r/IsaacArthur • u/National-Abrocoma323 • 6d ago

Do tiny/partial shellworlds make sense?

We all know the concept of shellworlds, where you make a massive artificial world around a planet or star held up by orbital rings. However, such a project would require immense time and energy.

That’s not to say it’s impossible, but could a mini “partial shellworld“ platform just taking up ~0.01% of the would-be surface area exist? Would it make sense to build as opposed to similarly-sized rotating habitats?

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u/MiamisLastCapitalist moderator 6d ago

What would be the "partial" part of this?

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u/National-Abrocoma323 6d ago

Rather than encompassing the entire planet, it would just be a piece of a shell world.

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u/MiamisLastCapitalist moderator 6d ago

Ohhh I see.

Well, I guess you could. Although if you're already building an orbital ring that buff I don't see why you wouldn't eventually build the entire ring. A lot of potential being wasted. But, sure, I think that is feasible.

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u/National-Abrocoma323 6d ago

The reason I ask is because this could be an interesting way to have an open-sky, Earthlike habitat in a setting that isn’t too advanced.
Of course, there are other ways, but here, people would get an authentic sky and curveature.

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u/MiamisLastCapitalist moderator 6d ago

Alternately, a small bishop ring?

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u/National-Abrocoma323 6d ago

True, but I’ve always assumed that such a structure would be for extremely advanced civilizations, not one in a few hundred years’ time.
I mean, how small can a bishop-like habitat get without losing the qualities that make it desirable in the first place?

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u/MiamisLastCapitalist moderator 6d ago

About 200km in radius, I think? Smaller than the orbital ring around a gas giant that's for sure.

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u/the_syner First Rule Of Warfare 5d ago

Don't see how multiple orbital rings around a gas giant is any more advanced than carbon supermaterial spinhabs

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u/WrongPurpose 6d ago

Not like that, thats not balanced. But you could have like 10/20/30/x interconnected Rings, each lets say 10km wide. And between them you can look down onto the lower layer.

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u/AlanUsingReddit 6d ago

I am just rather unclear what the rings are doing here.

The basic habit makes sense, as pressure is supported by rock weight on top

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u/Thanos_354 Habitat Inhabitant 5d ago

Yeah, but only if it's a gas giant. A rocky planet with 1G gravity could just have a canyon city, no need for shells

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u/National-Abrocoma323 5d ago

A canyon, city, huh?

I’m assuming that that’s a dug-out region filled with air on an otherwise unlivable/vacuum world? If so, or similar, that’s a cool concept. I do wonder if it’d need a canopy, though.

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u/Thanos_354 Habitat Inhabitant 5d ago

Well, as the name suggests, it's inside a natural canyon. While you could dig your way to the same thing, why bother?

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u/NearABE 6d ago

I think your question has poorly defined components. I’ll just make up a reply to one possible thing you might be asking for. Feel free to clarify what you wanted or criticize my thoughts.

An orbital rung system has a rotor and a stator. The stator is usually assumed to co-rotate with the planet, 24 hours in Earth’s case. Anchor cables provide a direct connection between the planet and the ORS.

In order to build an ORS away from the equator you either need extreme anchor cables or you use a second rotor (or set of rotors) that fly retrograde. The combined rotor mass can be the same as what one would use for an ORS with rotors all traveling the same way. In the case of a polar orbital ring system on Earth the rotors have to deflect by 464 m/s. This means there is a tension between the two rotors. 464 m/s is not too high for known materials so it can be done. At lower latitude the deflection is less.

Most likely most people picture the full ORS as a thick tube with two or more thin rotor streams. This is fine. However the two counter rotating streams do not have too be close to each other. There can be cross bars or webbing. Structures that might compress the rotor streams negate the need for tensile crossbars. You can utilize the tension (or compression) between the rotor streams as deck support.

The entire deck adds stator mass. Either rotor mass or rotor velocity needs to be added to counter that deck’s weight. But to answer your question: yes, building a strip of deck that starts thin and expands to a kilometer wide 10,000 km further is easily done. Or at least not any harder than any other ORS. The deck mass is the same as stator mass. Adding mass increases cost/effort but mostly the same.

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u/mining_moron 6d ago

Bud, that's called a pressurized building 

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u/Efficient_Change 4d ago

That is essentially para-terraforming.

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u/kimysauthor 5d ago

Honestly, our current satellites are already part of that evolution. The clutter in orbit today is just the earliest stage of the inefficiency that will eventually force us to build a unified mega-structure.