5

Recommended Path Forward

ORGANIZATION

As previously noted, this chapter provides additional details on the recommended evolution for the Ground-Based Midcourse Defense (GMD) system (i.e., the recommended evolution to GMD, called GMD-E in this chapter), as called for by Major Recommendation 5 in the Summary and Chapter 4 of this report, “as a means to provide adequate coverage for defense of the U.S. homeland against likely developments in North Korea and Iran over the next decade or two at an affordable and efficient 20-yr life cycle cost, the Missile Defense Agency should implement an evolutionary approach to the GMD system as recommended in this report.”

Before introducing the details of the GMD-E, the basis for Major Recommendation 5 and the key concepts of operations (CONOPS) for providing an effective defense of the United States and Canada at lowest cost are discussed.

BASIS FOR MAJOR RECOMMENDATION 5

As part of its congressional tasking, the committee assessed the practicality of boost-phase defense in comparison to other alternatives, taking into account realistic CONOPS, force structure, effectiveness, life-cycle cost (LCC), and resilience to countermeasures, among other things. In doing so, the committee’s analysis led to the following conclusion: The 30 current ground-based interceptors (GBIs), as part of the GMD system deployed at Fort Greely, Alaska (FGA), and Vandenberg Air Force Base, California (VAFB), evolved to their current configuration through a series of decisions and constraints. They provide an early, but fragile, U.S. homeland defense capability in response primarily to a



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5 Recommended Path Forward ORGANIZATION As previously noted, this chapter provides additional details on the recom- mended evolution for the Ground-Based Midcourse Defense (GMD) system (i.e., the recommended evolution to GMD, called GMD-E in this chapter), as called for by Major Recommendation 5 in the Summary and Chapter 4 of this report, “as a means to provide adequate coverage for defense of the U.S. homeland against likely developments in North Korea and Iran over the next decade or two at an affordable and efficient 20-yr life cycle cost, the Missile Defense Agency should implement an evolutionary approach to the GMD system as recommended in this report.” Before introducing the details of the GMD-E, the basis for Major Recom- mendation 5 and the key concepts of operations (CONOPS) for providing an effective defense of the United States and Canada at lowest cost are discussed. BASIS FOR MAJOR RECOMMENDATION 5 As part of its congressional tasking, the committee assessed the practicality of boost-phase defense in comparison to other alternatives, taking into account realistic CONOPS, force structure, effectiveness, life-cycle cost (LCC), and resilience to countermeasures, among other things. In doing so, the committee’s analysis led to the following conclusion: The 30 current ground-based intercep- tors (GBIs), as part of the GMD system deployed at Fort Greely, Alaska (FGA), and Vandenberg Air Force Base, California (VAFB), evolved to their current configuration through a series of decisions and constraints. They provide an early, but fragile, U.S. homeland defense capability in response primarily to a 130

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RECOMMENDED PATH FORWARD 131 potential North Korean threat. Moreover, the current GBIs are very expensive per round when compared to missiles of similar complexity at the same point in their development and has limited ability to defend the eastern United States against threats from the Middle East. Consequently, the committee believes that a properly designed midcourse defense is the most versatile and cost-effective way to provide a resilient limited defense of the United States. Specifically, the committee finds as follows: 1. The GMD system lacks fundamental features long known to maximize the effectiveness of a midcourse hit-to-kill defense capability against even limited threats. They could, however, readily be incorporated as part of the recommended GMD-E described in this chapter. The cost-effectiveness of various alternatives shown in Chapter 4 suggests that a substantially lower overall cost could be achieved through an evolution that is detailed in this chapter. 2. Discriminating between actual warheads and lightweight countermea- sures has been a contentious issue for midcourse defense for more than 40 years (see classified Appendix J for greater detail). Based on the information presented to it by the Missile Defense Agency (MDA), the committee learned very little that would help resolve the discrimination issue in the presence of sophisticated countermeasures. In fact, the committee had to seek out people who had put together experiments like the midcourse space experiment (MSX) and High- Altitude Observatory 2 (HALO-2) and who had understood and analyzed the data gathered. Their funding was terminated several years ago, ostensibly for budget reasons, and their expertise was lost. When the committee asked MDA to provide real signature data from all flight tests, MDA did not appear to know where to find them. MDA showed the committee summaries of results without the data to support them. It appeared to the committee that MDA has given up trying and has terminated most of the optical signature analysis of flight data taken over the past 40 years. In the committee’s view, this is a serious mistake. 3. It is clear that advances in technology for both long-wave infrared sen- sors and X-band radars that can coherently integrate and do Doppler imaging are impressive and offer new opportunities. The fundamental concept for maximizing the effectiveness is presented below (see classified Appendix J for greater detail). 4. In addition to its long-term cost and performance advantages, the recom- mended GMD evolution as provided in the following sections of this chapter, if adopted, would decouple the defense of North America from decisions and issues related to the configuration of NATO missile defense, even avoiding altogether the need for PAA. In short, the recommended GMD-E involves a smaller, shorter burn intercep- tor configuration that builds on development work already done by MDA under the Kinetic Energy Intercept (KEI) program, but with a different front end. The heavier, more capable kill vehicle (KV) with a larger onboard sensor provides

