WASHINGTON – September 29 has been set for the first-ever test of a prototype National Missile Defense system. The Integrated Flight Test 3 of the National Missile Defense (NMD) system will track, attack, and attempt to destroy a mock warhead attempting to enter the atmosphere in a simulated attack upon the U.S.

The test, the first of its kind, will use a Boeing-made launch vehicle carrying a Raytheon-made killer interceptor in space high above the Kwajalein Missile Range in the Pacific Ocean, according to a senior NMD official. The warhead mock-up will be launched from the Air Force’s Vandenberg Air Base in California and head westward across the Pacific. The interceptor killer will be launched from a Kwajalein island launching silo.

A previous series of two intercepts conduced in the Army’s Theater High Altitude Area Defense (THAAD) system was a simulation of an attack by intermediate range missiles in a battlefield theater, or limited area setting.

The NMD system under design would protect all of the continental United States, Alaska, and Hawaii against a limited nuclear attack "by a rogue nation" located anywhere in the northern hemisphere, the official told space.com this week.

The IFT-3 test has limited objectives, officials said. It will use the radar systems at the Kwajalein test site to feed steering and tracking data to the booster while ascending towards the warhead. A missile launched in defense against an actual attack would use the booster’s own guidance and tracking system.

The data will be gathered from radars at the test site, ships nearby, patrolling aircraft and from the orbiting Global Positioning System (GPS) satellites. Then, it will be fed into the Battle Management Center, which will send steering commands to the interceptor kill vehicle in space as it hunts the warhead.

The Strategic Arms Limitation Treaty (SALT) forbids the transmission of this tracking data directly from the site radars to any interceptors. "At this point, we’re trying to find the ‘bomb’," the official said.

Flight test four, in 2000, will actually use the rocket’s onboard radar system to detect and track the reentry vehicle. The intercepts will occur at least 120 km out in space above the Pacific.

In an actual NMD event, once an attacking missile lifts above the horizon, the U.S. Defense Support Program detects the launch and alerts U.S. forces. (Later in the next decade, Space-Based Infrared System (SBIRS) satellites will do the job.)

Early warning radars will track the missile as it flies and separates the reentry vehicle from the burned-out stages of its booster. These radars "paint" the field of rocket and reentry vehicle parts as they speed out in space, classifying the field of objects.

"This is an attempt to see what some of this material is, what is the rocket’s fairing, what are springs and other debris in that cloud", the official said. In an actual missile attack against the U.S., the incoming bomb might also carry with it countermeasures aimed at fooling the tracking radars, hiding the precise location of the bomb-carrying warhead as it heads towards the U.S.

A new series of X-band radars, among the most powerful ever built, are being designed to take the next step during the attack scenario. Where the tracking radars have eliminated decoys and debris, the X-Band systems would then "look into the cluster of remaining materials from the rocket and say ‘that’s the bomb’," the official explained.

As the interceptor kill vehicle is launched and ascends towards the target, the kill vehicle separates from the last stage of its launcher and then "opens its eyes," meaning its sensors then sweep the narrow field before it where the bomb is approaching. That distance, while classified, is "hundreds of miles," officials said.

With sensors tracking the bomb warhead, thrusters on the kill interceptor, guided by onboard systems and ground radars makes the final maneuvers to the target. The incoming bomb is destroyed upon collision with the interceptor, which carries no explosive. Officials call this final phase of the tracking and intercept "the endgame."

Following a limited number of such space intercept tests, the NMD organization will decide next summer whether to recommend to the White House that a national missile system can be deployed.

Such a system, if approved by the President, would be deployed by the year 2005. It would also require changes in the SALT and other treaties, which currently ban a national missile defense system by the U.S., although Russia has a limited missile defense system still in place around Moscow. That system was deployed before the fall of the former Soviet Union.