Cloud cities. You know them, you love them, and I want them in my conworld. The last story I posted here takes place in one.
Economically, here's how I see this panning out:
- A gas giant has economically exploitable gases.
- Floating extraction platforms similar to oil rigs are set up to extract those gases.
- These platforms develop ancillary economies to support the people mining those gases.
- These ancillary economies attract more and more people, diversifying the overall economy to the point that the platforms become floating cities.
In terms of physics and chemistry I'm on much shakier ground. This isn't a rock-hard sci-fi setting, so I'm willing to fudge things, but I like learning about the real world through my worldbuilding so it's fun to try and make it work.
The cities are held aloft by Flanar pontoons and stabilized in part by the extraction equipment hanging down from the underside of the city into the layer where the extractible gases can be found.
At first I imagined the cities being sealed from the outside, but that makes them no different than orbital colonies save for the presence of gravity, so I want them open.
Right now I imagine there being a belt of breathable air, encircling the planet, limited to a certain range of heights and possibly combined to certain latitudes, where the cities can be found. They would drift along with the wind currents, so the air speed would be near zero, allowing people to venture outside without being blown away.
One possibility I entertained was that the whole planet is mostly oxygen and argon, but that doesn't seem likely.
On other places where this question has come up people suggested a Venus-like super earth, so a massive rocky planet with a very thick atmosphere. That would still necessitate sealed cities I think.
One fun aspect of having open cities on a gas giant would be that you could have storms where the heavier potentially poisonous gases from the lower sections of the planet could be spun up by stellar activity and wash over everything so everyone would have to evacuate indoors during the storms.
Perhaps they could be there for mining where the heavier elements in gaseous form are lower down so they send down scouters and whatnot to scoop them up.
There could also be theoretical, lost alien technology hiding inside of it, or the gas planet could have formed over a shell that contains a black hole, so the core of the planet could have a very small, pebble-sized black hole with one mile schwartzchild radius or something.
Might be interesting, lots of opportunities to use the environment for storytelling.
All good ideas. Maybe it was a rogue micro black hole that accreted a breathable atmosphere before getting captured and settling into a stable orbit. Or if not breathable air than a mixture of gases that could be made breathable with Science™️.