Venus could have been habitable for billions of years (2019) | Hacker News Reader

Venus could have been habitable for billions of years (2019)

smithsonianmag.com

Growing up I absorbed all the space stuff I could find.

But it wasn't until recently that I realized that the solar system didn't just form into some static natural state where it largely didn't change until say the sun was finished with it's lifespan.

Rather it evolves, changes, planets are habitable, then not, moons are formed and break up, even frozen planets are geologically active and are changing, Saturn's rings are relatively recent and etc.

Not sure how I didn't pick up on that.

Not sure how I didn't pick up on that.

The sheer scale of it makes it hard to perceive, so probably you aren't the only one and probably a lot of the literature has similar blind spots which implicitly signals "this isn't happening" and we pick up on that and it gets implicitly repeated until it's hard to give any kind of push back in our own minds.

For sure. You'll find that our notions of our own world and societies are also very outdated on average due to how rapidly they're changing (and by and large improving).

A wonderful, easy to read book on this that I recommend is Factfulness.

https://www.ted.com/playlists/474/the_best_hans_rosling_talk...

https://www.amazon.com/Factfulness-Reasons-World-Things-Bett...

Until we started sending probes out there, we didn't know much about those bodies. Tectonic plates on Earth were not confirmed till the '60s or so, so... it's not surprising.

I think it's the way it's presented. We still have a sort of Newtonian "clockwork" view in primary education of astronomy.

The "clockwork" view is objectively incorrect due to being the wrong scale. (Some) Accurate scale models of the solar system get played out across city blocks.

If it's a tinkertoy style model or a drawing within a book, it's made up BS. There are no books large enough to actually show it to scale.

Edit: For the pedants of the world, I have added "(Some)" to my sentence. "Not all accurate scale models" of course. Some are even larger than that.

2nd edit: Folding another comment in here as well that I deleted :

https://en.wikipedia.org/wiki/Solar_System_model

The Sweden solar system scale is listed as 1:20,000,000. Others have used a different scale and been fit into less than an entire country. There are several around the world.

In York, it is spread across 6.4 miles:

https://astrocampus.york.ac.uk/cycle-the-solar-system/

There's another in Greater Boston:

https://foursquare.com/eric_odea/list/museum-of-science-bost...

City blocks? Sweden has a scale model of the solar system that stretches across the entire country - north to south. And even then it isn’t actually big/long enough for the entire solar system.

Depends how small you’re willing to make the bodies. In Sweden the Sun is a huge spherical building.

and if it was smaller the planets would be invisible.

It could be made smaller without risking invisibility of any of the planets. The smallest planet is Mercury at 25cm.

The best view of the solar system I've experienced that could be incorporated into classroom learning is a VR tour. It not only shows you the relative distance really well, it also shows you the size of the planets relative to each other and you really get an intuitive sense of the massiveness of the sun (and other stars), for example.

I read Doreen's comment as at least city blocks.

Sweden was, last I checked, larger than a city block.

Here's a Cody's Lab video showing a "to-scale" solar system. https://www.youtube.com/watch?v=dCSIXLIzhzk

It's astounding that astronomers have mapped out the skies just by looking up. It's like as if I mapped out my entire city just by looking out the windows of my house.

If your city was 99% empty by volume and your house rotated every day it wouldn't be THAT difficult :)

"We can only speculate as to what is on the far side of the house on 123 Anytown Road. Human exploration is needed."

In a geology class we learned what very few people realize, that Earth's landscape is constantly changing. Only on a scale humans generally can't perceive.

What's mindblowing is the search for planet 9...once you start to realize that we are surrounded by thousands of dead solar systems (brown dwarfs that very likely were red dwarfs before) in our immediate neighborhood.

Imagine what we could accomplish by mining their resources!

What does this mean? Surrounded by thousands of dead solar systems? Like nearby (dark) stars?

They are called brown dwarfs... but it's better to link the NASA backyard worlds project directly for the curious:

https://www.zooniverse.org/projects/marckuchner/backyard-wor...

I suspected so. But all those objects are in this solar system.Brown dwarfs are sub-stellar bodies.

Touche, you are technically correct.

Though some might argue that in the changing nature of fusion reactions and body mass, this sorting of sub-stellar bodies is only true for as long as our star is a red dwarf.

Once that's over (thinking in the larger timescale of things) and it becomes a brown dwarf, what then? Wasn't it a solar system at one point in time?

(I'm not an astronomer, my understanding is not absolute, please correct if I'm wrong) I believe our Sun is a type G, yellow dwarf. A red dwarf is usually much smaller, if considering "red dwarf" being a type M, then usually no more than 0.6 solar masses, usually much smaller, and a tiiiiny fraction of the luminosity of Sol. Brown dwarfs are not massive enough to fuse hydrogen, where red dwarfs generally are. According to https://en.wikipedia.org/wiki/Red_dwarf, above 0.25 solar masses, they should evolve into red giants, otherwise will shrink into a white dwarf once hydrogen fusion is ceased. The universe isn't old enough to have any red dwarf of 0.25 solar masses to do so, however as their lifespans are so long.

> Once that's over (thinking in the larger timescale of things) and it becomes a brown dwarf,

Our sun will never become a brown dwarf. Stars have their life-cycle and nomenclature. You cannot made your own willy-nilly.

I find it kind of weird to have a different word for the same object depending on where it is. As I understand it, Jupiter would be a brown dwarf except that the presence of the Sun disqualifies it.

Jupiter is orders of magnitude too small to be a brown dwarf. The "brown" implies IR radiation generated by gravitic collapse. If Jupiter was massive enough to generate its own radiance it's unlikely Earth would be around to observe it.

The simplistic solar systems and textbooks in grade school are not just misleading when it comes to scale, but they're really really misleading. Few people really comprehend the scale of things in the universe.

Scale isn't the right thing to complain about here. Compare https://en.wikipedia.org/wiki/Brown_dwarf :

> most brown dwarfs are slightly smaller than Jupiter (15–20%)

> Brown dwarfs are all roughly the same radius as Jupiter.

The suggestion that Jupiter is "orders of magnitude too small" to be a brown dwarf is obviously wrong in terms of size, but it's also wrong in terms of mass:

> at the low end of the range (10 [Jupiter masses]), their volume is governed primarily by Coulomb pressure

It means OP does not have the slightest clue of what he is talking about. I hope he is talking about trans-neptunian objects in THIS solar system.

Maybe a tangentially related question, what happens if you form a system very much like our solar system, but the central body never actually ignites and it just remains a dark ball of hydrogen. Would the system still be called a solar system?

That'd be more of a rogue planet with moons.

That's what i was thinking but if it's the size of our solar system and the 'moons' had moons it gets weird.

(But i guess our moon could have moons so it's moons all the way down)

Sometimes called moonmoons.

