The question of whether the planet Venus could, or ever has, hosted life is a complicated one.
Firstly, we have far from a complete understanding of this world. There are several reasons for this, not the least of which is that Venus is a harsh world with crushing pressure and temperatures that can melt lead on its surface. In the early years of space exploration, this was somewhat of a crushing blow in that before we started sending spacecraft out to explore the solar system, Venus was popularly seen as a world possibly hosting steamy jungles under its thick cloud layers.
This was clearly not the case, rather it was found that Venus was hell, with no clear chance for life to exist on its surface. Or for that matter spacecraft, the handful of craft that have ever landed there sent by the Soviet Union had trouble lasting minutes on the surface. But they were able to return images and data, and in that data were some findings that are unexplained to this day. But the story of strange behaviour at Venus goes back much further, more on that in a bit. But the reality is that the harsh conditions of Venus have favored the much more clement surface of Mars for exploration, at least in comparison. But it’s also known that while the venutian surface is not some place humans would want to visit any time soon, it’s atmosphere hosts a level that is actually the most earth-like atmospheric environment in the solar system off this planet.
This zone, which is miles high in the atmosphere of venus, hosts temperatures and pressures that would be comfortable even for a human, this is the one place in the solar system other than in our atmosphere where you could tear your space suit and it would not be a serious emergency, though you’d need to get back into your home environment, say a balloon, pretty rapidly. Venus also hosts many other mysteries, and in fact, the biggest is was it always like it is today? There are competing views here, one stating that it may have been a wet planet with oceans as recently as only 700 million years ago.
The other view is that it may always have been a hot house. If the former is true, then Venus would have also been on the table for the potential for life to have arisen on its surface in that liquid water environment, or have survived being deposited there from early earth or even potentially Mars if microorganisms existed there. But the big question is, could any life that had been there still be present in that comfortable upper atmosphere? This is very much an open question, especially in light that Venus has some atmospheric mysteries that are hard to reconcile without biology.
And this has only gotten more intriguing in light of recent findings. Before we get to that however, it’s best to lay out just what indicators Venus is giving for a potential biosphere.
As early as the 1920’s something was observed to be going on in Venus’s cloud deck that has defied explanation ever since. Known as the unknown UV absorber, there are strange features in Venus’ atmosphere that are known to absorb ultraviolet light, but also change dynamically in distribution and shape, not unlike how algae in Earth’s oceans bloom. Of course this could simply be some atmospheric chemical phenomenon, characterizing planetary atmospheres is an exercise in learning just how complex things can be, but at the same time if you can’t easily explain something after a century, you might have to consider more complex options. And that leads us to the next chapter in weirdness with Venus.
This involves something known as the Mode 3 particles detected in the lower clouds of Venus. The composition of these are still unknown, but the Pioneer Venus probe was able to determine their shape. They are non-spherical. This is interesting because it eliminates a liquid nature for the particles, in other words if they were something like sulphuric acid, they’d be rounded. Whatever these particles are, they’re something chemically new and unforeseen. Oddly, there is also evidence that they happen to be just about the size of bacteria here on earth, but that’s incidental, lots of things are that size. So more indicators are needed. And there are indeed more indicators.
The next bit of strangeness are atmospheric gases in the atmosphere of Venus that have no clear origin. Most famously as of late is the gas phosphine. The detection of phosphine in the atmosphere of Venus has been contentious to say the least. One the one hand, the researchers that announced it and associates have advanced that the detection is real, though may not have been as strong as originally suggested. On the other hand you have some saying that the detection was false, or too small to mean much and may be accounted for by volcanism.
The less phosphine you have, the easier it is to find reasons for why it’s there, if it indeed is there. Interestingly, the team that made the phosphine discovery have doubled down on the detection that it is indeed real, link in the description below for more information on that. But there’s a serious issue with volcanism as the cause. It’s also been argued that you’d need a whole lot of volcanism going on at Venus to reach the reported levels, as small as they may be.
There isn’t any evidence for this, only that volcanism is probably going at Venus regularly, and there is some evidence for that, and possibly even giant cataclysmic volcanic events. But at the same time, we have volcanism here on earth, and phosphine, yet the phosphine here seems largely biologically generated, though even that’s debated. Also, the argument has been made for lightning generating the phosphine, but this has not held up in the laboratory.
So while interesting for sure, the presence of phosphine at Venus is not conclusive. But it’s not the only gas in Venus’ atmosphere that raises eyebrows. There are a number of others, and together they suggest a chemical disequilibrium in the atmosphere of Venus. Something has to cause that, and with our own planet that disequilibrium is caused squarely by life. Our oxygen levels are due to the plants, and there just isn’t any other mechanism to cause them on this planet.
Venus also exhibits a similar, though not as pronounced disequilibrium, so either there is something chemically interesting going on there that we don’t currently understand, or something biologically interesting going on there that we don’t currently understand. Now to the chemicals. These include of course phosphine, but also Ammonia and Oxygen – which was dismissed in the past as a detection simply because it shouldn’t be there, and Hydrogen Sulfide, and some less reliable detections of other gases. All of that together suggests disequilibrium, and something must cause that.
