http://en.wikipedia.org/wiki/Aerogel

It's insulation capability is incredible, Mars twin rovers have an aerogel shielding that keeps their components at the 25 degress Celsius.

Pretty , it isn't ?

Venus Rover proposal;
http://www.agu.org/meetings/fm05/fm0...fm05_P54A.html

Huh, an engine that convert Venus's heat to electricity and simultanously provide cooling system...how clever

http://www.lanl.gov/thermoacoustics/TASHE.html
About temperature
"All rover systems would be housed in a pressure vessel in vacuum with the internal temperature maintained by the TASHE below 50 °C. No externally deployed or articulated components would be used and penetrations through the pressure vessel are minimized. Science data would be returned direct to Earth using S-Band to minimize atmospheric attenuation."

So good news; it will not heat up rapidly (that mission is designed to last 60 days), and I guess if they will use Aerogel than that temperature will be room temperature and that rover will last year.

Don't be so sceptical and pessimistic .

And about spacesuits, yes, there would be a need for a cryogen but spacewalks usually do not last more than a few hours, so it is not problem imo.

Floating Venusian cities are no more speculative than the terraforming concepts that we have discussed and are much more modest in physical scale. We're not discussing massive Star Wars style structures held up by anti-gravity machines. Breathable air is a lifting gas in the CO2 atmosphere of Venus. These structures would be somewhat similar to dirigibles, but much larger.

Mind you, I expect we would have many floating cities in Earth's oceans before we would be doing this on Venus, but this is well within the boundaries of physics, and we do have at least as much engineering knowledge related to this concept as we do for planet sized sunshades.

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Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

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If we can terraform a planet, I expect that high closure life support systems would be extremely well developed. There would be a massive space infrastructure. Given that, there easily could be more people living in space structures than on worlds. In the Earth-Moon system alone, there could eventually be habitats with the equivalent of thousands of times the Earth's living area.

One of the reasons why I like Mars as a target is that, with its relatively small gravity well and two orbiting asteroid-like moons, I suspect it would make a great center for economic growth. I could see the Earth-Moon and the Mars systems as two of the solar system's economic hubs in a few centuries. I would think that Venus would be something tackled later, rather than earlier.

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The Leif Ericson Cruiser

Yes, terraforming is quite difficult but Venus is really extra difficult. Occasionally fun to think about though. Mars is equally exciting in its own way. This is a far flung notion but if we were able to make Mars much more like the Earth, that might teach us how to make Venus become more like Mars is now, and then from there, eventually also make Venus more like the Earth.

I will reconsider the value of the floating cities scenario as you've explained it as I was under the impression it was more akin to magic beams in Star Trek. I think such structures should be a simultaneous addendum to a long-term Venusian transformation.

I found these writings on the internet about Venusian aerostats.
http://www.lunar-reclamation.org/pap...rehabpaper.htm

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I'm not an expert on aerogel, but after reading the wikipedia article I still wonder if they would be able to maintain themselves at the pressures of the venusian surface or if the friable aerogels would shatter. It's an interesting idea worth exploring.

However, something else comes to mind. Even if you manage to maintain the rigidity of the habitat shell, how do you plan to anchor it? After all, the bouyancy of a 1 atm shell under 90 atm would make it want to pop up like a cork. It'd be like trying to hold a balloon underwater.

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If God wanted you to post here, he would have created the forum with your posts already in it.

You never heard about deep sea exploration?Pressure on Venuse is like the pressure in the 1 km depth of the sea.It will stay anchored like a deep sea habitat.And batyscape get humans to the depth of 11 km and that wessel survived it without problems.The pressure on the Venus is not as high as you may think, in the laboratory condition there were created much higher pressure, and pressure 11x than on Venus is in the Marianic Abyss - even multicellular life survive there, under 990 bars!

And about the shattering of an aerogel;
http://eetd.lbl.gov/ECS/aerogels/sa-working.html

It will shatter only if there is a RAPID PRESSURE CHANGE, not only high pressure, it can support 1000x it's own weight but can shatter if you punch into it. And why not just place the aerogel under the carbon-metal layer under 1 atm.?The layer of the metal will be a little hotter but if white not too much and that aerogel will completely isolate it from the inside.

