Key elements of global defense

Current plans for a U.S. missile defense system include airborne lasers and other systems but will rely primarily on three systems that are either brand new or still in development.

Current plans for a U.S. missile defense system include airborne lasers and other systems but will rely primarily on three systems that are either brand new or still in development.

THE AEGIS BMD
Aegis BMD is a Ground-Based Midcourse Defense (GMD) system — meaning its radar and interceptors are both terrestrially based, but intercept their targets while they’re at the top of their orbit, usually outside the Earth’s atmosphere.

Also called Sea-Based Missile Defense, the Aegis system uses Ticonderoga-class guidedmissile cruisers and Arleigh Burke-class destroyers as its primary platforms.

The MDA deployed the first elements of the Aegis long-range surveillance and tracking capability (LRS&T) detection and control systems in 2004, though the interceptors are still being tested.

The SM-3 interceptors are hit-to-kill vehicles manufactured by Raytheon.

The kill vehicle is based on the Lightweight ExoAtmospheric Projectile (LEAP) approach that was one of the original parts of the Strategic Defense Initiative. LEAP vehicles are designed to detach from their boosters, acquire their targets in orbit and home in for the kill. The third stage of the SM-3 solid-fuel booster provides the final boost, but the kill vehicle contains its own attitude control and guidance system and heatseeking capability.

An enhanced version of the system is designed to intercept targets in lower orbits, too. Testing is scheduled to go on through 2012.

THAAD
Terminal High Altitude Area Defense is an integrated system consisting of interceptor, launcher, radar and fire control system, contained in a mobile launcher. It was developed as a theater defense system to protect troops on the battlefield and friendly countries within its region from Scud-type missiles. It is designed to operate in the upper atmosphere and beyond, killing enemy missiles by colliding with them.

The systems are due to go into initial operating capability in 2009, but the Missile Defense Agency announced last month that it was pushing acquisition back six months because of budget shortfalls.

It was first funded in 1992, in a contract with Lockheed Martin, and conducted its first out-ofatmosphere test using all elements of the system in 2006. The Army expects to take delivery of as many as 100 launchers, 18 radar systems and 1,400 missiles for two THAAD battalions.

Lockheed Martin got the contract for the first two production systems — six launchers, 48 missiles, two radars and two operations centers — in January 2007.

Raytheon is manufacturing the ground-based radars, early warning radars, X-band radars and out-of-atmosphere kill vehicle. Lockheed is manufacturing the interceptor itself; Northrop Grumman is making the Battle Management Command, Control and Communications (BMC3) command-and-control systems.

X-BAND RADAR
Though boosters, kill vehicles and ground-based radar are important elements of either global or theater-based missile defense, the key to stopping a missile is being able to not only find it but also decide which blip is the warhead and which are decoys or space junk. Sea-based X-band radar platforms — one of which is based in Adak Island, Alaska, and more of which might eventually be built — are designed as mobile platforms for high-reliability detection and tracking of inbound threats.

The radar domes are a phased-array radar with more than 30,000 transmit-receive modules. They are designed, according to public statements by MDA Director Lt. Gen. Trey Obering, to be able to sit in the Chesapeake Bay and track a baseball-sized object over San Francisco.

The array rides on a Russian-build CS-50 semisubmersible large enough to carry the more than 1,800 tons the radar reportedly weighs.

X-band radar is higher frequency than either the S-band radar used by existing Aegis systems or the C-band used by Patriot missiles. Its shorter wavelength allows finer resolution of objects it’s tracking.

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