Aegis Ballistic Missile Defense (Aegis BMD) will provide an efficient and highly mobile sea-based defense against short- and medium-range (and soon long-range) ballistic missiles in their midcourse phase.
The system will integrate the U.S. Navyâ€™s existing fleet of Aegis cruisers (Ticonderoga class) and Aegis destroyers (Arleigh Burke class) with the Standard Missile-3 (SM-3) interceptor currently under development. The system will allow the Missile Defense Agency (MDA) to move its defense capabilities close to enemy launch sites, thus providing a critical â€œlayerâ€ to the broader Ballistic Missile Defense System.
At present, each Aegis cruiser and destroyer is outfitted with the Aegis Weapon Systemâ€”the heart of which is the AN/SPY-1 radar system. AN/SPY-1 sends out beams of electromagnetic energy in all directions, thus allowing Aegis ships to track up to 100 targets simultaneously, while still retaining the ability to counter other air, surface, and submarine threats. AN/SPY-1 will be able to detect ballistic missiles as they rise above the horizon.
Once a hostile missile has been detected, Aegis BMD will launch its Standard Missile-3 interceptor from its MK41 Vertical Launching System (currently deployed on Aegis cruisers and destroyers). An evolution of the SM-2 Block IV interceptor, the SM-3 is a hit-to-kill missile comprised of a three-stage booster with a kill vehicle. As the SM-3 burns through its three stages, its GPS-Aided Inertial Navigation System will set it on an intercept trajectory with the hostile missile. SM-3 will also receive target updates from the Aegis destroyer.
Once close enough to the ballistic missile, the SM-3 will fire its kill vehicle, the Kinetic Warhead (KW), from its nosecone. The KW will immediately begin to search for its target. It will acquire the ballistic missile using a high-resolution seeker, and maintain an accurate trajectory using its internal navigational system. As it closes on its target, the KW will identify the missileâ€™s payload, and shift its aimpoint to ensure a lethal hit. When the KW finally slams into the enemy warhead, the kinetic energy of the high velocity impact will ensure complete destruction of the threat.
Since 1999, MDA has conducted five SM-3 flight tests. Four have been successful. The most recent test was on December 11, 2003, when a SM-3 from the Aegis cruiser USS Lake Erie tracked, targeted, and destroyed a short-range target missile launched from the Pacific Missile Range Facility in Kauai, Hawaii. Impact occurred at an altitude of 137 kilometers and a closing speed of approximately 3.7 kilometers per second. The entire operation, from detection to destruction, took four minutes.
President George W. Bush recently called on MDA to deploy a preliminary defense shieldâ€”including sea-based assets. In September 2004, the Navy will deploy an Aegis destroyer in the Sea of Japan capable of detecting and tracking missile launches from North Korea and China. In the event of a hostile launch, the destroyer will be able to transmit data to ten ground-based interceptors located in Fort Greely in Alaska and Vandenberg Air Force Base in California (also scheduled for deployment in September 2004).