I think one of the problems at the moment is that everything related to space exploration has improved - except the cost of putting things up into space. This really needs to improve, the shuttles replacement will be more efficient at lifting matter of the earth but is still painfully costly.
Unless something like a space elevator can be made (which is doubtful in itself, as even woven carbon nanotubes would be vulnerable) then i don't think the launch cost will ever be improved. The only way i can see it being feasible to make large vessels is to have manufacturing capacity in space, this would have to involve capturing an iron ore rich asteroid, and lifting heavy processing equipment onto it. I can't see something like that happening in the foreseeable future, or at least my lifetime. This kind of rules out a large cryostat style spacecraft.
If wormholes are a possibility it would solve a lot of problems, ie crossing large distances without everyone back home aging really quickly in relation to the travelers and getting equipment out of the mavity wells of planets. I doubt wormholes are possible tho. Anyway i'll stop waffling now.
Unless something like a space elevator can be made (which is doubtful in itself, as even woven carbon nanotubes would be vulnerable) then i don't think the launch cost will ever be improved. The only way i can see it being feasible to make large vessels is to have manufacturing capacity in space, this would have to involve capturing an iron ore rich asteroid, and lifting heavy processing equipment onto it. I can't see something like that happening in the foreseeable future, or at least my lifetime. This kind of rules out a large cryostat style spacecraft.
If wormholes are a possibility it would solve a lot of problems, ie crossing large distances without everyone back home aging really quickly in relation to the travelers and getting equipment out of the mavity wells of planets. I doubt wormholes are possible tho. Anyway i'll stop waffling now.