In terms of human habitation, the big advantages of Venus' atmosphere are:
1. It has essentially Earth-normal gravity. Zero-G long-term is a death sentence for humans. The long term effects of Martian gravity are unknown. It seems safe to assume that Venus gravity is fine.
2. It is protected from impact and radiation by an atmosphere in a way that Mars or asteroids never will be.
3. It has an essentially limitless supply of carbon, oxygen, nitrogen, and sulfur available to it.
4. It is reasonably well-positioned for solar power.
5. It is relatively temperate.
6. Low pressure differential between inside a habitat and outside of one means that leaks are less severe and containment breaches are easier to react to.
But there is at least one huge disadvantage:
1. Everything besides carbon, oxygen, nitrogen, and sulfur needs to be imported, either from a fantastically hostile surface, or down through reentry into an atmosphere in a deep gravity well and rendezvousing with an aerostat.
That disadvantage is a pretty goddamn significant one for human habitation.
But it's not a disadvantage for long-term robot probes, and it's... less... of a disadvantage for a minimal-population scientific base.
Mining the surface is required; importing any significant quantity of material from Earth is a non-starter. Unless you can come up with something insanely valuable to export to Earth, any planetary colony has to be almost-entirely self-sufficient. Interplanetary transit is too long, and too expensive. (This is true on Mars as well, and probably Luna and asteroids as well, though you might find some edge cases there due to lesser gravity or greater proximity.)
The pressure on the surface is that of about 3000 feet of water, so that's not too bad, and the reducing atmosphere can be handled, but the temperature is tough. Still, with practice, you could probably build such machines. Dunno how you make electronics survive long term at ambient 465 °C (oil wells have a hard time with electronics at much lower temps) but some combination of active cooling, limited duration, and novel fabrication should be possible.
Perhaps the easiest solution is to load up your Venus Mining Hopper with a whole bunch of liquid nitrogen, extracted from the atmosphere and compressed and liquefied using solar power falling on your floating platform. It deflates its balloon and drops to the surface, and starts scooping up material into its hopper as the LN2 boils off, cooling the electronics and other temp-sensitive systems. (These are buried in lots of insulation.) When the hopper is close to full, you start venting the N2 into the balloon, and the whole system takes off again, to rendezvous with a solar-powered tug to pull it to your ore-processing factory. That may be a long haul, because the upper atmosphere of Venus moves at 100m/s. Maybe you design your system to stay on the ground long enough for the platform to come back around the planet, a mere 4-5 days. Or maybe it just takes a big bite and goes straight back up so it doesn't get too far behind.
So maybe doable, but it makes the hurdle for setting up a self-sustaining colony much higher. Not that it's a much lower hurdle anywhere else.
The temperature is a reason why Venus would be a good place to test out the ideas for climate manipulation we have collected so far.
A first step could be to lower the CO2 content (my current favourite would be to release engineered bacteria into the atmosphere that can bind the Cs and after death collect it on the ground), and enhance the albedo (so more sunlight is reflected away).
In the longterm we will need climate control anyway since Earth's climate is somewhat unstable (global warming is just as bad as a new ice age, which, extrapolating from the past, would be about due by now, if not for mankinds influence). Testing it on a planet we are not critically dependent on should be a better strategy.
Geologically, Venus is very different from Earth due to the lack of water (which enables plate tectonics and all its implications). Some changes we can make would even influence the geology. (Hm, I wonder what would happen if we dumped enough water meteroids.. )
All of this of course premises a lack of preexisting life with planetary ownership rights and no natural reserve rules (which we kind of have at the moment - http://planetaryprotection.nasa.gov/about).
Please excuse the possibly stupid question, but what does water have to do with plate tectonics? I always thought that was a consequence of earth being a "live" (i.e. hot inside) planet.
The water in the interior is what matters. It's actually the fact that water is recycled into the Earth's deep interior that's thought to keep it "lubricated", so to speak, and allow the mantle to flow more readily. For the Earth, that's a feedback loop: water in the mantle allows plate tectonics to work, so water keeps getting recycled into the interior (via saturated crust and sediments) to keep it going.
What do you mean by "lubricated" exactly? The explanation I've had in classes for the "water is essential to plate tectonics" idea is that water causes dehydration melting, and that's thought to be critical to plate tectonics. Adding water to rock decreases the solidus temperature (temperature at which first liquid component is generated).
Yes, this is the current consensus of the scientific community. During subduction of plates (mostly oceanic crust full of water under continental plates of lower density) the volatiles (mostly water) exits the subducting plate and lowers the viscosity and density of the overlying mantle material (viscosity describing the 'fluidness' of the material, higher viscosity = less fluid). The material will then rise up and there will be volcanism, recycling the material back to the surface. This is what you see in most major volcanic arcs, such as the Andes or Japan.
The idea that plate tectonics and water are intrinsically linked (at given circumstances) is pretty solidified. The theory of why not such much; the idea above fits our current data best, but data from the planet's interiour is hard to come by and I expect some updates to the theory within a few decades. It's nice that this is currently not critical knowledge for humanity.
Note, this "water as lubricant" should not be confused with a creationist theory that tries to explain Noah's flood, suggesting that a huge portion of our current surface-water escaped at once.
Well, as a principle, anybody may try to claim rights/ownership over anything. The question that follows is how could that (no mater how far-fetched) given claim be further supported. Also, one way of securing good relations with others is to just recognize their claims.
Probably not, especially suitably advanced life, but we don't know. Our world is still very narrow. It's an ethical question that should be discussed before we destroy stuff. If the consensus was to go ahead anyway, that's fine too.
What about native Europeans, I mean the Neanderthals? They were the OG's before homo sapiens wiped them out...
It bothers me why we didn't just sit down on the edge of the world, as it is the Neanderthals, by the virtue of being there first (we call dibs!) who must have had planetary ownership rights to Earth. Not our usurping "natives".
You wouldn't steal a car, you wouldn't steal a handbag...
You can probably use half the arguments for vegetarianism here [1], and a lot more if there is sufficiently intelligent life (probably not on Venus; the argument is the same for other planets). Of course, not everyone agrees to those. Other extendable arguments include those for the preservation of species on Earth [2].
Your last sentence refers to the anti-copying campaigns, right? Since their analogy is so flawed, I don't see what you mean by that.. (Most people wouldn't steal a car, but they would totally copy one (as soon as they can).) If we could copy planets without disturbing orbit mechanics, there wouldn't be a problem?
[1] I'm talking about the ethics of using another species for one's own gain without dire need.
[2] For it's own beauty, but more importantly as a collection of ideas and examples for what is possible, as an information ressource, so to say. Since our state of knowledge is low, we cannot collect all the information without preserving the found state. Of course [1] also applies.
What ticked me off was this pretentious pseudolegal neologism of "planetary ownership rights". (No offence)
I would agree that humans should think twice - and some more - before damaging or contaminating an alien ecosystem, but that's even if it was only bacterial. Speaking about "ownership rights" in case of bacteria would be downright ridiculous.
Putting the entire moral problem under the category of "ownership" feels imposed to me. Not unlike the narration behind "copyrights" - and that's the association I hinted at. Not the idea of copying planets, although I can think of reasons why that would be your first guess.
If you put it like that, it does sound pretentious, haha.
I see why you might think it feels imposed. At this point it's probably more a problem of (loaded) word choice than ideas behind it. Thanks for clarifying.
