This is what life on Venus might look like – and how we will find it

NASA / Jet Propulsion Laboratory

It sounds ridiculous, weird, and even stupid. Life on Venus, the hottest planet in the solar system? This world is often seen as a fault on planet Earth, as extreme climate change has turned it into one of the closest estimates of hell we’ve ever seen. And now we are told it may be home to alien life. It’s a discovery that, if proven true, would have dire consequences for how we view our place in the universe. The only problem? prove that.

The idea of ​​life on Venus is not new, and dates back at least to the 1960s when the late American astronomer Carl Sagan discussed this possibility. “If small amounts of minerals were moved into clouds from the surface, it would not be hard in any way to imagine the local biology of Venusian clouds,” he wrote in a book. Paper in it nature In 1967.

Now, more than five decades later, scientists have discovered phosphine on Venus. Phosphine – a compound of phosphorous and hydrogen – is thought to be a possible biological marker. In other words, we know that life can produce it, and discover it Hints in biological production.

“[We tried] To duplicate the list of options to explain the presence of phosphine, “says Sucrit Rangan of MIT, a co-author of Spotting paper in Natural Astronomy. “It all didn’t happen. So we’re left with things that we haven’t fully ruled out yet. That includes chemistry and biology that we don’t know about yet.”

Phosphine can be produced by a number of non-biological processes. These include geological sources like volcanic activity, or even extreme pressure environments where hydrogen is squeezed together – like Jupiter and Saturn. On Earth, phosphine is also produced by some anaerobic microbial organisms, which require very little oxygen. Similar extreme life forms may have made their home in the clouds of Venus.

“This discovery is very exciting,” says Sarah Rogheimer of the University of Oxford, whose research includes the search for life on exoplanets, worlds outside the solar system. “It’s either a different, really unusual chemistry, or it’s life.”

The discovery was led by Jane Graves of Cardiff University, using two telescopes on Earth – the James Clerk Maxwell Telescope in Hawaii and the Atacama Large Millimeter / Less Than a Millimeter Array (ALMA) in Chile – to observe the phosphine fingerprint in radio observations of Venus.

It is thought to exist, in the atmosphere of Venus, 50 kilometers above the surface, in a region that could be hospitable to life, outside the infernal conditions on the planet’s surface where high temperatures and pressures make life as we know it. Unimaginable.

Before we even begin to consider whether it could be produced by life on Venus, however, there are a number of hoops to jump through. First, other astronomers will need to try to reproduce the results, using the same or other telescopes, to verify if phosphine is actually present. Astronomers will then want to conduct more experiments to explore ways of producing phosphine, and see if they can rule out abiotic processes. “[We need] Lots of lab studies [and] “Calculations to highlight some basic criteria,” Ranjan says.

Then we could consider sending missions to examine phosphine in more detail, perhaps even one day to search for life itself on Venus. But it will probably be a very cautious advance until we get to this point. There are actually a number of missions to Venus on the drawing board. NASA Consider two proposals To the planet, DAVINCI + and VERITAS, the first of which will include an atmospheric probe that can search for gases like phosphine. Many other missions are also in the works. India plans to launch the mission this decade, while Russia has long talked about sending a spacecraft there, having led much of the earlier exploration of Venus in the 1970s and 1980s. Europe is also considering a mission called EnVision in 2032.

However, many of these missions were designed with other goals in mind – such as mapping the surface of Venus or searching for volcanic activity. In order to search for life, if it really exists, we will need a new type of task. “Ultimately we’ll want to take a sample from the atmosphere and return that sample for testing,” says Richard Gale of Royal Holloway University in London, who is responsible for the EnVision proposal. “That means some kind of balloon with a sample coming back [capability]Or a big enough balloon with some tools on it. “

This task will likely take years or even decades, but in the short term, there are things that can be done. The American Private Corporation Rocket Lab hopes to launch A small mission to Venus as soon as possible in 2023, which will include an aerial probe, and the company is looking at the small tools it could include that could search for life.

Scientists will also want to continue studying Venus’ atmosphere from Earth, not only to independently confirm the presence of phosphine, but also to investigate the different processes that could produce it again here in laboratories.

If after all these studies the signs continue to indicate life, we can begin to question what kind of life it might have been. At the moment, it is believed that this will be an airborne type of microbes in the sky of Venus. Living in drops From the dense clouds of the planet.

“Our best guess is a kind of microbial life living in cloud droplets,” says William Baines of the Massachusetts Institute of Technology, who was also a co-author of the paper. “The chances of life on the surface are staggeringly small. That is likely in the clouds.” We know there are airborne microbes on Earth, so if the conditions are just right on Venus, there is an attractive possibility that they are there as well.

Conditions on Venus aren’t perfect. These droplets will become extremely hot as they fall from the sky, killing any microbial life present. Instead, the droplets may be in a continuous cycle of evaporation and fall, as microbes cling to each other throughout the journey. “You have a cycle running in the clouds,” says Pines, who also says that maybe even some drops will fall to the surface, although it’s unlikely that any life will survive that flight. “It will be baked in charcoal-like things,” he explains.

It’s a baffling prospect, but it remains that way for now. If phosphine continues to be discovered, and can’t be explained by non-biological processes – which most scientists agree remains the most likely outcome – things could get very exciting.

Venus has long been overshadowed by other, more attractive targets in the search for life, such as Mars or Jupiter’s moon Europa. Now, with this phosphine discovery, our solar system’s own version of Hell could find itself at the top of the list. “It would probably take more than a decade to determine what happens,” says Rogheimer. “Phosphine is very interesting as a bio-signature. It just comes from one of the places where we don’t expect life.”

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