A system the size of our solar system centred on a jupiter-sized object wouldn't be very stable - it'd be quickly disrupted by an encounter with a star.

Brown dwarfs are failed starts, something between a large gas planet and a red dwarf. Red dwarfs don't turn into brown dwarfs when they die. In fact a red dwarf's lifetime is so long (up to trillions of years) that its unlikely that we ever see one dying. It is believed that they turn into white dwarfs when that eventually happens.

Beltalowda! The expense series has an entire faction based on asteroid miners.

>(brown dwarfs that very likely were red dwarfs before)

This is incorrect. Red dwarfs will end their lives as black dwarfs. However, no black dwarfs are currently expected to exist because the universe is not old enough yet. Red dwarfs, in particular, are expected to have lifespan of trillions of years.

I'm not sure how old you are, but a lot has changed, recently, in our knowledge of Earth, its evolution, the solar system, and astronomy.

One of the books I had growing up was a Patrick Moore juvenile book on astronomy, probably Seeing Stars (1970). That had a ... pretty good ... description of the state of knowledge at the time, but it was published only about five years after the 4.5 billion year figure for the age of the Earth, and plate tectonics as a geological mechanism, were formally adopted.

The Viking missions, Voyager, Mars rovers, New Horizons, the Hubble Space Telescope, Keck observatory, LIGO ... were all in the future.

The degree of development in the field of geology in the 20th century alone has been staggering. Credible scientific estimates of the age of the Earth in 1900 were as little as 30 million years (Lord Kelvin's gravitational collapse/cooling calculation). Interestingly, parallel developments in physics (notably radioactivity) helped give us the clocks we finally needed to measure geological time. We could trace landmass movements, make some determination of interior structures using seismic (and I suspect nuclear blast) waves, and more.

Much of the more interesting physics (and some chemistry) Nobel Prize awards of the past 50 years have been in sensing and detecting, at large and small scales, again, giving tools to measure, detect, and distinguish patterns, structures, and phenomena.

Within my own lifetime notions such as the asteroid hypothesis for the mass extinction of the dinosaurs have passed from wild theory to accepted fact, we've got evidence of 300 million-year snowball Earths, strong evidence concerning early Earth evolution, atmospheric composition, and life. We have detected thousands of extrasolar planets (a value still strongly limited by what sizes, types, orbits, and distances at which such detection is possible). Pluto's been un-planeted, and imaged. We've kissed the face of comets and returned their dust to Earth.

And we're starting to get some idea as what the long-term stability of planetary orbits might be --- the notion that planets may wander not only in the skies but in their orbital characteristics ... would change things markedly.

So it's quite possible that what you didn't pick up wasn't there to pick up when you were learning it.

Very good point. I'm in my 30s and it's even come a long way since I was a kid.

We didn't know until recently that there were planets orbiting other stars. We suspected that there might be, but we didn't know. The idea that there could be other "earth-like planets" was a hopeful guess.

When the headlines started coming in from Kepler, that was huge. Very exciting and huge.

The big news we're looking for from James Webb is the possibility of grabbing evidence of chlorophyll fringes in the IR spectra of other planets.

That is going to be huge news if we find it (I suspect we'll get a lot of other results first though and a ton of new interesting work looking for alternative photosynthetic chemistries).

Wow, chlorophyll-equivalent detection? I though JWST was just going to be able to prove diatomic oxygen or other gas chemistries in atmospheres.

https://www.jwst.nasa.gov/content/forScientists/faqScientist...

> asteroid hypothesis for the mass extinction of the dinosaurs have passed from wild theory to accepted fact

We should NEVER accept a hypothesis as fact because that makes people stop thinking or searching for answers. And there’s no way we can even definitively say something that happened tens of millions of years ago actually happened.

I personally think it was an asteroid too, but I never want to be arrogant enough to think it’s a closed case now. For example, it could have been the switching of the poles causing cosmic radiation to cause mass extinction, similar to why the Neanderthals disappeared and there would be no way for us to know.

There have been recent advancements in the hypothesis you may find interesting:

https://phys.org/news/2021-02-asteroid-crater-case-dinosaur-...

We can of course continue to look for disconfirming evidence, alternate explanations, or Incontrovertible Signs That God Is A Prankster, but come a certain point and the focus becomes one of refining rather than overturning theories and models.

It’s rather arrogant as a species for us to believe that enough evidence remains tens of millions of years after something like that happened that we can come to a conclusion. For all we know, a pandemic could have swept across the globe and killed all the dinosaurs and there would be no way for us to detect it.

Occam's razor suggests:

1. Such a pandemic (or other calamity) occurring simultaneously with overwhelming evidence a catastrophic asteroid impact is exceedingly unlikely.

2. Cross-species pandemic resulting in mass extinctions are similarly unlikely. Boom-bust population cycles perhaps. Mass cross-species extinction not so much.

3. Patterns of extinction (and survival) far more closely match the presently-accepted conclusion.

4. Precisely because an infectious agent leaves few multimillion-year traces, any defence of such a hypothesis can advance no further than "it might have happened". This is not evidence-based argument. (Traces of pathology might be preserved in fossil or amber substrates.)

Point remains that multiple highly consistent widely-distributed lines of evidence point to the asteroid hypothesis.

One unsubstantiated Hacker News comment points to the epidemic scenario.

Absolutely, very well said. Our understanding of the cosmos has changed dramatically in the past 100 years. People forget that we were still debating whether galaxies beyond our own existed (!!!!!!!) just 100 years ago.

https://en.wikipedia.org/wiki/Timeline_of_knowledge_about_ga....

With such knowledge ready at hand for such a thorough comment on HackerNews, I am curious what your learning lifestyle is (books mostly? What kind? How many hrs a week? How much other media do you consume? Youtube? Netflix docos?). As I get older I'm realizing that life is too damn short to learn all the stuff I want to learn and so am constantly thinking about how best to spend my time.

There was a very interesting thinker in the 18th who wrote that eventually the Earth would gain a planetary ring. He talked about how everything changes, even though our lifespan is so short we don't see it. And he was particularly speaking about society: afterall, he was a very progressive member of the generation that indeed abolished slavery, even though a lot of people said before: "Slavery's been going on for 80k years, it will never end". I learned a lot from his writings, and I believe our society could learn a lot from them to this day.

The wikipedia article is very poor compared to the depth of his work/thought but here it goes anyway for reference: https://en.wikipedia.org/wiki/Charles_Fourier

Any books or writings of his you would reccomend in paticular?

I love almost all his work tbh - actually I've been translating a compilation of some of his writings from spanish to portuguese and I also contributed to his page on portuguese wikipedia :)

You can dive in from wherever, and you will be able to know his cohese and wonderful universe of thought - it really doesn't matter, because it's a single entity, so you can start from his thoughts about family, work, slavery, astronomy, architecture, higiene, urbanism, politics, religion, sex, tolerance, women, commerce, law, philosophy, love, etc

I should warn you to beware of the translation because there are bad ones - he's a guy coming up with words and concepts and always playing with language and meaning, so you gotta be able to read between lines. I wish you a good reading, if you can find them because they seem to be kinda rare, and mind = blown! If you'd like to exchange some ideas about it later, feel free to get in touch!

