Ringworlds

[marvo]

The three literary examples are all for different purposes. The Halo is a weapon, Banks' Orbitals are just more real estate in busy systems (but are a LOT smaller), while Niven's is a galactic-scale lifeboat.

I don't think Bank's Orbitals are just more real estate, it seem more like they ARE the real estate. The Culture doesn't seem to have any interest, or reason, to colonize real planets. The vast majority seem to live in orbitals or large spacecraft. And I believe the Orbitals can be moved if needed.

For anyone interested, I would recommend reading "Look to Windward". Almost the whole book is set on an Orbital. Although smaller, it's much stranger that Niven's Ringworld.

 

[far-trader]

I seem to have not mentioned my problem with ring worlds and such in this particular round of the subject. That is where does the material come from?

I seem to recall a calculation years back that it would take all the anticipated suitable material of a couple or more solar systems to build one ring world.

And if you have the ability to travel to other solar systems then you really don't need to build a ring world, you just settle the habitable worlds of the other solar systems. As a bonus you don't have all your eggs in one big basket.

The calculations I've seen for constructing a Dyson sphere seem to indicate that there is enough material in our solar system to build one. But it assumes that you are going to undertake the effort to dismantle every planet in the system, including the Gas Giants, and you have some matter conversion process (the output of a fusion engine works) to turn the mostly hydrogen into whatever element(s) you are building your construct from.

The energy requirements of dismantling Jupiter stagger the imagination, and if you have access to that kind of power, you should also be able to build high-fraction-of-c normal space engines and colonize other worlds that way.

Quite. Anyone capable of building a ringworld doesn't need to. And Niven's statement that by the time humanity needs a ringworld (re: population for it) we'll have the capability to build it is kind of off since we'd need the real estate long before that.

I found some of what I was recalling re construction challenges. It looks like what I was recalling was the energy required to spin it up to the proper speed and not the materials to build it. That is what takes several jovian worlds worth (of hydrogen) converted to energy. Actual building materials could probably be found within a single solar system if you clean it out entirely, which is advisable anyway since you don't want stuff hitting it.

The idea for a simpler, smaller, world orbiting, ring, a ringsat(?) might be more doable for the scale, but will still have some pretty interesting challenges as well.

It'll have to spin faster for gravity so you'll still need a lot of energy for that, and the materials will still have to be incredibly strong. If you go with less spin for lower g then you need higher walls to keep the atmo I think. Or you go for an enclosed structure which is about the same materials wise.

It'll probably need even more closely monitored and adjusted station keeping to not crash into the planet it's orbiting.

Still, I can at least imagine that a ringsat could be built without the magic tech needed for a ringworld, magic tech that would eliminate the need for building a ringsat or ringworld in the first place, if the only reason is population.

But we could easily, much more easily, simply build more habitation on a world, almost any world. Using Earth as an example we could much more easily, safely, and enjoyably (never mind cheaper and sooner) live under the sea than in orbit.

 

[Plankowner]

Arthur C. Clarke wrote a book called "The Fountains of Paradise" that deals with a future Earth that starts out with permanent satellites and beanstalks and that grows into a world ring. It doesn't deal too much with the final stage, but more with the beanstalk part of it. Remember, Clarke rarely uses FTL, so a high tech civilization that never developed FTL would be very likey to "grow" one of these Ring-Sats. Capital/Core and other very high population, high tech, long settled worlds (Terra?) might have them too.

A Ring-Sat certainly seems more doable than a Ringworld and wouldn't take nearly the mass or energy. The living space would still be enormous.

 

[GypsyComet]

Ring-sats would be a lot easier than free-floating rings, if only because the building materials are presumably coming up the beanstalks instead of needing to be hauled from some more distant body. They are still mighty impressive as macro-engineering goes. I don't see them being terribly common in the Imperial setting precisely because of the ease of FTL travel. Only a species that hits spacefaring tech but never stumbles onto gravitics or Jump is likely to even consider one, since those technologies allow easy access to orbit, then other worlds, then other systems. The need to build beanstalks vanishes, and the urge to extend multiple beanstalks into a ring-sat is easily replaced by finding additional life-supporting worlds. In the presence of standard Traveller tech, only some deeply rooted racial psychological quirk is going to lead to ring-sats.

 

[The Hinterworlds Rambler]

I am working on the Ringworld of Leenitakot for an upcoming mega-adventure for CT/T20 in my Pirate Campaign. I am going on the available data from Challenge 39. The primary focus of which seems to be that it is an unfinished Ancient site of unknown purpose.

I am already considering that most of the system it is in has been stripmined for raw materials, and maybe a surrounding system or six shows the same evidence.

Other thoughts:

Made of some indestructable material, some kind of Ancient Alloy maybe.

Part of it is a node and spar construction framework

The "ground" is a Kilometers thick Deck with bizarre unfinished features.

There are gigantic gravitic pylons that are powered by stellar radiation and maintain the structure's Orbit and position.

Niven's Ringworld is a great book. I of course dig that Puppeteer, and the fact that the lead character is super old. Thier group always seemed like a Traveller group to me.

 

[Peter Newman]

What if your Ringworld doesn't revolve - than it won't need to be super strong. Just put a bunch of grav plates under. The defining characteristic of a ringworld is that it is a ring, not that it is spinning.

 

[mike wightman]

IMTU the rigworld at Leenitakot is where Grandfather initiated his jump space membrane experiment...

 

[BigBadRon]

What if your Ringworld doesn't revolve - than it won't need to be super strong. Just put a bunch of grav plates under. The defining characteristic of a ringworld is that it is a ring, not that it is spinning.

It would depend on how grav plates work IYTU (how far above the surface does the grav field extend), and how thick an atmosphere they can hold down.

Sure, a ten or thirty metre layer of air gives you enough to breathe, but it's not going to block much radiation.

Unless, of course, your ringworld has a roof on it.

 

[BlackBat242]

I don't like "convertable" Ringworlds... make mine a "hardtop".

 

[Peter Newman]

It would depend on how grav plates work IYTU (how far above the surface does the grav field extend), and how thick an atmosphere they can hold down.

Sure, a ten or thirty metre layer of air gives you enough to breathe, but it's not going to block much radiation.

Unless, of course, your ringworld has a roof on it.

No I was figuring on using spill mountains higher than the atmosphere along the edges. Of course if grav plates don't have a long range effect than there's nothing from stopping it from floating out the top.

I figure that regular grav plates _do_ have a fairly short range, but that the range at which gravity can be manipulated gets longer as TL improves. (As evidence of this see consider the repulsor [TL 10 in 100 ton size, TL 14 in 50 ton size] and the Tractors [TL 16 in 100 ton size and TL 20 in 50 ton size].
Both move objects at range, presumably they're gravitic, but even if they're not it doesn't really matter. By the time you're ready to build a ringworld, even one made out of a real, non handwavium substance, you should have the TL for these. You could simply put repulsor bays along the tops of your mountains and use them to push the atmosphere down. Presumably you have them primarily to keep the ringworld stable and safe bu pushing away incoming threats and keeping the ring stable, you might as well use them for this too.