jedidia
shoemaker without legs
So my brain lately started of its own accord to pick together bits and pieces for a science fiction setting in a run-down dyson swarm. I find the idea appealing since it offers a lot of common space opera tropes like world hopping, exotic cultures and ancient abandoned ruins packed with high-tech treasures without bending physics and logic out of shape too much (no super-drives, no FTL, and "planets" of hats suddenly make a lot more sense too).
Naturally this got me interested into orbital megastructures like ONeil cylinders, but there's a few things about those that I don't quite get, and some people here might explain to me a bit better.
First off, there's them mirrors... I get that they're supposed to get sunlight in, but I can't quite figure out the benefits of that versus just sticking on solar panels and do the lighting with electrical power.
As I understand it, the actual interior of the cylinder is not used for farming, since that would require a ridiculous amount of soil and rather cumbersome irrigation systems. So the only benefit would be for people to enjoy actual sunlight, which we know is important for human health, but I figure if we can build an Oneil cylinder, we should be able to build a lamp that can emulate sunlight well enough for that.
On the downside we have transparent sections in the cylinder walls. What material would they be made of? Transparent Aluminium would be a candidate I guess, since that is an actual thing now, but that's a lot of very expensive material just to let the sun in.
You'd lose a lot of living area too, at least judging by the concept drawings, and then there's micrometeorites and space debries to consider, and people might get nausea from seeing the spinning starscape (though that probably wouldn't last more than a generation).
Radiation shielding would also be a concern, though probably not so much if you can keep cylinder facing the sun reliably enough (which is why, as I understand it, ONeil cylinders were originally proposed to come in coupled pairs, so you could control their attitude with slight manipulations in the spinrate of the cylinders.
But all in all, is there any significant advantage to the mirror/window design that I'm missing? You would still need solar panels anyways because you'll want electricity, so all in all they seem pretty useless for the effort.
Another point I'm a bit unclear about is armor... You'd need some form of it. Just having a steel cylinder won't cut it in the long run. But you also don't want to spin up megatons of dead mass. So now I'm wondering if it wouldn't be a much better idea to melt down some asteroids to form a protective shell, and then having the actual habitat cylinder spinning inside it. Might also be a nice idea to line that outer shell with a water tank or maybe a layer of ice, and you have radiation shielding and seizable water reserves. Having a static outer shell instead of spinning the whole thing also makes for a good dock, attachment points for all those solar panels and anything else you might prefer to do in a non-spinning frame of reference.
So the picture forming in my mind does not quite match the cool concept art... From the outside, this thing would be a still cylindrical block made out of molten down and reshaped silicates with a large solar farm, "surface" docks and possibly some factories and labs for zero-G specialised stuff sticking out of its surface, while on the inside it's an enclosed, window-less cylinder with an oversized neon tube equivalent running down its axis. Does that make sense?
The next thing I can't quite wrap my head around is how one would actually transit convieniently between the spinning interior and the outside. As far as I can see that's not just a problem of the design I outlined above, but a general one. It's my understanding that in the original oneil cylinder vessels aren't docking directly to the spinning part either, but maybe I'm wrong.
Now the problem here is not so much how you would get a person, or a couple of persons, through there. What about freight? If 10 million people are living in there, there would be some traffic. While it's technically possible to run such a thing as an enclosed ecology, if there's a swarm of such and similar structures it's hard to imagine there wouldn't be a decent amount of trade going on between them, though usually only limited to manufactured high-tech goods or maybe highly specialised agricultural produces (patents can be a female dog even in a dyson swarm, I imagine...). So how would you efficiently get a few tons of cargo per day in and out of such a thing without messing up its rotation in the long run?
And finally, there's those pesky farming modules of the original oneil cylinder. I have not found any clarification of why they have to be outside the cylinder, and why they take the shape of small cylinders arrayed in a ring much larger in diameter than the actual colony itself, though maybe the concept drawings are just misleading that way.
The drawings also make it look like that ring is not part of the spinning section of the cylinder, but rather part of the static structure connecting the two cylinders. That would excarbate the transition problem outlined above, as now you have to get the entire food supply for 10 million people in there each day (and presumably, at some point, a whole lot of garbage out of there again).
Wouldn't it be more sensible to have the whole agricultural "section" somewhere in the cylinder itself? Does anybody know the reason for their particular shape and positioning?
Anyways, it would be nice to discuss these things with some fellow geeks. And what better place than this?
