For a colony, be it O'neill or smaller like a Stanford Torus, it is economically un feasible to use material from earth, well the bulk material, some electronics, people yes. The main bulk material HAS to come from an asteroid, Moon "Might" work if they have a a mass driver to launch materials off surface for cheap.
for the asteroid, you can use the asteroid/comet itself for fuel, just install a mass driver with a power source, and use asteroid material accelerated away from itself as propulsion. may not be fast, but you kind of don't want it fast. one screw up and you have a mile wide asteroid hitting earth..
for an O'neill you would have to make a colony building machine. attach an asteroid to one end, and the other end extrudes a completed colony.
for the asteroid, you can use the asteroid/comet itself for fuel, just install a mass driver with a power source, and use asteroid material accelerated away from itself as propulsion. may not be fast, but you kind of don't want it fast. one screw up and you have a mile wide asteroid hitting earth..
for an O'neill you would have to make a colony building machine. attach an asteroid to one end, and the other end extrudes a completed colony.