[cyrus_]

The upper atmosphere of Venus is an extremely under-appreciated location in the solar system!

- Closer than Mars

- 90% of Earth gravity (compared to 30% for Mars)

- Atmospheric shielding mass equivalent to Earth's (protected from solar radiation, unlike Mars)

- Large amounts of carbon dioxide and sulfuric acid, with some other trace gasses. You can make fuel, extract water and grow plants from that.

- At 50km altitude, you have ~1atm of pressure, and breathable air is a lifting gas, so you can put a balloon full of air up there and it will float and support a good amount of extra weight. If it punctures then it will just slowly leak, not explosively decompress.

- Temperature ranges from 27-75C, so thermal issues are pretty easy.

- Ample solar influx for power.

Source: https://en.wikipedia.org/wiki/Colonization_of_Venus

Obviously you're floating in the air, so you'd have to bring in metals and minerals externally, e.g. from earth or via asteroid mining, or maybe in the future we could build machinery capable of mining the surface despite its brutal conditions. Or, you know, forests in balloons that you gather timber from.

So yeah, "build a cloud city on Venus" is definitely a crazy idea, but not nearly as infeasible as "terraform Mars" I think! Furthermore, as this paper demonstrates, there are some incredibly interesting and unresolved scientific questions that justify going (as if the sheer beauty of "cloud cities on Venus" is not reason enough!)

[ValleyOfTheMtns]

I agree that Venus is under-appreciated as a colonisation target, but I haven't seen anyone attempt to address the issue of how you "land" in the atmosphere without touching down on the surface? And if you ever want to get back to Earth, how do you launch a rocket within the atmosphere? These are non-trivial engineering problems that need to be addressed.

First things first, lets get a probe floating around in the clouds of Venus.

[avz]

> I haven't seen anyone attempt to address the issue of how you "land" in the atmosphere without touching down on the surface?

Spacecraft in the Venera program successfully deployed balloons following atmospheric entry, see [1]. The balloons stayed up in the atmosphere for more than 46 hours.

> how do you launch a rocket within the atmosphere?

Atmospheric launch into a suborbital trajectory was demonstrated by White Knight, see [2]. There exist air-to-space missiles, see [3]. Admittedly, none of these are fully fledged space launches from the atmosphere, but they show it's not entirely outside the real of the plausible.

[1] https://en.wikipedia.org/wiki/Vega_program#Balloon [2] https://en.wikipedia.org/wiki/Scaled_Composites_White_Knight [3] https://en.wikipedia.org/wiki/ASM-135_ASAT

[skykooler]

The Pegasus launcher launches satellites to orbit from an air-launched vehicle.

[ValleyOfTheMtns]

Thanks for the links.

[sohkamyung]

NASA is / was looking into this: the High Altitude Venus Operational Concept (HAVOC). Here's an article from 2014 about it [1]

[1] https://spectrum.ieee.org/aerospace/space-flight/nasa-study-...

[c22]

I've long also thought Venus was undervalued as a destination, mostly for the air and temperature reasons you listed. I didn't know about your other bullets so thanks for the info. I wonder why we haven't seen more focus on the yellow planet.

[everdev]

One guess would be that people enjoy visuals and scenery. On Mars, there are landscapes, sunsets, and the stars. From a think Venus atmosphere, I'm not sure what the view would look like, but I'm guessing it would be pretty consistent and confining. Traveling through a cloud in an airplane is fun for a few minutes because of how unique it is, but seeing the ground feels more enjoyable and inspiring to me.

[cyrus_]

Good points! I'm not sure how interesting the clouds would look. There is definitely some dynamic behavior there, including electrical storms, and you'd have a day-night cycle spanning 4 days total, not due to the rotation of Venus but rather the atmospheric dynamics.

Also keep in mind that due to the dangers of radiation, the denizens of a lunar or Martian colony would not be outside that often. The most realistic plans I've seen actually have the habitats completely underground (e.g. in lava tubes on the moon [1]). Certainly a few of the colonists will leave on science missions with some frequency, but the vast majority of the time people will be inside and underground, albeit probably tele-operating mining equipment and things like that in many cases.

I think if you think big enough, in both cases the problem isn't that bad: being in an underground habitat / cloud habitat the size of a small town will feel like you're on solid ground, not like you're in an airplane in the clouds / in a cave. Artists and architects can design artificial landscape to keep things from being boring.

[1] https://en.wikipedia.org/wiki/Lunar_lava_tube#Sites_for_huma...

[stevedonovan]

Judging from the happiness of my fellow city dwellers when they hang out in the mall, I suspect that colonists would not mind being inside as long as there was enough shopping.

[gsich]

Reaching Venus is also much harder then reaching Mars.

See: https://i.imgur.com/SqdzxzF.png

[jccooper]

Getting to Venus is somewhat easier with good mission design, utilizing aero effects. Getting back is notably harder.

[hackeraccount]

Dang it. Totally beaten to the punch.

[forapurpose]

I couldn't agree more. Also, liquid water boils away on Mars due to the low pressure, while on Venus it should be no problem (AFAIK).

When I've brought up similar points to the parent's, one response was that Mars offers solid ground which provides a base for heavy equipment (factories, etc.) and has minerals. I don't nearly enough to weigh all the factors.

[KodiakLabs]

If you are worried about water boiling of for human habitation, this is not a problem at all. Domiciles will be pressurized, and water will boil at Earth’s temperature.

[forapurpose]

Yes, but pressurization adds cost and risk. There's also the issue of water outside the domicile; now we need pressurized water bottles (or whatever). We need pressure suits.

Think of that - in our Venus cloud city, humans can wander around outside without pressure suits (though they still need breathable air and protection from other environmental hazards). No pressurization is needed inside facilities. Machines designed to function in Earth's gravity and pressure will work on Venus (ignoring other significant environmental issues). Venus, in that regard, is more economical and safer than Mars. I don't know how that balances with other costs and risks of the two planets.

[cyrus_]

I think you could imagine building city-sized habitats with enough raw materials, so you could certainly have industrial equipment operating. But yeah, having a source for raw materials would be essential in the long term. For smaller science missions though it would be totally feasible to just bring all the heavy stuff with you, just like we're going to do for early Mars missions.

[hackeraccount]

Closer than Mars. Only in distance. If you look at it in terms of Delta V http://i.imgur.com/SqdzxzF.png In those terms Venus is comparable to Saturn.

That said, I'm totally on board - it's the closest thing to Earth in the solar system.

[seszett]

> If you look at it in terms of Delta V http://i.imgur.com/SqdzxzF.png In those terms Venus is comparable to Saturn.

The high number here though is for going from low orbit to the surface, I think. It is very high because of Venus' very slow rotation, but the atmosphere probably makes that point moot, as you can pretty much "just" aerobrake as needed and use the wind to get going in the right direction at the right altitude.

So if you don't need to actually get down to the surface with a delta-V of 0 relative to the ground, the delta-V you need relative to Earth is indeed lower than the one needed to get down on Mars ground.

It makes it very hard to leave, though.

[keithly]

Atmospheric shielding, yes, but I recall reading somewhere that Venus lacks a magnetic field because it rotates so slowly. I’m not sure the atmosphere would totally compensate for this.