Brilliant Pebbles turns missile defence into an orbital interceptor network

Brilliant Pebbles proposed orbiting autonomous tungsten projectiles that could receive sensor data and maneuver into ascending ballistic missiles. Associated cameras and sensors reached practical use in the Clementine mission and other SDI satellites, making the concept look more mature than some of SDI's directed-energy schemes. The missile-interceptor idea differs from the popular image of unguided rods dropped on ground targets because the projectiles would be guided against an ascending missile. The program was nevertheless cancelled in 1994 amid treaty and ballistic-missile-defense constraints. A technically plausible weapon can still arrive before the political and arms-control environment will permit its deployment.