Exotic weaponry: Lasers, particle beams, and high-speed projectiles are expected to be the backbone of the SDI arsenal

The effectiveness of lasers, particle beams, and high-speed projectiles in achieving the goals of the Strategic Defense Initiative (SDI) is discussed. The factors that bear on the choice of a ground-based versus a space-based system are outlined. A table is included summarizing the strengths and weaknesses of the various systems being considered for the SDI system. The way in which an X-ray laser could provide `pop-up´ defense is described, as is the possible role of rail guns in the system. Finally, the problems that must be overcome in supplying power in space are outlined.