A system for defending a planet having a satellite against impact from an incoming body includes an explosive system and a propulsion system. The explosive system is adapted for deployment on the satellite and detonation thereon with sufficient explosive force to produce at least one ejectum to which is imparted a velocity increment sufficient for the ejectum to exceed the satellite's escape velocity and enter orbit about the planet. The propulsion system is adapted to be secured to at least one ejectum and impart a velocity increment to the ejectum sufficient to leave orbit about the planet and enter an orbit intercepting the incoming body. The system is used in a planetary defense method in which the explosive system is deployed at a deployment site on the satellite and detonated to produce at least one ejectum having a velocity that exceeds the escape velocity of the satellite. The ejectum enters into orbit around the planet, at which time the propulsion system is secured to the ejectum to produce a projectile. The propulsion system is then activated to increase the velocity of the projectile, causing the projectile to enter into an intercept orbit targeting the incoming body and subsequently intercept and impact the incoming body. The impact prevents the incoming body from impacting the planet.