The thought of enlarging the Houdini mines came up again in my head and made me remember exactly why they would not be used in space. Space is vast, mines are tiny. The only reason the minefield in front of the Wormhole would work is because there is only one way in or out of it in the Alpha Quadrent. Filling a few square miles of space around that will ensure a blocked path. Anywere else is just too vast to effectively mine. Even a planet. How to you be sure which orbit someone is going to enter? Space line between star systems? Sure there is the direct route, but how wide is that? A few light-hours across?