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Floating Cities On Venus
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.'"
urg, carbonite, not kryptonite...
-- Sex is the antonym of pringles. Once you pop it's time to stop.
Not to take the bait, but Venus is a lot hotter than Mercury. The all-important albedo can have a much bigger impact on temperature than distance!
I live in constant fear of the Coming of the Red Spiders.
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.
No, it's not: It's in 3:2 resonance with the sun. One mercury year is 1.5 mercury days.
Hard work pays off tomorrow, but procrastination pays off NOW!
Now you will.
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.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
I don't know if you got that from Wikipedia, but if you did, it's an over-simplification of the linked ESA article. 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 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?
(this is not a