Amy Butler Washington

After two years on the ground for technical problems, an upgraded version of the system designed to protect the U.S. from ballistic missile attack is finally flying again. But the U.S. Missile Defense Agency (MDA) has significant challenges not only to employing the modernized Ground-based Midcourse Defense (GMD) system but also incrementally improving other systems that protect areas abroad.

The Boeing-led GMD missile shield executed a long-awaited flight test of the Ground-Based Interceptor (GBI), carrying an upgraded version of its hit-to-kill mechanism, after repeated slips. The Raytheon Exoatmospheric Kill Vehicle (EKV) Capability Enhancement 2 (CE 2) failed to intercept its first ballistic missile target during a December 2010 test, and since then engineers have been working to isolate and fix a high-frequency vibration issue that affected the upgraded EKV's guidance system.

The GBI launched Jan. 26 at 2 p.m. local time from Vandenberg AFB, Calif. and did not have a target to intercept. The objective was to fly the system and its kill vehicle through “stressing” conditions to collect data.

The MDA did not definitively say what went wrong with the guidance system during the December 2010 failure, but spokesman Rick Lehner said the problem “did not show itself during extensive pre-test ground testing and [occurred] only in a space environment.” Boeing spokesman Scott Day says that “therein lies the demand and the challenge: developing a ground-test capability that could recreate a problem, which had only been observed in space, allowing us to understand the phenomenon and develop solutions.”

Boeing actually had to build a ground-based system that could recreate the high-frequency vibration conditions “mimicking the stresses of space flight and EKV maneuvers outside the Earth's atmosphere and gravitational pull” (AW&ST Dec. 3, 2012, p. 28).

Greg Hyslop, vice president for Boeing's GMD program, calls the failure “one of the toughest challenges facing the aerospace industry,” underscoring the complexity of the problem, especially given Boeing's challenges with lithium-ion batteries grounding its new 787 commercial airliner fleet (see page 20).

Early results of last month's flight test appear promising. Lehner says experts will pore through troves of telemetry data to assess the exact performance of the interceptor. “Data collected during the test will anchor digital and hardware-in-the-loop models for the EKV,” he says.