Although Venus is the closest planet to Earth, it’s also one of the Solar System’s most under-loved residents. While Mars is inundated with orbiting problems and visits from rovers, at the moment Venus only has one spacecraft keeping it company – the Japanese probe Akatsuki.
That might all be about to change. On September 14 an international team of scientists announced that they had found what might be a sign of life floating in the atmosphere above Venus. After decades of searching fruitlessly for life on Mars, our next door neighbour has surprised us with one of the most promising indicators of life anywhere in the Solar System.
Here’s everything you need to know about one of the most exciting discoveries in the hunt for extraterrestrial life so far.
What’s all the fuss about?
Astronomers have detected a gas called phosphine in the clouds 50 kilometres above the surface of Venus. This is intriguing because we don’t know any non-biological way that phosphine could be made on Venus, which leaves open the possibility that tiny alien microbes in the planet’s atmosphere could be farting out the gas.
So it’s just a gas? I was hoping for something a little more tangible. A photo or something
Sorry about that. In scientific terms, this is a pretty promising signal though. On Earth phosphine is only made in the lab or by microorganisms and can be found in swamps as well as animal intestines. It’s present in large amounts on Jupiter and Saturn, but that’s because those planets have violent storms ideal for producing the gas and these conditions aren’t replicated anywhere else in the Solar System, as far as we know.
There are two other things that make the biological origin of phosphine a credible hypothesis. First, there’s quite a lot of it up there – about five to 20 parts per billion. That might sound tiny, but it’s thousands of times more than what you’d find in Earth’s atmosphere. Second, we know that phosphine is constantly being broken down by light so in order to detect it now it means that some process is constantly replenishing the phosphine in the atmosphere.
Does that mean it’s definitely being produced by life?
No – not by a long shot. What it does mean is that we don’t know any chemical or physical process that could be generating this gas on Venus, which leaves biological origins as a plausible answer. It could be all down to some chemical process that we just don’t understand yet.
Venus is a pretty niche choice for life. I thought Mars was where all the action is?
For decades, scientists have argued that Venus might be able to support life, but we haven’t tried very hard to check it out as attention has focused on Mars and the icy moons of Jupiter and Saturn. It’s easy to see why – the planet’s surface temperature averages more than 420 degrees Celsius and its dense atmosphere exerts a surface press more than 90 times experienced at sea level on Earth. Its clouds, meanwhile, are more than 80 per cent sulphuric acid. This inhospitable environment is partly why we haven’t been able to study Venus as well as we’d like. The planet has a nasty habit of melting and crushing any spacecraft that we send there.
But conditions in Venus’ atmosphere might not be so dreadful. The clouds about 31 kilometres above the rocky surface of the planet might reach temperatures of 30 degrees Celsius and have a pressure similar to that of Earth. We already know that microbes live in the atmosphere on Earth, so it’s plausible that life that once lived on the surface of Venus – back when it was a more hospitable place – could have made its way into the atmosphere and stayed there while conditions on the surface deteriorated.
How do we find out for sure what’s really going on up there?
The phosphine measurements were made using two telescopes, the James Clerk Maxwell Telescope in Hawaii and the Atacama Large Millimeter/submillimeter Array in Chile and the team behind the discovery are working to confirm these observations with even more detailed measurements. But what we really need is a sample from the atmosphere so we can take a proper look at what’s going on.
A private company called Rocket Lab has a mission to Venus planned for 2023. Nasa also has shortlisted two possible Venus probes that could eventually head to our rocky next door neighbour while this discovery is likely to prompt a flurry of new proposed journeys. Any mission is likely to take a long time to be planned and carried out though, so we’ve got a wait on our hands until we have the next piece of evidence.
Matt Reynolds is WIRED's science editor. He tweets from @mattsreynolds1
This article was originally published by WIRED UK