Further, there are unexplained anomalies regarding the abundance of certain gases at certain levels in the Venusian atmosphere. This should be taken as an indicator that we simply don’t understand Venus’ atmosphere very well, but it should also be noted that there may be something going on biologically there that may best explain what is observed, which is certainly the case for Earth. This planet’s atmosphere is weird, and is best explained by the actions of its biosphere, and anyone in the galaxy that knows of this little world and have characterized its atmosphere, knows this. Earth screams its biosphere, and has done so for geologically significant time scales. But Venus only hints, at best.
And here is where we come up against a wall of sorts. Biochemistry as we know it here one earth cannot exist on Venus. Venus isn’t just a hot house with a small clement zone in its atmosphere, it’s bad for life on other counts. Chief among these is biochemistry as we know it, Venus is very dry, and very acidic, many times more so than earth. If there is indeed life on Venus, it has to reckon with both of these in a way not seen here on earth. But at the same time, earth life may not be the only way that microbial life can work. It may simply be that the conditions here on earth allowed for a certain type of biochemistry, but that other ways to the same end might be possible. And that’s where Venus becomes interesting, because it may be possible for an alternate biochemistry to be going on that we’ve never seen before.
To this end, experiments were done in preparation for the Venus Life Finder Mission study, more on that in a bit, that showed that sulfuric acid can actually support complex organic chemistry. Indeed, they found that certain lipids not only survived it, but were able to form structures. Fast forward to now, in a paper by William Bains and colleagues they advance that life on Venus may exist simply by neutralizing the acid completely allowing for pockets of habitability in the atmosphere of Venus. This would serve to solve some of Venus’ chemical mysteries, such as the presence of an apparent signature of ammonia in the atmosphere that has no known way to be generated on Venus, along with small amounts of oxygen. If the Ammonia is indeed there, then it’s difficult to explain it without life. And it’s certainly no secret that life can modify its environment, all sorts of life on earth does that, especially the photosynthesizing plants, but also we modify it ourselves constantly. Add in the phosphine and the strange unknown absorber, along with the strange oblong particles detected there, and you have enough of a hint for life that a closer look is warranted. Now for some obvious questions. What of dust being swept off the surface of Venus? This doesn’t really work because you’d need an implausible amount of dust to do it.
At the same time, you need some dust to provide the metals and elements needed for life to get into the atmosphere. And at the end of the day, you still need a mechanism to produce Ammonia. The researchers found that for life on Venus to produce ammonia, the reactions would produce oxygen, which is seen.
Even more interesting is that if you add in ammonia to the droplets of sulfuric acid, not only does it neutralize the high acidity, but also would make a kind of particle that could be non-spherical. In other words, this hypothetical type of life would explain essentially all of the observed anomalies in the Venusian atmosphere. So Venus hints stronger than ever that there may be something biological going there, and indeed if that’s the case, it promises to be markedly different from what we’re used to here on earth. But in the end, the only way to settle the question is to go to Venus and try to determine if that life is there. Such a mission would be useful regardless, because even if there isn’t life in the atmosphere of Venus, there is unknown chemistry at least. So either way we would gain a scientific understanding of Venus better than what we have now.
And that’s where the news gets interesting, we may actually get an answer to this question far sooner than I think anyone could have predicted just a few years ago. A plan for a life finding mission to Venus now exists, and even better, if these missions fly, they will be privately funded. This is a new era. It used to be that the only way to explore space and answer questions was for governments to fund them, often in collaboration. This led to enormous amounts of achievement and discovery spanning the entire globe and was far beyond worthwhile. And indeed, it kickstarted our exploration of space, though sometimes that was more due to rivalries and politics rather than purely scientific exploration. But those were, and continue to be, titanic, really expensive projects that must take into account not only scientific concerns, but also political ones, and that can lead to many questions of just what to do with taxpayer funds. But this new era offers us something a little different.
The private sector funding and sending missions either for science, or for profit by founding new areas of the economy, such as a Mars colony buying a steady flow of products from Earth, and finding ways to balance that trade by sending products back. Whether we think this will work or not, it seems to be coming regardless. And then there is private funding for targeted science missions intended to answer very specific questions, bankrolled by people that have the money that want to find out.
And that’s where a new proposed series of missions comes in, specifically designed to answer the question of whether there is life on Venus or not. It’s known as the Venus Life Finder Mission, and currently consists of a study and a plan compiled over 18 months and funded by the Breakthrough Initiative. It envisions the first mission not a decade from now, but in 2023.
The launch company Rocket Lab has floated the idea of a probe to Venus in that time frame, that may carry direct experiments to determine if Venus’ atmosphere is indeed habitable at certain zones, and expand our knowledge of that environment as well as try to gain further insight on the elongated particulate matter. The second mission is envisioned to entail exploring the upper layers of Venus’ cloud deck within the clement zone to further characterize its habitability and search for chemical signs of life. If the findings look good, a third mission is envisioned, again involving a balloon, but also a rocket to return samples of Venus’ atmosphere to earth.
After following NASA’s protocols on such material, it could be searched directly with much more precise laboratory instruments for direct evidence of life on Venus. If this plan comes to fruition, the question of life in the atmosphere of Venus may be answered in a much shorter time period than ever previously imagined. And if there isn’t life, they will at least shed light on the apparently very strange and poorly understood chemistry going on with Venus. It’ll be amazing to see it all unfold, regardless of what is found. Thanks for reading! wishing everyone a happy new year.