Defense News
WASHINGTON — Should North Korea fire a long-range ballistic missile in anger, America’s only line of defense is an integrated system of interceptors and sensors known as the Ground-based Midcourse Defense system (GMD). The program currently provides a thin layer of defense against small-scale attacks of relatively unsophisticated missiles. This level of protection, however, will be strained unless the United States takes steps to improve the system’s reliability, capacity, and capability.
This need applies particularly to the Ground-based Interceptor (GBI) itself. Perhaps the most recognizable component of U.S. homeland missile defense, a GBI includes the booster rocket that propels it into space and an Exoatmospheric Kill Vehicle (EKV) that hunts down and collides with an incoming warhead. Some 37 GBIs are currently deployed in Alaska and California, and that number will rise to 44 by the end of 2017.
The Missile Defense Agency (MDA) has recently laid out a plan to address some GBI issues, but that roadmap in some ways falls short relative to emerging threats.
Reliability
Current GBI reliability leaves much to be desired — the unfortunate result of inconsistent funding, uneven prioritization, and rapid deployment. In less than two years between the 2002 withdrawal from the ABM Treaty and the 2004 declaration of initial defensive operations, prototypes based on 1990s-era technology were converted into operationally fielded interceptors. A global network of sensors for supporting long-range intercept was also stitched together in short order.
It was a remarkable achievement, but the effort to simultaneously complete development and field a complex weapon system has produced what could be described as an advanced prototype that did not continue to receive adequate modernization.
Since initial deployment 13 years ago, GMD has matured considerably, particularly with the integration of sensors. Improvements to the GBI itself, however, have been comparatively incremental and somewhat ad-hoc, focusing largely on addressing reliability problems uncovered during flight testing.
To be sure, GBIs have a lackluster intercept test record — just over half have been successful — but the majority of failures have been due to non-systemic test anomalies that do not challenge the feasibility of long-range missile defense.
An incremental approach to evolution has also resulted in a mixed GBI fleet, with three different kill vehicle configurations and two different boosters. Some improved kill vehicles have been deployed, but funding has never permitted a fleet-wide upgrade.
Lower reliability directly affects how many interceptors would need to be fired at a single incoming missile to ensure a kill, also known as “shot doctrine.” The higher the shot doctrine, the fewer the threats that can be engaged.
The basic problems with GBI reliability are not in dispute. The question now is what to do about them.
MDA is developing the Redesigned Kill Vehicle (RKV). The RKV does not add many new capabilities to the current EKV, but does take a fresh approach to production by applying lessons learned both from the 1990s-era EKV and the Aegis Standard Missile (SM). RKV will have a simplified design, fewer failure points, and be more easily manufactured at lower cost. The seeker for the RKV and other improved communications abilities will be derived from the SM-3 IIA, which had its first intercept in February 2017.
Recent plans have assumed initial deployments of RKV around 2020. This timetable is in danger of slipping to the right, but it remains imperative that MDA, industry, and Congress keep it on track…