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132 MAKING SENSE OF BALLISTIC MISSILE DEFENSE the capabilities absent in the current GMD system but responsive to the recom- mended CONOPS, which will be discussed. The GBIs would first be deployed at a new third site in the northeast United States along with five additional X-band radars using doubled Terminal High-Altitude Area Defense (THAAD) Army Navy/transportable radar surveillance (AN/TPY-2) capabilities integrated together at each upgraded early warning radar (UEWR) site and at Grand Forks, North Dakota. At a later time, the more capable interceptor would be retrofitted into the silos at Fort Greely, Alaska, with the existing GBIs diverted to the targets program supporting future operational flight tests. Much of the basis for the recommended GMD-E has been provided in Chapters 3 and 4. The committee believes that the recommended GMD-E offers a much more resilient although limited U.S. homeland defense against any threat at the lowest 20-yr life cycle cost, and that it can be accomplished within the same requested cumulative 5-yr total obligation authority (TOA) through FY 2016 as in the current plan. Before providing additional information on the recommended GMD-E, it is important to consider the key CONOPS for providing an effective defense of the United States and Canada. KEY CONOPS FOR EFFECTIVE DEFENSE OF THE UNITED STATES AND CANADA Defending high-value assets against attack from ballistic missiles requires minimizing the possibility of leakage through the defense for any reason while also minimizing the wasting of interceptors. The contributors to leakage and wastage are discussed in classified Appendix J. In general, these requirements demand, to the maximum extent possible, a level of robustness that can overcome or at least minimize the effects of uncertainties in threat knowledge, the failure of hardware to function as anticipated, or surprises in the adversary’s tactics or capabilities. Realistic Approach to Maximizing Midcourse Discrimination Effectiveness While good intelligence provides knowledge of the adversary’s capabilities, it is rarely perfect, and surprises are to be expected and accommodated. The com- mittee believes that the key to maximizing the ability to discriminate lethal war- heads in the presence of countermeasures is exploiting the concurrent intermittent viewing by X-band radar and interceptor optics for an extended (>100 sec) time as the interceptor closes on the target complex. Yet this has been ignored in the current GMD system architecture. The reason for this seems to be a reluctance to commit an interceptor before having high confidence about the threat complex from some source. Yet, in an attempt to avoid the midcourse discrimination issue, proponents of boost-phase (or early) intercept are willing to commit interceptors before even knowing where

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RECOMMENDED PATH FORWARD 133 the threat is going. Surely, then, we should be willing to commit interceptors after the threat has burned out and its throw weight impact point has been determined by both space-based infrared system (SBIRS) and forward radars so we know where to look for the threat and where the threat is going. An interceptor launched with only that knowledge, its own observation abil- ity, and enough maneuver ability to cover the remaining uncertainty along with a forward ground-based X-band radar (GBX) observation provides the most valu- able threat discrimination tool as the interceptor closes on the threat, hunting for the right target. Has it been wasted? Not unless the adversary expends missiles with no payloads on them. May more interceptors be required? Perhaps, depend- ing on what is observed by the first one, which serves as a scout and together with radar observations provides more data than any other source. But this requires getting time on the side of the defense. It requires maximizing and making ef- ficient use of the battle space, i.e., it calls for shoot-look-shoot (SLS). Figure 5-1 illustrates how the synergy of concurrent observations can be exploited. The high-resolution X-band radar enables Doppler imaging to measure SBIRS OPIR TWAA THREAT • TW trajectory est. ELEMENTS • Raid size 1 • Typing by location Boosters and plume signature (t) INTERCEPTOR X-BAND RADAR 2 • Load and update Threat • Cued search w/ Search Cue object state vectors Complex coherent pulse and Tasking BATTLE MGR • Fly-out toward integration. 3 assigned threat • Early acquisition • Attack assess Prelaunch and track of the • Select threat complex 6 and Update threat complex complex to 5 via Radar KILL VEHICLE IR engage and plan SENSOR/COMPUTER • Object track files intercept • Acquire and track state vectors and • Intercept complex and objects initial TOM assignments in assigned view area • Doppler imaging • Assess results • Create object files Threat of threat objects and follow-up Compare • TOM correlated Objects 4 shots 11 Radar and 9 with radar metrics • Dynamics, size, and • Override option Optical Metrics • Send IR scene (t) scattering centers • Apply optical 8 • Credibility ranking discriminants (t) 7 • Dynamics, size, and • Communicate with in-band intensity (t) interceptors • Credibility ranking • Kill assessment Communication Links via Radars Communication Links via Radars 12 • Designate target 10 FIGURE 5-1  Synergy of concurrent radar and KV optical observations. OPIR, other pro- - gram infrared; TWAA, tactical warning and attack assessment; IR, infrared. FIGURE 5-1