Adding your point of view to mine, and taking into account the memes concerning planetary settlements I've aquired, ownership might be a bad word choice indeed.
Desertification, increased sea levels causing flooding, higher atmospheric CO2 causing ocean acidification that will kill nearly all life in coral reefs sans jellies, etc etc.
Global warming probably isn't inherently bad if spread out over enough time, but large temperature fluctuations within a few centuries doesn't leave time for non-human species to adapt.
> Desertification, increased sea levels causing flooding, higher atmospheric CO2 causing ocean acidification that will kill nearly all life in coral reefs sans jellies, etc etc.
Yes .. or Maybe .. but that all still sounds preferable to an ice age, if kaybe is right, right?
> Global warming probably isn't inherently bad if spread out over enough time, but large temperature fluctuations within a few centuries doesn't leave time for non-human species to adapt.
Eh, I don't know about that - you're not wrong but I don't think this is a relevant/useful consideration given that
(1) given that reasoning "spread out over enough time" everything and anything will work out fine
(2) in the long run (or rather the "even longer run", considering the first point) we're all dead anyways
Is there actual clear evidence that global warming has truly prevented an ice age? It's certainly the first time I've seen that assertion put forth and I'd need some actual scientific evidence that's the case.
I do agree though, an actual ice age would probably have a much more severe impact that global warming...but I'd definitely prefer that neither occur.
No, there is no clear evidence for that, unless you count models. It is all extrapolation founded in data - we have the temperature curve for the last few hundred thousand years (basically this: [1]), as well as information about the composition of the atmosphere. It is not even clear why and how ice ages happen exactly [2].
I'd not even be sure how to show evidence for that unless we waited a few hundred thousand years to make sure the temperature curve does not behave as before. I can, however, give some links to the discussions (e.g.[3][4]). The people in [4] ran a model, here's the paper: [5], and found a small effect (contact me if you can't access it). It's hard to say how good model evidence is, however. A lot of influences are missing, and we'd need to validate the model with more data, which isn't there. (So yeah, I wouldn't count that as evidence, just a hint.)
At this point, this is just an idea discussed by people with domain knowledge and experience, nothing more. It doesn't change the fact that we have a problem, it just influences how people look at details of climate models, and which questions to ask the models.
This is a great comment and I really appreciate you putting it together for me. I've read through all the links but can only read the abstract of the paper linked at:
Earth's surface is already 70% water, so lowering the sea level is better than raising it (coasts are productive, so 50% would probably be ideal); high temperatures also have implications for e.g. parasites (one possible explanation for why countries in cooler latitudes have been generally more successful than those closer to the equator).
You're right that cooling would be bad, and maybe a certain amount of controlled geoengineering through CO2 emissions would have been in order by now. But the level we currently have is past that, to the point where we're going to get far too hot, which is worse than being a bit too cold. If you're about to drive into a ditch then turning left a bit is good, but driving into oncoming traffic is worse than doing nothing.
Why not get other resources from near-Venus asteroids and Mercury? It would be easy to imagine a near-sun economy that mostly involves people, information, and raw materials making the trip up and down the Venusian gravity well -- with most raw materials and finished goods making the trip down. Most of the energy would be dissipated by aerobraking. In essence, Venus could participate in such a solar-system spanning economy by supplying relatively friendly radiation-shielded Real Estate and fluorine. Raw materials would largely go down, and people, culture, intellectual property, and fluorine would come up.
> Why not get other resources from near-Venus asteroids and Mercury?
The exact same reason we don't get our resources from near-Earth asteroids and Earth's neighboring planets: It's freaking expensive. One of the aspects that makes Venus attractive for colonization--similar surface gravity--also makes it expensive to launch anything. More-so, given that you'd be doing it with a frontier outpost's industrial base.
> Raw materials would largely go down, and people, culture, intellectual property, and fluorine would come up.
So why bother going to Venus at all, as opposed to creating such an economy around Earth? Barring catastrophe, Earth will certainly have a lot more people, culture, intellectual property, value-dense high-tech goods, etc., as well as significantly nicer/cheaper real-estate.
All successful colonies require an economic driver, and Venus is no exception. "Like Earth but less-profitable" is unlikely to do much.
> The exact same reason we don't get our resources from near-Earth asteroids and Earth's neighboring planets: It's freaking expensive.
Remember that I referenced its relative price. We don't get Earth's resources from near earth asteroids because we can get them more cheaply from Earth. Obviously, this wouldn't apply to Venus. Likewise, lots of things on the west coast of Alaska come from Seattle, not because it's cheap in absolute terms, but because it's the cheapest.
> So why bother going to Venus at all, as opposed to creating such an economy around Earth?
For the express purpose of not living on Earth. For the express purpose of spreading our civilization beyond the confines of one planet. Such an Earth independent economy and culture might be more likely to exist around Venus than Earth, simply because the proximity of Earth is more likely to pull investment away.
> All successful colonies require an economic driver, and Venus is no exception.
Not all colonies on Earth were motivated primarily by economics. People have lived in a variety of places on Earth motivated by religious and military concerns. Successful colonies will need economies to keep themselves going, but economic concerns are merely the strongest motivator for settlement, not the only ones. Granted they are in the minority, but there are people who live in the middle of deserts, in pressure vessels at the bottom of the ocean, in all kinds of remote wilderness, in many cases for the sake of living in such places as private citizens.
Granted, it will be a long time before such civilizations would begin to remotely rival the scale of Earth's, but I'm sure they will come to exist and that they will achieve near self-sufficiency.
Summary: People will live in space because they want to be there. Once a spacefaring population reaches a certain threshold, it will become self sufficient.
«"Like Earth but less-profitable" is unlikely to do much.»
1. Don't underestimate the human psychic. People are said to be rational, but we often come to surprise ourselves. As a joke, if you don't have sane/rational volunteers, just create a religion!
2. Don't overestimate the general conditions on our home planet. I hope I won't come to see it in my lifetime, but escaping from here could be similar (at least in sentiment) to escaping from one's home-town/home-country or worse. Things can always get worse in a lot of different ways, and then when comparing again, the Venus option could start to appear as a pragmatic one.
I have a hard time imagining Earth getting so awful that Venus looks like the better option. Even after an all-out nuclear war, it wouldn't be that bad.
This is what made the fundamental plot kicker of 'Interstellar' so daft. "Oh, we have a crop disease problem and dust storms? Clearly we must move the human race to another planet, even if it's a frozen hellscape with no breathable atmosphere." As opposed to, say, building some greenhouses, or ramping up aquaculture or aeroponics.
I have a hard time imagining Earth getting so awful that Venus looks like the better option.
The moving to the new world involved taking on all sorts of new risks, but people still did it for non-economic reasons. Instead of religious freedom, perhaps others will be attracted by the prospect of starting new civilizations or escaping oppression?
They moved to the New World. They didn't move to the middle of Antarctica or the bottom of the Mariana Trench, both of which are far more hospitable than Venus.
Make sure you're not stopping at absolute difficulty when you should really be thing about difficulty in the context of technological capability. The near-arctic is a remarkably hostile environment, but humans can live there and thrive with only stone age technology. We are far beyond the stone age level of technology. The number of places that private citizens can live is far expanded as a result. (There are actually people now who have privately-funded undersea habitats!)
