Once you get a rank - any rank - you will receive a mission that will lead you outside of Pilots Federation District.
If you take that mission and get out of the said Pilots Federation District you cannot come back
Those being said, you can stay in that district as long as you want - no one will kick you out.
Can you still gain other ranks or further develop your existing rank as long as you don't take this final mission?Thanks for answering dumb newbie questions. If I stay in the district after getting an Exploration rank, can I then also get a Trade rank, giving me two ranks, or is that not even logical. Do you have to choose one rank and stick with that?