Scientists have discovered phosphine in Venus’ atmosphere, a gas produced here on Earth by bacteria.
The search for signs of life has taken an unexpected turn. Astronomers have discovered phosphine in the atmosphere of Venus; a rare chemical produced by bacteria here on Earth. It is a very promising find. Because could this mean that there are actually living organisms in the cloud cover of Venus?
Venus, often described as Earth’s twin sister, is about the same size, but has an average surface temperature well above the melting point of lead. In addition, the planet is surrounded by a layer of clouds laced with corrosive sulfuric acid. Not really the most favorable conditions for life, you would say. Still, scientists have long wondered if Venus is possible it could be home to certain microbes. Because the upper cloud cover – about 52 to 62 kilometers above the surface – has more moderate conditions, with a pleasant temperature of 30 degrees Celsius. And it could well be that some microbes – despite the acid – can thrive here.
The discovery of phosphine in the atmosphere of Venus now bolsters that theory. On Earth, this gas is mainly produced by organisms that live in low-oxygen environments. And so the question arises whether the same could be true for Venus. “This discovery is very exciting for the exploration of Venus,” said researcher Brad Tucker, who is affiliated with the Australian state university, not involved in the study. “Studies on Mars have also found unexplained processes, such as the varying concentrations of methane in the Martian atmosphere. This may indicate unknown geochemical processes or possibly the occurrence of life. The discovery on Venus is similar. The fact that possible traces of life have now been discovered on two neighboring planets – Venus and Mars – is very exciting. ”
More about phosphine
On earth we know phosphine as a colorless, flammable and highly toxic gas that is only soluble in water in minute amounts. It is sometimes used as a pesticide. Pure phosphine is odorless, but when mixed with other compounds, it can smell like rotting fish or garlic. The discovery of the gas on Venus could therefore indicate that the planet is smelly. Incidentally, it is not the first time that phosphine has been found on another planet. Phosphine makes up 0.0001% of the atmosphere of the planet Saturn. Traces of the gas also exist in Jupiter’s atmosphere, albeit in very small quantities.
The researchers discovered the gas using the James Clerk Maxwell Telescope, located on the dormant volcano Mauna Kea on the island of Hawaii. The team was then given time to verify their discovery with 45 telescopes of the Atacama Large Millimeter / submillimeter Array (ALMA for short). “We eventually came to the conclusion that both observatories had seen the same thing,” says researcher Jane Greaves. The researchers estimate that the clouds of Venus harbor about 20 ppb (parts per billion) of phosphine.
The astronomers then performed calculations to see if the phosphine could be the result of natural processes on Venus. Among other things, sunlight, minerals that are blown up from the surface, volcanoes and lightning were discussed. But none of these processes can fully explain the amount of phosphine detected. In addition, terrestrial organisms would have to function on only 10 percent of their capacity to produce the observed amount of phosphine. However, we must remember that any microbes on Venus are likely very different from their cousins on Earth.
Despite the promising discovery, the question is whether microbes are actually able to reside in very acidic environments. “On Earth, some microbes can tolerate up to about five percent acid in their environment,” says researcher Clara Sousa Silva. “But the clouds of Venus are made almost entirely of acid.” So microbes must come from a good home if they are to thrive in such conditions. At the same time, microbes are certainly possible. Because the clouds are so acidic, they quickly destroy the phosphine. The fact that researchers have nevertheless found traces of phosphine means that ‘something’ is re-creating the gas on the planet. The question now, however, is whether this can actually be attributed to living organisms, or whether it may be based on chemical processes that are unknown to us.
The team is eagerly awaiting more time with telescopes to determine if the discovered phosphine is in a relatively temperate part of the clouds. The team also wants to start the hunt for other gases that have to do with life. “This research marks the beginning of a new era in the search for extraterrestrial life,” said researcher Laura McKemmish, of the University of New South Wales. “I therefore expect probes to be sent to Venus soon to find an answer to that one pressing question: does life exist on Venus?”
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