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home > March 24, 2008 issue > article
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.
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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