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134 MAKING SENSE OF BALLISTIC MISSILE DEFENSE the dynamic behavior of each object in the threat and to see unique signatures from scattering centers as the objects spin, tumble, and nutate in response to disturbances due to deployment methods. It also provides accurate metrics on the position and state vector of each object in the complex and provides all that information through the battle manager to the interceptor to correlate with its op- tical measurements. The interceptor optics also measure the time-varying thermal signature, which provides information about thermal mass, object dynamics, and the movement of objects in the threat; this information is transmitted back to the battle management command, control, and communications (BMC3) for contin- ued use. Together, these observations make countermeasures more difficult over the total viewing and engagement time. Moreover, countermeasures that may be effective against the first interceptor will in many cases have outlived their ef- fectiveness against subsequent interceptors. Exoatmospheric discrimination by definition requires identifying the threat- ening reentry vehicle (RV) from among the cluster of other nonthreatening objects that will be visible to the defense’s sensors after the end of powered flight. Initially the nonthreatening objects may be “unintentional”—for example, spent upper stages, deployment or attitude-control modules, separation debris, debris from unburned fuel, insulation, and other components from the booster. However, as threat sophistication increases, the defense is likely to have to deal with purposeful countermeasures—decoys and other penetration aids and tactics to include salvo launches and antisimulation devices—that adversaries will have deliberately designed to frustrate U.S. defenses. Evaluating discrimination effectiveness is an uncertain business. One should avoid overstating the ease with which countermeasures that are theoretically possible can actually be made to work in practice, especially against advanced discrimination techniques using multiple phenomenologies from multiple sensors and exploiting the long observation time that midcourse intercept makes possible. It is perhaps noteworthy that U.S. (and U.K.) experience with the development of high-confidence penetration aids during the Cold War was of mixed success. It would be difficult for an adversary to have confidence in countermeasures without extensive testing, which the United States might be able to observe and gather data on that would permit defeating the countermeasures. The art of midcourse discrimination, developed over many decades, does not provide perfect selection of RVs, but the committee believes that by designing a ballistic missile defense (BMD) architecture based on the capabilities described below, an adequate level of discrimination performance can be achieved in the near term, and that this approach has a reasonable chance of keeping the United States generally ahead in the contest between countermeasures and counter- countermeasures. This having been said, the reader should understand that there is no static answer to the question of whether a missile defense can work against countermeasures. It depends on the resources expended by the offense and the defense and the knowledge each has of the other’s systems.

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RECOMMENDED PATH FORWARD 135 While the current GMD may be effective against the near-term threat from North Korea, the committee disagrees with the statement in the BMDR report concluding that this capability can be maintained “for the foreseeable future.” 1 The committee understands this to mean the next decade or so. If the threat is to be countered for the foreseeable future, the United States needs to take the steps outlined below to maintain discrimination capability. The BMD system capabilities that provide reasonable discrimination pros- pects are mostly supported by the available hardware and techniques, but they have yet to be included in the existing or planned GMD architecture. The system capabilities include the following: 1. The threat complex must be observed at frequent intervals by instru- ments capable of obtaining discrimination data from the time of booster burnout until intercept occurs (see Figure 5-1). 2. Observation of the threat is possible and necessary in both microwave and optical bands, and the resulting data must be fused into a target object map (TOM) to be used by the interceptors. 3. While other observations can be useful, it is the high-resolution data from X-band radar and IR seekers such as those on the KV that contribute most of the discrimination capability. Those instruments must be located, tasked, and equipped to provide these data as soon as practical after booster burnout on- ward, with minimal distractions for housekeeping and other duties. Investment in low-­ esolution measurements should have lower priority than investments in r high-resolution measurements. 4. The ability to form and interpret TOMs over a time that is typically many hundreds of seconds for midcourse intercept increases the likelihood of successful discrimination. The TOMs must therefore be exchanged frequently with the interceptor KVs during fly-out. 5. Data from the KV’s onboard seeker can be used to improve the dis- crimination effectiveness of subsequent intercept attempts and should therefore be downlinked from the interceptor during flight. 6. To take full advantage of combined radar and KV observations, the BMD system architectures and firing doctrine should enforce and exploit the maximum battle space for SLS capabilities. More generally, the committee believes that a long-term approach to mid- course countermeasures involves the following: 1. Recognizing that discrimination is not separate from the overall BMD system architecture and that synergies should be exploited where possible, spe- cifically through layered defenses such as postboost intercept and SLS tactics. 1  Department of Defense. 2010. Ballistic Missile Defense Review Report, Washington, D.C., Febru- ary, pp. 9, 15, and 47.

