i have never bin lucid enough to carry out a experiment of mine, but maybe someone has. i have thought of if it was possible to travel in space when having a lucid dream, one must be if one is able to do anything right? and we can even do that in reality : )
but how does the “space” look like, and how far can one travel?
It depends on what the person thinks space will look like and how far they think they can go. In a lucid dream you could go from one side of the universe to the other in an instant, you could also visit any planet you wanted in any ship you wanted, or in no ship at all. space might look like some of those space pictures on tv, or something you create in your own mind. you could even change the look of space
In other words you can do anything
Alex is absolutely right… although I think that one’s subconscious plays a big role in how you construct your surroundings. If you know how to access and work with your subconsious, then I think you can color your astral environment more easily. I like just popping up at places in my lucid dreams if I don’t know the long, “practical way” of getting there. I don’t really use flying or skimming across the land for general travel - only for entertainment - yay!!! 
