It seems pretty obvious that we don't currently have the technology to become a spacefaring civilization. Certainly there is stuff in space we could be doing using existing technology, and with great expense, but to really begin the human utilization and colonization of space we need a large variety of technological innovations.
Jon Goff gave a great list of short term technologies that need to be developed before we can really consider society to be spacefaring.
This should be the start of the story.