The Trieste, the only manned sub to visit the Challenger deep, had a spherical pressure vessel 6.5 feet in diameter. A vessel designed to handle only 90 atm on Venus might not need to be that over-engineered, but it would require engineering beyond that of most military submarines, which reach maximum depths of around 800 to 1000 ft instead of the equivalent pressure depth of 3300 ft. (BTW, the Trieste did have problems, one of the outer lexan window panes shattered under the pressure. Also, the depth you referr to is the Marianas trench, not an abyss. Abyssal plains are flat and relatively shallow. And though there is life, even vertebrate life, in the ocean depths, those pressures are incompatible with human life.)

A sphere, instead of a dome, would be the optimal pressure vessel geometry. This isn't impossible, and a spherical shell also has the benefit of having the smallest surface area to volume ratio, meaning that insulation is more effective. It would also maximize the strength of the pressure hull, but a dome would be vulnerable on it's flat underside or the seams to it's foundations. Remember, fluid pressure works in all directions, not just downwards.

If you wanted to design a surface colony with a habital volume it would be so large as to make negative or neutral bouyancy incredibly expensive to achieve. Perhaps you could build such a heavy structure on Luna or Venus from your expensive, exotic and fragile materials and anchor ballast and then move it to venus, but it would be incredibly heavy and require massive rockets to lift it even from the lunar surface. Emplacing a ballasted surface colony structure onto the venusian surface would require enormous retro-rockets because aerobraking would risk disintegration from thermal and acceleration forces and either method could result in damge to the internal aerogel insulation from acceleration shock.

A better idea would be to build the shell light and let bouyancy float it in the venusian atmosphere and then add ballast that is gathered from the surface of Venus or sent from another solar system body like Luna or Mercury (which would still be expensive). At this point you've basically designed a floating city that sinks and is more dangerous to live in. The surface colony idea doesn't argue against the idea of floating cities on venus, it argues in favor of it and practically requires it.

Take this idea. Design a surface habitat/factory that looks like the Titan A.E. from the movie of the same name. It's a sphere with multiple hollow legs that could house retro or ascent rockets or ballast or elevators to the surface. Painting the outer hull white probably couldn't hurt, and might help reflect thermal infrared radiation, but convection/advection and conduction would probably result in the outter pressure hull rapidly warming to ambient temperatures anyways. White paint pigments are often titanium or lead. You might just use solid titanium alloys anyways, and the hull might naturally accumulate lead frost if it's on the surface long enough.

I'm not against the idea of surface structures on Venus. I think it'd be necessary to have small habitats for mining operations and for research. However there is no need to place colonies on the surface when it is safer and cheaper and easier to place them in the clouds.

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Another idea might be to have kamikaze automated excavating machines that land and, based on earlier detailed surveying research, start digging out underground spaces. Such specialized construction equipment would be tough and last for a certain time after which further machines land, cannibalize them if possible and continue building and finishing underground dwellings. (This of course would be applicable where cooler, underground areas are discovered.) There would still be the problem of access to and escape from the harsh surface to upper atmosphere locations, but such surface access points would present a much lower surface profile than a dome and could be very durable below the intense heat and pressure.

Maintaining breathable atmosphere, water, food, life support, etcetera, would be similar to a surface dwelling. Gravity would feel almost the same as on Earth.

To me, the eventual long term goal in this poll/thread is altering the surface for habitation.

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I wonder...

Would it take more or less energy than this to build a sunshade, freeze out the atmosphere, and then transfer it to orbit or beyond? After all, if you are already talking about building a planet-sized solar collector, a simple shade would be easier, and you wouldn't have any friction/wind resistance or weather conditions to worry about, plus the stuff would be easier to move.

The excess gasses could be stored frozen in some convenient orbit behind a permanent sunshield, ready to transfer its contents wherever needed.

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Sorry, I badly translated it to abyss.
Good ideas!

But aerogel would be even better to use than just white paint

Well, if the long term goal in this thread is altering the surface, then it is best to do it from structures locating in the clouds which will survive long enough to accomplish some of those goals. I'm all for terraforming Venus so that we can eventually live on the surface, but floating cities will be crucial to that project, not a diversion from it.

BTW, what makes you think that Venus is cooler underground? Part of the reason that Venus is so hot is because of it's geothermal/volcanic activity. You'll have to determine the heat flow of the crust before digging in it. Also, the immediate surface can't cool much because of the greenhouse effect so it is likely as hot as the lower atmosphere. The earth's crust is only cool for the top few hundred feet, and then it starts getting hot again as you go deeper, and the earth's top crust is only cool because of longwave radiative cooling, atmospheric advection and hydrology, all of which Venus can't do.

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