July 26, 2013:
The latest test of the U.S. GMD (Ground-Based Miscourse Defense) ballistic missile interceptor missed its target during a July 5th test. This was the third test failure following two failures in 2010. The last successful test was in 2008.
This time a target missile was launched from Kwajalein Atoll in the Pacific Ocean west towards the United States. To intercept the missile, the Capability Enhancement 1 Exoatmospheric Kill Vehicle was launched using a three-stage solid fuel rocket. The Exoatmospheric Kill Vehicle seeks out the target using multicolor sensors and guidance data from ground radar and must also deal with potential decoys. It intercepts the target by colliding with it head on, destroying it through kinetic (impact) energy, as opposed to fragments from a high explosive warhead. This leaves very little margin of error, though it reduces the weight of the interceptor.
The GMD system recorded eight successful intercepts out of 15 tests since 2001. The primary purpose of the GMD is to defend against nuclear missiles from hostile foreign nations. There are some 30 anti-ballistic missiles deployed so far.
The next scheduled test is expected to be in 2014, to determine if the Capability Enhancement 2 kill vehicle is successful enough for the Pentagon to purchase. In January 2013, a flaw in the guidance system was fixed for the Capability Enhancement 2 kill vehicle.
So far the program costs about $34 billion and has its origins in the "Star Wars" defense program. It is supplemented by the AEGIS anti-ballistic missile system, used by US naval warships. The U.S. is already building 14 more GMD batteries for $72 million each.