Floating Cities On Venus 501
Geoffrey.landis writes "Some of you may have heard me talk about colonizing Venus. Well, for those who haven't, Universe Today is running story about floating cities on Venus. It's a reasonable alternative for space colonies — after all, the atmosphere of Venus (at about 50 km) is the most Earth-like environment in the solar system (other than Earth, of course). '50 km above the surface, Venus has air pressure of approximately 1 bar and temperatures in the 0C-50C range, a quite comfortable environment for humans. Humans wouldn't require pressurized suits when outside, but it wouldn't quite be a shirtsleeves environment. We'd need air to breathe and protection from the sulfuric acid in the atmosphere.'"
Re:don't trust the locals (Score:5, Informative)
Re:Instant Global Warming (Score:5, Informative)
Not to take the bait, but Venus [wikipedia.org] is a lot hotter than Mercury [wikipedia.org]. The all-important albedo can have a much bigger impact on temperature than distance!
Re:So we'd need to... (Score:3, Informative)
Distance. Jupiter is 4.2AU away as the crow flies (3.1 if you use a perfectly osculating orbit), while Venus is under 0.3AU away.
That extra fuel is a deal breaker. For now.
Re:why Venus? (Score:3, Informative)
Re:Instant Global Warming (Score:3, Informative)
Not to take the bait, but Venus is a lot hotter than Mercury.
Surface temperatures yes, but is the temperature 50 km above the surface of Venus hotter than the temperature 50 km above the surface of Mercury?
The all-important albedo can have a much bigger impact on temperature than distance!
I doubt albedo is all-important in this instance. For a start Venus has a far higher albedo than Mercury, which would make it cooler, no? What is all-important is the composition of Venus' atmosphere, which is largely made up of C02 and other greenhouse forcing gases.
Re:Energy supply for the cloud cities (Score:3, Informative)
No, it's not: It's in 3:2 resonance [wikipedia.org] with the sun. One mercury year is 1.5 mercury days.
Re:Instant Global Warming (Score:3, Informative)
The all-important albedo can have a much bigger impact on temperature than distance!
Erm, your statement does not make any sense at all. The albedo of Venus is roughly 65%, Mercury's is below 20%. That alone should make Venus much, much cooler than Mercury, which it isn't.
In fact, Venus' albedo is high enough that it receives about as much solar heating as Earth (Earth's albedo is roughly half of that of Venus, Venus receives roughly twice as much solar input of Earth) - the only reason that Venus is such a hellhole is its super-thick atmosphere (calling it a "gas ocean" isn't too far off the truth) consisting mostly of CO2.
Re:Pure science-fantasy (Score:3, Informative)
Go look in the mirror.
Sentient, self replicating robots exist.
Go open a history book to 1908. Tell me I'm wrong.
Re:So we'd need to... (Score:3, Informative)
No it's not and I never said excavation since soil can be put on top of structures.
A layer of dirt isn't radiation shielding.
And floating cities in a poisonous acid atmosphere AREN'T science fiction?
Cities of any kind are science fiction. Flying habitats are not science fiction, no. We already have long-term aircraft prototypes. Hell, given a sufficient supply of fuel, all you really need is a more corrosion-resistant aircraft.
It is a meaningful way if you need 10000 times the volume to hold up something as then you need to ship in even more material.
What?
Just because it doesn't agree with your point doesn't make something implausible.
When did this become a binary discussion? We have a basic grasp on technologies for habitat modules, surface or floating. Rotating spacecraft and space elevators are not impossible, but they are extremely implausible. We don't even have a realistic roadmap.
since you seem to like selectively saying things are impossible I claim space planes are impossible in turn.
I said nothing was impossible, and again, we already have working prototypes of suitable space planes. The space shuttle is one important step. Various X-projects are another.
Rotating spacecraft and space elevators haven't even advanced to a prototype stage. They're not in the same ballpark. They're not feasible based on anything we have now.
Last I checked there have been no studies on the prolonged effects of low gravity since so far we've had either gravity or no gravity. In fact I believe the general view was that low gravity wouldn't be that harmful.
Check again. Low gravity causes loss of bone density, muscle atrophy, decreased production of red blood cells, headaches, weakened immune systems, and gastrointestinal complications. Prolonged exposure requires significant readjustment and often physical training upon returning to Earth. The closer the gravity to earth-normal, the more attenuated these effects.
Re:Fix Venus with Limes (Score:4, Informative)
Re:Fix Venus with Limes (Score:3, Informative)
Re:"LV-426 Shake-and-bake" Terraforming... (Score:4, Informative)
Actually, I wouldn't list Venusian chemistry as the primary barrier to terraforming. Yeah, there's acid and CO2 out the ying-yang, but there are other, bigger problems.
