I don't think there are any serious technical issues that would necessitate inventing something major -- all you need is a lot of engineering.

If I understand correctly, a round trip mission (land, plant a flag, pick up some rocks, take pictures and return) is currently technologically feasible. It's pretty much a matter of scaling up Saturn V / Apollo. The main technical issue is cancer risk from radiation, but I suppose that even if that was ignored there would be no difficulties finding astronauts who would be willing to fly.

A colony that doesn't depend on frequent supply launches, on the other hand, seems beyond current technology.