[The E]

Mars has much more extreme temperatures,

AAAAHAHAHAHAHAHAHAHAAAAA

Mars Temperatures:
     Lowest: -133 Degrees Celsius
     Mid:       -55 Degrees Celsius
     Highest: 27 Degrees Celsius

Mars atmosphere:
    Ambient pressure: 6*10^-3 bar (or about 0.006 bar)
    Mostly CO2, N

So, in other words, it's not that far away from a high-altitude environment on Earth, minus the oxygen of course. We kinda know how to deal with that, and given that the greatest natural obstacle would be sand storms (Something we know a lot about too), I have a bit of trouble seeing how Venus would be _easier_.

Whereas the construction of giant, permanently floating structures is an area of engineering we have little to no experience with, not to mention doing so in an atmosphere that is highly corrosive. And much as I hate to point it out, but asteroid impacts are pretty much a null issue, given how rare these things are.
   

[QuantumDelta]

Terraforming, or getting a habitat on venus will be insanely hard, the moon is easier, and mars easier still (despite the initial distance problem).

I wonder if slamming some comets into venus might help

[TwentyPercentCooler]

Mars has much more extreme temperatures,

AAAAHAHAHAHAHAHAHAHAAAAA

Mars Temperatures:
     Lowest: -133 Degrees Celsius
     Mid:       -55 Degrees Celsius
     Highest: 27 Degrees Celsius

Mars atmosphere:
    Ambient pressure: 6*10^-3 bar (or about 0.006 bar)
    Mostly CO2, N

So, in other words, it's not that far away from a high-altitude environment on Earth, minus the oxygen of course. We kinda know how to deal with that, and given that the greatest natural obstacle would be sand storms (Something we know a lot about too), I have a bit of trouble seeing how Venus would be _easier_.

Whereas the construction of giant, permanently floating structures is an area of engineering we have little to no experience with, not to mention doing so in an atmosphere that is highly corrosive. And much as I hate to point it out, but asteroid impacts are pretty much a null issue, given how rare these things are.
   

I clarified my temperature remark.

I realize that my field is nuclear engineering and not materials or structural engineering, but from a medical standpoint, humans would be better off on Venus. It's not even known if we can exist for long periods of time in low- or microgravity situations without permanently debilitating bone loss, nevermind the various other physiological concerns.

What I do know is that, if someone's pitching the idea to people, health concerns are gonna trump engineering concerns.

[Nuke]

given that mars is right next to the asteroid belt i think it would be a better idea just to hit mars with asteroids, especially in the ice caps, to help thaw them out. mars's moons are small enough it might be possible to just push them in as well. id just use solar sails and a lot of time, as it would be the cheapest way to deal with that. then again this just might make the conditions on mars less habitable.

[The E]

What I do know is that, if someone's pitching the idea to people, health concerns are gonna trump engineering concerns.

Uh. And they wouldn't just cancel the whole idea why, exactly? Sure, we don't know a lot about long term effects of low gravity environments, but we DO know about the effects of being crushed to death by atmospheric pressure, being exposed to acidic rain, and all the other fun deaths one may have on Venus. And seriously? "Health concerns trump engineering concerns?" You're awfully optimistic about our ability to build safe floating environments, you know. And you still haven't answered the question why the hell we should go to Venus, when there's almost nothing to do there but float in the clouds. Making an argument for a moonbase is easy, there's ressources there. Making an argument for a Mars base isn't much harder, given that turning it into a more friendly environment seems rather straightforward, and can be accomplished with a minimum of yet-to-be-discovered magic technology. Venus? What the hell is on Venus that would make going there a worthwhile pursuit?

[Mars]

Venus could be a lot like Earth. . .

in several million years.

[TwentyPercentCooler]

What I do know is that, if someone's pitching the idea to people, health concerns are gonna trump engineering concerns.

Uh. And they wouldn't just cancel the whole idea why, exactly? Sure, we don't know a lot about long term effects of low gravity environments, but we DO know about the effects of being crushed to death by atmospheric pressure, being exposed to acidic rain, and all the other fun deaths one may have on Venus. And seriously? "Health concerns trump engineering concerns?" You're awfully optimistic about our ability to build safe floating environments, you know. And you still haven't answered the question why the hell we should go to Venus, when there's almost nothing to do there but float in the clouds. Making an argument for a moonbase is easy, there's ressources there. Making an argument for a Mars base isn't much harder, given that turning it into a more friendly environment seems rather straightforward, and can be accomplished with a minimum of yet-to-be-discovered magic technology. Venus? What the hell is on Venus that would make going there a worthwhile pursuit?

