Hot off the (zoom) press: A potential detection of life on Venus!!!
Venus is a very inhospitable planet. It has a thick, crushing atmosphere with clouds of carbon dioxide and sulfuric acid which never disperse and which trap the heat in (think greenhouse effect gone wild!) On top of that there are crazy 360 km/h winds! So really not a very easy place for life to exist.
A team of astronomers thought carefully about what would be a potential sign of life on Venus. They realised that if there was microbial life in the atmosphere of Venus, it might be producing a chemical called phosphine. It is possible to detect the presence of phosphine as a dip in the light coming from Venus at a wavelength of light of 1.23mm, which is invisible to our eyes. Fortunately, there are several telescopes on Earth that can “see” this wavelength.
One of these telescopes is called ALMA. It is in the Atacama desert in Chile. The astronomers looked at Venus with ALMA, and to everyone’s surprise they found the signature of phosphine! You can see it in the following. In the background is a picture of Venus, but it’s just there to look pretty. The main thing to look at is the dip in the red squiggly line. The dip is called an absorption line.
The absorption line was also picked up by a big telescope on a mountain in Hawaii called JCMT. That’s the yellow line. Since both telescopes picked up same the signal, we can be sure it’s real and not a “false” detection.
From this absorption line, we can tell that the phosphine is present in Venus’ atmosphere in a concentration of 20 parts per billion. This is very scarce, but thankfully ALMA and JCMT are incredibly powerful telescopes, so they are still able to detect it. Once phosphine is created, it will eventually be turned into other chemicals by Venus’ atmosphere. So if enough of it exists for us to detect, something must still be producing it.
To figure out what could be producing the phosphine, the astronomers modelled the atmosphere of Venus using lots of advanced computer simulations and hella complicated thermodynamical calculations. Many abiological (non-life) ways of producing phosphine were considered. These included rock chemistry like volcanoes, chemical interactions in the atmosphere, lightning, meteorites etc. Many of these things can produce phosphine, but only a very tiny bit and no where near as much as was detected by ALMA and JCMT.
We already know that Jupiter and Saturn’s atmospheres do actually have phosphine. Those giant planets have the pressures, densities, gas composition etc. needed to produce it. But Venus does not. However, there could be some sort of other abiological chemical process happening to produce phosphine that we don’t know exists.
And now for the biological (life) option! Microbial life on Earth sometimes produces phosphine. If there is microbial life on Venus which is only about 10% as efficient at producing phosphine as Earth’s microbes, then that could explain the concentration of phosphine found in Venus’ atmosphere. It’s possible that life existed on Venus when it was cooler, but that was much earlier on in the history of the Solar System. As Venus got hotter and hotter, this life may have migrated up into the clouds, where it is chilling out now among all that delicious sulfuric acid and stuff and happily producing its phosphine.
So….has life been detected on Venus? No. But maybe. Either there is some sort of chemical process that can happen out there in the universe that we haven’t discovered yet, or there is microbial life on Venus. Either way, that’s pretty darn cool.
This work has been published today in Nature Astronomy, which is a very reputable journal. Usually you have to pay to see the articles published in this journal, but fortunately this one has been made public for free. So if you want to scrutinize the science yourself, check it out here: https://www.nature.com/articles/s41550-020-1174-4.pdf
Four of the main authors of the article announced their discovery during a virtual, socially-distanced press conference held today by the Royal Astronomical Society. They are Prof Jane Greaves, Prof Sarah Seager, Dr Anita Richards and Dr William Bains. You can see them in the picture below.
They have a really incredible story about how they didn’t know each other but eventually met and realised that if they worked together they would have the combined skill set required to pull off this ambitious project. This is a perfect example of why it’s so important for scientists from different places with different areas of expertise to interact and collaborate. Because then you just might be able to do something crazy like detect life on Venus!
A huge congratulations to them and the rest of their team on this amazing discovery! Next step: More observations, simulations and exploration of Venus’ atmosphere! (With spacecraft and robots. Not with humans! We wouldn’t last a second there.)
Feature image credit: NASA.