The decision of some individuals to move from the british isles to N. America for religious reasons happened in a specific economic, geopolitical, and technological context. If the available vessels and navigation were poorer or more expensive, it would not have happened, and they would have done something else. You have to consider these things in their specific context.
So, given a strong enough desire for people to live "in space" or "on Mars" or "on Venus" combined with the technological and economic wherewithal to do it, people are going to try. Combine this with very wealthy national powers led by a class of engineer-technocrats with a demonstrated track record of implementing multiple decades long-term payoff projects (China) and the conclusion I come up with is that there is a significant chance that we will wind up with civilizations elsewhere in the solar system.
Also, the specific environment they're talking about in the article isn't anywhere close to the Mariana Trench. It's at about 1 atmosphere pressure. The most hostile thing about it would be constantly encountering sulphuric acid clouds. (This would also be a tremendous benefit, however.) Another important difference: The physics of building livable volume favors by far Venus human-aerostat altitudes over the Marianas Trench. Equipment for working "outside" in that specific Venus environment is something we already have a good idea about implementing inexpensively. The basic physics of the Marianas Trench makes doing the same down there orders of magnitude harder. Likewise, other basic physics around energy would preclude economically feasible agriculture in the trench, but indicates that it's quite doable at those altitudes on Venus.
A Venus colonist would probably sing songs praising PTFE. (One's already been written: "Polytetrafluoroethylene -- that's Teflon, you @ssholes!") Fortunately, we already know that one could condense fluorine directly out of the atmosphere of Venus with basically just energy as input.
I don't think I am. I can imagine high-tech settlers having a strong enough desire to move to orbit, or Mars, or the asteroids. I can imagine it becoming possible to survive on Venus, although the extreme shortage of water (it's what, 20ppm atmospheric?) would be a major issue.
I just can't imagine Venus specifically ever making it the top of anyone's list. Where's the plus to compensate for the many many minuses? It's certainly not the view.
the extreme shortage of water (it's what, 20ppm atmospheric?) would be a major issue.
Given enough energy, you can get water from the Venusian atmosphere. Granted, you basically can't have Venusian civilization without exploitation of space resources and having solved transportation costs to and from orbit, but water is not a hard barrier for a technological civilization.
Where's the plus to compensate for the many many minuses?
It may well become the cheapest place in the solar system to build human-habitable volumes. If you posit that there will be a solar system-spanning civilization in the first place, then physics and chemistry seems to suggest Venus has a lot of plusses in that particular context.
Granted, the only way that such a thing can come about could be properly termed sheer insanity. However, human history is practically made out of sheer insanity, chief of which can be called "nationalism". My money is on some power or powers at the scale of an industrialized nation-state eventually solving the problem of cheaply getting to and from orbit, motivated by the same sort of geopolitical insanity that motivated the Cold War. Given that, such a solar-system wide context of civilization will inevitably exist. All you need is one faction that makes it look like they might eventually establish such a civilization in their own image. Then competition will drive the rest. Look at it the other way: basically all such programs must 1) fail then acquire the aura of impossibility or insurmountability 2) forever remain out of the reach of private entities. It's entirely possible civilization may fall or some other circumstance would bring about those two conditions, but it's far from a certainty. Viewed in this way, completely earthbound humanity doesn't look like a stable configuration.
I absolutely agree with the plot flaws. I'm sure there are much easier ways to solve crop disease and dust storm problems. It'll probably involves alot of genetically modified crops and building dust proof houses.
> any planetary colony has to be almost-entirely self-sufficient.
Is this even remotely possible anywhere with current technology? Can we even make completely self-sufficient colonies on Earth (like the technologically advanced kind we want to make in space, not just people living in the woods.)
I don't think anyone's really tried, outside the Gingery books and such. (And even Gingery bootstrapping is just a machine shop, much less modern technological civilization.) Here on Earth we have to trade long distances to get raw materials anyway, so we might a well trade other things. Even in the most isolated areas, outside goods tend to leak in.
A new planetary economy would certainly have to be very tightly circumscribed in terms of materials and techniques, and even then I think it would be dismayingly huge, though modern techniques like 3D printing would help. It would be a worthwhile exercise just to plan such a thing on paper. Might make an interesting if overly-complicated game with sort of a Dwarf Fortress feel.
In Biosphere 2 the human volunteers ended up IIRC needing a few millilitres of liquid oxygen injected every 6 months or so. Perfect? No, and we'll probably never get to 100% perfection. But it's pretty damn close; if that was all you needed you could ship a big supply from Earth every decade or so, and it starts to look relatively affordable.
(Of course most parts of space are much more hostile than an Earth desert)
http://www.nytimes.com/1993/01/05/science/the-environment-ox... says "Project leaders, expecting the decline to continue, have made arrangements to pump tons of pure oxygen into the 3.15 acres of glass domes. ... "If we decided to raise the level by 2 percent, that would be 100,000 cubic feet of gaseous oxygen,""
A short ton (907.2 kg) of oxygen is 635 cubic meters or 24160 cubic feet as a gas and 794.5 liters as a liquid ( http://www.uigi.com/o2_conv.html ) so they would have needed 5 tons to raise the O2 levels by 2%. For what it's worth, the concrete depleted the O2 levels from 21% to 15%, so about 30 tons would have been need to fully restore the O2 levels.
800,000 mL/ton means that it was not the case that it needed "a few millilitres of liquid oxygen injected every 6 months or so." More like a few thousand liters every 6 months.
I was talking about the direct injections into the participants' lungs; I wasn't aware they'd also needed to pump oxygen into the whole thing. Thanks for the correction.
Self contained is also different than self sufficient. With a lot of carbon dioxide in the atmosphere, all you need is a good energy supply, then oxygen is easy.
(A similar example, some submarines use electrolysis for oxygen)
We probably could, but even in the most hostile and remote places on Earth it's easier to air-drop food and other resources than it is to grow and mine them. So there is no financial incentive to do so.
1g at 1 atmosphere has disadvantages. Namely: to get off the planet, you will need a fully fuelled multistage rocket with an almost identical profile to rockets you'd launch from ground level on Earth. Something like a Falcon 9. That's a bit heavy to lug all the way from Earth.
Bonus: you have to launch by dropping it into a hell-cauldron of poison gases miles above a crushing, melting surface, better hope you don't have an engine out, because there are no launch aborts or do-overs. Then you have to fly it out through a hot corrosive acid atmosphere which I don't imagine would be very friendly to machined aluminum.
Not quite an identical profile; it's not quite 1g, since Venus is less massive, and you're already quite a ways off the surface.
It's still not trivial, but it's not like there are a whole lot of do-overs when launching valuable human cargo from Earth, either. (What happens if the space shuttle's engines go awry? Everyone on board dies, and everyone on the ground speculates as to whether they died within 30 seconds, or survived to hit the ocean.)
The shuttle was an outlier, a rocket without an escape mechanism once the crude, firework-like boosters were lit, which relied on ultra-advanced, brittle and damageable heat shielding for re-entry because it had wings.
> 1g at 1 atmosphere has disadvantages. Namely: to get off the planet, you will need a fully fuelled multistage rocket with an almost identical profile to rockets you'd launch from ground level on Earth.
