All this talk about ringworlds and moving Venus into Earth orbit has refreshed a bit of my memory about a project I came up with a few years back to encapsulate a star, and I figured this would be as good a time as any to let you all in on it.
Next week, I'm leaving Earth for a while to perform a science experiment: I'm going to encapsulate a star, so as to capture all its energy and live on the construct, something like a Dyson Sphere, but not quite.
For one, I want to live on the OUTSIDE. This will allow the entire inside to be covered in solar energy collectors or whatever, and the entire outside to be usable as living space. There will be no permanent noonday sun, and the stars will be visible. I want this thing to be capable of surviving for a very long time, even after some kind of disaster, so living on the outside means we need no expensive, prone-to-fail gravity generators that the Puppeteers could sabotage, no walls to hold in the air, no colliding with shadow squares...
Note: The following numbers may be slightly inaccurate, as I did this planning a few years back and am going from memory.
Initial thoughts:
At a distance of about 5 million miles from the Sun, you would feel a force of 1 Gee. So why not build our shell at that distance? Heat. I found out that it's REALLY HOT at that distance, and you're going to have to do something with it. The surface of the shell at that distance would be pretty much unlivable.
Ok, so we need to build in the Hab zone.
Next, to keep the land interesting, we need some mechanism to allow it to change. How about crustal plates, floating on a sea of magma? Some number-fiddling, and I found out that with a shell about 330 miles thick, if it was Earth-density, it didn't matter what the distance from the star was, my surface gravity would be 1 Gee. 330 miles was probably good enough... 30 miles for the crust, 300 for the magma. Probably enough mass to keep it under enough pressure to keep it hot and liquid. Maybe we'll have to shrink the size of the shell a bit, so we're less than an AU, just to make sure it stays molten. I don't know how reasonable that part is, though.
So you're living on the surface, and you look up, and it's always night time. How are crops supposed to grow? How are we supposed to appreciate colors and stuff? Well, we could have lots of towers that provide sunlight for a region, and these towers could be set to be on half the day and off the other half. There would be one time zone for the entire structure, if they are all on and off at the same time.
But towers would recreate the distasteful problem of always having your sun in the same location. So maybe build some orbital suns? Huge space stations that would orbit the construct, blasting their fusion rockets at the surface... I dunno, it just sounds wrong. Maybe we could just coopt a couple stars to do it?
A shell 330 miles thick, even 5 million miles in radius would require quite a few suns' worth of mass, one that's most of an AU in radius would require HUNDREDS if not thousands! There's going to be a rather lot of empty star systems... or a large dark hole in the sky that some one's going to notice, and I think something like that is going to take more than a couple minutes to build. But an object with a few hundred solar masses could surely get a star to orbit it much faster than the 2 years something at the Mars orbital distance would require. Still, I'm sure the day is going to be a month long at least. The artificial suns are looking more attractive, since they can orbit much closer and be over the horizon quickly. A few hundred of those, in varying orbits to treat the whole surface to light, would make a spectacular ballet.
With so much mass requirement, it may take the energy output of a galaxy to build something that size. Back to the 5 million mile radius... or as close as feasible. This means we need a cooler star than a G2. I believe I determined an M8 would be needed. Something like that... is it going to turn into a giant any time soon, or is it going to just burn quietly for a few trillion more years? I want this place to last a while.
Then it occurs to me that we are going to need to move the interior star around, maybe replace it once in a while. We're also going to need conduits to get all that happy energy from the inside to the outside. This is not easy if you have continental shelves floating on magma... your access tunnel's top point will always be moving, or if it's fixed in place, will cause havoc with the other plates. You'll need at least 3 access ports, maybe 6, to control the location of the star and keep it centered. So much for free-floating continents! Well, maybe you could get by... trillions of square miles IS a pretty big number.
And what about impacts with other objects? And spacecraft that manage to teleport themselves into the inside of the shell using some as-yet undiscovered technology? I think a black globe and a forest of early warning satellites will go a long way to helping out with some of that, as well as having a tough defense network, segregated to reduce the threat from things like superconductor plagues and Virus.
Still, if civilization should manage to fall back to the stone age, well, 30 miles of crust is a lot of space to hide ore deposits or caches of knowledge.
Ok, so the burning questions are these:
1) what kind of star to encapsulate?
2) what radius to make the shell?
3) what thickness and materials? Concrete or metal lawns are out of the question.
4) how do we make it feel like being on a planet? This includes things like the day-night cycle and growing crops.
5) defending against natural and intentional damage should be done how?
