Three Phases of Missile Defense

There are three phases of missile defense: the boost phase, the midcourse phase, and the terminal phase. In the boost phase, the missile is being propelled through the atmosphere into space. In the midcourse phase, the warhead separates from the missile body and proceeds through space. This phase generally lasts from 30 seconds to one minute. Finally, in the terminal phase, the warhead re-enters the atmosphere and falls to earth towards its intended target.

Boost Phase — The boost phase is the part of a missile flight path from launch until it stops accelerating under its own power. Typically, the boost phase ends at altitudes of 300 miles or less, and within the first 3 to 5 minutes of flight. During this phase, the rocket is climbing against the Earth’s gravity. Intercepting a missile in its boost phase is the ideal solution. The two types of boost defense elements are directed energy systems using highpower lasers such as the Airborne Laser, and kinetic energy interceptors.

The Airborne Laser’s role is to defend the United States, its allies, and American troops deployed around the globe by detecting, tracking, and destroying hostile ballistic missiles soon after they are launched. It is designed to detect, track, target, and kill threatening missiles, whether they are short-, medium-, or long-range. The system uses an amalgamation of technologies including deployment on a Boeing 747-400 freighter and a Chemical Oxygen Iodine Laser (COIL). The laser destroys the missile by heating its metal skin until it cracks, which causes the boosting missile to fail.

The Airborne Laser will represent the world’s first use of a directed energy weapon system in an airborne combat environment. The six-module COIL system is capable of producing a megawatt-class beam effective out to a range of several hundred kilometers. To ensure the laser beam hits its target with sufficient destructive power, the system uses adaptive optics to compensate for beam deflection and dispersion caused by atmospheric disturbance.