Condense Carbon Monoxide and Sulphuric Acid from Venus's atmosphere for use as fuel and oxidizer in a hypersonic rocketplane that tops out at about Mach 11. Have the rocketplane rendezvous with the end of a rotating tether.
No multi-stage rocket. No expendable launch vehicles. That's probably not the actual solution, but it shows that you don't have to have a Falcon 9 equivalent.
> Then you have to fly it out through a hot corrosive acid atmosphere which I don't imagine would be very friendly to machined aluminum.
It should be possible to condense HF out of the Venusian atmosphere, so we should be able to manufacture PTFE locally with input from non-Earth resources. (Mining chondrites from Mercury and Venus-crossing asteroids.)
Why not a space plane? Surely reaching orbital velocity on a platform that is already moving at a decent speed around the planet would ease it somewhat?
For the first problem, we can probably build small "launcher" platforms from lighter gases so it brings the spaceship to an altitude with much less gravity.
The sulfuric acids should be fine with enough protective coating. Earth's atmosphere isn't all that friendly either with rust able metals. Thus we have corrosion-resistant paint.
For the first problem, we can probably build small "launcher" platforms from lighter gases so it brings the spaceship to an altitude with much less gravity.
Uh, no. Sit down with the equations yourself. The main way one counteracts gravity is by gaining orbital velocity. Astronauts aboard the ISS experience almost as much pull from Earth's gravity as you do on the surface. It's that their orbital velocity puts them in a frame of reference that has "microgravity."
When I posit launcher platforms on Venus, the point is to launch from a higher altitude, thus avoid some losses to air friction, and also to use the entire station as reaction mass for launching the payload from an electromagnetic cannon. Doing this avoids the near-exponential nastiness of the rocket equation.
Why aren't people thinking about sending various robots/devices that could terraform planets before humans going in to live there? Is this something that is impossible to do/imagine? what am I missing?
Alternatively, why aren't we talking about venusforming humans? All space operas seem to start with the earth-standard human in a suit. Compared to geoengineering a whole earth-standard atmosphere, bioengineering an intelligent organism that can thrive in nonearth environments seems fairly sane.
There's a social taboo against human genetic experimentation (hell, some people seem to struggle with vegetables) but that will eventually pass.
That's if you wanted them to live on the surface, which seems to be a pretty tough problem to solve in any fashion. If we're contemplating living in the clouds, maybe a lifeform more birdlike or gasbag-jellyfish-like would make sense.
Granted, I'm not sure I would want to show up to a blind date with a human/portuguese man-o-war hybrid.
Plus ATP, the cell-internal energy distribution mechanism that is a property of all life on earth destroys itself at 52 degrees celcius. That means no controlled energy actions can happen in cells above 52 degrees celcius. We'd have to redesign every enzyme, every single cell function.
I am confused about your point. The original statement was "ATP, the cell-internal energy distribution mechanism that is a property of all life on earth destroys itself at 52 degrees celcius". I pointed out that thermophilic bacteria exists and reproduce at over 52 C. Therefore, there's an apparent contradiction.
Is your statement about "roll differently" mean that there is no ATP synthesis? Certainly not, as your link shows. Is your statement that thermophilic bacteria isn't alive? I strongly doubt it. What then does it mean to "roll differently" in the context of ATP presence being a requirement for all life on earth, and hence a 52C upper limit?
That sounds intriguing as well, but I can't seem to wrap my mind around the kind of knowledge needed to "venusform" a human. I have to say that the idea of sending a swarm of robots and setting up a bunch of chemical reactions seems less daunting (due to my lack of imagination, I presume).
Or just engineering some. Biological organisms seem overly tuned to their environment and complex ones need a supporting biological ecosystem to thrive (so far that we've seen). It may be more effective to get robotics to our level and expand intelligence into the galaxy 'synthetically'.
The line between "biological" and "synthetic" is blurry and gets blurrier all the time. You can (and probably should) see biology as super advanced tech. One of the primary benefits is self-replication - ability for components to consume various resources and build copies of themselves. This is huge, and it enables everything from self-regenerating materials to in-situ upgrades. 3D printing is a joke compared to that. So while maybe Earth organisms are a bit over-tuned (on the macro scale) to planet's environment, we'd do good to treat life as superior nanotech we don't control yet, and not some kind of joke that can be replaced with steel and silicon (not that you said that; it's just a point of view I often see on the Internet).
I don't get why more people don't think this way.
Humans as they are today will probably never be able to thrive in space or even on other planets similar to earth, that is without a lot of genetic engineering or something of that sort.
Create intelligent self replicating machines and a large part of the problems related to space travel just disappear.
If creating an AGI is possible I would be surprised if the universe isn't already full of artificial life.
once you've gotten to the tech level where you can artificially engineer a lifeform advanced enough to do something useful, but hardy enough to survive venus-
by that point I'd say the distinction between robot and organism would be pretty blurry. ;-)
"why aren't we talking about venusforming humans?"
We're all humans here on Earth and yet it seems that that is not always enough to relate on a personal level and keep a human attitude over each other in order to prevent destructive escalations and the risk of wiping out each-other in mass. Just imagine the dirty politics that would arise around the (hypothetical) results of your idea.
Even without deliberate intervention, humans in space and on other worlds will evolve quite rapidly if interplanetary intercourse--as it were--ever breaks down.
With the order of magnitude of resources we are talking about (enough to colonize) yes it would be impossible to terraform either Mars or Venus. People are thinking about it, but not in the near-term. I think that the easiest way to terraform Venus involves scooping a gas giant for hydrogen to burn with Venus' CO2.
> It has an essentially limitless supply of carbon, oxygen, nitrogen, and sulfur available to it.
Are you able to provide a rough summary of how the quantities of these materials compare with the quantities available on earth?
It wasn't that long ago that humans spoke about things like the number of fish in the sea, the ability of the earth's atmosphere to absorb waste gases etc as being effectively infinite until we eventually discovered that this was unfortunately not true. It is just something that pops into my head whenever the word unlimited, infinite or limitless get used when talking about energy, resources and so on.
As long as we're talking about one mostly self-contained city, resources available will likely be infinite from practical point of view. The problem with Earth is that there are 7 billions of us living now; our impact thus becomes significant.
It would be nice to hope so but I'm actually unsure. We are becoming more efficient with resource management because our resources are increasingly constrained. If those constraints are removed, over the course of a few generations, it would be easy to slide back to doing whatever is fastest and cheapest (might be the cleaner way, might not be).
> reentry into an atmosphere in a deep gravity well and rendezvousing with an aerostat.
What about rendezvous of a rotating tether with a hypersonic craft? We can make cables now that are strong enough to support a "rotorvator" rotating tether at the lengths required. What about very large, very long, aerostat facilities that are mostly huge electromagnetic cannon for launching robot hypersonic craft? These could be built to withstand 1000's of gravities, to allow ballistic launch from high altitiude facilities, but have a return flight profile suitable for passengers and other fragile cargo. We could also have Venusian hybrid jet/rocket hypersonic craft that are fueled with liquid carbon monoxide. This technology could mean that getting to the colonized Venusian ecosphere would be a lot cheaper than getting off of it, if you are a biologically standard Homo sapiens.
