Astronomers just detected the presence of a gas, phosphine, in the clouds of planet Venus that shouldn’t be there. On Earth, phosphine is associated with biological processes — it’s believed to be made by some species of anaerobic bacteria that live in environments starved of oxygen, such as animal guts or landfills, or released when microbial matter starts decaying; phosphine is also associated with chemical processes — it’s used in the preparation of flame retardants, rat poison, and in the semiconductor industry. Either way, as far as scientists know, phosphine can only be present around microbial life forms on Earth, or in man-made, potentially destructive objects. Scientists are now asking: how did it get up in the clouds of Venus?
Phosphine is considered a biosignature gas — its presence in non-Earth places, such as exoplanets, can signal their habitability, or at least the presence of some alien life form unknown to humankind, according to research published in the journal Astrobiology in January. It recommended scientists start trying to evaluate the presence of phosphine in outer space as a potential new method to test exoplanets’ habitability. Now, the latest study published in Nature Astronomy shows a group of scientists did exactly just that — they used a highly sensitive array of telescopes to observe radio frequencies in the sky, in an attempt to detect the ‘absorption line’ of energy released and consumed by phosphine molecules in the Venusian atmosphere. They found a surprising abundance of phosphine — 20 parts per billion and way more than we find on Earth — in an atmosphere in which it should have been destroyed immediately.
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This is because Venus — once a planet considered Earth’s twin — was found to harbor high temperatures (reaching 471 degrees Celsius) and almost 100 times more pressure than what we experience on Earth. Its clouds, however, provide a completely different, and more ambient atmosphere, despite the presence of sulfuric acid clouds. Scientists have harbored hope for life in the Venusian clouds, mostly due to the presence of sunlight and water. Now, with the latest research, scientists have surmised there must be either an unknown abiotic production of phosphine that scientists on Earth are currently unaware of or that some version of biological replenishment of phosphine is happening in the Venusian clouds for it to exist in such large amounts. Either way, “something weird is happening,” study co-author and molecular astrophysicist Clara Sousa Silva tells National Geographic.
So, what now? First, some scientists are asking for confirmation of the phosphine itself, as they think it might be an artificial signal during the extensive process of evaluating data from the telescopes. In order to verify the signal, the team would have to set up more telescopes and do multiple rounds of observation to conclusively prove the presence of phosphine, and rule out the margin of error. Others, however, are sufficiently excited by the discovery and are gunning for a mission to Venus, to bring back actual particles that can further this discovery.
For now, it has elicited cautious optimism in the scientific community, once again inciting interest in an avenue we had considered almost completely unexplorable.
