Ballistic missile

A ballistic missile is a weapon, usually of substantial range, that follows a generally parabolic trajectory, as adjusted by guidance and control mechanisms, from launching point to target. The term ballistic comes from the idea that the basic energy is imparted, usually by a rocket motor or motors, during the initial boost phase rising to the edge of space, then into a midcourse where it coasts ballistically subject to guidance, followed by a final reentry where the reentry vehicle or vehicles travel towards their target by gravitational affection.

During the midcourse, several reentry vehicles can separate for fixed reentry (i.e., Multiple reentry vehicles, or they can be fired onto a final path by a midcourse bus, which can align itself, essentially above the atmosphere, so reentry vehicles are on a specific trajectory.

Guidance for the boost and midcourse phases are usually inertial guidance, although some system also use celestial guidance.

Reentry can be affected by the aerodynamics of the reentry vehicle, the way in which it deals with the sometimes extreme heating of atmospherics, and other environmental affects near the target. Most reentry vehicles are essentially pure ballistic, although some advanced types have aerodynamic controls or internal weights that allow them to be maneuvering reentry vehicles (MARV).