EDIT: So, how this would play out in a cyberpunk space opry: Many people choose to emigrate to Venus because of the price of labor there. However, economic pressures cause a large fraction of the Venusian populace to undergo radical cybernetic modification, because it opens up job opportunities on the hostile surface and makes it less expensive to get back to Earth and other parts of the Solar System. This pathway is chosen by desperate and marginal people, who often take advantage of the radical modification surgery to shed their old identities. Voila! Gritty Sci-Fi cyberpunk future based on chemistry, physics, and economics.
EDIT: It turns out that the energy cost for getting between Mercury and Venus isn't so large. Also, there are a good number of Venus-crossing asteroids. So anything you can get from a carbonaceous chondrite asteroid shouldn't be precious to the point of rarity on Venus. Among other things, both silicon and hydrocarbons could be mined in industrial quantities.
EDIT: An interesting idea for surface resource extraction -- bombard the surface with rocks from orbit, with the intention of creating clouds of dust which can be harvested by specially designed airships. Though this is inefficient materially, it might result in far less wear and tear on equipment, which gets to remain at higher and friendlier altitudes.
EDIT: Carbon monoxide and sulphuric acid can be used as a fuel/oxidizer pair in a rocket engine! Both can be condensed right out of the Venusian atmosphere. Granted, these are a bit cantankerous even as far as rocket fuels go.
Your disadvantage 1 is the result of a failure of imagination. The vast majority of life on Earth is built from nothing but carbon, oxygen,nitrogen, hydrogen, etc., and human life requires not much else. We could easily subsist on just these elements.
Note that "hydrogen" lists among your rather crucial elements necessary for life, and does not feature in Venus' atmosphere in significant quantities.
And, more so, while human life per se requires very small amounts of non-carbon, oxygen, and hydrogen elements, human technology requires very large amounts of non-carbon, oxygen, and hydrogen elements.
AFAIK, sulphuric acid is present in the Venusian atmosphere in large enough quantities to cause obscuring clouds. Though, I imagine that equipment to harvest the hydrogen from those clouds would end up being quite expensive. (Given my limited chemistry knowledge, I'd guess that large amounts of silicon would be involved in their manufacture.) There are also significant amounts of hydrogen sulfide. (Which could be quite a complication for human settlers as well.)
EDIT: FTFA -- "Moreover, while both planets boast ample amounts of volatile life-sustaining materials like hydrogen, carbon and nitrogen, only Venus’s dense atmosphere would be helpful in shielding human colonists from the harsh assault of solar radiation."
'Subsisting' does not include 'artificial cities floating in the sky'. Similarly, getting a computer to run on nothing by carbon, oxygen, nitrogen, hydrogen and sulphur, none of which are metals or semiconductors, is a massive task, if doable at all.
I don't think getting things from Venus orbit down to human friendly aerostat altitude is going to be an insurmountable problem. When sending things into the Venusian atmosphere, you can always take advantage of aero-braking. Then, the aerobraking equipment can itself be taken apart and used.
Running an economy on mostly carbon, oxygen, nitrogen, hydrogen, and sulphur would make for an interesting hard sci-fi book!
Any real colony needs to be mostly self sufficient (hopefully entirely self sufficient) so the problem is not getting materials down from orbit, but up from the surface.
In a far-seeing, long term analysis, I don't think we should limit "colonies" to discrete heavenly bodies. Long term, we should consider the complex of Venus, Mercury, and Venus-crossing asteroids as a local resource pool.
The notion that a single planet has to be largely self-sufficient as an independent unit is a bit of prejudice that comes from our upbringing on Earth. On Earth, in terrestrial economic terms, it's generally relatively expensive to get things off the planet and back onto its surface in one piece. For this reason, we think of planet Earth as a practical (if not absolute) boundary for economic transactions and resources. In the larger context of a solar system spanning society, it's costly in absolute terms by current-day Earth standards, but in the larger context, it's also relatively cheap to ship things down into the Venusian atmosphere from Mercury, Venus-crossing asteroids, and even Mars. In fact, one can make it materially inexpensive by applying lots of energy, which shouldn't be nearly as expensive by that point.
It's probably true that Earth's gravity well will limit trade of material goods between itself and the rest of the solar system. But there's no reason that a solar system spanning culture couldn't exist as a largely separate entity. I suspect people will live out there just for the idea of it, and that nation-states will help in the endeavor just to propagate their own cultures.
Right. History is full of land-based powers that didn't realize they needed a navy until they enlarged their context. This just involves an even larger new context.
Sure.. except, nature has conveniently put those elements into forms we can use. So until we're able to do that ourselves, that's a disadvantage we'll have to deal with. It's less a failure of imagination, and more a failure of our current level of technology.
Thought of the day, which is said mostly tongue-in-cheek:
If we really must think of a planet to terraform, it seems like the best body in the solar system to work on might be... Earth. There are large swaths of it that are more or less currently uninhabitable in its polar regions, and most changes to the atmosphere we make have their greatest effects in those same polar regions. A 5C increase in global average temperatures might be a 10C or more increase in those polar regions, opening up millions of square miles for human habitation and intensive agriculture. It's even self-sustaining: about a quarter of known fossil fuel reserves are available in the Arctic, and those will become much more accessible with warming temperatures.
Needless to say, there are costs elsewhere on the planet for that kind of intervention, but those are very definitely far, far smaller costs than building floating cities on Venus or reheating Mars' core. Many of those costs could even be recouped by adding a terraforming tax on new residents of polar regions and redistributing them to Bengali refugees fleeing their homes.
Economically, it makes a lot more sense than investing resources in terraforming other bodies in our solar system, though it doesn't offer the same risk mitigation.
Disclaimer: I think terraforming Earth, purposefully or not, is a bad idea. I think it's just a better idea than investing real resources into terraforming other planets.
Huh. That's a very interesting thought. The first thought that pops into my head is the risk. The appeal of trying to terraform Venus (or Mars) is that there isn't a huge existing population of humans. If we mess it up, well...that's unfortunate and expensive, but we didn't just make the only place we currently have uninhabitable.
The second though, pretty related to the first, is the ethical one. Do we have the "right" to do what we want to our planet, including probably causing mass extinction of existing animal life in order to terraform our planet? I'm not sure if I'm even willing to argue that one either way.
Like I said, it's interesting to consider your idea. If we can be sure that anything we do to "terraform" our planet isn't at all risky in terms of human survival, you're probably right!
Longterm, we will have to find some kind of climate control. The last ice age was not too long ago, but mankind has almost entirely lived without. A return of the glaciers would be even worse than global warming (in my estimates), and extrapolating the curves shows that the next ice age is due (were it not for the fact that we changed the atmospheric composition sufficiently to avert that for sure).
Right now we already are playing around with the climate, but very uncontrolled and destructive. I'm also not in favour of using methods designed for climate control in our situation due to the risk (which is different for the different methods, and the failure results are very different also, but still) - the better solution is clearly to stop emitting CO2 - but longterm, we will need the knowledge. Best to test it on another planet first..
>Do we have the "right" to do what we want to our planet
You have a right to make good decisions. Don't sweat about whether we have rights to modify the planet, and instead worry about whether it is a good decision.
At this point there is not enough data or control to ensure success. We are already changing our planet, and we can't even tell if it's good or bad, so this is not the year to make that kind of determination.
