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Floating city in the atmosphere of a gas giant.

In this Scenario; My colonizing business finds a gas giant in the goldilocks zone. Some of the crazy engineers want to build floating cities in the atmosphere of the gas giant. These cities, I don't know how they will look like- you guys will determine that. Im thinking these cities will be less dense then the atmosphere below, so they float That is my guess...

This will help What is the feasibility of a floating city on Venus?

Im thinking these cities will:

  • Float in and on the atmosphere

  • 2.5 mile radius of surface area

  • Have a giant dome over the city for climate control

  • space enough for a sustainable colony

Questions:

  • Can I build cities like this?

  • What will the cities look like?

If needed, ask questions in the comments :)

You can handwave at a minimum if needed.

Aaron
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  • No need of a gas giant, in fact this a idea for Venus Colonization. Also note gas giants have a crushing gravity – jean Oct 29 '18 at 19:43
  • I just want to try to put it in a gas giant. – Aaron Oct 29 '18 at 19:44
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    I was going to link the same article as @jean . All you need for a floating city is an atmosphere dense enough to float an air bladder, and an air bladder strong enough to support your structures. For Venus, it so happens that breathable air is enough to make it float, which means people can literally live in bubbles. – Stephan Oct 29 '18 at 19:48
  • Also, even if your gas giant got a survivable gravity (note even 10% increase can kill you in weeks) the escape velocity from those big guys makes them less attractive for a colony – jean Oct 29 '18 at 20:14
  • too many questions in one posts. please narrow it down. – L.Dutch Oct 29 '18 at 20:25

3 Answers3

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The problem with this is that gas giants' atmospheres are composed of very light gases; Jupiter is mostly molecular hydrogen and helium. You'll have a hard time keeping afloat due to that. Sure, you can keep your contained gas very hot to make it less dense than the surrounding atmosphere, but you'll have diminishing returns of flotation per weight as you need an ever bigger balloon.

It also gets really windy in those planets. The winds in Jupiter's spot are nearly twice as fast as the fastest winds ever recorded on Earth. Not good for any aircraft, much less a city that is supposed to stay level over a gas.

The Square-Cube Law
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First off, the colony will have to be very, very high off the ground, as Gas Giants have gravity that would crush you in an instant. Once a sustainable height is found, the platform will need to be very strong, so it's not crushed in the gravity. Once that is completed, yes, you may need a dome to sustain a controlled oxygen and temperature level. The required oxygen level is between 19.5%-23.5%, and the (comfortable) temperatures range from 4-35 degrees C. After all that is done, the actual city can be built. As I stated earlier, the platform can't be too small, as it can't hold that many people, but it also can't be too large, as it may get sucked closer to the center and crushed. A good, comfortable city will need all the following things:

  • Plants- for both food and oxygen
  • Housing- For obvious reasons
  • Recreation and parks- so they don't get bored
  • Artificial 16-30 hour night/day cycles (if not already present)
  • Electricity, Fresh water, Waste disposal, etc.- The basics
  • Places to work and buy things
  • Healthcare- to keep them alive, and deathcare for when they do die.
  • Government and law enforcement- so nobody has to get pushed off the platform
  • Not too many tall buildings- they could make the platforms loose stable gravity
  • and a way to get back to Earth

If all of these requirements are fulfilled, then you will have a functional, comfortable colony.

Firebird
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  • "Gas Giants have gravity that would crush you in an instant." Not properly accurate. Jupiter has only 2.5x the gravity of Earth, which can be manageable by humans, and Saturn, Neptune and Uranus have a really close gravity to Earth. – Alastor Oct 13 '22 at 14:51
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As has already been said, the atmospheres are composed of very light gases. By the time you reached a level that your city could float on, it would be crushed by the weight of the atmosphere above it.

Aidan Kapur
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