My limited understanding says that his prediction is spot on as we seem to be building a planetary ring of space junk.

I sort of got the impression it was static as a kid as that's how all the books were written. I think its changing nature is a relatively recent discovery. I remember a lot of debate as to whether a meteor could have done for the dinosaurs because people were skeptical that sort of stuff happened but it turns out chunks of rock smashing into planets is quite common and basically how they got here. I also got the impression Earth was more unchanging than it is. It was a surprise to find you could walk from England to France 10,000 years ago or so.

Highly recommend anyone to look into Oceanography! The ocean floors reveal a lot of ancient geological history and the Earth is much more dynamic than what meets the eye. Sea floor spreading, plate tectonics, and much more can be studied simply by observing the ocean floor!

A lot of things we think are static do actually change quite a bit. Tiny changes add up to a lot over time. I once buried a little canister with some money inside (in a shallow hole next to a distinctive tree) in the woods while hiking, just to see if anyone would find it. I came back a couple months later, took me a very long time to find, I did eventually, and it was much, much deeper than I had buried it. The soil must have shifted way more than I thought it would in that short period of time but it's not something you would ever notice from day to day.

And it could be again...

I wish we would plan ahead and try a solar shield at L1. If we cooled the planet sufficiently, the CO2 would solidify and we could get to work processing it. Venus is far more interesting than the dusty little rock we keep probing. Sure, it may take a millenium, but the sooner we start, the sooner we finish.

Or send some microbes which convert it into oxygen. You are right Mars doesn't have enough resources to support anything.

that's an interesting proposition. If terraforming is really about engineering the right microbes to slowly (over several millenia even?) the atmosphere to habitable for humans, do we currently have the technology to actually accomplish it? Or is it still too advanced form of engineering?

With concerted effort I’m sure we can do something about it in a couple decades at best.

We can't even terraform the Earth.

we are terraforming the earth - see how much co2 is being pumped out!

It is being prepared for species better adapted to high temperatures than us.

Since we're trying to move _away_ from "terra", should we call the current state maybe "marsforming"?

Terraforming refers to 'turning another planet into a second terra'. Marsforming would be 'turning the planet into a second Mars', which wouldn't be particularly useful, since we can't live on Mars anyway.

The joke they're making is that since we are in the process of turning the Earth into a second Mars, we should be calling what we are doing now marsforming.

i think you'll find that venus is the place with the runaway greenhouse effect, not mars!

Whoosh... Sorry

The combining form would be marti-. (Compare "Martian".)

We're going towards Venus rather than Mars, though. So "veneraforming".

I think biology-wise it’s a question of money. We might not be able to engineer such microbes just right now, but we could if we had more resources dedicated to it.

Also Venus is closer (minimum 38.2 million kilometer for Venus vs minimum distance of 55.7 million for Mars).

However I don't know about the microbes, i fear that they might get killed at an average temperature of 737 K (464 C).

https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.htm... https://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.ht...

Hopefully someone can provide more info, but apparently there are some bacteria in geothermal vents near Baja California that seem to be able to handle venus-like conditions. No idea what the details are though

Interesting, wikipedia says these microbes are called thermophiles, and that they can survive for up to 122 degrees celcius. That is still less than what they have on Venus, that is 464 degress. https://en.wikipedia.org/wiki/Thermophile

You cant really use distances for orbiting bodies like that. But it is true it's easier to get there.

The problem is that Venus is missing important ingredients for life. Most notably is the lack of hydrogen.

If you are interested in learning more on hypothetical approached of terraforming Venus, I suggest reading this Wiki article: https://en.wikipedia.org/wiki/Terraforming_of_Venus#Biologic...

But the outer planets have excesses of hydrogen, so round trips could help there?

The upside is, of water aka H2O that we need, the 2 H atoms are the lighter component, specifically:

2H = 2 * 1.67 * 10(-24) grams 1O = 1 * 2.65 * 10(-23) grams

So hydrogen is 11% of water, and oxygen is 88%;

meaning every kg hydrogen can combine with 8kg oxygen to give 9L water.

So all the Oxygen already being there (in CO2) is good.

If we were capable of planetary-scale transportation of materials, we wouldn't really need to live on planets anyway - it'd be a rather moot point.

Space stations would also be practical, yes, but I'm not sure how desirable they'd be (for long-term habitation). Also, we don't really know the long-term effects of low gravity, whereas earth and Venus have similar gravity wells.

Transportation no, but with large enough reflective surfaces we could redirect comets to impact courses on Venus.

Early stage terraforming need not be too fussed about collateral damage from multiple extinction-events (and the footage I presume would be spectacular).

Venus is interesting in so many ways.

It did not, so far as we can tell, get blasted by a Mars-sized proto-planet like Earth did, which made the Moon and entirely re-melted Earth, so probably got a good head start on breeding life. But maybe Earth's plate tectonics came from that event, too.

AIUI, our Moon is also the reason we are not tidally -almost- locked to the sun, with a permanent equatorial 250 mph wind.

If Venus wasn't hit with something massive why the weird backwards and slow rotation that no other planet has?

I feel like even if Venus had Earth-like atmosphere it'll still be hard for life to endure the 121-day long "day" and "night" where temperature would go from like 250°C to -250°C (numbers from the top of my head). Maybe only on poles there would be possible for water to stay in liquid form for long enough so that life could emerge.

Tidal locking is the normal condition for solid planets. Literally all large and all close-in moons, and most of the distant ones, are tidally locked to the parent planet. Pluto and Charon orbit a common center, locked.

Mars and Ceres get a pass being far from the sun and close to Jupiter. Earth gets a pass because it has a massive moon keeping things stirred up. Venus, like Mercury, is not quite locked. As your rotation period gets close to your orbital period, tidal forces are much reduced. Venus could be oscillating around a resonant point, not yet settled into it.

Temperature difference between day and night cannot be large with a 250 mph global wind keeping the atmosphere well-stirred. Under an ocean, life would be further protected from temperature extremes, with high wind performing evaporative cooling on the day side, and surface ice insulating on the night side.

A solar shield would be a serious space structure. A mega-structure even.

We (any/all nations of humanity) don't really have much of a space presence, let alone industry. If we did, I think we'd first build solar array, around earth, to help our energy shortage; I'm not sure we have a space shortage, so Venus doesn't really solve any current problems.

Maybe we can find a light gas that could form a thin layer in the upper Venus atmosphere to change its reflective profile?

That would be a very long extension cord

Either stuff could be manufactured in space or, light could be beamed down to the planet; I wasn't thinking of a solar array of photo-voltaic panels, but rather an array of mirrors and something to condense it into a deathray / beam.

