I think about a space opera, and a Death Star like scenario in it. I intend to make it harder than SW. I had the following idea : they hollowed out a big metallic asteroid, spinned it up, kept a large portion of the outer layer as armor, and built a fusion reactor in the middle of it. They want to build a superweapon inside the well protected belly, the entryway is heavily fortified. However it is possible to enter inside the asteroid through other shafts (used for mining), big enough for a small manned spacecraft. What can be the weakness of such structure? I dont think that they just leave a wide open entryway to the reactor core. I also would like to rule out nukes (nations already get rid of all nukes, orbital bombardment is better) Can it be realistic to send a bomb into the reactor core through a large coolant pipe?