You can build an 8km diameter O'Neill cylinder[1][2] with titanium. From memory his calculations used a 200% safety margin.
Where does the titanium come from? The moon, which absolutely lousy with the stuff.
Where does the energy to work titanium come from? Your friendly neighbourhood fusion lamp: the sun.
If you have mature carbon nanotech, you can jump up to McKendree cylinders[3]. These are O'Neill cylinders scaled up to a 920km diameter.
[1] http://en.wikipedia.org/wiki/ONeill_cylinder
[2] http://en.wikipedia.org/wiki/The_High_Frontier:_Human_Coloni... (worth reading if you can find it)
[3] http://en.wikipedia.org/wiki/McKendree_cylinder
Thanks.
You can build an 8km diameter O'Neill cylinder[1][2] with titanium. From memory his calculations used a 200% safety margin.
Where does the titanium come from? The moon, which absolutely lousy with the stuff.
Where does the energy to work titanium come from? Your friendly neighbourhood fusion lamp: the sun.
If you have mature carbon nanotech, you can jump up to McKendree cylinders[3]. These are O'Neill cylinders scaled up to a 920km diameter.
[1] http://en.wikipedia.org/wiki/ONeill_cylinder
[2] http://en.wikipedia.org/wiki/The_High_Frontier:_Human_Coloni... (worth reading if you can find it)
[3] http://en.wikipedia.org/wiki/McKendree_cylinder