From Starfleet Commander
Space Mines provide an excellent deterrent to enemy raids when placed in large numbers. However, this comes with risk. In each round of battle any space mine remaining has an approximately 20% of detonating and causing damage. No more than 5 mines may detonate per attacking ship in a round. If a space mine detonates it has a 75% chance of striking an attacking ship, and a 25% chance of striking a defending ships and defenses.
Cost and Specifications