The great thing about a solar array in space is it can be in sunlight 100% of the time, without needing to change orientation, and the shadow it casts needn't be on earth (i.e. nothing is deprived of sunlight).

The difficulty is that since the earth spins, and we couldn't beam down to the same location, so maybe we'd need an array of geo-statically orbiting beam relay stations to switch between.

> And it could be again...

It could. On the other hand Earth could become the next Venus, if climate change runs out of control. No?

No.

For one, Earth is much further away.

But most importantly, we have no clue if our current carbon levels are any sort of maxima in regards to what the planet can handle. We just have our own little recent industrialized history, and some charts about the past that are, at best, educated guesses.

As George Carlin would say, "The planet will shake us off like a bad cold"

Climate change is more important for our species survival much more so than the planet. The planet will be fine. The planet will recover after we're gone.

I’m curious if you’ve read research on this? “The earth cannot become like Venus” seems like a strong positive statement that should come from research. I genuinely don’t think our innate intuition is enough here, even if it aids in comedic punchlines.

This innate intuition comes from the familiarity of the research. Much of science in this realm is essentially conjecture, useful for securing funding dollars and keeping bright minds entertained.

Comedians such as Carlin were highly intelligent, part of what made their genius. His jokes are typically funny because they contain much truth that otherwise few others would say.

The planet might be ok after us, but still might not be able to birth another potentially space faring civilization, dooming earth life to extinction.

Look at how:

- no other earth based space faring civilization has evolved before us.

- other intelligent species do not seem well equipped to do so, as it's hard to evolve tools without hands / prehensile organs (cetaceans), or when your lifespan is short or you're not social (octopuses & squids).

- we used up pretty much all easily accessible fossil fuels for our industrial revolution and they may take hundreds of millions of years to reconstitute, and it's unclear if anyone could evolve an industrial civilization without that kickstart of easy energy.

It's far from certain that if we disappear earth will get another good shot at evolving a space faring civilization before it's too late.

Considering the industrial revolution had been in full swing for a century before the use of fossil fuels became widespread I think you make a poor argument.

Just because we were the first doesn't mean we'll be the last. A billion years is a very very very long time, and there are multiple billions of years in the Earth's future.

The industrial revolution's beginning is defined by coal mining and the steam engine.

I don't understand what you mean about it having been in full swing for a century before that.

The riverfront up and down the Jones Falls in Baltimore is littered with "mills" or factories, which are located there because they needed water power. My understanding is that real industrialization got started with things like the Arkwright water frame, and then the steam engine allowed factories to spread to more convenient locations.

Ironically, one of the first uses of coal-powered steam engines was to pump the water in ship canal locks so goods could be moved to and from water-powered factories.

> no other earth based space faring civilization has evolved before us.

needs citation

Anything placed at geosynchronous orbit will stay up there effectively forever. There was nothing up there until Humans placed things there. Therefore, there was no previous Earth based space faring civilisation.

> But most importantly, we have no clue if our current carbon levels are any sort of maxima in regards to what the planet can handle. We just have our own little recent industrialized history, and some charts about the past that are, at best, educated guesses.

The article mentions massive amounts of C02 released 500 million years ago by volcanic activity in the Siberian Traps. The dinosaurs evolved on an Earth with six times the amount of C02 in the atmosphere we have today. So we're nowhere near a maxima. It's just a question of how difficult climate change will be for our civilization and parts of the biosphere we rely on.

> Sure, it may take a millenium, but the sooner we start, the sooner we finish.

For technology with uncertain results and uncertain resource requirements, this does not follow. It may well be that any effort we spend today is entirely wasted 100 years from now.

But you won’t learn anything unless we try. And having some shared goal for the humanity could be life changing.

And thus the argument on which absurdly expensive shared goal to choose begins. You want to terraform Venus. I want to develop mind uploading and thus optional immortality. Another person wants to solve world hunger. Somebody else wants to cure cancer. Etc.

the cost, feasibility, and moral imperative of each of those things is vastly different. "curing cancer" has been happening and world hunger has been dropping for decades now, mind uploading is still far on the horizon, and thinking of terraforming at this stage seems silly

Venus has lost almost all of its atmospheric hydrogen. Teraforming a planet like this to sustain life would be quite a challenge.

Here's an excerpt from the wikipedia page ( https://en.wikipedia.org/wiki/Terraforming_of_Venus )

Difficulties include the fact that the production of organic molecules from carbon dioxide requires hydrogen, which is very rare on Venus. Because Venus lacks a protective magnetosphere, the upper atmosphere is exposed to direct erosion by the solar wind and has lost most of its original hydrogen to space.

Something's missing. Earth isn't able to retain atmospheric hydrogen either. (And, obviously, therefore doesn't have any.)

Earth's atmospheric hydrogen is oxidized

Venus has plenty of atmospheric sulfuric acid.

Find a few comets with a lot of hydrogen (ice), attach a rocket to it, send it to Venus. Problem mitigated.

"Because Venus lacks a protective magnetosphere, the upper atmosphere is exposed to direct erosion by the solar wind and has lost most of its original hydrogen to space."

Venus has a magnetosphere, although not as strong as Earth's. The problem with Venus' atmosphere, AFAIK, is that the heavier carbon dioxide layer is so thick that reaches the limit of that magnetosphere and in doing so it pushes the lighter molecules like hydrogen or even water to be exposed to the mentioned solar wind. If enough of that atmospheric carbon gets somehow fixated, then the freed oxygen should act as a capture net for all the solar wind's incoming protons and form water molecules (which, being heavier than oxygen, should then sink into lower atmospheric layers).

P.S.: I assumed only "enough" of carbon taken out of the atmosphere, so enough carbon dioxide should be assumed as left there untouched, which now with newly available water molecules should result in bicarbonate, carbonic acid, and other goodies, thus preserve Venus' traditional acidic environment, so no worries there! ;)

Wouldn't a solar shield get heated up by a force equal to the amount of energy it's providing shielding for minus whatever it can reflect away? That would require some significant cooling even if the shield is 99 9999% reflective. How would you stop it getting too hot and eventually breaking down?

Nah. It would radiate out heat if it got hot, especially if the back was dark. I don't think the heating would be much worse than putting something out in the midday sun on earth.

I may talk out of my arse, but my understanding is that the majority of the heat is coming from the inner planet core which can't cool to space due to the insulating blanket of CO2, not from illumination from the sun (something like an order of magnitude more)

so nothing will be practically solved with a sun heat shield, we need to find a way to break the CO2 somewhat quickly

but then we have the same challenge here on Earth....

I agree that it is interesting but we haven't learned how to take care of this planet and it has unlimited (with appropriate behavior/population changes) resources. We never consider that humans evolved for this gravity and have no permanent home on the moon but people want to terraform Mars or Venus. Even if we did, we'd destroy them even quicker. We don't need another option until we've proven we can take care of the free gift we already have.

