The Earth’s twin planet, barely smaller than ours in diameter and mass, could indeed be a much better candidate for life than its incandescent surface temperature would assume, which,
with over 450 ° C, far exceeds the melting point of lead (327.5 ° C).
The study raises on the basis of new and more precise data an idea that had already been proposed by Harold Morowitz and Carl Sagan in 1967 in an article published in Nature, „Life in the clouds of Venus?“
In the research scientists have turned all types of rocks on each planet, looked at every single image that has arrived, even the powerful SETI program has never yielded results, yet they all agree: We cannot be alone in the universe.
In an article published online March 30, 2018 in the journal Astrobiology, an international team of researchers, from the University of Wisconsin-Madison’s Center for Engineering and Space Sciences, exposes a case for the atmosphere of Venus as a possible niche for extraterrestrial life .
Venus has had a long time to make life evolve, so much so that, unlike what is thought, it has had a habitable climate, with liquid water on its surface, for a good 2 billion years.
It is much longer than is believed to have occurred on Mars.
On Earth, terrestrial microorganisms – mostly bacteria – are able to move in the atmosphere, where they were found alive at altitudes up to 41 kilometers high. Bacteria can inhabit incredibly difficult environments on our planet, including Yellowstone thermal springs, deep ocean hydrothermal vents, toxic sludge from polluted areas, and acid lakes all over the world.
On Earth, we know that life can thrive in very acidic conditions, it can feed on carbon dioxide and produce sulfuric acid. So the cloudy, highly acidic atmosphere of Venus is mainly composed of carbon dioxide and water droplets containing sulfuric acid.
The habitability of the clouds of Venus was first raised in 1967 by the famous biophysicist Harold Morowitz and the famous astronomer Carl Sagan.
The conditions of the planet’s surface, however, are known to be inhospitable, with temperatures rising above 450 degrees Celsius.
The idea was dusted off after the existence of bacteria on Earth with light-absorbing properties was discovered, which in measurements are really very similar to unidentified particles, which are the dark spots observed in the clouds of Venus.
The particles that make up the dark spots have dimensions almost equal to those of some bacteria present on Earth, even if the instruments that have sampled the atmosphere of Venus so far cannot distinguish between organic or inorganic materials.
To date we do not know if the extensive lava flows, in the last billions of years, have destroyed or covered the previous history of the planet.
In the hunt for extraterrestrial life, planetary atmospheres other than terrestrial ones remain largely unexplored.
The research of Limaye and the five colleagues focuses on the possibility that the clouds of Venus host microbial life forms with a wealth of details. Although it may seem surprising, not so many kilometers from the fiery surface of the planet, its dense atmosphere offers temperature and pressure conditions very similar to those on Earth. In particular, the lower layer of the thick cloud cover, at a height between 48 and 50 km above the ground, has an average temperature of around 60 ° C and a pressure of 1000 mbar, that is 1 atmosphere: the ground pressure at the level of sea.
If the clouds of Venus really house a biology, then these biotic materials could potentially exhibit spectral signatures that match those of the clouds of Venus. For example, the contrasts observed at 270, 283, 365, 410 and 430 nm (Pioneer, Akatsuki, Galileo and MESSENGER) are alluringly similar to the absorption properties of terrestrial biological molecules, which have absorption peaks at wavelengths that cross the regions of the electromagnetic spectrum from ultraviolet to visible.
There is in particular a terrestrial microorganism that seems made to live among the clouds of Venus, not only for its spectral signature, but for its metabolism. It is the Acidithiobacillus ferrooxidans, a proteobacterium that belongs to the same phylum as rather infamous pathogens such as Escherichia coli, Salmonella typhi, Vibrio cholerae and Helicobacter pylori.
Acidithiobacillus thrives in acid and sulfur-rich environments:
In terms of survival in sulfur-rich environments with low pH, A. ferrooxidans represents an exemplary terrestrial analogue for life in the clouds of Venus: this bacterium indeed thrives at extremely low pH values (pH 1 or 2), fixed or CO₂ is gaseous hydrogen directly from the atmosphere and obtains the energy for its growth by the oxidation of hydrogen, ferrous oxide, elemental sulfur or partially oxidized sulfur compounds.