Space the final frontier? I know it's a star trek reference but what does it mean?

I always guessed that it was like man's domains of exploration. The land, then the sea, the sky... then there's space... there's nothing (that we know of) outside of space so it has to be the last place to explore, the final frontier. (though there are at least other kinds of explorations one can make like subjective introspective ones (the mind)).

Man had conquered all the known worlds and now he was off on a five year mission to explore others.

Hope this definition is what you are looking for:
It just means the last unexplored area - the final adventure for those seeking the unknown. American frontiers men were those who explored the unknown areas in the American west - the final frontier would just be the last unexplored area in either a peticular region or, as the Star Trek phrase indicates, the ultimate unexplored, unconquerable frontier.

The last place to explore I think.

space: the final frontier. the last place that hasn't been explored/developed/settled.

Another place for man to fuck up

The great unknown

some with 3 ears i think

It was a phrase used before anyone had ever walked on the moon.