It's interesting that multi-cellular life developed on Earth around the same time these scientists hypothesize Venus would have become uninhabitable. Unrelated... still, fun to think about.

https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_h...

Not overly. The Great Oxidation Event nearly destroyed all life on the planet. If it wasn't for a mutation that allowed life to live in an oxygen rich environment Earth could have gone the say way as Venus.

It might also be thought of as a natural consequence, i.e. evolution at work.

My working hypothesis is that the galaxy (if not at least the solar system) is teeming with rocks containing Protozoa that are ready to colonise any planet with the right conditions (in a matter of thousands of years after the conditions are right) the moment they are ready. Perfectly explains everything we see and honestly would not be surprising at all.

We need to start developing meaningful working hypotheses and make judgement calls instead of waiting till we have definitive proof. This was similar to how basically no one was surprised that every star out there has planets around it yet we were writing sci-fi under that assumptions for basically a century before definitive proof.

Wow, that's... actually pretty sensical. The science part of me rejects it for having no evidence. But the pragmatic part of me would put its money underneath the theory. The reason

The bigger question is: how did the first Protozoa form? The usual primordial soup theory of random chance?

One good thing about this theory is that if there are 10^7 habitable planets at any given moment, each of them are "trying to produce life." So the chance that life gets to Earth increases multiple fold.

One problem for this theory is that if it takes a thousand years for Earth to get protozoa from another planet, then we would expect to have gotten multiple different types of Protozoa. But there is basically no variety on Earth: it's all carbon, and 99% uses oxygen (a few use sulfur).

So evidence pointing towards a common ancestor for all life here on Earth, or at least very similar common ancestors, might imply that of a seeding event, there wasn't much variety.

However, if we assume a seeding event happened, what's to say it couldn't happen on a lot of planets around the same area at the same time? The Fermi paradox is too speculative to say we aren't the only ones.

One thing that's missing is a seeding mechanism. Can an asteroid eject enough debris for some of it to reach escape velocity on a planet like ours? Did these protozoa come from a very different (but chemically compatible) environment?

I am curious if floating microbes in our atmosphere can just randomly leave the planet - like are particles small enough to undergo Brownian motion subject to the same escape velocity ?

If we work under this assumption, then I’d expect all the living material out there to be of the same chemistry and origin - again unproven conjecture but I’ll be surprised if two life forms of completely different chemistries can compete on comparable levels in the same environment - one will probably always be more efficient than other due to fundamental limits on the chemistry of their constituent molecules; I feel like new life of any chemistry can only form in a sterile environment since pre existing life seems to find ways to harness all available energy in any environment quite soon. Thus if we have life of a particular form floating ready to contaminate any new planet, then it’s possible that life of no other form can form in that galactic neighbourhood!

So the Star Trek episode where they discover why all the species around the galaxy all have DNA based genetics is probably on the money if you ask me!

If all the environments are made of rocks and water (and therefore oxygen and hydrogen atmosphere) then chemically you've got enough for converting sunlight to power, surely?

It's an interesting theory but I feel like it doesn't reflect the reality. If galaxy was indeed teeming with rocks containing some sort of microbes than where did they all come from? It'll take an enormous amount of effort to populate an enormous amount of rocks and scatter them across the galaxy. I wouldn't presume that Protozoa would appear on asteroids just by itself. For this mechanism to work there would have to be millions or even billions of such rocks for every star system to ensure that at least a couple of them land on a ripe planet and some of the microbes survive the impact. Most of these rocks would end up falling into a star or a massive gas giant. And we have to think in terms of billions of years here. So these populated asteroids would have to keep falling on a potential life-supporting planet for a couple billions of years until it indeed become habitable.

Ok, even if this mechanism of fertilizing planets was indeed functional as you suggest, we still don't see any evidence of intelligent life out there in our galaxy. Surely, out of billions of planets and billions of years time there would emerge at least a couple of civilizations capable of colonizing a significant part of our galaxy. There's certainly a slim possibility that we may be the first of such civilizations, but I'd be surprised to find out that humanity is THE smartest and most reasonable civilization out of billions others that our galaxy was capable to produce so far.

Well I’m unfortunately digging even deeper into my unproven conjecture well but I do have a working hypothesis for the lack of intelligent life - it’s actually really hard to develop intelligence in the human sense. It looks like there are a lot of extremely intelligent creatures even here (parakeets dolphins elephants) which can’t do shit because they lack thumbs and a peoper larynx so it’s possible the real great filter is what Id like to call actionable intelligence where you are smart and are able to apply and communicate this.

Another possibility is that the window in which life following similar intelligence trajectory as us will actually broadcast in measurable frequencies for a short while (centuries) before rapidly moving on to the next phase of their evolution (who knows what it is? Star child? Transcendence? Warp dimension) so we only have thin shells of radio waves expanding from each planet that developed intelligence making it impossible to detect.

"The Hot Spring Hypothesis for an Origin of Life" - https://www.liebertpub.com/doi/10.1089/ast.2019.2045

Maybe they crashed their huge spaceship on Earth and killed the dinosaurs. Two of them survived and started gardening.

Is this an EYES ref?

I love thinking about an alternate reality where Mars and Venus swapped orbits so that both were habitable.

Having three planets with their own unique plants and animals, and having colonization by humans at our current tech level, is a fascinating alternate reality.

I wonder if one were to install a solar shade in front of Venus to block all light from the sun, how long would it take to cool to "normal" temperatures?

The Earth cools pretty fast between day/night and seasonally, but Venus has a much thicker atmosphere, almost more like an ocean. And then the ground itself wouldn't cool instantly either. That's a lot of thermal mass.

Would cooling it help to reduce the amount of pressure the atmosphere has? Isn't the pressure on the surface something like 95 times that of earth.

Which is also largely why it’s hot.

Surely it would cool below the point where Co2 becomes solid (most of the atmosphere is Co2).

Imagine walking around on fields of Co2 :)

Reminds me of the short story "A Pail of Air".

I read that short story as a kid and tried to remember the title for years, you’ve just scratched that itch!

I read an SF story a few years ago where the idea was to sequester the carbon of Venus into blocks of diamond. A minor bit of (ahem) atmosphere in a pretty good novel . . . just don't remember the title.

You beat me to it. Just posted a comment saying the same thing. I think if we solidified the CO2 we would have an easier time dealing with it, but IDK. Then again, we might be able to get to work now by just suspending some blimps in the upper atmosphere. They could use solar energy to sequester the CO2 and start lowering the pressure & temperature.

PV=nRT, so yes, reducing the temperature would reduce the atmospheric pressure.

Edit: wasn't thinking at all about the volume

Volume would vary in this instance, too, right?

Or volume. More likely volume, since the pressure is just a function of how much stuff is above me.

