A New Venus Life Panspermia Possibility

[00:00:00]When discussing the concept of panspermia,  the idea that life originating from one planet can be transferred through meteorites to  another planet, one major aspect of it is that if that can indeed happen, which it certainly  appears possible, then almost certainly Earth has projected its microbial life in this way,  through impacts, it’s effectively sneezed all over the inner solar system and beyond, and  may well have landed on other solar system bodies that might offer habitability  enough for microbes to get a foothold.

[00:00:33]This can of course include Venus and Mars  ostensibly, but also ice shell moons like Europa and Enceladus, who knows what gets  churned below into the subsurface oceans as far as meteorites potentially from  earth, and it’s entirely possible that if we ever find life on or within any of  these bodies, that life may not be alien, but rather a presumably distant cousin of  earth life originating from the same source, whatever that might originally have been.  Indeed, we can’t even demonstrate that life on earth isn’t a product of Panspermia  and we actually are alien to this planet, particularly in regards to Mars. What if it  started there and came here? We simply don’t know.

[00:01:18]The reason for this thinking is that life on  earth seems to have arisen at the very earliest possible moment it could, perhaps suspiciously  so, when the planet had calmed down just enough after its formation and the late heavy  bombardment to allow it. Just as it did that, life appears. This could mean that life is  straightforward as far as abiogenesis, and it’s so easy that it just happens quickly. Or it  could mean that life on earth was deposited here from somewhere else, perhaps through a constant  rain of meteorites from Mars in those days.

[00:01:52]Originating somewhere else can mean  several possible things here though.

[00:01:56]One is that rather conspicuously,  at the time that Earth became alive, Mars actually had been habitable for a bit longer  of a time, by virtue of it cooling faster because it’s smaller and becoming stable faster. At  the time, it had plenty of liquid water. With Mars at the time seemingly presenting better, more  stable conditions for abiogenesis than earth was, it must be considered whether our life actually  started on Mars, and it is our true home world.

[00:02:28]Sadly the only way to determine if we are  in fact Martians however is if life still existed on Mars. Perhaps subsurface or in a moist  lava tube. There we could study its genetics, and it would be evident if it originated  from an earlier iteration of life that also spawned earth life, and thus Mars  must be the origin. Without extant life, it would be very difficult, but not  impossible, to make a case for a Mars origin from fossil evidence alone. Almost  certainly impossible from mere chemical evidence.

[00:03:02]But there are other possibilities,  and another is that some other planet somewhat older than the planets of this  star system within the sun’s original, then undispersed birth cluster and that  life on earth started in another star system entirely that is now far distant from us. It’s  possible that progenitor life, if it existed, still exists out there somewhere, or perhaps just  as likely, went extinct while we flourish here.

[00:03:29]Or perhaps it also spread itself elsewhere,  and earth has cousin life dotting the galaxy.

[00:03:35]But there’s always been a question hidden in here.  While it seems that a meteorite entering earth’s atmosphere could survive to hit the ground  and spread life without much of a problem, what of the other planets? Would earth life  survive the fall into another atmosphere enough to disperse? Mars seems a solid yes, in  principle, the only problem being once it hits the surface would it be able to withstand the  dry conditions and the increased sterilizing ultraviolet radiation the surface of Mars sees.  And the chemistry of the Martian regolith itself, which is hostile to earth life, at  least in its very uppermost layers.

[00:04:14]The answer to that is that it depends on just what  period of Mars’s history you’re talking about.

[00:04:20]In the past, warm, wet Mars with liquid water  probably could have easily seen it happen and earth microbes gained a foothold. Today however,  it does not seem likely that anything could hang on very long in the harsh environment, though it’s  not totally out of the question. But perhaps a bigger question would be Venus. Venus is a strange  world because while it's unbelievably unforgiving and hot on the surface, it has a layer of its  atmosphere that is perfect, and presents the most earthlike environment outside of earth in the  solar system as far as atmospheric conditions go.

[00:04:55]So could earth life somehow have deposited in  the upper cloud deck of venus through panspermia without the surface being involved? This is  the subject of a new analysis and paper by E.

[00:05:07]L. Guinan and colleagues, link in the description  below, and they detail how that might work between Venus and Earth. Now Venus is a strange world  on the life count. We have all the hints Mars gives as for past life, and some indications  of current, but certainly extremophile life, but Venus is different here in that every  hint it gives of a potential biosphere would point to current active life in its  upper atmosphere rather than the surface.