Besides the low gravity, there's also flash-freezing and near-vacuum concerns if the environment is breached, along with a large pressure differential. If your suit gets a hole knocked in it, the air is gonna leave. Quickly. Same goes for the habitats themselves. Air leaks would be extremely dangerous. Full pressure suits would be necessary for any exploration, with exposure to the exterior atmosphere resulting in internal hemorrhaging and flash-freezing of the skin. On Venus, since the temperature and air pressure would be very close to Earth's, a full pressure suit wouldn't be required, although it would be advisable. A leak in the suit would diffuse air outward very, very slowly (see the "space suits" used in handling extremely dangerous biological substances), slowly enough to make patching the leak as easy as putting a piece of tape over it.

Neither planet has much to recommend it as far as resources go, really. Mars' surface is mostly basalt. However, Venus' atmosphere has useful concentrations of some trace gases like argon and neon: useful in industrial processes as non-reacting atmospheres. But I don't want to justify it that way because that's not a big deal. What is a big deal? Doing it because we can. Doing it because maybe some people don't want to live on this planet anymore. Either way, we stand to learn a lot about ourselves, and either way, who knows what science will get out of overcoming the obstacles necessary to colonize other planets. I don't care if it's inflatable habitats on Mars, floating cities on Venus, or submarines on Europa - I'm going to advocate doing it. Venus wouldn't require any "magic" technology, and neither would Mars. But, regardless of the science, it's going to boil down to protecting ourselves from hostile environments. And despite the conditions on the surface, the proposed habitats in the upper atmosphere have only one hostile factor - corrosive gas, which we can be sealed away from with minimal difficulty. It also stands to be mentioned that Venus receives quite a bit more solar radiation thanks to the inverse-square nature of light intensity, and thus solar panels wouldn't have to be as large.

[watsisname]

There is no evidence for plate tectonics, possibly because its crust is too strong to subduct without water to make it less viscous.

[citation needed]

The presence of water in the crust is what helps drive volcanism along subduction zones, since the water gets heated and converted to steam, which rises and melts rock along the way to generate rising magma plumes. 
I'm not convinced water helps to make the crust "less viscous" or that this has any role in allowing subduction to occur.  The primary mechanism for subduction is the presence of a collision boundary, with one side of the crustal mass being less dense than the other.  For an ocean-continent subduction zone, the oceanic crust is the one to sink because the oceanic crust, being made of basalts, is more dense than the continental crust, primarily made of granites.

I also read somewhere that Earth's crust would not subduct without an ocean because of its size. If Earth were larger, its crust would be able to subduct without any liquid water at all.

As I understand it, the reason a larger planet is more capable of having plate tectonics is because it takes longer for a larger planet to cool down, so those convection currents continue for quite some time.  I recall reading (I think in Scientific American) a couple months back that Earth is hypothesized to be about the minimum size planet capable of sustaining active tectonics for as long as it has.
Again I'm not sure how water would play a role, but I'd be interested in seeing that research.

[IronBeer]

On Venus, since the temperature and air pressure would be very close to Earth's, a full pressure suit wouldn't be required, although it would be advisable. A leak in the suit would diffuse air outward very, very slowly (see the "space suits" used in handling extremely dangerous biological substances), slowly enough to make patching the leak as easy as putting a piece of tape over it.

You're operating under the assumption that these conditions exist on your posited "floating colonies". The engineering challenges for such colonies are so large so as to make my head spin. Besides, Venus is famous for sulfuric acid rain. According to my Chemical Process Safety textbook, the OSHA-mandated 8-hour Personal Exposure Limit is 1mg H2SO4/1m^3 air. Chemical companies that expose their workers to concentrations higher than that face fines and legal action. On Venus, a suit breach, even at high altitudes (you're sticking with this idea, seriously?) wouldn't result in some fines and upset lawyers, it would result in a case of sulfuric-acid-in-environment-suit, likely followed by injury and a very possible irreversible death.

Venus wouldn't require any "magic" technology, and neither would Mars. But, regardless of the science, it's going to boil down to protecting ourselves from hostile environments. And despite the conditions on the surface, the proposed habitats in the upper atmosphere have only one hostile factor - corrosive gas, which we can be sealed away from with minimal difficulty. It also stands to be mentioned that Venus receives quite a bit more solar radiation thanks to the inverse-square nature of light intensity, and thus solar panels wouldn't have to be as large.

