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Comment by stickydink | Hacker News Reader

How would we float a platform at that height?

By attaching it to a steel balloon filled with breathing gas, which can provide lift in the Venusian atmosphere.

Inside the baloon you get a really nice habitat with the correct Temperature, pressure and gas composition for humans to live in.

Other than a basically unlimited supply of CO2 however, what would the advantage be compared to a just a space station?

With Mars, you can mine building materials from the surface.

You can live there long term since there is gravity.

Also, there is a lot of protection from radiation, from the mass of atmosphere above you and the mass of the planet below you.

Is Mars' gravity too low for long-term habitation?

I know that we know that zero-G is a negative, but do we have any idea if it's a threshold that needs to be reached, a linear response to G-force that scales from untenable to fine, etc?

The only way to really find out is to go there and live for a while :)

I would imagine that it's going to be a gradient. Just like any other form of exercise, the more effort you put in, the more positive effect. Humans would need to put in much less effort on Mars. Once we are spread across the solar system there will probably new exercise systems for 0 and .3 G environments.

I am also unsure about how it would affect the prenatal development as the way "layering" occurs is highly dependent on gravity.

CO2 has carbon in it. Strip off the oxygen to breathe, the rest makes very strong building material.

Attach hydrogen, you get rocket fuel. Or plastic. Bind in some nitrogen, you can have proteins. There is probably silane lower down; send down a balloon to collect it, for silicon. Or all the way to the surface, to collect rocks.

Nuke power is totally practical there; no shielding needed, or worry about leaks; you just hang it a mile below your living-space balloons.

We can float things in the earth atmosphere at sea level. My completely ignorant prior is that we should be able to do it there too, if the temp and pressure are the same.

Much better: the air at normal pressure is much denser, so ordinary breathing air supports a balloon.

Most methods of flying things through Earth's lower atmosphere should apply well to Venus at 50 km: balloons, planes, helicopters, etc. To gather energy for rotors, maybe we could siphon heat from below to power a generator or other type of converter.

Just playing with ideas. :-)

Send your mining robot below. It cools itself with phase change liquids, but also opens high pressure tanks to the 90 bar atmosphere. When you hoist it back, just plug those pressure tanks in to turbines connected to generators. That wouldn't be a huge amount of power, but maybe wildcat prospectors could operate like that in the early days.

Lisa, in this house we respect the laws of thermodynamics!

Why not use liquid oxygen as the phase change liquid? Then the gas could be caught in a bladder tethered to the ground. When it comes time to ascend, use it as a balloon?

There must be some way to exploit the temperature difference between the surface and 50km up, without mega-engineering.

Hmm, maybe some variant of a solar updraft tower where hot lower atmosphere gases are siphoned up to generate power and heat lifting balloons?

Would it be enough energy to compensate for the work you'd need to do to lift the robot back up? Presumably there's some energy gained from sending it down but not enough to bring it back, especially since it is coming back heavier. I just don't know how to work the math on that.

> "Most methods of flying things through Earth's lower atmosphere should apply well to Venus at 50 km: balloons, planes, helicopters, etc."

The kind of flying logistics needed to operate a station like the one proposed is something that hasn't been demonstrated on Earth, so doing it on Venus seems like one hell of a stretch. The closest match is the airship aircraft carrier experiments, which did not go well. If it can't work reliably on earth, how can it work reliably above Venus?

I think it's one of those things that looks great on paper but in reality has a ton of trouble. I think airships are like that on Earth and on Venus.

OK that's just opened my eyes a little. It sounds so obvious - if the atmospheric pressure is the same then yes we should be able to fly aircraft. Maybe not with the engines used on Earth but in principle at least. Slightly terrifying that a loss of power should result in a 50km drop to a crushing hot acid death, but probably not much worse in reality to smashing into rock like you would on earth. Very interesting comment - thanks!

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