Cool - I won't be around to see it. I don't expect to see affordable one bit per atom in my remaining lifetime even though it can be achieved in labs. Maybe some superbright AI will work its magic and make it happen sooner.
What can we make? (no Earth)
- Thread starter evilchumlee
- Start date
Just realised I got my calculations wrong for the strength required for the ring material - probably too much Christmas cheer (that is, wine) on my part, I expect.
The tensional stress σ in a rotating thin ring is given by σ = v²ρ, where ρ is the density of the ring material.
The centripetal acceleration due to the ring is given by a = v²/r, where r is the radius of the ring. Therefore, we can substitute for v² in the first equation, giving:
σ = arρ
Let's assume the required acceleration is one Earth standard gravity a = 9.81 m/s². Note that σ is directly proportional to r for a given a and ρ. That makes calculation simple. Where I went wrong was inputting the wrong numbers, leaving out factors of 1,000, due to alcohol and possibly incipient senility. I've also found better yield strength figures for the materials.
For an O'Neill cylinder of radius 4 km, the tensional stress would be 9.81 x 4,000 x ρ or 55 Mpa, 78 Mpa and 314 MPa for Kevlar, carbon fibre and steel - within their yield limits of 3.6 GPa, between 4.0 GPa and 7.0 GPa and between 0.2 GPa and 2.0 GPa. Only certain grades of steel would be suitable - something like AerMet alloy perhaps, but I'm neither a metallurgist nor a materials scientist.
For a Bishop ring of radius 1,000 km, the tensional stress would be 250 times greater at 14 GPa, 19.5 GPa and 53.5 GPa for Kevlar, carbon fibre and steel - well beyond the yield limit for those materials, but for carbon nanotube and graphene, a stress of about 15 Gpa would be well within their limit of between 50 and 60 Gpa.
For a Banks orbital of radius 1,650,000 km, the tensional stress would be 1,650 times that for a Bishop ring, so well outside the capability of even carbon nanotube or graphene to withstand. You're going to need something approaching Niven's scrith with the tensile strength of roughly the strong nuclear force.
So, my conclusion is O'Neill cylinders, no problem given the will; Bishop rings, doable eventually, perhaps; Banks orbitals, probably in the realm of science indistinguishable from magic.
These are just my rough back-of-envelope calculations - hopefully, correct this time.
The tensional stress σ in a rotating thin ring is given by σ = v²ρ, where ρ is the density of the ring material.
The centripetal acceleration due to the ring is given by a = v²/r, where r is the radius of the ring. Therefore, we can substitute for v² in the first equation, giving:
σ = arρ
Let's assume the required acceleration is one Earth standard gravity a = 9.81 m/s². Note that σ is directly proportional to r for a given a and ρ. That makes calculation simple. Where I went wrong was inputting the wrong numbers, leaving out factors of 1,000, due to alcohol and possibly incipient senility. I've also found better yield strength figures for the materials.
For an O'Neill cylinder of radius 4 km, the tensional stress would be 9.81 x 4,000 x ρ or 55 Mpa, 78 Mpa and 314 MPa for Kevlar, carbon fibre and steel - within their yield limits of 3.6 GPa, between 4.0 GPa and 7.0 GPa and between 0.2 GPa and 2.0 GPa. Only certain grades of steel would be suitable - something like AerMet alloy perhaps, but I'm neither a metallurgist nor a materials scientist.
For a Bishop ring of radius 1,000 km, the tensional stress would be 250 times greater at 14 GPa, 19.5 GPa and 53.5 GPa for Kevlar, carbon fibre and steel - well beyond the yield limit for those materials, but for carbon nanotube and graphene, a stress of about 15 Gpa would be well within their limit of between 50 and 60 Gpa.
For a Banks orbital of radius 1,650,000 km, the tensional stress would be 1,650 times that for a Bishop ring, so well outside the capability of even carbon nanotube or graphene to withstand. You're going to need something approaching Niven's scrith with the tensile strength of roughly the strong nuclear force.
So, my conclusion is O'Neill cylinders, no problem given the will; Bishop rings, doable eventually, perhaps; Banks orbitals, probably in the realm of science indistinguishable from magic.
These are just my rough back-of-envelope calculations - hopefully, correct this time.
For my concept of the "Earth-Sized" Banks Orbital, I was thinking that in a Star Trek type setting where you have the material science to make it happen.
(They have Bloody Neutronium, so I'm pretty sure some simple Neutronium Alloys would be good enough for the "Core Structure")
But having the inner Ring rotating in one direction via EM and/or Gravimetric Seperation of the Inner Ring layer from the fixed outter structure and rotating it in one direction while the outter layer would use advanced Gravity Plating network to make sure nothing flies off into space.
This way the "Banks Orbital" would be effectively Double-Sided and allow a total of 100x the Surface Area of Earth.
It would also function as the largest "Artificial Space Colony" made by the UFP & be parked at the Sun-Earth L3 point with a StarFleet Base in the dead center for protection.
There is a separate forum for Trek Tech. Star Trek science is mostly fantasy - sometimes it gets it correct, sometimes it doesn't. If the Federation had all the advanced tech it discovered in TOS then it would have been more like the Q by the time of TNG.
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