Nuclear explosive spacecraft propulsion offers the high thrust and high specific impulse required for manned interplanetary missions. To achieve high velocity requires either long shock absorber or a large number of tiny nuclear explosions. Microexplosions are attractive, but presently conceived drivers are very massive. Antiproton induced microfusion/fission may provide a light-weight alternative. Generally the energy from antiprotons is deposited over such a large region of space that it cannot efficiently drive nuclear capsules. Antiproton induced fission and self-generated magnetic fields may greatly enhance energy localization.