While the equation you give is valid, I think it is probably not that useful given the "volume" is open to space and so we can't solve this equation.

I think more useful is a static equilibrium, specifically that d(pressure)/d(altitude)=-density(pressure,temperature)*gravity(altitude).

Which gives you roughly an exponential falloff with altitude if you assume gravity is constant (which is fine if it's a small fraction of planet radius) and molecular weight and temperature are constant (that's definitely not true but oh well)

EDIT: for the question asker: reducing the temperature would have a first order effect of just making the density gradient steeper, but surface pressure would be the same. The second order effect might be that the surface absorbs some CO2, which would actually reduce surface pressure.

It's not, though, the Venus atmosphere does not behave like an ideal gas all around, it transitions into a supercritical dense liquid towards the ground.

I think the average pressure should stay about the same because the mass stays the same, but if it compresses maybe the pressure goes up in low-lying areas and goes down at higher altitudes.

According to Wikipedia, CO2 can liquify at around 5 atmospheres, though it has to be pretty cold at that pressure. The phase diagram shows it as a liquid around room temperature (300K or so) at about a hundred atmospheres. Which makes a liquid ocean of CO2 is at least sort of plausible if the temperature drops far enough.

https://en.wikipedia.org/wiki/Carbon_dioxide#/media/File:Car...

No, and the other comments about gas laws and volume are overthinking it a bit. Pressure at the surface is caused by the weight of the atmosphere. On earth, a column of air extending from sea level to space, with cross sectional area one square inch, weighs 15 pounds.

Neither the temperature or volume of the atmosphere changes its weight. (Ok, I suppose a hotter atmosphere has more volume and extends higher into space and weighs slightly less, as it is farther from the planet on average, but I assume that’s a fairly negligible effect)

You forget things like condensation/solidification of things like CO2 in lower temperatures, so atmosphere composition would change dramatically, and so would overall 'weight' of the column to space you mention.

Anyway as other mention it doesn't change that much in survability, having 116 days long single Venus-day would mean temperature differences would be extreme, probably in hundreds of degrees.

Mars, shortly before sunset, a few billion years from now.

Martian: "Are you saying seriously believe that people used to live on Earth? And that the only thing they managed to send here from their civilization are spores to grow these mushrooms?"

Or maybe someone's asked that about Mars before we did?

https://en.m.wikipedia.org/wiki/Silurian_hypothesis

That one kinda blows my mind.

Such Lovecraft vibes from that one... I love it.

Color me mind blown too... That's worth a submission on its own

If you're interested in ancient civilisation speculation, you must read some Graham Hancock. Or watch his interviews with Joe Rogan.

Good idea, it gets posted once in a while on HN in comments, but not submissions.

Submitted.

A lot of CO2 and sulfuric acid is not a problem, it is an opportunity. CO2 means a lot of carbon, and oxygen, sulfuric acid means a lot of sulfur, oxygen and hydrogen.

Oxygen and hydrogen is water. Carbon is life and is solid.

We just need to engineer a process that can use solar energy to convert these substances into some more interesting form. Perhaps some engineered bacteria could do the trick?

Question I'm asking myself is, what's the likelihood there would have ever been fossil fuel deposits with the potential to kickstart a civilization?

Humans had civilization before we knew how to use fossil fuels, we just didn't have industrial civilization. AIUI civilization mostly consists of agreeing to live and work together in groups bigger than Dunbar's number.

Yeah of course would you'd need to redefine civilization as "inudstrial" civilization for my argumentn to make sense. Still, check out parent post: https://news.ycombinator.com/item?id=26563017

tl;dr: we've kickstarted civilization due to our harnessing of energy. If the venusians didn't have that option they would've probably lived as cavemen and couldn't have prevented or foreseen the disaster.

Unless the disaster was self-inflicted by the Venusians, when they unleashed the sequestered carbon by harvesting energy.

This is one of the reasons this story sticks in my mind.

I've seen two pretty common definitions of "civilization". One is agriculture; one is writing.

There have been plenty of "barbarian" groups that coordinated on very large scales.

We could always have done a lot with wood and steam engines or even making wood gas or ethanol.

A lot yes, but anything near what we've done now? Over the course of a couple of [thousands|million|billion] years sure.

And if at a slower pace that would definitely (or should have) resulted in quicker reaction skills/abilities than we have now with a 50-100 year timespan within where our established way of being will have collapsed.

We eventually would have discovered fission, and without fossil fuel alternatives it would have taken off on a much larger scale.

I recently learned about the estimated age of the universe. It’s only 13.8 billion years.

So when it says Venus was hospitable for billions of years, let’s say 2 billion years, that amounts already to 14% of all there was and will ever be.

What marvel did happen in this time?

> So when it says Venus was hospitable for billions of years, let’s say 2 billion years, that amounts already to 14% of all there was and will ever be.

Huh? You're saying the universe is about to end?

I guess he meant that Venus' habitable days will never return.

That would be 14% of all there ever has been.

In order for it to also be 14% of all there ever will be, the future would need to have zero duration.

We've had life for about 500 million years on earth. Maybe a billion as single celled life forms. I used to worry that in 5 billion years it'll all be over on account of the sun entering a new phase and engulfing Earth. But it appears in about 800 million years photosynthesis will no longer be possible [1], which puts an even closer limit on our time here. There's a good chance some will get off this rock, but many won't. And all that we know will be lost, and we'll need space suits to visit, no more nature to enjoy, just barren rock. We'll not be us anymore either of course, time will tell what we evolve into.

[1] https://en.m.wikipedia.org/wiki/Timeline_of_the_far_future

> We've had life for about 500 million years on earth.

Somewhere from 3.5 to up to 4.5 billion years: https://en.wikipedia.org/wiki/Earliest_known_life_forms

You're right though; our time here is very short and if we want to ensure survival of Earth-based life then we need to start considering panspermia, first to other planets in our own planetary system (assuming they don't have native life already -- we're not entirely sure about that yet), and then to other systems.

If we can colonize a world around a red dwarf, preferably a young one, then Earth-based life should be set for billions of years into the future.

4.5 billion years until by the laws of physics a state emerged, where macrobodies consisting of billions of cells, fueled by exploitation of energy from chemical reactions, are using movement devices that employ triggered explosions, and are constructing machines which assemble elements on atomic level in such way to make apparatuses which enable the harvest of information by the laws of logic.

I don’t know, people. Maybe I am turning pessimistic, but it took the universe in between a third and a half of its duration of existence to produce a system which yields mass produced RGB keyboards, failed SpaceX launches and climate destroying lifeforms. I would estimate the probability of another biogenesis happening in parallel to ours is very low.

On a single other planet? Very close to 0. But multiply this number by say 400 billion for our galaxy, and maybe additional 150-2000 billion for all the galaxies, and the chances are not that bad. Probably.

