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Until now, there has been little to suggest that there could be life on Venus. But two research teams have now independently detected phosphine gas on the planet, an indication of biological processes.
By Uwe Gradwohl, SWR Scientific Editor
“When we saw the first signs of phosphine in the atmosphere of Venus in the measurement results, it was a shock for us,” says Jane Greaves, an astrobiologist at Cardiff University and head of the international research team that measures measurements in the atmosphere of our neighboring planet. has done. The scientists got a sensational result. This team says that there is a clear indication of extraterrestrial life on Venus: phosphine gas.
Venus: an inhospitable planet
Venus is not the type of planet to look for alien life in the first place. It’s over 400 degrees hot on its surface. There is a crushing pressure of around 90 bar on the ground. Venus’s atmosphere is made up of 95 percent carbon dioxide, a greenhouse gas, and Venus’ clouds are made up of corrosive sulfuric acid droplets.
But it is precisely there, in the high layers of clouds, where life forms could hide. At an elevation of 50 kilometers, it’s only a pleasant 30 degrees. The pressure is one bar, so it is similar to the air pressure at the surface of the earth.
Two radio telescope teams have now independently discovered phosphine in these high cloud layers. This gas cannot easily arise in nature. It consists of a phosphorus atom to which three hydrogen atoms are attached. Such a molecule does not arise in an atmosphere in which there is free oxygen, because phosphorus reacts much faster with oxygen than with hydrogen.
A sign of life
On land, therefore, phosphine can only be produced in places where there is no free oxygen involved in the chemistry, for example in the subsurface of peatlands. Phosphine has also been found in the intestines of fish. And in the droppings of the penguins. Basically, however, phosphine is a strong poison for oxygen-dependent living things. However, conversely, it can be an important part of your metabolism for living things whose metabolism does not require oxygen. When looking for life on planets without an oxygen atmosphere, astrobiologists consider phosphine to be a strong biomarker.
Venus focused from telescopes
In June 2017, the James Clerk Maxwell Telescope in Hawaii first pointed its radio antenna at Venus. And I quickly found phosphine in the clouds of Venus. However, the scientists were skeptical about the result.
They began to examine all the ways phosphine could be produced on Venus without the help of alien microbes: lightning strikes in the atmosphere, volcanic eruptions, the chemical reaction of swirling minerals with sulfuric acid in clouds. But the computer simulations showed: In this way, a maximum of one ten thousandth of the amount of phosphine that was discovered in the radio light of Venus could be produced. In March 2019, measurements with the ALMA telescope network of the European Southern Observatory in Chile confirmed the surprisingly large presence of phosphine in the clouds of Venus.
Microorganisms in the clouds of Venus?
For decades, astronomers have been wondering about the inexplicable ever-changing dark spots in Venus’s clouds that appear when the planet’s cloud cover is viewed in the ultraviolet light range. This phenomenon has already fueled speculation about microorganisms floating in the clouds of Venus. If Venus microbes really do exist, they must have found an extremely ingenious way to deal with up to 90 percent of the sulfuric acid content in Venus cloud droplets.
For terrestrial microbes, an acid content of more than five percent is fatal. Also, cloud droplets tend to get larger over time and sink into the deeper hot cloud layers on Venus and evaporate there. But astrobiologists might imagine that this is even an integral part of the life cycle of organisms on Venus. As they dry, they could form spores that are carried by updrafts to become new microbes.
Venus missions
What is really happening in the clouds of Venus can only be determined by space probes. Russia plans to continue the traditional series of its flights to Venus in 2026 or 2031. The Venera-D probe could also launch a solar-powered balloon or plane into Venus’s upper atmosphere to see if Venus microbes actually exist. NASA has appropriate concepts and Russia would be interested in working together.