...Floating cities don't need "magic technology". Indeed.

Also, "it's just some corrosive gas" (paraphrase)? Oilfields on Earth that have to deal with high concentrations of hydrogen sulfide gas (corrosive and notoriously toxic) have to apply perhaps the best petroleum engineers on the planet to simply avoid killing workers, while using one of the most expensive gas separation and removal processes in the industry.

Furthermore! While the inverse-square law does apply to Venus, you have forgotten to take Venus' famed cloud cover into consideration. Modern-day solar panels are minimally functional (if at all!) during cloudy days on Earth; without sparing a few minutes for some back-of-the-envelope calculations, I'm pretty sure that solar power would not be a very viable option for power on Venus.


I doubt this post is really going to alter anybody's mindset, but I'd grown tired of ill-informed speculation and magical engineering.

[watsisname]

Hey TwentyPercentCooler, have you read the Red Mars trilogy by Kim Robinson?  I think it'd be right up your alley!

[TwentyPercentCooler]

On Venus, since the temperature and air pressure would be very close to Earth's, a full pressure suit wouldn't be required, although it would be advisable. A leak in the suit would diffuse air outward very, very slowly (see the "space suits" used in handling extremely dangerous biological substances), slowly enough to make patching the leak as easy as putting a piece of tape over it.

You're operating under the assumption that these conditions exist on your posited "floating colonies". The engineering challenges for such colonies are so large so as to make my head spin. Besides, Venus is famous for sulfuric acid rain. According to my Chemical Process Safety textbook, the OSHA-mandated 8-hour Personal Exposure Limit is 1mg H2SO4/1m^3 air. Chemical companies that expose their workers to concentrations higher than that face fines and legal action. On Venus, a suit breach, even at high altitudes (you're sticking with this idea, seriously?) wouldn't result in some fines and upset lawyers, it would result in a case of sulfuric-acid-in-environment-suit, likely followed by injury and a very possible irreversible death.

Venus wouldn't require any "magic" technology, and neither would Mars. But, regardless of the science, it's going to boil down to protecting ourselves from hostile environments. And despite the conditions on the surface, the proposed habitats in the upper atmosphere have only one hostile factor - corrosive gas, which we can be sealed away from with minimal difficulty. It also stands to be mentioned that Venus receives quite a bit more solar radiation thanks to the inverse-square nature of light intensity, and thus solar panels wouldn't have to be as large.

...Floating cities don't need "magic technology". Indeed.

Also, "it's just some corrosive gas" (paraphrase)? Oilfields on Earth that have to deal with high concentrations of hydrogen sulfide gas (corrosive and notoriously toxic) have to apply perhaps the best petroleum engineers on the planet to simply avoid killing workers, while using one of the most expensive gas separation and removal processes in the industry.

Furthermore! While the inverse-square law does apply to Venus, you have forgotten to take Venus' famed cloud cover into consideration. Modern-day solar panels are minimally functional (if at all!) during cloudy days on Earth; without sparing a few minutes for some back-of-the-envelope calculations, I'm pretty sure that solar power would not be a very viable option for power on Venus.


I doubt this post is really going to alter anybody's mindset, but I'd grown tired of ill-informed speculation and magical engineering.

You're assuming that the acid leaks into the suit - I invoked a comparison with chemical and biological hazard suits for a reason. If there's a leak, the air goes out, not in. Positive pressure. There are currently people working with things much more dangerous to humans than acids ensconced in such suits. They carry tape with them to seal holes quickly. It's nothing incredibly high-tech besides the materials science that went into the suits' construction.

Fighting corrosive gas doesn't require magical technology. Those oil industry workers are trying to avoid being exposed to the gas in an open environment. These proposed habitats are a closed environment - the difficulty is in sealing the environment in the first place. Yes, it's difficult, but we already have materials that can do this. No magic necessary.

Solar panels would likely be floated much higher than the habitats themselves, attached by cables. Nitrogen-oxygen mixture is a lifting gas, something lighter would be even more so. These habitats will already be above a great deal of the atmosphere, things floating higher could be comparatively unobstructed by cloud cover. You have to remember that these won't be anywhere near the surface; I certainly haven't forgotten that the cloud cover is legendary.

