Categories
MDA divides its systems into 4 phases, boost, ascent, mid-course and terminal, each corresponding to a different phase of the threat ballistic missile flight regime. Each phase offers different advantages and disadvantages to a missile defense system (see missile defense classified by trajectory phase), and the geography of each defended area dictates the types of systems that can be employed, thus the flexible and layered defense approach concept should improve overall defense effectiveness. The more opportunities you have to shoot it down, the better the chance of success.
Alternatively activities are categorized in 5 "blocks". For example, block 4.0 is "Defend Allies and Deployed Forces in Europe from Limited Iranian Long-Range Threats and Expand Protection of U.S. Homeland". It includes the US missile defense complex in Poland to be constructed, and the European Mid-course Radar (EMR) currently located at the Ronald Reagan Ballistic Missile Defense Test Site at Kwajalein Atoll, to be modified and relocated to the Czech Republic.
Boost Phase
- Can intercept all ranges of missiles, but the missile boost phase is only from one to five minutes. It is the best time to track the missile because it is bright and hot. The missile defense interceptors and sensors must be within close proximity to the launch, which is not always possible. This is the most desirable interception phase because it destroys the missile early in flight at its most vulnerable point and the debris will typically fall on the launching nations' territory.
Ascent Phase
- This is the phase after powered flight but before the apogee. It is significantly less challenging than boost phase intercepts, less costly, minimizes the potential impact of debris and reduce the number of interceptors required to defeat a raid of missiles.
Midcourse Phase
- This phase begins after booster burns out and begins coasting in space. This can last as long as 20 minutes. Any debris remaining will burn up as it enters the atmosphere. Ground based missile defense systems can defend from long-range and intermediate-range ballistic missiles in this phase. Mobile elements can defend against medium and short ranged missiles in midcourse.
Terminal Phase
- This phase is the last chance to intercept the warhead. This contains the least-desirable Interception Point (IP) because there is little room for error and the interception will probably occur close to the defended target.
Read more about this topic: Missile Defense Agency
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