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Comment by capableweb | Hacker News Reader

Putting aside the fact that Venus's clouds consist of concentrated sulfuric acid, shouldn't our assumptions about colonizing the planet be based on what we are capable of achieving? I am not aware of any floating settlements in the air (though I do know of floating settlements on water), so it's hard to imagine one on Venus.

Moreover, if we are to consider possibilities beyond our current capabilities, why not focus on building space stations with artificial gravity instead? There would be no need to be tethered to Venus when we could exist without any attachment (although we would still be subject to gravity of other entities).

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A point in favor is that normal earth-like atmosphere is a lifting gas on Venus, so just large, lightly built structures would float naturally.

The main point against is that there is no reason for anyone to go there. Cloudtops on Venus are immensely resource-poor, most importantly in hydrogen. I agree with you that there is no advantage to a floating colony over a spinning one.

The one place on the solar system whose colonization is often ignored is Mercury. It has an extremely low axial tilt, meaning that all the craters on it's poles are permanently shadowed. It is also constantly bombarded by solar wind, which produces water (ionized hydrogen impacts oxide rocks, and binds to the oxygen). Then the water is a gas that bounces around until it impacts the bottom of a shadowed crater, which is cold enough to freeze it. Based on data from the MESSENGER mission, the south pole of Mercury alone has more water than all of Mars.

>A point in favor is that normal earth-like atmosphere is a lifting gas on Venus, so just large, lightly built structures would float naturally.

That's not really a point in favour compared to an orbiting spinhab. You only need it to float so that it doesn't fall to the ground. And you can achieve that by not leaving orbit in the first place.

A orbital habitat struggles with higher pressure differentials, no gravity and more challenging thermal management.

A floating habitat would have less access to orbit, would have density / weight contraints and would have to deal with the corrosivity of the venusian clouds.

Gravity I'll grant you, but heatsinks are not difficult technology, and Venus has its own problems with pressure. It's not the overall pressure you worry about; each component of the gas has its own partial pressure. The outside is poison and it's trying to get into the livable parts, and that partial pressure against the breathable air is of the same order of magnitude as breathable air against a vacuum. The engineering challenges are similar.

> that partial pressure against the breathable air is of the same order of magnitude as breathable air against a vacuum. The engineering challenges are similar.

Those are very different engineering challenges. Separating similar pressure gas mixtures is question of porosity, but not force. Separating different pressures of the same gas mixture is not just a question of porosity, but you also need manage the forces created by the overall pressure differential.

Edit: If you take a helium balloon into space (or high enough in our atmosphere) it explodes rather than just slowly leaking and equalizing it's gas mixture with the atmosphere.

Yes you're right, I didn't think it through properly

> Based on data from the MESSENGER mission, the south pole of Mercury alone has more water than all of Mars.

That will come in handy when we deconstruct Mercury to provide the raw materials for a Dyson swarm.

On the other hand Mercury is pretty hard to get to.

(Because Earth isn't at rest, it's travelling at 30km/s around the sun, and that's a free boost in terms of getting out of the solar system but velocity you need shed to lower your orbit sunward.)

So, AIUI, it's easier to get to Alpha Centauri than to "fall into" the star we orbit.

Space stations with artificial (spin) "gravity" has all kinds of complexity. They need to be huge to avoid being nauseating to be on at anything resembling sufficient "gravity",. It's not remotely clear it'd be easier to build structures that size than build blimps able to withstand the sulfuric acid clouds at 50km above Venus.

Note that at sufficient height over Venus, air is buoyant, so quite a few designs for Venus assumes at least part of the habitation itself is within the structure of the blimps, and the pressure means leaks are much more manageable. You also get a "free" radiation shield on Venus thanks to the induced magnetic field, and that alone might well be enough to make it more attractive than a larger space station.

>They need to be huge to avoid being nauseating to be on at anything resembling sufficient "gravity",

We don't know if a full Earth gravity is necessary for human health in the long term, or if we could get away with something less, like half a gee. And we don't know how small the centrifugal force gradient has to be between the feet and the head for people to be comfortable. It might turn out that we could just get used to it, like how people get over space-sickness, so a spinhab with a relatively small radius might be fine. All we know for sure is that prolonged exposure to zero gravity causes a gradual decay in bone and muscular strength.

There was a plan for the ISS to have a spinning module to study these questions but it never happened. It's a shame, that kind of experiment would be far more valuable than whatever public relations crap they're doing up there. I actually find it astounding that we haven't even tested long term partial-gravity on animals yet.

We have an idea re: spin, based on actual research. Spincalc has sources.

There have been studies on mice and I think rats on the ISS and they’ve shown promising results in preventing a number of health issues humans experience in zero g. Here’s some pictures of the setup they used for mice to generate 1 g on the ISS, it’s not very big and I don’t think the mice experienced any adverse effects:

https://hackaday.com/2021/06/08/iss-artificial-gravity-study...

A floating settlement on Venus is not far off in terms of what we can achieve. Perhaps we even already have the technologies required.

It would actually be easier than on Earth because on Venus atmospheric pressure increases like crazy as you get near the surface. So an habitat pressurized at 1 Earth atmosphere would naturally float in Venus' atmosphere like a submarine or whatnot floats in Earth's oceans.

My understanding is that at the relevant altitude in Venus' atmosphere the temperature would also be very Earth-like so no big heating/cooling issues, either. I have read some say that the upper atmosphere of Venus is actually the most human-friendly environment in the solar system outside of Earth.

It's actually not a far-fetched proposal.

Columbia from Bioshock?

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