If you have cities floating in the air, how does considerations with respect to transport and logistics change compared to the earth?
The most realistic plans for Venus colonization involves aerostat habitats floating 50km above the Venus surface as I’ve discussed before.
Historical Reasons For Settlement Patterns
Because habitats are movable the fundamental conditions which has shaped transport networks and settlement patterns on the earth no longer applies.
Cities people on earth live where they live by historical accidents. There was at some point resources that could be extract there or it was a good harbor etc. As towns sprung up inertia develops. All the infrastructure and housing can’t simply be moved to some other location even if the original reasons for settling in that location no longer applies. Because people already live there they will develop various kinds of businesses and industries which will attract more people causing the cities to grow.
However because of this history we end up with cities and towns all over the planet which need to be connected by roads, railroad and ship and airplane networks.
Where To Place Cities on Venus
That would be different for a Venus cloud colony. Moving the whole town is easy because it is just floating around in the air. Imagine if London and Tokyo started doing extensive trading and depend a lot on each other. There is no way to move the cities closer together.
If all the towns and cities of Britain and Japan were floating cloud cities however they could easily be moved within proximity of each other. Relative placement of cities could be optimized for which products and services are needed where. E.g. if the products of one city is needed by five other cities but they don’t all depend on each other then, we could arrange these five cities in a circle around the city they all depend on.
City Sizes and Proximity
How big should a Venus cloud city be? Lets just consider the most extreme versions first. On one end you make a mega city of enormous dimension where everybody lives. At the other end of the spectrum you make every dwelling, factory and store its own airship.
Mega City Pros and Cons
For simplicity, say all cities were sphere or dome shaped. When you enlarge a sphere the volume grows more rapidly than the surface area. That means providing a cubic meter or livable space requires less material in a mega city than in a small one. Hence there are significant benefits of scale.
A large city also means more opportunity for specialization and economies of scale. A lot of facilities need to be made for every floating city, so fewer bigger cities means less waste having to replace these structures.
However there are significant downsides:
- You put all your eggs in one basket. Should the city fail for some reason and fall down, you end up wiping out your whole civilization on the planet.
- With a large city, moving goods around where they are needed becomes a more complicated matter as the distances increase. You need may need some sort of cars, trucks or railroad to move goods and people around. This will add significant weight, which we want to avoid to keep the city floating.
Micro Cities Pros and Cons
The other extreme that every building is essentially an airship has the advantage that moving things around is suddenly quite easy. If you need new IKEA sofa for your airship house, you can simply fly your whole house over to the IKEA airship store, dock and load up your sofa, before returning. No need for trains or cars, because the airships take care of that directly.
So the benefits are:
- Easy transport.
- Redundancy. If one airship falls down, it has an insignificant impact on the overall civilization.
There a huge downsides however:
- Every little airship has to replicate control mechanisms to manage elevation, mass pressure, navigation etc.
- Many small ships require much more material to construct.
Finding a Suitable Size
We have to find some combination of airship sizes somewhere in the middle of these two extremes.
I think it makes sense that factories are essentially separate airships, because if you bundle together lots of factories, people and other facilities into one structure then you get the problem of moving raw material inputs and manufactured outputs effectively between the different units. One solution would be that each factory moves itself over to and docking with airships it requires input from or where it delivers finished goods.
However that might not be an efficient setup as you have to move the mass of the whole factory to every location. It makes more sense for smaller freight airships going point to point between supplier and consumer.
For humans it makes more sense to live in larger airships with several facilities:
- Food production
- Energy production and storage
The reason why you want to combine these is that in case the airship lose contact with other airships, you are self sufficient for a long time. You can survive a long time without being able to manufacture more chairs, bowls, clothes etc.
One is probably best of utilizing different types of airships. For habitable airships it makes sense that there is a lot of space. Hence these airships should utilize breathable air as the lifting gas and people should live inside the ballon rather than just in a gondola. That gives significantly more space for each inhabitant, while providing space for storing lots of breathable air.
For heavier industry the tradeoff would be different. One need less space to move around but significant ability to lift heavy machinery. It then makes more sense to use lighter non-breathable gasses. The equipment is then placed in a gondola beneath, where humans will work.
So we settled on using smaller airships for point to point transport between larger aerostat habitats and factories. The benefits with respect to avoiding a lot of unnecessary travel and moving unnecessary mass is that is should be safer. Do one really want to move massive aerostat habitat close to each other to dock? What if there is a wind gush as they are about to dock and two massive structures crash into each other?
A smaller airship will not cause the same impact.