6) how resistant to the wears of time can we make this?
7) would it just be better to build a series of ringworlds instead?
Have at it, then.
Next week, I'm leaving Earth for a while to perform a science experiment: I'm going to encapsulate a star, so as to capture all its energy and live on the construct, something like a Dyson Sphere, but not quite.
For one, I want to live on the OUTSIDE. This will allow the entire inside to be covered in solar energy collectors or whatever, and the entire outside to be usable as living space. There will be no permanent noonday sun, and the stars will be visible. I want this thing to be capable of surviving for a very long time, even after some kind of disaster, so living on the outside means we need no expensive, prone-to-fail gravity generators that the Puppeteers could sabotage, no walls to hold in the air, no colliding with shadow squares...
Note: The following numbers may be slightly inaccurate, as I did this planning a few years back and am going from memory.
Initial thoughts:
At a distance of about 5 million miles from the Sun, you would feel a force of 1 Gee. So why not build our shell at that distance? Heat. I found out that it's REALLY HOT at that distance, and you're going to have to do something with it. The surface of the shell at that distance would be pretty much unlivable.
Ok, so we need to build in the Hab zone.
Next, to keep the land interesting, we need some mechanism to allow it to change. How about crustal plates, floating on a sea of magma? Some number-fiddling, and I found out that with a shell about 330 miles thick, if it was Earth-density, it didn't matter what the distance from the star was, my surface gravity would be 1 Gee. 330 miles was probably good enough... 30 miles for the crust, 300 for the magma. Probably enough mass to keep it under enough pressure to keep it hot and liquid. Maybe we'll have to shrink the size of the shell a bit, so we're less than an AU, just to make sure it stays molten. I don't know how reasonable that part is, though.
So you're living on the surface, and you look up, and it's always night time. How are crops supposed to grow? How are we supposed to appreciate colors and stuff? Well, we could have lots of towers that provide sunlight for a region, and these towers could be set to be on half the day and off the other half. There would be one time zone for the entire structure, if they are all on and off at the same time.
But towers would recreate the distasteful problem of always having your sun in the same location. So maybe build some orbital suns? Huge space stations that would orbit the construct, blasting their fusion rockets at the surface... I dunno, it just sounds wrong. Maybe we could just coopt a couple stars to do it?
A shell 330 miles thick, even 5 million miles in radius would require quite a few suns' worth of mass, one that's most of an AU in radius would require HUNDREDS if not thousands! There's going to be a rather lot of empty star systems... or a large dark hole in the sky that some one's going to notice, and I think something like that is going to take more than a couple minutes to build. But an object with a few hundred solar masses could surely get a star to orbit it much faster than the 2 years something at the Mars orbital distance would require. Still, I'm sure the day is going to be a month long at least. The artificial suns are looking more attractive, since they can orbit much closer and be over the horizon quickly. A few hundred of those, in varying orbits to treat the whole surface to light, would make a spectacular ballet.
With so much mass requirement, it may take the energy output of a galaxy to build something that size. Back to the 5 million mile radius... or as close as feasible. This means we need a cooler star than a G2. I believe I determined an M8 would be needed. Something like that... is it going to turn into a giant any time soon, or is it going to just burn quietly for a few trillion more years? I want this place to last a while.
Then it occurs to me that we are going to need to move the interior star around, maybe replace it once in a while. We're also going to need conduits to get all that happy energy from the inside to the outside. This is not easy if you have continental shelves floating on magma... your access tunnel's top point will always be moving, or if it's fixed in place, will cause havoc with the other plates. You'll need at least 3 access ports, maybe 6, to control the location of the star and keep it centered. So much for free-floating continents! Well, maybe you could get by... trillions of square miles IS a pretty big number.
And what about impacts with other objects? And spacecraft that manage to teleport themselves into the inside of the shell using some as-yet undiscovered technology? I think a black globe and a forest of early warning satellites will go a long way to helping out with some of that, as well as having a tough defense network, segregated to reduce the threat from things like superconductor plagues and Virus.
Still, if civilization should manage to fall back to the stone age, well, 30 miles of crust is a lot of space to hide ore deposits or caches of knowledge.
Ok, so the burning questions are these:
1) what kind of star to encapsulate?
2) what radius to make the shell?
3) what thickness and materials? Concrete or metal lawns are out of the question.
4) how do we make it feel like being on a planet? This includes things like the day-night cycle and growing crops.
5) defending against natural and intentional damage should be done how?
6) how resistant to the wears of time can we make this?
7) would it just be better to build a series of ringworlds instead?
Have at it, then.