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136 MAKING SENSE OF BALLISTIC MISSILE DEFENSE 2. Understanding that the countermeasure threat is not constant and that there is no permanent solution. A continuing program of test and analysis is nec- essary to maintain the technical capacity that will support an adequate level of discrimination as new countermeasures are developed and deployed. 3. Implementing a more realistic and robust program to gather data from flight tests and experiments (including on flights of U.S. missiles) from the full range of sensors and making full use of the extensive data collected from past experiments to continue developing the applied science from which robust dis- crimination techniques and algorithms can be developed. 4. Maintaining an active R&D program on discrimination techniques. Radar Discrimination Opponents of BMD systems correctly point out that the system is defective if it lacks the ability to select threatening targets among the many objects that accompany them. This ability can be enhanced by observation over the longest possible time by X-band radars. Classified Appendix J discusses issues of radar discrimination, with the conclusion that an adequate solution of the problem is possible. A generalized summary of those considerations is as follows. • Bandwidth. X-band radars are used in defense systems to perform preci- sion tracking and target classification functions. The choice of this band by both U.S. and foreign radar engineers is based partly on the broad system bandwidth inherent in X-band operation, which allows transmission of wideband waveforms that resolve and measure individual objects without interference from others in a target cluster. Wideband waveforms permit direct measurement of the radial extent of each object (called range profiling, a standard approach to radar target classification in air and missile warfare). The radial extent of objects that change their aspect angle by a significant amount over the observation time—for ex- ample, rotating objects or stable objects viewed from a position outside the plane of the trajectory—provides measurement in two dimensions. • Cross-section. For objects that are resolvable with wideband waveforms, tracking radars can collect and measure the radar cross-section (RCS) of each object within the target cluster. The absolute RCS is sensitive to details of the object’s size, shape, surface roughness, and material. • Range Doppler Imaging. Wide-bandwidth echoes from an object, col- lected over an extended train of coherent pulses, can be processed to provide a two-dimensional image of the object, as illustrated in Figure 5-2.2 Such images can be collected simultaneously on objects in a target cluster while they remain within the beamwidth of the radar. Some fraction of the objects can be expected 2  JosephM. Usoff, MIT Lincoln Laboratory. 2007. “Haystack Ultra-wideband Satellite Imaging Radar (HUSIR),” 2007 IEEE Radar Conf., Boston, Mass., April 17-20, Plenary Session, pp. 17-22, ©IEEE.

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RECOMMENDED PATH FORWARD 137 FIGURE 5-2  Example of ISAR satellite imaging from the Haystack radar complex. to rotate at rates that permit rapid classification of small or irregular nonthreaten- ing debris. Decoys too small to present a threat can also be discriminated over periods of several seconds. The coherent process used in imaging also improves the sensitivity of a radar so that objects with cross-sections smaller than required for acquisition of the track can be located and their relative positions measured. • Position measurement. With adequate signal-to-noise ratio, a monopulse tracking radar can limit measurement error to less than 1 percent of its beam- width. Over extended track periods, the relative positions can be refined by a further order of magnitude. Along with measurement of relative range to within fractions of a meter, using wideband waveforms, these position data provide a three-dimensional target object map that can be converted to the angular coordi- nates of a homing seeker, ensuring proper registration of each object in the target cluster.

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138 MAKING SENSE OF BALLISTIC MISSILE DEFENSE • Precession and nutation. The range-Doppler image of each object is sensitive to small angular motions of the object, representing precession and nutation of its axes.3 Observation of these parameters over an extended period provides additional discriminants that are not available by other means. • Object mass. Objects having insufficient mass to constitute threats can be excluded as targets for defensive action. To the extent that forward-based X-band radar siting permits viewing the threat before booster burnout, tracking of the booster through burnout and deployment of the RV can be useful in this regard. • Capabilities of other radars. It has been suggested that the Aegis AN/ SPY-1 and the upgraded UHF early warning radars can provide discrimination, or at least classification, of target objects. These radars have only limited range resolution capability, far below that of the X-band radars. The signal bandwidth of the UHF radars is limited to a few megahertz, both by equipment design and by ionospheric propagation effects. The resulting range resolution is measured in tens of meters. The beamwidths of the UHF radars are approximately 2 degrees. The lack of resolution increases the probability that two or more objects will lie in the same resolution cell, precluding accurate measure- ments of any sort on the individual objects that would be useful for discrimina- tion or classification. Widely spaced targets might permit classification, but the contribution to discrimination and target selection is negligible. In summary, it is concluded that observation over the longest possible time by X-band radars is a prerequisite for midcourse discrimination. These radars were designed to perform this function, and it is essential that they be assigned to perform tracking and discrimination functions using all their resources, leaving search and warning to the low-resolution radar systems and overhead sensors that were designed for that purpose. The failure to exploit fully the ability to extend the synergy between the two sensor classes, which permits extending the range of the X-band radar tracking and discrimination, has unnecessarily compromised the performance of the present BMD system. Finally, although much of the early work on decoy discrimination involved optical techniques, it appears that with the advent of very capable X-band ra- dars, MDA has shifted away from this approach over the past decade. While the committee largely agrees with this shift in emphasis, work on sensors and optical discrimination should be continued because optical techniques have not been exploited to their fullest as the committee recommends. Classified Ap- pendix J provides additional discussion and analysis related to classical optical discrimination. 3  V.V.Chen and H. Ling, Naval Research Laboratory. 2002. Time-Frequency Transforms for Radar Imaging and Signal Analysis, Artech House, Norwood, Mass.