Plus the idea that life needs to look the same as here on Earth has no logical base - it could be from number of other elements, forms etc. Basic premise is just multiplication, where it goes from there is anybody's guess. Carbon with water is convenient but its not the only option.

What other elements do you think could form life?

Or are you speculating there could just be such different physics out there we struggle to image what different worlds could be out there.

Silicon has been suggested as an alternative to carbon as basis for biochemistry. Ammonia-based life has also been suggested (and is also a rather common sci-fi trope).

It's both water and carbon that are necessary for our kind of life.

Interestingly, I was reading about how a silicone environment could have similar traits as a water/carbon one. Silicone can form polarized matrices.

It took several billion years for the stars to form, blow up, and fuse the elements into heavier and heavier elements that then formed our galactic neighbourhood, our sun and ultimately Earth. Then it took more than 4.5 billion years for Earth to cool, develop life (or get contaminated, if it was panspermia) and evolve that life to a point where it split the atom and built a planetary communications network that allows ordering pizza from any single point on the planet's surface.

I'm certain this process could have been quicker elsewhere, and there's no reason to believe life could not develop under different circumstances, but it's definitely plausible that extra-terrestrial life -- assuming it exists -- is a rare thing and that any alien civilizations may be few and very, very far in-between. On the other hand, the Universe is a rather big place, and even if there's just a single species who reached space in the entire galaxy, that still leaves us with the possibility of life elsewhere.

"A long time ago, in a galaxy far away" is quite fitting. Other technological civilizations could have developed, risen and fallen and crumbled into dust while life on Earth was nothing more than a bunch of proteins chilling in a hot spring.

On the ther hand, it implies that if at some other place these processes happened 1% more quickly, or started 1% earlier, then that civilization would have had tens of millions of years head start to us; they'd have rocket launches back long before Earth had its first primates

It indicates that if we ever meet someone, it's extremely unlikely that they'd be of remotely comparable tech level, more likely they'd be millions of years behind in evolution (i.e. pre-intelligence) or millions of years ahead in technological development i.e. something that's hard to imagine, our fantasies are mostly about extrapolating a millenium of actual novel development.

If you’re worried all will be lost, perhaps focus on how we can make sure Information survives for a thousand years as a first step. It’s really not so trivial.

Why is everyone so caught up on the atmospheric pressure of Venus being 90 atmospheres? That's only 3K feet of water, and plenty of stuff lives deeper then that in the oceans - so obviously things can survive the pressure ?

I think the issue is that we can't.

Fair enough. I just see the pressure mentioned often in a context that makes it seem its a problem for 'life'.

The heat is a bigger problem

That’s enough time for a civilization to have been born, lived, and died. Unfortunately there’s probably no way to find evidence of their existence by now it seems? Some day they may say Earth could have been habitable for billions of years.

That's practically guaranteed.

Eventually, the Sun will expand so much that Earth's atmosphere will boil clean off.

A mega-civilization with enormous power could move Earth, buy some time, but nothing lasts forever.

> buy some time, but nothing lasts forever

That reminded me of The Last Question by Isaac Asimov. Quite enjoyable if you haven't read it already: https://www.multivax.com/last_question.html

I remember, when I first read this story, thinking how quaint this notion was:

"In his father's youth, the only computers had been tremendous machines taking up a hundred square miles of land. There was only one to a planet. Planetary ACs they were called."

Yet here we are, consolidating our planet's computing power to a handful of cloud computing providers.

Why move earth when you could just throw up some shade?

By then things would be so different it's impossible to imagine what humans might do or be capable of our interested in - if we're still around.

Shade won’t help much when the sun is a red giant star…

Why not? Shade continues to function the same.

If placed at the Lagrange point between Earth and the Sun (supposing that's not too close to said red giant), you wouldn't even need that much.

That's why I made reference to a generic "mega civilization".

We're talking hundreds of millions of years from now, the only safe bet is that "humans" as we understand them won't be around. That would be as weird as the vernacular language of a people being an English we would understand, in 100,000 years!

Our descendants might be a mega-civilization. Our creations might be, or rather the descendants of our creations. We might get wiped out by an alien von Neumann probe, get wiped out and then get von Neumann probed, or ordinary colonization, or, maybe we'll uplift the rats and they'll overthrow us, or dolphins will come back on land and grow thumbs!

It's a lot of time, is what I'm saying.

It's a bit extreme to make that leap. Multi-cellular life only emerged on Earth ~600 million years ago, after the supposed habitable period of Venus.

It's unclear for how much of the 4.6 billion year history of the earth multicellular life could have emerged and just how improbable the evolution of multicellular life is.

There are certainly events such as the symbiosis of mitochondria which appear to have occurred only once in the history of life on earth.

Complex multicellularity and cellular endosymbiosis have both occurred multiple times on earth. Those aren't the hard part. Further, there's no reason to assume that having mitochondria (rather than just having an intrinsically more efficient metabolism) is optimal, much less necessary, rather than a path-dependent accident of Earth eukaryotes.

> both occurred multiple times on earth

Citation?

Any Biology & Ecology 101 book from the last decade and a half.

Provide a link to one.

There are several kingdoms with multicellular life. Plants, animals, most fungi, some protists (many protists are more closely related to animals, fungi, or plants than they are to each other for that matter). See: https://en.wikipedia.org/wiki/Eukaryote#Five_supergroups

Note e.g. that animals and fungi are closely related on this diagram, but there are unicellular fungi (notably yeast). I would guess that this means the common ancestor between animals and fungi would have been unicellular. At any rate, both are far from plants, and other protist species unrelated to all of these are multicellular.

Endosymbiosis is generally accepted to also have occurred with chloroplasts. I believe there are also contemporary observed cases of protists consuming photosynthetic organisms and becoming immobile.

Check out the abstract of this paper: https://www.pnas.org/content/99/18/11558 It takes for granted not only the long-established belief that chloroplasts were once free-living blue-green bacteria, but a number of eukaryote-within-eukaryote endosymbioses. As for multi-cellular life, plants, animals, fungi, and {brown,red,green} algae independently developed it: https://en.wikipedia.org/wiki/Multicellular_organism

This seems like a good article that describes the multicellularity problem in general, several interesting borderline cases, experiments in inducing the evolution of simple multicellularity (in one case, just by introducing predators into a culture), and ideas as to why it took as long as it did: https://www.sciencemag.org/news/2018/06/momentous-transition...

If we could get heavy rock-moving equipment on the surface and blast through the lava, maybe we could find out. Or if we got lucky and landed a probe on a high spot that escaped the lava and found either fossils or artifacts. All that to say, not likely in our lifetimes.

If there was a civilization on Venus anything like our current civilization on Earth, I expect there would still be evidence of it, even in that hostile environment. If nothing else, there'd probably be unnatural formations of ground from mines or freeway construction or whatever.

