The biggest inhibitor I think would be the lack of economical justifications for it. We don't need the space (or rather, what we would like is the space to be close. Take a plane trip across the U.S. and you'll find a whole lot of empty), and our natural resources will last us for the foreseeable future.
What benefits are there? What we would need is a space 'gold rush' if we wanted to realistically expect any sort of real progress in that direction. Maybe we'll discover that there's oil (for example) on Mars. Maybe we'll see a lot more space speculators.
That's it for financial issues. Of course finances will drive the technology. The most prominent pieces of technology we're missing are faster than light (or warp) engines, and artificial gravity. Warp would let us travel very far very efficiently, and artificial gravity would allow humans to spend extended periods of time in space. A couple other things we're missing are materials to build such starships (not sure if we have anything that would hold such large ships together in space), replicator and transporter technology, phasers, shields/forcefields, and last but not least, proton torpedoes. If anyone knows of technology listed above that exists today, please let me know.
warp engines: not needed for colonization. Materials: plentiful, no shortage. Replicators: missing, no obvious food alternative around. Transporter Tech: unneeded. Phasers: unneeded. Shields: unneeded. Photon (or proton) torpedoes: unneeded.
All we really need is a way to be confident that if we send some people out, they will be good for 1000 years. That means food and environment, not forcefields and transporters. Look into the experiments where they tried to isolate humans from the earth environment by sealing them in a airtight greenhouse. (hint: the ants started dieing within a month)
That depends on what you mean by space. LEO to Geosynchronous orbit is still a lot more than 1% of energy to orbit.
Anyway, orbit is only 17,000 MPH which is way to slow to go travel to the next star. Traveling at at 17,000 mph would take about 40,000 years to travel one light year. The good news is you slowly accelerate in space over a long time, so smaller high efficiency engines would work just fine. The bad news is the closet star is over 4 light years from earth.
So getting something the size of the space shuttle to the next star in 1,000 years would take 2x (168^2) as much energy as it takes to get to LEO. ~56,500 * 2.2 * 10^12J = ~10^17 jules for comparison that's ~28 thousand megawatt hours.
What benefits are there? What we would need is a space 'gold rush' if we wanted to realistically expect any sort of real progress in that direction. Maybe we'll discover that there's oil (for example) on Mars. Maybe we'll see a lot more space speculators.
That's it for financial issues. Of course finances will drive the technology. The most prominent pieces of technology we're missing are faster than light (or warp) engines, and artificial gravity. Warp would let us travel very far very efficiently, and artificial gravity would allow humans to spend extended periods of time in space. A couple other things we're missing are materials to build such starships (not sure if we have anything that would hold such large ships together in space), replicator and transporter technology, phasers, shields/forcefields, and last but not least, proton torpedoes. If anyone knows of technology listed above that exists today, please let me know.