WASHINGTON — A panel assembled by the U.S. Missile Defense Agency (MDA) to investigate a Dec. 15 intercept test failure of the nation’s territorial missile shield is not expected to complete its work for several months, MDA spokesman Rick Lehner said Jan. 5.

The botched test marked the second consecutive failure for the MDA’s Ground-based Midcourse Defense (GMD) system. The MDA said in a statement that both the intermediate-range target missile and the GMD interceptor performed as intended after launch. All sensors, as well as the Sea-Based X-band radar blamed in the January 2010 test failure, also performed as planned. But the interceptor’s Exoatmospheric Kill Vehicle, after successfully deploying, missed its target.

The January 2010 failed intercept attempt marked the first time the Sea-Based X-band radar system, built by Raytheon Co. under subcontract to GMD prime contractor Boeing Co., was the primary source of tracking and targeting information, MDA said at the time. That test also was the first in which the target launched from the U.S. Army’s Reagan Test Site on the Kwajalein Atoll in the Pacific.

During the Dec. 15 test, the ballistic missile target again launched from Kwajalein, with the Sea-Based X-band radar cueing the launch of a GMD interceptor from California’s Vandenberg Air Force Base north of Los Angeles. The cause of the failure has not yet been determined, and the next flight test has not yet been scheduled, Lehner said in a Jan. 5 e-mail response to questions.

Brian Berger is editor in chief of SpaceNews.com and the SpaceNews magazine. He joined SpaceNews.com in 1998, spending his first decade with the publication covering NASA. His reporting on the 2003 Space Shuttle Columbia accident was...