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RECOMMENDED PATH FORWARD 139 Fundamental Precepts of a Cost-Effective Ballistic Missile Defense The following principles should be respected: 1. Understand the threat variables and the adversary’s objectives and de- sign to deny them; 2. Provide margin and options for unanticipated events or behavior; 3. Make time an ally not an enemy; 4. Keep it as simple as possible; 5. Delegate responsibility for real-time decisions to the proper level rather than centralize them; and 6. Make the best use of the nature of the assets available and minimize the need for new ones. The committee finds the current GMD system deficient with respect to all of these principles. Functional Delegation Table 5-1 displays the functions that must be performed in defending against a ballistic missile attack independent of where it is launched from or where it is going. It indicates what sensors are needed and what they do and do not provide in the way of information that the defense can use. In effect, the information in the table helps define the CONOPS and the architecture. The following discus- sion amplifies Table 5-1 vis-à-vis the four missile defense missions discussed throughout this report. Threat Characterization The characteristics of threats in the scenarios delineated by the congressional task are discussed generally in Chapter 1 and in detail in classified Appendix F. In addition, Chapter 2 presented the challenges of the timelines for boost-phase defense. Here, some timelines are recapped as the committee considers CONOPS for the various missions. • An intercontinental ballistic missile (ICBM) launched from central Iran to the U.S. East Coast would have a maximum range total flight time of about 40 minutes. If it were liquid propelled, the boosted portion of that flight time would last about 250 sec, and if solid propelled, it would last about 180 sec. Similar flight durations would apply to threats from North Korea. At least some if not all solid-propelled missiles and all liquid-propelled missiles would have thrust termination capability and could also use excess energy to loft or depress their trajectory at less than maximum range.

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140 MAKING SENSE OF BALLISTIC MISSILE DEFENSE TABLE 5-1  Recommended Missile Defense CONOPS and Function Delegation Phase of Command Threat Function Level Intelligence Surveillance Sensors Peacetime Surveillance Approve Monitor Broad area surveillance doctrine developments and and ROE assess capabilities, for lower order of battle, levels and intentions Heightened Alert Increase Estimate Respond to DEFCON tensions DEFCON intentions status with focus on level and tactics of adversary AOR adversary Threat TWAA Delegate Determine Determine raid size, launch and defense adversary’s throw weight, impact powered authority to remaining assets, prediction, missile typing. flight appropriate locations, and Cue defense acquisition COCOM capabilities and tracking sensors Threat Defense acquisition, Monitor Support NCA/ Maintain surveillance for midcourse tracking, and COCOM response follow-on attacks from flight engagement planning and contingency same or other sources planning Engage and plan 2nd Monitor shot Target designation Implement contingency plan Postdesignation Response assessment plan Intercept Monitor Reentry Follow-on Monitor engagements Terminal engagement within atmosphere NOTE: AOR, area of responsibility; ROE, rules of engagement; NCA, National Command Authority; COCOM, combatant commander; TWAA, tactical warning and attack assessment; DEFCON, Defense Readiness Condition.

