An Introduction to Ballistic Missiles

A ballistic missile (BM) is a a missile that has a ballistic trajectory over most of its flight path, regardless of whether or not it is a weapon-delivery vehicle. Ballistic missiles are categorized according to their range, the maximum distance measured along the surface of the earth's ellipsoid from the point of launch of a ballistic missile to the point of impact of the last element of its payload.

Various schemes are used by different countries to categorize the ranges of ballistic missiles.

The United States divides missiles into four range classes.

Intercontinental Ballistic Missile ICBM over 5500 kilometers

Intermediate-Range Ballistic Missile IRBM 3000 to 5500 kilometers

Medium-Range Ballistic Missile MRBM 1000 to 3000 kilometers

Short-Range Ballistic missile SRBM up to 1000 kilometers

The Soviet and Russian military developed a system of five range classes. Strategic over 1000 kilometers

Operational-Strategic 500 to 1000 kilometers

Operational 300 to 500 kilometers

Operational-Tactical 50 to 300 kilometers

Tactical up to 50 kilometers

Delivery systems vary in their flight profile, speed of delivery, mission flexibility, autonomy, and detectability. Each of these considerations is important when planning a chemical or biological attack.

Ballistic missiles have a prescribed course that cannot be altered after the missile has burned its fuel, unless a warhead maneuvers independently of the missile or some form of terminal guidance is provided.

Most current long-range missiles consist of two or more rockets or stages that are stacked on top of each other. The second stage is on top of the first, and so on. The first stage is the one that

lifts the missile off the launch pad and is sometimes known also as a "booster" or "main stage".

When the first stage runs out of propellant or has reached the desired altitude and velocity, its rocket engine is turned off and it is separated so that the subsequent stages do not have to propel unnecessary mass. Dropping away the useless weight of stages whose propellant has been expended means less powerful engines can be used to continue the acceleration, which means less propellant has to be carried, which in turn means more payload can be placed onto the target.