– The U.S. Missile Defense Agency (MDA) has revised flight testing plans for its national missile defense shield in 2008 due to difficulty with a sensor on the kill vehicle for the system’s interceptor.

The sensor in question feeds data to officials on the ground about the performance of the kill vehicle during testing, and would not have interfered with the Ground Based Midcourse Defense System’s (GMD) ability to intercept a missile in an operational scenario, according to Scott Fancher, vice president and general manager of Boeing Missile Defense Systems in Arlington, Va.


The issues with the kill vehicle were uncovered during recent testing prior to installation of
the interceptor in a silo at Vandenberg Air Force Base in California.
The installation was part of preparations
for an intercept test in July, Fancher said during a May 29 interview. The subsequent investigation found that program officials needed to address the problem on all
the kill vehicles used in testing, Fancher


MDA officials opted to reschedule the flight test for November or December while the fixes are made to avoid any possibility of losing
data about the health and status of the kill vehicle during the demonstration. Such a loss of data
would have made the test less productive, Fancher said.


Instead of conducting the intercept test in July, program officials instead will launch a target missile from Kodiak, Alaska, and run the first demonstration involving all of the primary ground-based sensors around the world that are used to track incoming missiles during flight, Fancher said.


Those sensors are the Aegis Long Range Surveillance and Track system, Sea Based X-band Radar, Upgraded Early Warning Radar, and AN/TPY2. Previous tests
generally have been limited to using just two of those sensors, Fancher said. The sensor test, which
previously was scheduled for late 2008, will involve feeding the data into the GMD fire control system
and conducting a computer-simulated intercept, he said.

MDA and Boeing
previously had anticipated conducting two flight intercept tests in 2008, with the second occurring late in the year. Moving the intercept test planned for July into November or December will bump the planned second test into early 2009, Fancher said.


However, the revised schedule will allow program officials to incorporate lessons learned from the sensor demonstration into the intercept test in December, which would not have been possible had the intercept test taken place in July, Fancher said.


The upcoming test in December
also will be the first time that MDA incorporates countermeasures into a test that involves the operational configuration of the GMD kill vehicle, according to Air Force Lt. Gen. Henry “Trey” Obering, MDA director. The absence of countermeasures from previous tests has been a sticking point
with missile defense critics in Congress.
Critics of the U.S. missile defense program insist that
are needed to provide
realistic tests of the capabilities of the interceptor.


Obering, who said in a May 30 interview that he generally is pleased with the progress that the GMD program has made in recent years, said that all intercept tests that follow the late 2008 demonstration likely will include countermeasures as well.


Obering noted that the agency
previously has conducted intercept tests with a prototype version of the GMD kill vehicle that included countermeasures. MDA’s efforts in this area also include its Critical Measurements and Countermeasures program, which has used missile defense sensors to monitor launches of target missiles equipped with complex sets of countermeasures and test the use of discrimination algorithms, he said.