7. According to U.S. intelligence estimates, North Korea and Iran could develop or acquire solid-propellant ICBMs within the next 10 to 15 years (3.3). Boost-phase defenses not able to defend against solid-propellant ICBMs risk being obsolete when
deployed.
8. The time constraints imposed on any boost-phase defense system by the short du- ration of ICBM boost phases would pose significant real-time decision issues.
• In most situations, interceptors would have to be fired within a few seconds after confirmation of the launch of a large rocket to intercept it in time to defend the
xxxvi Findings United States (5.3). The decision to fire interceptors would have to be almost automatic (5.3–5.6).
• Because of the potentially similar flight profiles of ICBMs and space launchers, in many cases the defense system would have diculty distinguishing a space launch from an ICBM attack. In these cases, the defense would have to shoot at every
rocket, unless it had been identified as non-threatening before it was launched (10.4).
9. Despite the variations and uncertainties inherent in the boost-phase trajectories of ICBMs, our analysis indicates that a kill vehicle incorporating current sensor and
guidance technology could home on ICBMs in powered flight with a precision com-patible with direct hit-to-kill requirements, assuming the kill vehicle’s booster could place it on a trajectory that would take it within homing range of the ICBM. The
kill vehicle would also have to meet certain critical performance requirements. Critical kill-vehicle performance requirements include:
• Capacity to shift from guiding on the rocket’s exhaust plume to guiding on the rocket body. The Study Group believes this requirement in particular requires
more investigation (10.4).
• Ability to acquire and track the rocket body within the plume at ranges of at least 200 kilometers and with sucient precision, using sensors on board the kill vehicle
(12.3).
• Sucient kill-vehicle acceleration (7–8 g initially and 15 g in the end game), velocity for maneuvering (2 km/s for terrestrial-based and 2.5 km/s for space-based kill vehicles), and guidance system response (0.1 second or less) (12.5).
These requirements would result in kill vehicles with masses substantially greater than is generally appreciated. In our judgment, kill vehicles using technology that would
be available in the next few years would have masses on the order of 90 kilograms to 140 kilograms: 90 kilograms for the total divert velocities of 2 km/s that would be required for most ground- and air-based interceptors and roughly 140 kilograms for 2.5-
km/s divert velocities that would be appropriate for space-based interceptors and the fastest ground-based interceptors (14.4).
10. Although a successful intercept would prevent munitions from reaching their target, live nuclear, chemical, or biological munitions could fall on populated areas short of the target, in the United States or other countries. This problem of shortfall is
inherent in boost-phase missile defense.
• Warheads and submunitions are loosely coupled to the final stage of the ICBM and cannot be assumed to be destroyed by an intercept that destroys or disables the ICBM booster, as borne out by numerous destruct events during flight tests (13.1).
• After an intercept, the munitions and debris will continue on a ballistic trajectory,
albeit one that is shorter than intended by the attacker (5.8).
• The warheads or munitions and debris of an intercepted missile will not fall on the country that launched it (5.8).
• Preventing warheads or submunitions and debris of intercepted missiles from hitting the territory of U.S. friends and allies would sometimes require the defense to intercept
missiles within a time window as small as 5 to 10 seconds, greatly complicating
the already daunting intercept management problem (5.8.1).
• Given the unpredictable variations in trajectories and thrust that characterize ICBMs in powered flight, it is not clear that the intercept can be timed to occur
within the narrow window required (5.8.2). The problem of controlling shortfall could be avoided if the boost-phase defense system could destroy the missile’s warheads or submunitions during boost, rather than simply disabling the booster. This is a much more dicult task, and it has not been established
that it can be accomplished (13).
11. Airborne interceptors oer some unique advantages for boost-phase defense, but they also have significant limitations in defending against ICBMs. They could be de-
ployed more quickly than land- or sea-based interceptors in response to new threats, but several backup aircraft equipped with interceptors, as well as refueling aircraft and defensive air cover, would be required for every airborne-interceptor aircraft on
station (16.5.3).
• An interceptor of any given size has a slightly greater range if launched from a highaltitude platform, because it uses less energy to overcome gravity and aerodynamic drag as it flies out toward its target. However, the constraints on the size and weight of missiles that an aircraft can carry limit the flyout velocity of high-acceleration airborne interceptors to about 5 km/s (16.5.3).
• Because of their limited flyout velocity, airborne interceptors could engage ICBMs only in situations comparable to the situations in which a 5 km/s surface-based interceptor could engage them. Consequently, using airborne interceptors to defend the United States against long-burning liquid-propellant ICBMs would be possible only if the required intercept locations are within about 500 kilometers of the nterceptor-carrying aircraft (5.3.2, 5.5.1).
Concluding remarks
In assessing the feasibility of boost-phase missile defense using hit-to-kill interceptors or the ABL, we attempted to make optimistic assumptions to bound the performance of such
systems. In some cases we made assumptions that appear technically possible but may not be realistic on other grounds. An important example is the assumption in some of our analyses that interceptors could be fired as soon as a target track has been constructed, without allowing additional time for decision or assessment. In other cases we simply examined the performance that would be required to make the system workable, without
making any judgment about whether such components could realistically be deployed. An example of this kind is our consideration of an interceptor having a flyout velocity 40 percent
higher than an ICBM’s velocity. We emphasize that the choices made in this study were used to obtain upper bounds on performance; their use does not imply that the Study Group endorses these choices as realistic in all cases. Given the results that follow from our assumptions, we conclude that while the boost phase technologies we studied are potentially capable of defending the United States against iquid-propellant ICBMs at certain ranges of interest, at least in the absence of countermeasures, when all factors are considered none of the boost-phase defense concepts studied would be viable for the foreseeable future to defend the nation against even first-generation solid-propellant ICBMs (5, 6.11, 8.6).
FOR THE FULL REPORT GOTO
http://www.aps.org/public_affairs/p...ports/nmd03.cfmBoost Phase Defense Timeline - PROBLEMS with it.
http://www.aps.org/media/pressreleases/nmdfig2-2.pdfPotential Impact Sites
http://www.aps.org/media/pressreleases/nmdfig5-3.pdfInterceptor Basing areas:
http://www.aps.org/media/pressreleases/nmdfig5-10.pdfHypothetical Interceptor Models - LOOK AT IT
http://www.aps.org/media/pressreleases/nmdfig16-9.pdf