Property rights
Some sort of objective rules for "claiming" property in space need to be worked out, maybe similar to the way homesteading or mining claims were and are done, requiring evidence of real productivity from a given site before title to a piece of land (or rock floating in space) can be given. Treaties prevent nations from claiming space bodies, but I think there is still a loophole for private citizens or corporations.
Obviously, there will be no idiotic planting of a flag and claiming a whole planet like some of our ancestors did when "claiming" the New World.