The U.S. Missile Defense Agency (MDA) is planning more realistic demonstrations of the Terminal High Altitude Area Defense (THAAD) system in the near future as it prepares to move to a new testing site, according to a program official.

Those tests could help demonstrate the Pentagon’s ability to shoot down ballistic missiles launched from ships near the U.S. coastline, according to U.S. Army Col. Charles Driessnack, the service’s THAAD project manager.

THAAD is the only U.S. missile defense system capable of intercepting targets both inside and outside the atmosphere, Driessnack said in a Feb. 28 telephone interview.

Lockheed Martin Missiles and Fire Control of Orlando, Fla., builds the THAAD system, which includes interceptor rockets, truck-mounted launchers, radar sensors, and command and control elements.

The Pentagon plans to field two THAAD fire units in 2009, each of which will likely include one radar sensor, fire control equipment, and three launch systems , Driessnack said. Each launcher will be equipped with eight interceptors, so the two fire units together will have a combined total of 48 rockets, he said.

The military will keep the fire units at Fort Bliss in Texas until they are needed for deployment, he said.

The total cost of those two fire units is expected to be about $900 million.

The military has conducted its past THAAD flight tests from White Sands Missile Range in New Mexico, but plans to move to the Pacific Missile Range Facility in Kauai, Hawaii.

Testing over the water in Hawaii removes many of the safety constraints that were necessary for flight demonstrations over White Sands to protect the local population, Driessnack said.

One of the most notable of those safety measures is a corkscrew-like maneuver that the THAAD interceptor must take to burn off excess energy when flying over the White Sands, Driessnack said.

Once testing begins over the Pacific Ocean, that maneuver will no longer be necessary, and program officials will be able to plan tests in which the target vehicles to be intercepted can be launched from much farther away than was possible at White Sands, Driessnack said.

“So the flight test program gets very interesting, with very threat representative targets and very tactically oriented scenarios,” Driessnack said.

One threat that can be much better represented in Hawaii than over White Sands is the threat of ballistic missiles launched toward the United States from ships and barges off the U.S. coast, a concept that gained public attention last summer following a Lockheed Martin briefing for reporters in Washington.

The Pentagon and industry refer to that scenario as the “asymmetric threat,” and Congress added money to the 2006 budget for the Missile Defense Agency to study potential architectures that could defend the country from that type of attack.

The target launches in the Pacific Ocean will take place from barges, and will fly with the same type of trajectory over water that would be seen from an asymmetric threat, Driessnack said.

Several successful intercepts at the Pacific Missile Range Facility could give the Pentagon confidence that it is ready to defend against the asymmetric threat, Driessnack said.

Testing in the Pacific Ocean also gives the THAAD program the ability to link in sensor data from Aegis ships equipped with missile detection and tracking sensors that could point out targets for the THAAD interceptors, Driessnack said.

The mobility of those Aegis ships could enable them to use their sensors to play a significant role in defending against the asymmetric threat as well, according to U.S. Navy Rear Adm. Alan Hicks, program director for Aegis Ballistic Missile Defense.

Some Aegis ships are equipped with interceptors, and they could help shoot down missiles in addition to spotting and tracking them, Hicks said in a March 2 telephone interview.

However, Hicks expressed hope that ships that intended to strike the United States with missiles could be intercepted before they get close enough to U.S. shores to launch their attacks.