Life After People was a good series about this. IIRC, the only thing left of humanity after some appreciable amount of time (say a couple millenia), would be the pyramids. Evidence might be on Venus, but we might have to look thoroughly to find it.

The oldest known undisturbed area of the Earth's surface is only about 2 million years old

It turns over very fast in geological time

https://www.livescience.com/3542-oldest-surface-earth-discov...

A fair point. I wasn't thinking about tectonic subduction, which would hide pretty much all evidence that anyone was there. Though I think that article is talking more about having the same surface exposed to the air for a long time, without being worn down by weathering or covered in silt. You could have an area covered in dirt or partly eroded away, and still be recognizably an artifact of civilization for a long time. I don't know if such things would last billions of years though.

Also, I expect weathering and erosion would happen a lot faster on Venus, what with the high heat and extreme winds that are more like a flowing ocean current than what we'd think of as "wind".

Have a look at the Silurian Hypothesis. If one can examine things very closely, literally on the ground, then the window of detectability might extend to hundreds of millions of years, even billions perhaps. But from orbit, there's not so much hope of detection after a million years

And yet we have fossils from half a billion years ago. "Oldest surface" is not a good measure for how long evidence can survive.

But can we even see it through that thick atmosphere? Even probes we'd send down get corroded by the acid.

Not if a resurfacing event destroyed that evidence.

Lava seems to destroy everything. Tectonic plates shifting would eventually turn everything over.

If the Venusians ever became atomic, and then space faring, then the best way to find evidence of them is probably in their ancient technology in space. Maybe dead satellites floating around the sun in a stable orbit. Or floating around in a geosynchronous orbit around Venus itself.

Or maybe they even sent spacecrafts to other outer planets, like Earth or Mars. I would look there, to find ancient alien Venusian technology.

A couple of NASA scientists published a paper on this a little while back and apparently we’d have a hard time even detecting a previous advanced society on earth. Pretty mind blowing. I often wonder if Venus had an industrial society that set off a runaway greenhouse effect.

Exactly what I thought. Maybe there was a civilization and they totally messed up their planet like we do now.

Only half joking by the way.

I must be the only person on the planet who thinks humans are doing a phenomenal job taking care of Earth. Within a couple hundred years we went from struggling to survive to thriving with significant pollution, to rapid iteration on the energy sector with environment being a top priority. That all happened very quickly.

Imagine the timeline if humans and our technology were around 700 million years ago, at a time when some of our sibling planets were potentially habitable.

I think it would be a real nightmare. After their climate change we then would have to rapatriate every marsian and venusian human to earth, making our little rock absolutly overpopulated. Imagine then rivalries between planetary immigrant and their descendant.

I feel like I have to mention an 1951 novel:

Stanisław Lem - The Astronauts ( https://en.wikipedia.org/wiki/The_Astronauts )

[ SPOILERS TO FOLLOW ]

which plays with the idea that Venus was fine, inhabited, with sentient life, until recently, when they blew themselves up, throwing the planet into the state it is today.

Did some planetary body hit Venus and destroy all life 700 million years ago ? Maybe even changed its rotation the other way ?

Yes [0]. About the same time we were being visited by aliens if I'm correct [1].

[0] https://en.wikipedia.org/wiki/Worlds_in_Collision [1] https://en.wikipedia.org/wiki/Ancient_astronauts

What was the atmospheric pressure of Venus ~700 million years ago? Right now, it's 90 atmospheres.

Do you think there could be more landings on Venus like the Russian one in the 1960s?

How did the Russian probe even land and take a photo if the surface temperature is enough to melt metal?!

Could you build a small rover to withstand the elements for a few hours?

It lasted what, 8 seconds before transmission ceased? It was definitely a success since they expected it to last about 5 seconds.

You're probably joking, but I'll post this comment anyway, as the Venera program was actually quite impressive.

Venera 7 lasted 23 minutes before failing (although landed in an awkward orientation due to parachute failure).

Venera 8 transmission for nearly an hour, but wasn't equipped with a camera.

Venera 9 operated for 53 minutes, had issues with the lens cap so only took pictures from one of the cameras.

Venera 10 operated for 65 minutes, same lens cap issue as above.

Venera 11 operated for 95 minutes, and Venera 12 operated for 110 minutes. Neither of these successfully released their lens caps.

Venera 13 managed 127 minutes, and both lens caps deployed.

Venera 14 which had the same design as Venera 13 only lasted for 57 minutes. Its lens caps deployed, but one landed directly underneath the surface compressibility tester arm, and returned information for the compressibility of the lens cap rather than the surface.

The last one is facsinating... the sheer amount of stuff that can go wrong on a mission like this is mind-boggling.

Also the frustration they must've felt seeing the same lens cap malfunction over and over.

Was or wasn't describe knowledge. Could or may or might or should or maybe all describe ignorance. "We are ignorant of the state of venus for billions of years"

This gives me real "Inherit the Stars" vibes!

Does this mean at some point Venus was in the habitable zone and slowly moved out of it towards sun?

No. Venus is still (barely) inside the habitable zone. The sun did get hotter during its lifetime.

So it becomes cool again and we can roam, digging around. What traces could we find?

So women may really be from Venus

It could have been habitable, but probably wasn't - if it had been, life there would almost certainly have resisted the greenhouse effect, as it probably will on Earth, though almost certainly not soon enough to save us monkeys.

We don't know if it wasn't inhabited and we don't know if it is currently uninhabited.

Of course, which is why I said "probably".

Well we know that it's not inhabited by 'life as we know it' right now at the very least. Because that's just not going to survive there. It'd be a pretty far stretch to come up with something that can.

There is a habitable zone on Venus in the upper atmosphere, so it's not completely out of the question.

That's been thoroughly debunked.

Note that a habitable zone does not necessarily mean there's any life actually there.

You are probably thinking of the reports last year of phosphine in the upper atmosphere where the quantity turned out to be overstated by a significant amount.

On the other hand, there is a sweet spot in the Venusian atmosphere where the temperature is low enough and the atmosphere provides enough protection from solar radiation that microbial life could conceivably survive (which is not the same as saying there is any life there); there are certainly plenty of Earth microbes that live in environments just as inhospitable if not more.

Except, there's no hydrogen in Venus.

There is hydrogen on Venus. Very little. Some hydrogen chloride and hydrogen fluoride.

I'm just gonna leave this here.

https://en.wikipedia.org/wiki/Venus_atmosphere

Hydrogen chloride 0.1–0.6 ppm

Hydrogen fluoride 0.001–0.005 ppm

Like I said, it's very little, but that's not none.

It's none :D

If you knew anything about chemistry past checking wikipedia, you'd just call it none.

Venus is almost guaranteed to be currently uninhabited because that planet has almost no hydrogen in it.

Almost all "complex chemistry" that we know of involves hydrogen.

So to those people who say "but but but that's just life as we know it". No, it's also chemistry as we know it.

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