monly referred to as the interceptor “dead zone”) around the interceptor launch location shown as the notch around the origin (see Figure J-1 in Appendix J of the classified annex). The maximum interceptor time of flight and burnout velocity establish the outer boundary. The size of the powered-flight exclusion zone is established by the GBI burnout velocity and total burn time of the booster including any coast periods between stages and EKV separation from the final stage plus the minimum time it takes to orient the EKV and engage the target. A minimum EKV operation time results in a second powered-flight exclusion boundary. The outer boundary is driven primarily by EKV coolant supply and the useful life of the thermal batteries used to power the guidance and control systems on the EKV. However, in a tactical engagement situation, many other factors may come into play that reduce the outer boundary of the kinematic envelope. Examples include interceptor launch delays caused by weapons release authorization; availability of data on launch quality from the forward sensor; communication link limits of the IFICS data terminals (IDTs) in providing IFTUs and TOM handovers to the EKV for acquisition and target discrimination; sun, moon, and Earth limb viewing avoidance during EKV target acquisition and homing; and maximum divert capability of the EKV to take out initial interceptor targeting errors. The lower boundary is at an altitude to ensure that the EKV is above the sensible Earth atmosphere for reliable LWIR sensor performance.

The implications of these limiting boundary conditions are that a powered-flight exclusion zone eats up the battle space around the threat midcourse trajectory. Significantly shorter burn boosters and shorter launch decision delays would improve engagement performance. Long-time-of-flight complications can be removed by having multiple widely dispersed interceptor sites to reduce the need for extremely long-range, long-time-of-flight interceptor trajectories, which permits an SLS firing doctrine as opposed to a wasteful salvo firing doctrine, as discussed in classified Appendix J. It also permits more data collection on decision time and target for more accurate and reliable intercepts.7 While it is kinematically possible to defend the eastern part of CONUS against threat ICBMs from the Middle East using GBI sites at FGA and VAFB, an additional GBI site located in northeastern CONUS would be much more effective and reliable and would allow considerably more battle space and firing doctrine options. The current GMD system architecture must be and can be fixed, as discussed in Chapter 5.


7In the 2011 Defense Science Board Task Force Report on Science and Technology Issues of Early Intercept Ballistic Missile Defense Feasibility, it was noted, among other things, that “If, as an alternative to simply firing salvos of defense missile at each incoming missile, time is available to fire one missile, observe what happens from that engagement, and then fire the remaining missile(s) only if the assessment is made that the first shot was not successful, then the potential exists to save significant defense resources.” 2011 Defense Science Board. Defense Science Board Task Force Report on Science and Technology Issues of Early Intercept Ballistic Missile Defense Feasibility. Office of Under Secretary of Defense for Acquisition, Technology, and Logistics, Washington, D.C., September.

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