currently rampant.
It is true that it would not be little green men who we greet at first contact, but mute microbes floating in the sulfuric acid clouds of our neighboring planet. But even then, the implications for our human-centered worldview would be enormous.
However, the emphasis should be on “would”, because what scientists discovered on Venus is exciting and puzzling, but not yet proof of life. “We are not saying that we have found life,” Sara Seager of the Massachusetts Institute of Technology (MIT) said at the news conference. The find is at best a first indication.
Monophosphine (English: phosphine) is a simple molecule, consisting of only one phosphorus atom and three hydrogen atoms. On earth one can find PH3 where microbes thrive in an environment rich in phosphate and in the absence of oxygen. The exact identity of terrestrial phosphine producers or their metabolic pathways is unknown, but phosphine has already been discussed as a possible biomarker in the search for extraterrestrial life. The gas is relatively easy to detect with radio telescopes, so one could look for it in the atmosphere of distant exoplanets in other solar systems.
Mystery of the Venusian atmosphere
That it has now been found very close, on our neighboring planet Venus, is thanks to the persistence of Jane Greaves, professor of astronomy at Cardiff University. In early 2016 she had the idea to search for monophosphane on Venus and then carried out the project against all odds. First, the search began with the James Clerk Maxwell telescope in Hawaii.
To their great surprise, the astronomers found a signal: rotating monophosphine molecules absorb radio waves emitted at a characteristic frequency. The result was later confirmed by the Alma telescope, which is located 5,000 meters above sea level in the Atacama desert in Chile.
After the data is published in Nature Astronomy, there should be little doubt that phosphane exists on Venus. What that means, however, is still open. “There are many things we still don’t know about the atmosphere of Venus,” says Sara Seager.
Signs of life on Venus
International researchers have discovered phosphine gas on Venus. This gas is produced by microbes on the ground. So there is a justified hope of discovering life on Venus. The researchers themselves are surprised by the finding.
In principle, there are also possible ways in which phosphane could be formed without the metabolism of living cells: lightning, solar radiation, and volcanic eruptions are possible sources. MIT’s William Bains explained that the team had analyzed all the possibilities and reactions they could come up with, which was “quite a grueling procedure.”
With each review, the calculations showed that there would be much less phosphine than the 20 particles per billion that researchers have calculated for the atmosphere of Venus. But perhaps chemists’ knowledge and imagination are simply not enough to devise possible abiotic reaction pathways.
After all, the discovery fuels new speculation that there might be life in the clouds of Venus. It is almost impossible for single-celled organisms to exist on the rocky surface of the planet.
The dense atmosphere of Venus is made up mostly of carbon dioxide. If there ever were oceans, then a rampant greenhouse effect on our neighboring planet, which developed at the same time as Earth, has long since evaporated all water. There is high pressure and temperatures over 400 degrees Celsius.
It looks so beautiful on Venus, at least that’s how astronomers imagine it
Quelle: Getty Images / Science Photo Libra
But it looks different at an altitude of 53 to 61 kilometers. With much milder temperatures around 30 degrees Celsius, life would be more imaginable here. However, conditions are also extreme in the cloud layer. The sulfuric acid in the clouds of Venus is a thousand times stronger than the acid in a car battery and the atmosphere a hundred times drier than any desert on earth. Living organisms should decompose in such circumstances, life on Venus seems highly unlikely.
Life cycle in the clouds
On the other hand, terrestrial microbes have adapted to the most varied habitats in the most surprising way and can thrive in conditions in which a human being would only survive a few seconds. Therefore, the Venus researchers are speculating about a possible life cycle of microbes that thrive for a time in the sulfuric acid droplets in clouds. Over time, the droplets collide, gradually becoming heavier, and eventually sinking to the depths.
However, unlike on Earth, they never reach the ground, instead evaporating in the warm, hazy area below the clouds. Here, according to the speculation of the researchers, only spores of the possible inhabitants of Venus could remain, which float for a while in the warm atmosphere, rise again and finally contribute to a new life in the clouds.
However, so far all of this is nothing more than pure speculation. But Venus is now moving up the list of celestial bodies in the solar system in which life could be possible. Only space missions to Venus could provide more accurate evidence, for example if a balloon could be deposited in Venus’s atmosphere for a long time, which would ideally be equipped with a mass spectroscope and a microscope.
Both India and Russia are currently planning missions to Venus that could possibly begin in 2023 and 2026, respectively. Excitement about the results they will send to Earth is increasing due to the findings in the clouds of Venus.