The thing about farming in the Arctic is you're gonna have a short growing season no matter what the temperature is. However, you're not going to get that far, because you're talking about an area that is substantially underlaid by permafrost. When that melts, it subsides and usually fills with water, which is why there are millions of boggy lakes on the North Slope of Alaska. Fertile topsoil is not just dirt, it's a complex ecosystem of its own, and it takes a great deal of time to produce. It's probably slightly easier to start farming in the melted Arctic than in your average desert, but it's a pretty near thing, and your 5C difference is going to wreak havoc on current farming areas. The odds of success on this one are not good.
I think there's probably some limit to how much Earth-resources should be used to terraform other planets, but with what we spend on bombs I don't think it'd be a big deal. Terraforming Earth is a spectacularly bad idea, so it would take a lot of spending to be in any sense worse than that.
Desert habitation is actually something I've been really curious about lately- does anyone have links to some good source material I could read into? I'm currently envisioning construction like you'd see in passive homes- hyper insulated, probably powered by solar/wind, and some means of reusing water since it's obviously a limited resource. It's very possible I'm hugely naive though so I'd love to find some hard numbers on the actual viability of what I've described.
I don't have any expertise in this, but off the top of my head:
- wind power would be tough because of sand in the wind. I imagine that would make the tech break down often. Guess it depends on what kind of desert you're talking about.
- Bedouin/Saharan peoples are probably a good reference. They had/have cisterns throughout the desert to preserve water between rainfalls. I think they were largely nomadic but I don't know the motivation for that (trade vs food supply vs ?)
- Bill Gates reports drinking water from human waste tastes fine, you could probably get your hands on the tech his people are developing.
Like... reshaping the Earth in a Earth-like shape! Cool, isn't it? Now, getting the tongue off the cheek, you're right, it makes a lot of (at least an economical) sense to look under our nose at the swaths of unexploited but with a higher promise land and, you know, use them?! Only that the thing is, Venus colonization is more than just a new place that we could find useful to extend into for a current-way of day-to-day human life. It is a lot more! Some may tell you that it is bad to have all the eggs put in the same basket and Venus would be a good second basket, but again it would be a lot more than that. Imagine that so far we haven't had any signs of another life-form living in our universe. As small the chance for this to stay this way as it may be, we can assume for now that the entire universe is ours to extend into. And we need to become capable of doing it. We may "start" doing that by colonizing our own galaxy. For that we should become capable of colonizing planets in some reasonably-close star systems first. And for that it would be desirable for us to learn how to do that using a planet somewhere nearby, in our solar system. And yes, for that we should become capable of colonizing without much struggle harsh places like deserts (in polar or other regions), subterranean and ocean depths here on Earth. And more, those should become self-sustained, to mimic conditions of some far-away colonization prospects. In the long run Venus is just one of the intermediary steps, but an important one. We as a species need that kind of colonizing experience. Of course it won't happen right away, but setting the goal of colonizing Venus is in itself a task that rise awareness and spurs in the meantime other important intermediary necessary goals. Biosphere 2 falls in this category, but we need more, and more - we need context for which these kind of projects would come to make sense.
Could someone weigh in on the following quote? Sounds fishy / wrong to me:
To put this in perspective, a balloon that is one kilometer in diameter is capable of lifting about 700,000 tons, or the weight of two Empire State Buildings. Add a second balloon of the same size and the lift capacity of these two balloons increases exponentially: it’s now capable of supporting nearly 6 million tons of weight.
I assume they meant that if you were to double the diameter of the balloon, it would be a superlinear increase in lifting capacity (since volume is cubic in radius). However, it wouldn't actually be exponential, and two balloons added together definitely does not equal more than the sum of their individual lift capacity.
Some back-of-the-envelope calculations suggest that first number is in the right ballpark. From [0], the lift generated by helium vs Earth air at STP is approx. 1.03 g/L. This suggests a lift of approx. 590,000 short tons on Earth:
Then, if we assume that the gravity on Venus is 90% of Earth standard, you get about 656,000 short tons of lift. Note that this doesn't take into account the different air density on Venus.
You're right, that doesn't make any sense. The buoyant force is equal to the weight of the fluid displaced. Doubling the volume of your balloons doubles the buoyant force and therefore doubles the weight you can carry. The relationship is linear, not exponential.
I'd agree, that doesn't sound right at all. Perhaps they meant doubling the size of the balloon? Doubling the diameter of a sphere indeed increases its volume many times more than double.
I've always been surprised that NASA hasn't gone for a blimp type 'probe' for Venus. Something which floated above the clouds and allowed us to do long term observation from that point.
We think in terms of "flying" through the atmosphere, but once it gets dense enough you can make the equivalent of fish to "swim" through it. With internal bouyancy compensation bladders, and a skin impervious to the atmosphere. Smaller probes swimming down into the clouds to collect data about the surface and other conditions.
If nothing else it would be completely different than exploring Mars :-)
My guess would be that NASA hasn't done this because they feel like they have the traditional "lander" or "descent" type of probe worked out. They've done the engineering, they know the difficulties involved. What you're suggesting requires more expensive R&D, and means that the new probe has more chance of failing.
The conservative thing to do is to stick with what works. I do think you're right that the conditions are very different from Mars and this makes it possible to explore alternative approaches that may be better suited to the planet. I also believe that innovation entails some degree of risk taking. Just gotta get SpaceX onboard.
I'm not sure that's the case; the latest Mars lander required some pretty incredible engineering - I mean, they basically built a rocket-powered hovercraft, something that's never been done before.
I'd wager that the real reason is that Mars is more interesting to explore than Venus's atmosphere. Mars has the potential to have (or have had) life, and it has interesting geological features that may be directly applied to what we know about Earth.
Plus, the whole "we might go live on Mars!" mentality doesn't hurt, and Venus is only recently getting this kind of attention.
"they basically built a rocket-powered hovercraft, something that's never been done before"
They basically built a retro-rocket¹. Rockets existed, the principle of retro-rocket-like descent braking existed too (usually deployed on parachute drops of heavy equipment like tanks).
"I'd wager that the real reason is that Mars is more interesting to explore than Venus's atmosphere."
As you also noted, it's about public attention, which was fed with a lot of Mars stories. Mars' surface was more observable and thus made it more easily for Sci-Fiction writers to speculate about. It had less to do with practical considerations like those related to its atmosphere.
>If nothing else it would be completely different than exploring Mars
Which is likely why it hasn't been done. If it's something completely different, it takes more time and money to get it working. Starting from nothing, exploring Mars and exploring Venus might both cost $100b. But if the research has already been done to research Mars exploration, sending another probe there might only cost $2b, whereas Venus still costs $100b.
No doubt you are correct in that assessment. Time to fire up Kerbel to see how much payload a Falcon 9 Heavy can get into an Earth/Venus transfer orbit :-)
Do we know what it would look like to float in these safe regions? Would it be all haze, or clear skies? What color would the sky be? What would you see if you looked down?
There's one gaping hole in the idea though: where are we going to get water?
One other interesting possibility is colonizing Mercury. It turns out to not be as crazy an idea as it seems at first. Mercury does have water, there's plenty of solar energy, and it's not too hot at the poles. The trickiest part would really be getting there. As deep as it is in the sun's gravity well, it would take 6 years to get there!
Does Mercury offer any protection from the solar wind? I (naively) expect the solar wind intensity to go as the inverse-square of distance, and I know that surviving the solar wind on Mars is a big challenge, given the lack of a magnetosphere there. I expect the difficulty would be worse by many orders of magnitude on Mercury? Not to mention that you have to survive six years with no protection just to get there; just surviving the trip to Mars is a challenge.