[00:05:36]Venus presents a number of hints. Most recently  and famously was the detection of phosphine gas in the atmosphere of Venus. While phosphine  isn’t exclusively a gas made by biology, it is one of them. But Venus had been hinting  at something going on far earlier that was worthwhile to investigate, going from the  Venera probes of the Soviet Union detecting particulate matter of unknown origin at a  certain level in the Venusian Atmosphere that matched the size of bacteria, all the way  to a mysterious unknown UV absorber present, again of still unknown origin, that might  indicate the presence of microbial life very high up and away from the crushing  heat and pressures of the surface.

[00:06:21]But Venus is not off the table as far as having  hosted abiogenesis early in its history. In the distant past, it’s thought it might have been an  oceanic water world for a time that might have allowed for it. But that planet’s proximity to  the sun prevented the long term stability of that environment, if it existed, and it evolved  into what it is today. But it is volcanic, albeit in a little bit different way than Earth,  and perhaps life arose there and has gone extinct on the surface only to have maintained a  foothold in the temperate upper atmosphere, perhaps not even requiring water,  but using droplets of sulfuric acid helped by a coating of certain molecules  that might allow for it to metabolize in such an environment. You won’t have birds  here, but maybe very high altitude microbes.

[00:07:11]The paper goes into how the harshness of Venus  presents unique challenges for panspermia to occur. You need for it to be possible  for organic material to survive falling to the atmosphere of Venus, though there is a  body of existing work that suggests that yes, it could actually happen. But the real trick  is for the microbes to be dispersed in the upper atmosphere and cloud deck of venus to even  have a chance. If you go too deep on that planet, no earth life traveling by meteorite will  survive it. It has to be in the temperate zone.

[00:07:44]The modeling for this is a specific type of  analysis model for how meteorites, bolides, pass through an atmosphere. Basically you treat  the bolide as a single fragmenting and ablating object, ultimately forming a pancake shape which  results in the object rapidly decelerating. It can then explode as an airburst spreading even more  fragments. The modeling looked at meteorites of masses in a variety of sizes. A lot depends on how  strong the material actually is, meteorites vary greatly in that regard, the weaker the material,  the higher up the airburst tends to happen.

[00:08:21]They also looked at various concentrations of  cells inside the meteorite and what’s left after ablation and fragmenting of the mass as it gets to  the right height above the surface of Venus where life could deposit in the temperate zone. What’s  left? It turns out that many billions of cells might get deposited by a meteorite into the cloud  deck of Venus. Certainly, most would not survive or find a foothold, but even if a tiny fraction of  them did, it still represented billions of cells.

[00:08:52]Extend this over the multiple billion  year history of life on earth, and many billions of tons of meteoritic material  originating from earth must have fallen on Venus, and very well could have deposited life on  it, even as harsh as the Venus of today is.

[00:09:08]This may get complicated as there are private  plans to do Venus life finder missions and directly sample the temperate layer of Venus  atmosphere and see if there are microbes there.

[00:09:19]If there are, then where are they from? Presumably  this would require genetic testing, probably only doable here on earth to determine if the life, if  Venus indeed has it, came from Earth or natively from Venus. One particularly interesting scenario  would be if Venus life were found, and Mars life were found, and the life at Venus ended up  not being from earth, but instead originated from Mars. Or all three planets might have seen  distinct abiogenesis events, and if that’s the case, that it happened separately three times in  a single star system would make a very solid case that the universe at the very least teems with  microbes, seemingly if not intelligent life.

[00:10:03]The researchers note that the modeling  is rather general, as bolides can be notoriously unpredictable, but it does show that  in general, it’s possible for at least earth life to be deposited in the upper atmosphere of venus.  Whether it can get a foothold is another question, sulfuric acid is not friendly to earth life,  and adaptation to it would be somehow needed, but it may also be possible that sulfuric acid,  being a liquid, can be a solvent for life though work there is still in its early stages as  far as figuring out how. But anyway, it will be an interesting next few decades as we try to  unravel if anything lives in the clouds of Venus.

[00:10:44]Thanks for listening! I am futurist and science  fiction author John Michael Godier currently wondering about interstellar objects. If  you can have panspermia between planets, you should be able to have panspermia in  rocks being exchanged with passing star systems. Such encounters occur regularly  over geologic time and you have to wonder if some planet bearing star system out there  passed close, caught a meteorite from earth, and out there somewhere are the cousins. Not  likely for most interstellar objects though, they spend billions of years in the interstellar  medium and be sure to check out my books at your favorite online book retailer and subscribe to my  channels for regular, in depth explorations into the interesting, weird and unknown aspects  of this amazing universe in which we live.