Any colonization efforts are going to involve a lot of speculation and a lot of surprises when we get there. But please, I'm not the smartest guy on the planet but I'm not an idiot, either. I'm a fairly vocal advocate of colonization efforts, so I try to stay informed. I'd be happy with us going anywhere at all at the moment.

[G0atmaster]

This thread has a lot of information that is contrary to what I've been taught. For starters, the hydrogen isn't missing... It's found in the sulfuric acid that is present in much of the atmosphere.

Second, if I remember my astronomy class correctly, the fact that there is an atmosphere at all is evidence that there is a magnetic field, otherwise solar winds would have stripped it away.

Third, that magnetic field is evidence of a yet molten core, as the molten convection  processes are what create the magnetic fields. On Mars, there are "wrinkle" ridges that denote a shrinkage of the core, likely due to cooling and solidification of the core, which is why Mars has almost no tectonic activity, almost no magnetic field, and consequentially, almost no atmosphere. And that's the fundamental difference that makes Venus a more viable terraforming target. Even if we got an atmosphere on mars, without core activity it would just blow away under the sun.

[Nuke]

i think the colonization of venus would be a good canidate for a third or fourth colony, definitely not the first colony we would consider. if anything it would be no more than a gas mining outpost. the moon then mars are prime first and second colonies. you need the moon as a base for further colonization. moon is a good candidate for mining, and once a colony is established it becomes your shipyard and space port as well. you also have access to helium 3 to power fusion reactors, to provide power for climate control on extremely hot or extremely cold planets. you need this infrastructure long before you even can consider a colony on another planet.

you need to be able to launch some serious tonnage in materials to build floating cities on venus. then the question is where and how do you build it. your best bet is to build the floating city as several modules that can be joined in the atmosphere. youd need to launch a large number of these if launching from earth, or you can build fewer, larger modules on the moon. it might be possible to drop the entire city in the atmosphere if you can make it survive re-entry. it might have a large enough cross section and relatively low mass to volume ratio and slow down rapidly in the upper atmosphere, then let it fall til buoyancy takes over.

of course then youre back to why. gas mining is about the only reason to do this. mars at least has the possibility of being terraformed. also being closer to the sun it is not a viable backup colony for humanity for the eventual solar expansion, and i very doubt it would be a self sufficient colony thanks to the lack of useful access to the surface for resources. also having gravity close to that of earth, export of mined materials (gasses) becomes less economically viable, as you cannot launch them cheaply (cheaper than earth-launch however). its not as high a value in terms of colonization that the moon or mars, and so those places should be colonized first. we already know how to deal with zero/low atmosphere situations.

[TwentyPercentCooler]

i think the colonization of venus would be a good canidate for a third or fourth colony, definitely not the first colony we would consider. if anything it would be no more than a gas mining outpost. the moon then mars are prime first and second colonies. you need the moon as a base for further colonization. moon is a good candidate for mining, and once a colony is established it becomes your shipyard and space port as well. you also have access to helium 3 to power fusion reactors, to provide power for climate control on extremely hot or extremely cold planets. you need this infrastructure long before you even can consider a colony on another planet.

you need to be able to launch some serious tonnage in materials to build floating cities on venus. then the question is where and how do you build it. your best bet is to build the floating city as several modules that can be joined in the atmosphere. youd need to launch a large number of these if launching from earth, or you can build fewer, larger modules on the moon. it might be possible to drop the entire city in the atmosphere if you can make it survive re-entry. it might have a large enough cross section and relatively low mass to volume ratio and slow down rapidly in the upper atmosphere, then let it fall til buoyancy takes over.

of course then youre back to why. gas mining is about the only reason to do this. mars at least has the possibility of being terraformed. also being closer to the sun it is not a viable backup colony for humanity for the eventual solar expansion, and i very doubt it would be a self sufficient colony thanks to the lack of useful access to the surface for resources. also having gravity close to that of earth, export of mined materials (gasses) becomes less economically viable, as you cannot launch them cheaply (cheaper than earth-launch however). its not as high a value in terms of colonization that the moon or mars, and so those places should be colonized first. we already know how to deal with zero/low atmosphere situations.

I absolutely agree that the moon should be our first target. Helium-3 and titanium deposits, both useful for our future endeavors, and a much better launch platform for further explorations. After that, though, you're right that Mars has more useful resources (iron, nickel, chromium, some titanium, and who knows what else). I agree that it's likely Mars will be the second logical target for launches and development. Mining efforts, certainly. But, unless we can develop some kind of counter for bone loss induced by low-gravity conditions, I also think it's likely that either humans will only build the infrastructure and let robots take over the mining, or else tours of duty on the surface will be short, with the inhabitants shuttling back up to a space station with artificial gravity. Not that there's anything wrong with that at all.