If you wanted to build a habitation on Mercury, you'd either build a mobile one that stays on the dark side of the planet, or you'd stay in always-shaded areas at the walls of craters. So you're shaded from the solar wind by rock.
You actually wouldn't have to do either of those. There's actual frozen ice on Mercury's poles, which means you have a relatively temperate environment, plenty of sunlight for energy, and water.
The atmosphere and gravity situation on the other hand are about the same as Mars.
The ice around Mercury's poles is in permanently shadowed craters. The polar aspect is what allows there to be substantial permanently shadowed areas (because the sun never rises high in the sky).
Question to those with science backgrounds: Would it be possible to 'seed' venus with co2 crunching algae, provided we figured some way of suspending them in the atmosphere above the point where they'd cook to death? Some sort of superlight-algae that could live in the clouds and crunch the CO2 in to O2? It would grow and spread and begin reducing the pressure downwards, allowing it to also eat downwards.
Not really, venus atmosphere is way too thick and heavy. It would takes millions of years. Better would be ice ring on orbit to block sunlight, or bombarding surface with comets.
I think the problem could be water. The fraction of water vapor on Venus' atmosphere is ~200 times lower, although I don't know if that should factor that Venus' atmosphere would have many times Earth's mass.
I think you need some way of binding the O2 so that it does not just recombine with the C, perhaps by importing large quantities of H2 allowing you to turn the Oxygen into water.
The carbon absorbed in the photosynthesis does not just go free to burn again in oxidation, it stays as a building material for the living creature itself. Considering a positive process, in which more organisms are created (reproduced through mitosis) than those that die, in time the raw quantity of CO₂ should decrease. I'm not sure what to do afterwards with that mass of algae though.
The carbon does not go free because it is bound up in some organic compound, almost always a hydrocarbon (which of course requires Hydrogen) and would still combust at 460 Celsius. Perhaps if this life-form lived exclusively in the upper atmosphere? Then it would just have the problem of getting anything but carbon, oxygen and nitrogen.
Only argument for Venus atmosphere is that it sucks much less than its surface. Any asteroid would be better place. Someone must really love Star Wars.
Asteroids don't have gravity, forces you to figure out radiation shielding (which, granted, is probably as simple as digging into the asteroid), and requires you to keep a pressured environment with a 1-atmosphere difference.
I wish the article had expanded more on the idea of removing a lot of the atmosphere. I wonder if an asteroid could be sent in such a way that it tears through the atmosphere and rips a lot out into space. The rock would pass through and back out into space.
The ~50-megaton Tsar-Bomba reputedly "lifted" the atmosphere above its mushroom cloud off the Earth and into space. The Russians allegedly had or have a 100-megaton version which could presumably perform more "heavy lifting". There are probably more scientifically-minded readers here who possess a formula which will show the ridiculous number of Tsar-Bombas needed to make Venus safe for Humanity.
I've read that comets could be slammed into Venus, modifying its rotation, and somehow reducing or eliminating the runaway greenhouse effect. Of course, if mankind is at the point of being comfortable terraforming with comets, it may make more sense to point them toward the desert planet Mars.
"There are probably more scientifically-minded readers here who possess a formula which will show the ridiculous number of Tsar-Bombas needed to make Venus safe for Humanity."
Not to mention the nuclear fallout that would drift for a long time all around in the atmosphere - basically anything but "safe for Humanity".
Very unlikely; imagine swinging a pendulum through a water tank. Gravity pulls things down, not up; you're more likely to add some vaporized asteroid to Venus' atmosphere than have it "rip a lot out".
I'm trying to think of some kind of space-elevator-siphon, but there's no getting around the fact that, unless you want to expend energy to pump it, you have to have an equal amount of mass coming down as is going up.
I don't like the idea of provoking the loss of mass of some colonizable planet that already has less gravity than it would be natural for us. A better solution would be to trap as much of that atmospheric mass in solid aggregation state somewhere on its ground. Our planet had a lot of atmospheric carbon too, which is now trapped mainly as coal or other kind of fossil fuels.
"In more expansive visions, pumping Venus full of sulfur dioxide or hydrogen—or surrounding it in Sun shields—could terraform its climate into submission".
Couldn't bio-genetics create some sort of virus that inhabits on Mars' or Venus' atmosphere and grows on it while converting it into friendly environment? Or am I speaking pure sci-fi?
Probably none. The Earth's core is hotter than the surface and the surface temperature of the crust basically reflects the average atmospheric temperature.
Up north in the US the average ground temperature is maybe 40F at 10ft down (which is why there are basements up north, to get below the frost line) but here in Texas the average ground temperature is about 70F. At the equator it's probably more like 90-100F.
Given that Venus' atmosphere is so hot it seems likely that the deeper you go the hotter it gets.
Even in a storm, you won't feel a thing on a big ship (over 300m) with stabilizers. And you have to understand that there is a difference between a storm which involves different mediums, like gas (atmosphere), liquid (sea) and sometimes solid maybe (the shore or some sea cliffs) and a storm which resides in one medium only. The Venusian equatorial winds which surround the planet in a few days (at 300-400 km/h) and which are pretty permanent, can be considered storm winds. Those plans with balloon deploying were designed especially to take advantage of such winds, in order to get shorter days.
Venus has a LOT more CO2 than Mars does. And the band that people are envisioning putting the aerosats in has, well, less sulfuric acid than does the denser lower atmosphere.
Honestly, probably the realistic view is that it never makes sense to colonize, or even send long-term human presence to, any planet besides Earth. But to the extent that we want to dream of human presence on another planet, I think that the big obstacle to Venus is not the hostility of the upper atmosphere, it's the difficulty in getting any non-gaseous resources out of it.
At the very least, it seems like sending a robotic balloon probe to Venus to try to tool around in the upper atmosphere for an extended period of time is at least as worthwhile as sending another lander to Mars.
It would be much cheaper to establish a dozen independent biospheres here on Earth than one off Earth. Put one in the Canadian Shield, another under the Australian desert, etc. If scattered well, several should survive even a Chicxulub-class event.
But I suspect you mean something different than independent biospheres. If so, what risks are you thinking of?
> several should survive even a Chicxulub-class event
That's an interesting proposal. I'd love to read a study on that.
> But I suspect you mean something different than independent biospheres. If so, what risks are you thinking of?
Well there are degrees of independence. Perhaps "isolation" in the systems engineering sense is a better term. There are a lot of high-risk probabilities that arise as technology advances - and the Fermi paradox isn't encouraging about our chances. For some example risks, let's say grey goo, cybernetically enforced self-destructive tyranny and unexpected stable artificial black hole. In some case, the light-minutes of separation may make the difference.
It might make more sense to build an artificial orbital habitat at L5 or the like, but these seem so fragile compared to biospheres that could be constructed on Mars. Being out of the gravity well is a huge advantage, but the gravity on Mars is low enough that space elevators become a real possibility. Perhaps Ceres is a good compromise - lots of water, metal rich asteroids all around.