The atmosphere is incredibly dense. Think "deepest trench in the ocean floor" dense. We'd need to get rid of most of it. Burying it seems unwise, if only because all it would take is one major geological upheaval to undo all our hard work.
That leaves dragging vast amounts of mass up past escape velocity. We'd also need to make sure that the gas didn't subsequently get pulled back onto the surface by the planet's gravity, which means doing more than just bottling it on the surface and decompressing it in orbit. Barring teleportation, artificial black holes, or direct conversion of matter into energy, this problem may be unsolvable.
On the plus side, any measure that we could use to eliminate the gas could probably also be used to retool the atmospheric chemistry. In other words, if we solve the pressure problem, the problems of acidity and CO2 levels become moot.
Additionally, Venus' rotational period is too long. Venusian days are on the order of two hundred and forty Earth days. If the surface were otherwise habitable, in terms of chemistry and pressure, you'd still get extremes of temperature during the day/night cycle. The current level of insulation prevents this - the whole planet is blanketed, so that sunlight never reaches the surface, and heat gets spread evenly. A less dense atmosphere would pave the way for scorching days and freezing nights, not unlike Mercury (though admittedly less so if the surface isn't in vacuum).
Increasing the planet's angular momentum would solve this, but the sheer amount of energy needed is mind-bending. I'm not even sure what spinning up a world would do to it's surface or internal structure. Forget centuries, we'd need a millennium or two to fix this.
Now, that being said, I've long believed that attempting to predict future technological advances is futile. Past attempts at prediction bear this out. I do not like to say that something is impossible, because it is all too likely I'll be proven wrong in the long run.
It is entirely possible that at some point in the future, some unknown or presently implausible techniques may exist for dealing with the listed problems. However, there is not a single thing we can do now, or in the foreseeable future, to drastically change Venus into something remotely habitable. If we wanted to live there, my choice would be the way mentioned in TFA, since that at least we could do if we really put our minds to it.
Re:They did (Score:4, Informative)
I don't know if you got that from Wikipedia, but if you did, it's an over-simplification of the linked ESA article [esa.int]. That talks about the solar wind stripping water molecules away before disassociation, not molecular hydrogen.
H2 molecules don't actually need any extra help to escape the atmospheres of Venus or Earth: even at the low temperatures of the very upper atmospheres of those planets, a statistically significant fraction of the molecules have a velocity that exceeds the escape velocity. Over long periods of time, almost all unbonded H2 simply wanders off in to space. This is something you examine if you take a statistical thermodynamics [wikipedia.org] course; it also explains why the Moon has almost no atmosphere, Mars a very thin atmossphere, and why the "gas giants" hang on to all that gaseous hydrogen and helium.
Besides, there is still plenty of hydrogen on Venus: in the sulphuric acid (H2SO4) already discussed. 8) Now, how do we convert sulphuric acid to water... is there any Copper on Venus?
Re:Its not C02, its PRESSURE!!!! (Score:3, Informative)
Mars as lots of c02, it aint god damn hot.
Only about 8 times as much as Earth. And it would be even colder if it wasn't there.
You could have HIGH PRESSURE fart gas or xenon gas, its still going to get HOT if its 800 PSI.
I have a couple of books on thermodynamics that disagree with your hypothesis. You probably have a refrigerator that also disagrees with your hypothesis, or it would not work. What pressure a fluid is at has absolutely nothing to do with its temperature. You'll only see changes in temperature when you change one of the other parameters (volume, pressure), and I don't think there's any proof of billions of compressors on the surface of Venus. But you probably know all that and are just trolling.
Re:Its not C02, its PRESSURE!!!! (Score:3, Informative)
Actually, I thought when freon expands, it rapidly cools. It is a lot warmer freshly compressed, which is why the condensing coils are f'ing hot in addition to dumping their newly acquired "heat" from the ice box. As the compressed vapor cools, it returns to liquid form where it is a lot easier to dump heat. This is where the GP messes up, assuming the 800 PSI is constantly going thru state changes with heat exchanges.
Hence why you need to keep you A/C unit's compressor coil airflow unobstructed.(For those not familiar with A/C's, it is the big unit they put outside).
Again, correct me if I'm wrong here. I'm not the Thermodynamics fella, just a guy who vaguely remembers working with an A/C man two summers.
Though your point is all the same. If things under pressure were always hot, then why don't propane tanks explode all the time? Volatile gases are fine well over 800psi. (though whether the GP meant explosive or flammable gasses we won't know)
Re:Instant Global Warming (Score:3, Informative)