Thinking more upon Project Horizon, I decided that you should be able to build your own space stations. This would require 0% gravity, jetpacks, and gravitational blocks as well as a variety of other blocks, like launching stations. Launching from your space station, although expensive to make a first, would save on massive amounts of fuel. You could also expand upon the launching options, like ion engines or solar sails (a personal favorite of mine, although your could only really travel AWAY from the sun...) The possibilities are endless really.