How big is a sector and how are they generated?
All sectors are pre-generated using a computer algorithm. It’s impossible to go to a “not generated” sector; some sectors are empty, without asteroids. You can think about a sector as a cube, 100x100x100km or so. What’s more important is how long it takes to travel from the center of a sector to its border. If I remember correctly, it takes 16 minutes utilizing the turbo/afterburner, which is quite enough yet still not too big to be boring. Of course, you can travel between sectors, so these 16 minutes aren’t a real limit. If you wish, you can travel forever. The pre-generation is quite random, just like real asteroids. The algorithm that creates them is made like we think asteroids were really created – collisions, breaking, etc.