Earth II

> While I'm sure the concrete and steel/carbon-allotropes could keep going for
> a few thousand years... What about the 'glass'? Either as massive windows,
> or fiberoptics, some part of it is going to be exposed to the deep space
> enviroment. If it gets cloudy (micrometorite pitting or plain dirt) for any
> reason, then the sunlight gets blocked and the leaves will fail.

If this is a cause for concern, then I would recommend the Bernal Sphere design. In that configuration, straight-line paths to the windows are not allowed. That's done to reduce the amount of cosmic rays getting through, but it would also have the effect of greatly reducing fogging due to micrometeorite bombardment.

http://ssi.org/assets/images/Ch08p125.gif

Regards,

Mike Combs