Regarding building stuff and shipping it out there, I think there is a reason "Venusian Gardens" are a sci fi trope. Get plants to grow in nearly pure CO2, get them to grow acid-resistant materials, these are doable long-term goals, and then we skyelves now?
Lots of things are more worthwhile energy wise in orbit, up in the clouds of Venus you get more sunlight than we do here in orbit, take something which WOULD be too expensive and draw a line under it, with an arrow pointing to the insolation at Venus cloud tops.
You have the opposite problem at Mars, btw, though as a quirk of planetary physics, both atmospheres are ~95% CO2!
Re: meters thick lead, well no, a meter or so of water will generally suffice, but that is in contrast to plastic balloons still, a lot less mass to deal with.
We don't have the money to lift a critical number of people and habitats out to Mars, but we'll be a lot closer to doing so for Venus than we will for Mars, so to answer the earlier question: would I prefer to go to Venus or Mars to live in a hab? I assume the first crew on Mars will die, or be rescued at tremendous expense, no fucking way would I be part of that, get back to me in a hundred years and we'll see if we have regular habitation and transport there down to a regularly thing yet. We could start launching habs down to float in Venus and make sure the maintenance systems work before people even arrive, which is a lot more comforting.
Sure we don't have the money to lift all that to Venus neither, no matter how much less expensive it turns out. On the other hand which could be the long term plans for floating habitats on Venus? How much larger can they become? How much weight can they support per tonnage? Could it support industrial scale operations? How do you deal with the high winds blasting acid toward those tanks? Are they designed to withstand wind as fast as 360 km per hour? How are you going to lift those thanks there? How are you going to manage them to stay in a single place? This last point is critical. How are you going to simply dump those habitats in Venus and then expect to get to them without an anchor. And a ~60K anchor that can withstand acid and +400C° temperatures sure seems like a huge weight to carry there.
Oxygen is a lifting gas in a CO2 atmosphere, designing things to deal with acid is a well developed technology, and you have something like 2k W/m^2 that close to the sun and that high up, I'm sure you could find something for station keeping or broadcasting location, and that's
before getting into things like the electric potentials you can develop from hanging a tether down into the hotter atmosphere.
Long term plans: do science, build more habs, establish another population of humans off-planet which can begin growing, mine the sky for carbon
I do get the perks of the upper atmosphere of Venus, but they do not outweigh the troubles just yet. Sorry but I'm for one, not buying your hypothesis that it's actually easier making colonies on Venus, for a reason NASA has manned plans for going to Mars and not Venus.
In Mars inflatable (lighter) habitats partially sunken and covered in martian soil are a possibility, as it is using the landing module as an starting habitat. I once saw a plan that involved sending several unnamed ships beforehand to land in a place and then using the empty fuel tanks as an habitat, which is possible because you actually have a solid place to start.
You don't have a solid place to start building in space either, but we're going to have to get better at that at some point, we already know how to build floating structures in the ocean, these are not super difficult problems, it's just a matter of engineering out the known and existing technologies to solve the problems at hand.
Solving the problem where outside your environment is thinner than the air 100km above the surface here is also something we know how to do, but space stations are leaky and only survive through regular boosts and resupply missions. I don't expect a colony on Mars to survive without regular resupply missions, on Venus we could get by with a lot less shipped in.
Mars you need a spacesuit, Venus you need little more than a gas mask and an outer layer, biiiig difference there.
How do you think you're going to deal with 75 degrees Celsius atmosphere, still denser than on Earth = better heat transfer, trying to cook you alive, night or day? You won't be leaving your habitat without a spacesuit either, bub.
There is a range of altitudes where you only need an air supply and protection from acid, I don't think there is a reason to prefer one over another besides whatever works best at the time, and indeed making it so habs could be floated in a range of them, and even change altitudes seems smart, and doable.
for a reason NASA has manned plans for going to Mars and not Venus.
Nor really plans, but there is a proof-of concept study:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160006329.pdf
I do agree with your general conclusion, though - a floating habitat is a cool idea, but if somebody tries to tell me that it's also cheaper and/or easier than plonking some prefabricates on Mars and constructing a colony out of them, then that person is to me full of hot air (somewhat fittingly).
Dropping them on Venus is going to be at worst the same cost energy wise.
http://clowder.net/hop/railroad/Venus.htmlMore interesting, and which I should not have assumed was commonly known: windows to Venus occur 8/5 years, windows to Mars are 14/7 years, it takes about 5 months to do a Hohmann transfer to Venus, vs 7 months for Mars, and the only times Venus really loses on delta-V are when you want to go surface > orbit, which we wouldn't be doing here. Upper atmosphere > orbit is a different issue entirely.
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