I wanted to create an extremely large space city which will be made up of many different large space habitats of ringed and cylindrical varieties.

Although each habitat will contain its own city or environment I wanted the collection of all habitats to seem like a city, rather than just a collection of habitats in close proximity.

To give the collection of habitats a city-like feel and look I wanted to join them all with tubes, these tubes will have different forms of zero gravity transport and provide a view of space and the other habitats, which couldn't be viewed inside a habitat as most areas will be enclosed.

The transport tubes could also be a lot safer and more organised than allowing vehicles to freely fly between locations.

There are designs for multiple cylinders counter rotating to provide stability but I am after something that looks similar to skyscrapers of different shapes and size joined by roads in a city, but instead it will be different designs of space habitats joined by tubes.

The tubes will either join at a stationary axis point or to a stationary outer shell, but as these rotating habitats can often spin out of position and will need thrusters to correct it, could they actually be joined by tubes if they are all unstable at times and not completely stationary.

So my question is, can many rotating space habitats be joined together by tubes or will they not stay still enough for this to be possible?

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    $\begingroup$ Ever try to hang on to a spinning gyroscope? Same problem. $\endgroup$
    – user535733
    Feb 21, 2020 at 23:20
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    $\begingroup$ By tunnels you mean tunnels in space bodies (like asteroids) or tubes connecting space stations (like ISS)? $\endgroup$
    – Alexander
    Feb 21, 2020 at 23:26
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    $\begingroup$ Look at the IIS ;) What you want is a bigger, more elaborate space station. $\endgroup$ Feb 22, 2020 at 2:34
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    $\begingroup$ London Bridge was a transportation link across a river that had an interesting twist. Rather than waste the real estate on an expensive transportation corridor, they put shops along the sides of the bridge itself. It would seem that these tubes are likewise a waste of resources, unless they are also lined by useful rooms, even if only for storage. Just like transportation corridors on earth, these tunnels would have developments built up along them. Why build a new habitat and then build a transportation corridor to it, when the corridor and potential development space along it already exists? $\endgroup$ Feb 22, 2020 at 2:38
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    $\begingroup$ If this were the case, I would envision a long, rigid spine along which multiple habitats would extend from and be built up according to their own designs and purposes, and the spine itself would have warehouses or other structures along its entire length. $\endgroup$ Feb 22, 2020 at 2:47

1 Answer 1


Presuming your different habitats depend on rotation to establish an equivalent of surface gravity, then your tubes will need to construct using some form of rotary union design, letting each tube to remain relatively stationary with respect to another habit, but permitting each connected habitat to spin on its own axis.

In the image below, taken from a diagram of a rotary union used for fluid transfer between a fixed input and rotating machine, the blue region would be stationary and the grey region would rotate with the bearing (circles in the image) maintaining a dynamic seal.

enter image description here

The transit tubes wouldn't need to be fixed or rigid. They could be thin plastic with reinforced ribs for temporary connections. Then they could be more durable for long term connecting conduits.

This means that you can also sort of reverse the joint to create rigid struts -- sort of like a shaft bearing -- that hold the habits in a fixed relationship to each other. Imagine rigid radial spokes with mount points or bearing surfaces that habits are built around. The spokes would provide the basic layout of the space city. More hubs and spokes can be added as the city grows. These wouldn't be constrained by any plane or orientation. -- letting the space city sprawl organically in 3 dimensions, unlike a terrestrial city which sprawls in a plane.

  • $\begingroup$ This is great, I really didn't know how the joins would work before this. Thanks a lot. $\endgroup$
    – user69935
    Feb 24, 2020 at 23:15

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