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164 MAKING SENSE OF BALLISTIC MISSILE DEFENSE TABLE 5-3  Typical Mission Timeline Mission Timeline (sec) Mission Event Sequence 0 Threat launch 30 Initial DSP report 125 Begin track Azerbaijan XBR (R = 872 km; elev = 2.2 deg) 180 Threat booster burnout 190 First shot interceptor launched from Poland site (commit on track from Azerbaijan XBR) 260 Interceptor burnout 339 KV sensor acquires threat complex (R2Tgt = 1,994 km; T2Go = 177 sec; R2Int = 1,061 km) 349 Initial course correction divert (R2Tgt = 1,883 km; T2Go = 167 sec; R2Int = 999 km) 516 First shot intercept opportunity (Alt = 836 km; R = 1,462 km; ITOF = 326 sec; closing vel 11.3 km/sec; Xang = 36 deg) Second shot (SLS) interceptor launched from Poland site (commit on Fylingdales GBX track + TOM from previous KV sensor) Interceptor burnout KV sensor acquires threat complex (R2Tgt = 1,000 km; T2Go = 116 sec; R2Int = 692 km) Initial optional course correction divert (R2Tgt = 915 km; T2Go = 106 sec; R2Int = 636 km) Second shot intercept opportunity (Alt = 1,111 km; FO R = 302 km; ITOF = 196 sec; closing vel = 8.6 km/sec; Xang = deg) Kill (hit) assessment by Fylingdales GBX (R = 2,780 km; elev = 6.3 deg) 526 Second shot (SLS) interceptor launched from Poland site (commit on Fylingdales GBX track + TOM from previous KV sensor) 616 Interceptor burnout 626 KV sensor acquires threat complex (R2Tgt = 1,000 km; T2Go = 116 sec; R2Int = 692 km) 636 Initial optional course correction divert (R2Tgt = 915 km; T2Go = 106 sec; R2Int = 636 km) 742 Second shot intercept opportunity (Alt = 1,111 km; FO R = 302 km; ITOF = 196 sec; closing vel = 8.6 km/sec; Xang = deg) 752 Kill (hit) assessment by Fylingdales GBX (R = 2,780 km; elev = 6.3 deg) 772 Third shot (SLS) interceptor launched from Caribou (commit on Fylingdales GBX track + TOM from previous KV sensor) 842 Interceptor burnout 1,081 Threat reaches its trajectory apogee 1,201 KV sensor acquires threat complex (R2Tgt = 1,992 km; T2Go = 180 sec; R2Int = 985 km) 1,211 Initial optional course correction divert (R2Tgt = 882 km; T2Go = 170 sec; R2Int = 929 km) 1,381 Third shot intercept opportunity (Alt = 1,144 km; R = 2,770 km; ITOF = 609 sec; closing vel = 11.1 km/sec; Xang = 8.4 deg) 1,391 Kill (hit) assessment by Fylingdales (R = 2,382 km; elev = nm19/4 deg) 1,411 Fourth shot (SLS) interceptor launched from Caribou (commit on Fylingdales GBX track + TOM from previous KV sensor) 1,481 Intercept burnout

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RECOMMENDED PATH FORWARD 165 TABLE 5-3  Continued 1,515 KV sensor acquires threat complex (R2Tgt = 1,998 km; T2Go = 167 sec; R2Int = 1,031 km) 1,525 Initial optional course correct divert (R2Tgt = 1,879; T2Go = 157 sec; R2Int = 967 km) 1,682 Fourth shot intercept opportunity (Alt = 780 km; FO R = 1,174 km; ITOF = 271 sec; closing vel = 12 km/sec; Xang = 16 deg) 1,692 Kill (hit) assessment by Cape Cod GBX (R = 1,870 km; elev = 16.6 deg) Battle space remaining = 319 sec 2,021 Threat reaches minimum intercept altitude if not intercepted 2,050 Threat reaches target if not intercepted NOTE: Hypothetical Middle East to East Coast CONUS four-shot SLS scenario. R, range; FO, fly-out. This analysis represents a reasonably thorough conceptual analysis of hypo- thetical threats and is by no means optimized to achieve a good balance among the sensor and interceptor elements. Such a balance would require a much more rigorous and broader-ranging assessment of parametric technical requirements and an evaluation of system design. However, the committee believes the analysis presented below can point the way to a layered missile defense concept that will be very effective and highly responsive to the changing strategic environment and to the uncertainties surrounding who our adversary might one day be. Middle East Threat to CONUS East Coast Figures 5-16 and 5-17 show two different views (a ground track view and a three-dimensional view) of a hypothetical East Coast engagement with at least two SLS opportunities from CONUS-based interceptors, with the first engage- ment just after apogee. If the same interceptor type were also based in Poland, two additional ascent shots would be possible. Table 5-3 displays an event time- line for this case. Figure 5-16 displays the intercept event times for each shot in the four-shot SLS sequence and the apogee point looking down along the ground track of the threat trajectory. In this example the first two shots are taken from the Poland interceptor site prior to apogee. The first shot, if it misses or sees more than one credible object, can be considered as a pathfinder for the second shot in the SLS firing doctrine. Likewise, this discrimination data stream cascades downward to each succeeding shot in the SLS sequence. The continuous ground-based radar (GBR) track and hit/kill assessment data along with data from the earlier inter- ceptor sensor TOM are fused by the BMC2 and provided to each interceptor in the SLS succession until a kill is assessed as complete or until the battle space is exhausted. The last two shots, if needed, come from a CONUS East Coast interceptor site, in this example at Caribou, Maine.