Long-term colonization, though, will be a different animal. What I'm really arguing is that Venus is a better option for long-term habitation by humans for medical reasons. Why would people live there? Independence. Food, water, and air would likely be sustainable without outside intervention, and it's possible that people would want to live there for the same reasons that humans expanded to different territories on Earth. But the way things really turn out will likely be more nebulous. Really, I'm happy with any moves our stagnant society makes in regards to any of this.

[Mars]

By the time living on Venus is viable, I honestly believe we will have come up with the technology to survive in low G environments indefinitely. It's feasible that we'll figure out that problem in the next couple decades.

[watsisname]

If I remember my astronomy class correctly, the fact that there is an atmosphere at all is evidence that there is a magnetic field, otherwise solar winds would have stripped it away.

No, Venus has no magnetic field... it's possible it had a stronger one in the past, but presently the upper limit on its strength is 10^-5 that of the Earth's, based on measurements from a number of spacecraft that went there, namely the Venera and Pioneer missions.

A magnetic field is not strictly required to maintain an atmosphere.  It certainly helps prevent the gradual erosion of particles from the upper atmosphere by direct contact with the solar wind, but the primary force at work is the planet's gravity.  Venus is massive enough to hold onto a substantial atmosphere despite the solar wind.
Other factors are the temperature (at higher temps particles move more quickly and thus can escape the planet more easily) and molecular weight (lighter molecules like H2 can escape more easily then heavier ones like CO2).

Third, that magnetic field is evidence of a yet molten core, as the molten convection  processes are what create the magnetic fields. On Mars, there are "wrinkle" ridges that denote a shrinkage of the core, likely due to cooling and solidification of the core, which is why Mars has almost no tectonic activity, almost no magnetic field, and consequentially, almost no atmosphere. And that's the fundamental difference that makes Venus a more viable terraforming target. Even if we got an atmosphere on mars, without core activity it would just blow away under the sun.

It's possibly a combination of several factors.
For one, Mars has weaker surface gravity so is less able to hold onto an atmosphere.  And as you mentioned, Mars it has also cooled down and ceased all tectonics.  This is also because Mars is smaller, and smaller planets cool more quickly.  It may very well be that both Mars and Venus had magnetic fields in the past, but Mars lost its field well before Venus did, which would also help explain why Mars has little atmosphere now while Venus still has a significant one.

[Nuke]

i see that eventually we will have colonies everywhere. eventually they will have at least some degree of trade once the infrastructure is in place. right now were still prospecting, looking for viable modes of colonization. might even involve moving celestial bodies into more favorable orbits. i could imagine landing very large nuclear-water engines on ice rich dwarf planets or small moons, using the ice itself as propellant. granted you would consume most of the body in the process, but once its in the goldilocks zone it becomes potentially habitable. you might even build artificial planets by collecting a number of smaller objects and artificially coalesce them. things like lack of useful gravity and pressure are not as insurmountable as one might think. it may also turn out that gravity is not as critical to survival, and we could also allow natural selection or genetic engineering to adapt humans to low gravity environments.

[FlamingCobra]

Umm.

Why? Because, way I see it, colonizing Mars represents a huge challenge, but it could actually be done using current technology. The same can not be said about Venus, not by a long shot. And still the question would be why, because as far as I can tell, the ressources that may be available on Venus are so inaccessible as to make retrieval somewhat challenging....

Because we do not know what long-term effects on human biology will result from Mars' lesser gravity?

[Mars]

Umm.

Why? Because, way I see it, colonizing Mars represents a huge challenge, but it could actually be done using current technology. The same can not be said about Venus, not by a long shot. And still the question would be why, because as far as I can tell, the ressources that may be available on Venus are so inaccessible as to make retrieval somewhat challenging....

Because we do not know what long-term effects on human biology will result from Mars' lesser gravity?

By the time living on Venus is viable, I honestly believe we will have come up with the technology to survive in low G environments indefinitely. It's feasible that we'll figure out that problem in the next couple decades.

[FlamingCobra]

All I'm saying is, for terraforming purposes, Venus is more desirable than mars because of one factor - size.


How did we go from terraforming to floating colonies anyway?


Also, mars has no magnetic field so its atmosphere would have to be replenished constantly.