EDIT - appended a question I had but completely forgot when writing this initial post
Wind... To produce one G, the floor of the habitat will be spinning at about 9 m/s, which is a lot slower than we move on earth, but there's no rotating gravitational field pulling the air along with it... Would that mean that you'd essentially get a constant stiff breeze? If no, why not? And if yes, what are the possibilities to mitigate that?
Naturally this got me interested into orbital megastructures like ONeil cylinders, but there's a few things about those that I don't quite get, and some people here might explain to me a bit better.
First off, there's them mirrors... I get that they're supposed to get sunlight in, but I can't quite figure out the benefits of that versus just sticking on solar panels and do the lighting with electrical power.
As I understand it, the actual interior of the cylinder is not used for farming, since that would require a ridiculous amount of soil and rather cumbersome irrigation systems. So the only benefit would be for people to enjoy actual sunlight, which we know is important for human health, but I figure if we can build an Oneil cylinder, we should be able to build a lamp that can emulate sunlight well enough for that.
On the downside we have transparent sections in the cylinder walls. What material would they be made of? Transparent Aluminium would be a candidate I guess, since that is an actual thing now, but that's a lot of very expensive material just to let the sun in.
You'd lose a lot of living area too, at least judging by the concept drawings, and then there's micrometeorites and space debries to consider, and people might get nausea from seeing the spinning starscape (though that probably wouldn't last more than a generation).
Radiation shielding would also be a concern, though probably not so much if you can keep cylinder facing the sun reliably enough (which is why, as I understand it, ONeil cylinders were originally proposed to come in coupled pairs, so you could control their attitude with slight manipulations in the spinrate of the cylinders.
But all in all, is there any significant advantage to the mirror/window design that I'm missing? You would still need solar panels anyways because you'll want electricity, so all in all they seem pretty useless for the effort.
Another point I'm a bit unclear about is armor... You'd need some form of it. Just having a steel cylinder won't cut it in the long run. But you also don't want to spin up megatons of dead mass. So now I'm wondering if it wouldn't be a much better idea to melt down some asteroids to form a protective shell, and then having the actual habitat cylinder spinning inside it. Might also be a nice idea to line that outer shell with a water tank or maybe a layer of ice, and you have radiation shielding and seizable water reserves. Having a static outer shell instead of spinning the whole thing also makes for a good dock, attachment points for all those solar panels and anything else you might prefer to do in a non-spinning frame of reference.
So the picture forming in my mind does not quite match the cool concept art... From the outside, this thing would be a still cylindrical block made out of molten down and reshaped silicates with a large solar farm, "surface" docks and possibly some factories and labs for zero-G specialised stuff sticking out of its surface, while on the inside it's an enclosed, window-less cylinder with an oversized neon tube equivalent running down its axis. Does that make sense?
The next thing I can't quite wrap my head around is how one would actually transit convieniently between the spinning interior and the outside. As far as I can see that's not just a problem of the design I outlined above, but a general one. It's my understanding that in the original oneil cylinder vessels aren't docking directly to the spinning part either, but maybe I'm wrong.
Now the problem here is not so much how you would get a person, or a couple of persons, through there. What about freight? If 10 million people are living in there, there would be some traffic. While it's technically possible to run such a thing as an enclosed ecology, if there's a swarm of such and similar structures it's hard to imagine there wouldn't be a decent amount of trade going on between them, though usually only limited to manufactured high-tech goods or maybe highly specialised agricultural produces (patents can be a female dog even in a dyson swarm, I imagine...). So how would you efficiently get a few tons of cargo per day in and out of such a thing without messing up its rotation in the long run?
And finally, there's those pesky farming modules of the original oneil cylinder. I have not found any clarification of why they have to be outside the cylinder, and why they take the shape of small cylinders arrayed in a ring much larger in diameter than the actual colony itself, though maybe the concept drawings are just misleading that way.
The drawings also make it look like that ring is not part of the spinning section of the cylinder, but rather part of the static structure connecting the two cylinders. That would excarbate the transition problem outlined above, as now you have to get the entire food supply for 10 million people in there each day (and presumably, at some point, a whole lot of garbage out of there again).
Wouldn't it be more sensible to have the whole agricultural "section" somewhere in the cylinder itself? Does anybody know the reason for their particular shape and positioning?
Anyways, it would be nice to discuss these things with some fellow geeks. And what better place than this?
EDIT - appended a question I had but completely forgot when writing this initial post
Wind... To produce one G, the floor of the habitat will be spinning at about 9 m/s, which is a lot slower than we move on earth, but there's no rotating gravitational field pulling the air along with it... Would that mean that you'd essentially get a constant stiff breeze? If no, why not? And if yes, what are the possibilities to mitigate that?
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