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166 MAKING SENSE OF BALLISTIC MISSILE DEFENSE Figure 5-17 displays the same engagement using a three-dimensional pro- jection to give an altitude perspective along with additional data indicating the geometry between the line-of-sight (LOS) at the KV sensor acquisition of the target complex and the time to go (T2Go) to intercept of the target. The intercep- tor total time of flight (ITOF) from launch to intercept of the target is also shown. The divergent blue line is the LOS to the target, and the red line is the path of the interceptor KV to the target. The angle at which the KV trajectory (red) ap- proaches the target trajectory (yellow) gives an indication of the crossing angle between the KV and target. Crossing angles of less than 90 degrees result in head-on intercepts, and crossing angles greater than 90 degrees are referred to as tail-chase intercepts. Head-on intercepts are preferred due to their higher closing velocity, which results in much greater energy exchange between the colliding bodies and therefore a much more lethal engagement. Table 5-3 presents a more detailed timeline and provides metrics for an en- gagement such as this. It can be seen from an examination of the event timeline that a significant battle space is left after the fourth shot in the SLS engagement sequence. This provides a lot of flexibility in the timing of the actual shots and allows more time for certain functions that might be impacted by natural backgrounds and unexpected events during the course of the engagement. For example, when the first interceptor first acquires the threat complex at 339 sec and tracks long enough to determine that there is more than one credible object in the threat, this TOM information can be transmitted back to the BMC2 and an additional interceptor(s) can be launched before the first interceptor to make its intercept. This strategy is referred to as shoot-engage-shoot (SES) and can make use of the approximately 150-160 sec of battle space available before the first interceptor reaches its intercept point. Likewise, if the first interceptor should fail at any point in its flight, and this information is available to the BMC2, it can be replaced immediately by another interceptor using a strategy referred to as shoot-fail-shoot (SFS). Effect of Time Delays Between Planned SLS Engagements If the second shot is taken at its normal planned time, based on SLS, it would be launched at 546 sec and would intercept at 742 sec in the mission timeline. This assumes a 30-sec time delay for XBR tracking and kill assessment between the first intercept and launch of the second interceptor. Kill assessment is based on real-time analysis of X-band radar track and debris data to determine if a credible threat on a continuing ballistic path survived and should be engaged. It is noted that the closing velocity for the second intercept is about 8.6 km/sec and the crossing angle is about 81 degrees, with a total time of flight from launch to intercept of 196 sec at a fly-out ground range of only 302 km. Additional analysis shows the second interceptor launch could be delayed by as much as 2 min (120 sec), at 666 sec in the timeline, and still engage the target with a closing velocity of about 4.8 km/sec and a crossing angle of 127 degrees (a tail-chase geometry) at

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RECOMMENDED PATH FORWARD 167 931 sec in the mission timeline compared to the 742 sec in the normal sequence. When analysis is taken to the kinematic limit of being able to engage with the second shot, it shows the maximum additional delay between the first intercept and launch of the second interceptor is 3 min (180 sec), resulting in a second interceptor launch at 726 sec and an intercept at 1,353 sec. This results in a clos- ing velocity of only 1.7 km/sec and a crossing angle of 165 degrees (a severe tail chase) and may not have enough closing velocity to effect a lethal collision with the target. Interceptor SFS Replacement in Each Layer The timeline that results if this additional 120-sec interceptor launch delay is flowed down to each layer of the four-shot SLS sequence can be compared with the timeline of Table 5-3. Launch Intercept Closing Velocity Crossing Angle Sequence (sec) (sec) (km/sec) (deg) First shot 190 516 11.3 35.7 Second shot 666 931 4.8 127.0 Third shot 1,081 1,525 11.5 10.3 Fourth shot 1,675 1,811 12.2 34.2 Figure 5-18 displays the ground track view of the baseline engagement (same as Figure 5-16) and compares it with the case of 120-sec additional time delays between intercept and launch of each remaining interceptor in the four-shot SLS sequence. In short, if the second interceptor is launched in a normal SLS sequence and there is a failure during boost phase or even a KV sensor failure at target acquisition, at 626 sec into the mission timeline, there is still ample time to launch a replacement interceptor in an SFS mode and not eliminate the downstream op- portunities for the third and fourth shots in a continuation of the SLS sequence. In fact, were this same kind of interceptor failure to occur at each layer in the four-shot sequence there still would be enough battle space in each layer for an SFS replacement, as shown in the bottom part of Figure 5-18. Effect of Individual and Multiple Radar Outages on SLS Performance The issue of radar outage is a likely source of single-point failure in a missile defense system. However, with proper layering of critical radars, the concept is very resilient to the loss of one, two, and even three radars. Using an approach similar to that in the interceptor failure example, the result of losing one, two, or three of the four X-band radars at play in this scenario—Azerbaijan TPY-2 (XBR); Fylingdales, U.K. (GBX); Thule, Greenland (GBX); and Cape Cod, Massachusetts (GBX). The Azerbaijan TPY-2 FBX could just as well have been placed in eastern Turkey for the purposes of this analysis.