The Chicxulub impact had global consequences, but far enough from the crater would have been survivable in any bomb shelter. http://users.tpg.com.au/users/tps-seti/climate.htm gives an estimate of the damage radius, with 1 psi overpressure to 4000 km. While it says there was a global firestorm, the most recent analysis believes that that wasn't the case, see http://www.exeter.ac.uk/news/featurednews/title_430274_en.ht... . It does says that being on the other side of the planet would have been worse than North America, in terms of heat flash, so the Canadian Shield would be survivable, as would most nuclear bomb shelters in the world.
It's very hard to model those risks. A non-terrestrial habitat will certainly be more fragile than one on Earth, and easier to fall prey to a malicious computer attack by rogue AIs. A gamma ray burster would be more survivable in a shelter 1,400 m underground[1] than anything we are likely to build soon on another planet, or Ceres. A "Dark Star" scenario as in Fritz Leiber's "A Pail of Air" feels more likely than an unexpected stable artificial black, and in that story, access to nuclear fuels, along with a stockpile of liquid atmosphere and frozen materials, helped keep civilization going. Or perhaps the Free Peoples of Ceres will send an asteroid killer our way, to keep the solar system from being infested by flatlanders.
So while there are scenarios where separation is important, there are also scenarios where separation won't help, and might end up taking funding away from something which would have helped. With probabilities that low, and with such high error estimates, it's hard to tell which approach is best. The cheapest is self-sufficient here on Earth. If that works, then there's the base knowledge for how to set that up off-planet.
([1] I refer to the Laboratori Nazionali del Gran Sasso, which is a neutrino lab. While not the deepest lab, it's one with an access road instead of an elevator. Very handy if you want to supply your colony.)
Most people who have ever tried living in an isolated biosphere on earth decided, after some number of months, that cities and trees and sky were pretty desirable, opened the airlock and left. Possibly it would work on another planet with no return vehicle.
In any case, the first step would be to develop a long-term, viable independent biosphere. We haven't yet figured out that one. Once we get that working, we need enough excess free capacity to raise and educate children to be the next generation of biosphere caretakers.
Economy is an engine of progress, but some people raise it to the level of a God. It's a tool, not a justification. We shouldn't limit our actions only to those that turn profit, 'lest we turn into mindless drones generating entropy without much purpose.
>Honestly, probably the realistic view is that it never makes sense to colonize, or even send long-term human presence to, any planet besides Earth.
I think it could make sense when we have robots that are able to mine material and construct habitats without requiring human supervision. Just build the robots, drop them off on Venus, Mars, etc, then come back in 30 years and sell condos.
> I think that the big obstacle to Venus is not the hostility of the upper atmosphere, it's the difficulty in getting any non-gaseous resources out of it.
We can get non-gaseous resources out of Venus accessible asteroids. Venus could supply two things -- a beautiful and relatively friendly place to live and also fluorine condensed out of its atmosphere.
I could envision huge aerostat supported structures hundreds of kilometers long that house electromagnetic accelerators to launch raw materials into orbit. Rotating tethers could deposit cargo carriers into the Venusian atmosphere at hypersonic speeds, to deploy ballutes and slow down through aerobraking and then to float awaiting retrieval. In doing so, the tethers would re-accelerate themselves to haul other cargo up from hypersonic aircraft.
Maybe it's not economically and politically feasible now or ever, but it's tons of fun to think about. This sort of thing also demonstrates that it's not physically impossible.
> At the very least, it seems like sending a robotic balloon probe to Venus to try to tool around in the upper atmosphere for an extended period of time is at least as worthwhile as sending another lander to Mars.
Exactly. Enough with Mars already. Red sky, red sand and red rocks : it gets old, frankly.
"Honestly, probably the realistic view is that it never makes sense to colonize, or even send long-term human presence to, any planet besides Earth."
The sole point is the experience of colonizing other planet. We're not looking to get there for the resources (stop for a second and just think out of the box), we're looking to get there to be able to live there as a species.
> At 50 kilometers up, Venus is remarkably Earth-like ... The atmospheric pressure is a comfortable one bar, the gravity about 90 percent that of Earth's, and temperatures fall within a hospitable range of 0-50 degrees Celsius.
Nothing to sneeze at, but I don't think it is an exaggeration to say that a flying habitat of sufficient reliability is orders of magnitude more difficult. Are there studies that suggest otherwise?
> At least we know how to transform CO2 into oxygen.
That's so, but the atmosphere on Mars is so thin it's not as if you can step outside there either - you'd die quickly as it's well below the Armstrong limit. You still need a full-body pressure suit on Mars.
Venus, FWIW, is 96.5% CO2 and has a surface pressure of 93 bar. That's a lot of oxygen if you just want to make some for your space station.
Personally I hold out hope for terraforming Venus. Adding gravity or atmosphere to Mars seems like it'd be much more difficult.
They were talking about adding a jet to pump CO2 out of the atmosphere. Is there a chance you could direct the jet such that it intercepts Mars in a useful way?
Then you get to rebalance both the planets atmospheres at once.
However, Mars has pretty weak gravity so even if you could, I don't know if it would stick around.
Depends on the timescale. Mars obviously has an atmosphere half-life much shorter than Earth's. At the same time, if its lifetime is a million or even a couple thousand years, it might be entirely suitable for terraforming for humans, depending on the rate at which we can replenish it.
Of course, at some point we have to ask questions about how renewable a resource various elements are...
At 52km you don't need heating, and in the case of a breach the clouds would stay mostly out because of equal pressures on both sides of the dwelling. A scientific outpost, like those in Antarctica, would be highly appealing. For permanent settlement, Mars takes the cake.
I imagine Venus being closer to the Sun (and having a higher temperature in general due to the greenhouse effect of its atmosphere) makes it easier to generate usable energy there, RTGs notwithstanding.
I didn't read it through & through, but i think the benefits of going to mars over venus is longevity. As the idea would be (provided we last long enough) that when the earth starts to swell, earth will get too hot to live on, and therefore so would venus. We'd still have time on mars before having to move further away.
You mean "when the sun starts to swell," not "when earth starts to swell."
And this is a laughable concern. The Sun's main sequence is predicted to last another 4 billion years. That's more time than life has existed on Earth, about 16,000x as long as homo sapiens has existed.
If we're concerned with the survival something vaguely descended from homo sapiens in 4 billion years, there's little enough harm in taking another million years for our tech to get a little better before starting the project.
To nitpick, The End Of Life We Care About on Earth is only ~800 million years off[1], at the outside, barring some unforeseen catastrophe or some truly astounding planetary engineering. Still a long time, but no 4 billion years.
1. It has essentially Earth-normal gravity. Zero-G long-term is a death sentence for humans. The long term effects of Martian gravity are unknown. It seems safe to assume that Venus gravity is fine.
2. It is protected from impact and radiation by an atmosphere in a way that Mars or asteroids never will be.
3. It has an essentially limitless supply of carbon, oxygen, nitrogen, and sulfur available to it.
4. It is reasonably well-positioned for solar power.
5. It is relatively temperate.
6. Low pressure differential between inside a habitat and outside of one means that leaks are less severe and containment breaches are easier to react to.
But there is at least one huge disadvantage:
1. Everything besides carbon, oxygen, nitrogen, and sulfur needs to be imported, either from a fantastically hostile surface, or down through reentry into an atmosphere in a deep gravity well and rendezvousing with an aerostat.
That disadvantage is a pretty goddamn significant one for human habitation.
But it's not a disadvantage for long-term robot probes, and it's... less... of a disadvantage for a minimal-population scientific base.