November 9, 2007: The U.S. Navy has two more successful tests of its Aegis anti-missile system. So far, the Aegis system has knocked down 85 percent of the missiles fired towards it. The navy modified its Standard anti-aircraft missile system to knock down ballistic missiles. This system, the RIM-161A, also known as the Standard Missile 3 (or SM-3) [PHOTO], has a range of over 500 kilometers and max altitude of 160 kilometers. The Standard 3 is based on the failed anti-missile version of the Standard 2, and costs over three million dollars each. The Standard 3 has four stages. The first two stages boost the interceptor out of the atmosphere. The third stage fires twice to boost the interceptor farther beyond the earth's atmosphere. Prior to each motor firing it takes a GPS reading to correct course for approaching the target. The fourth stage is the 20 pound LEAP kill vehicle, which uses infrared sensors to close on the target and ram it. The Aegis system only operates from warships (cruisers and destroyers that have been equipped with the special software that enables the AEGIS radar system to detect and track incoming ballistic missiles.

The U.S. has two other land based anti-missile systems. The U.S. Army THAAD [PHOTO] anti-ballistic- missile (ABM) system has a range of 200 kilometers, against targets as high as 150 kilometers. THAAD is intended for short (like SCUD) or medium range (up to 2,000 kilometer) range ballistic missiles. THAAD has been in development for two decades. Each THAAD battery will have 24 missiles, three launchers and a fire control communications system. This will include an X-Band radar. The gear for each battery will cost $310 million.

The 18 foot long THAAD missiles weigh 1,400 pounds each. This is about the same size as the Patriot anti-aircraft missile, but twice the weight of the anti-missile version of the Patriot. Ultimately, the army would like to buy at least 18 launchers, 1,400 missiles, and 18 radars.

THAAD is a step up from the Patriot PAC-3 anti-missile (which is an anti-aircraft missile adapted to take out incoming missiles). The PAC-3 works, but it has limited range (20 kilometers).