Does this mean something about the set mapsize or that you can't move it any further than 50k points from where you started to move them?
Both has nice solutions and both seems rather logical. And Pilchard: if you open Asteroid Designer 5, which uses 200 k units², it uses around 350 000 K, which I guess by wild is ca. 350 Mb of RAM usage, compare that to the 4 Gb that usually or minimally now adays sits inside of the computer. It isn't very much
And for the other case: Just drag, release and then drag again... It isn't an elegant or nice way to move the asteroids, but it is doable more than nothing atleast