That's the thing: We have a start, but, is it good enough for a colony? Probably not. Can we improve it enough? Don't know. The ISS doesn't make it's own food, or spare parts. I'm thinking that water is recycled, but solid waste is not. A 3D printer, as described upthread, sounds very useful -- until the printer breaks down and needs a part itself.
To me, that makes putting people into space (or on the moon, or mars), maybe feasible, but not definitely. I think we have a long way to go until we make the technology work well enough for a mostly self sustaining colony.
Thx!
TomB
On a "micro" scale, a lot of our cities and towns are not self sustaining any more.
So a space colony wouldn't have to be any more self sustaining than the transportation requirements to bring stuff (huge at the moment).