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168 MAKING SENSE OF BALLISTIC MISSILE DEFENSE BASELINE ENGAGEMENT GBX GBX TPY-2 POLAND Interceptor Site Apogee at 1st Shot (SLS) MAINE 1,081 sec Intercept Point Interceptor 2nd Shot (SLS) (at 516 sec) Site Intercept Point (at 742 sec) Total Time 3rd Shot (SLS) GBX (2,050 sec) 4th Shot (SLS) Intercept Point Intercept Point (at 1,381 sec) GBX (at 1,682 sec) ADDITIONAL 120 SECOND SLS LAUNCH DELAY 1st Shot (SLS) Intercept Point 120 sec additional time delay between (at 516 sec) intercept and launch of all following SLS shots 2nd Shot (SLS) Intercept Point (at 931 sec) 3rd Shot (SLS) 4th Shot (SLS) Intercept Point Intercept Point (at 1,525 sec) (at 1,811 sec) FIGURE 5-18  Example of Middle East to CONUS East Coast four-shot SLS engamement scenario (ground track view).

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RECOMMENDED PATH FORWARD 169 Single Radar Out • Case 1, Figure 5-19. Azerbaijan out (earliest first-shot commit): Fyling- dales GBX fills this role with the following result (can still get four shots, one from Poland and three from Maine): Launch Intercept Closing Velocity Crossing Angle Sequence Site (sec) (sec) (km/sec) (deg) First shot Poland 474 690 9.5 67.4 Second shot Poland Not enough battle space for second shot Poland site Second shot Maine 720 1,357 11.1 8.3 Third shot Maine 1,387 1,671 11.9 15.3 Fourth shot Maine 1,701 1,825 12.1 39 • Case 2, Figure 5-20 (two possibilities). Fylingdales out (first-shot kill assessment and second- and third-shot commit). —Thule GBX fills the third-shot commit role with the following result: Launch Intercept Closing Velocity Crossing Angle Sequence Site (sec) (sec) (km/sec) (deg) First shot Poland 190 690 9.5 67.4 Second shot Poland No radar for first-shot kill KA (use KV TOM and hit/miss report) Third shot Maine 1,373 1,664 11.9 14.9 Fourth shot Maine 1,694 1,821 12.1 37.5 NOTE: KA, kill assessment. FIGURE 5-19  Case 1: Azerbaijan radar out.

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170 FIGURE 5-20  Case 2: Fylingdales radar out.

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RECOMMENDED PATH FORWARD 171 —Cape Cod GBX fills the third-shot commit role with the following result: Launch Intercept Closing Velocity Crossing Angle Sequence Site (sec) (sec) (km/sec) (deg) First shot Poland 190 516 11.3 35.7 Second shot Poland No radar for first shot KA (use KV TOM and hit/miss report) Third shot Maine 1,481 1,716 12.1 18.5 Fourth shot Maine 1,746 1,849 11.7 50.3 As shown in the engagement map in Figure 5-20, with the Fylingdales radar out, the second shot comes out of the interceptor site in Maine based on track data from either Thule (launch at 1,373 sec) or from Cape Cod 108 sec later (1,481 sec). This second shot is provided the TOM and hit/miss data from the first interceptor out of Poland even though no radar KA data are available. This second shot is not a true SLS engagement, but it is given significant new data by the BMC2 from the first shot KV sensor combined with the new Thule and/or Cape Cod GBX track data and can be considered an SLS shot. The third shot, if necessary, is a true SLS engagement. Two Radars Out • Case 3, Figure 5-21. Azerbaijan and Fylingdales radars out: (1) Azer- baijan out (earliest first-shot commit) and (2) Fylingdales GBX out (first- and THULE Azerbaijan GBX (TPY-2) OUT FYL GBX OUT 1st Shot Intercept 2rd Shot (SLS) at 1,664 sec Intercept CAPE COD at 1,821 sec GBX FIGURE 5-21  Azerbaijan and Fylingdales radar out.

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172 MAKING SENSE OF BALLISTIC MISSILE DEFENSE second-shot commit, third-shot KA). Thule fills third-shot commit role with the following result: Launch Intercept Closing Velocity Crossing Angle Sequence Site (sec) (sec) (km/sec) (deg) First shot Poland No radar for interceptor commit out of Poland (satellite) Second shot Poland No radar for interceptor commit out of Poland (satellite) Third shot Maine 1,373 1,664 11.9 14.9 Fourth shot Maine 1,694 1,821 12.1 37.5 Figure 5-21 shows the system rollback to a single SLS capability when both of the forward-based radars are out (Azerbaijan and Fylingdales). In this case the first-shot commit is provided by the Thule GBX radar. Three Radars Out • Case 4. Azerbaijan, Fylingdales, and Thule radars out: (1) Azerbaijan out (earliest first-shot commit), (2) Fylingdales GBX out (first- and second-shot commit, third-shot KA, and (3) Thule out (third-shot commit). Cape Cod fills third shot commit role with the following result: Launch Intercept Closing Velocity Crossing Angle Sequence Site (sec) (sec) (km/sec) (deg) First shot Poland No radar for interceptor commit out of Poland (satellite) Second shot Poland No radar for interceptor commit out of Poland (satellite) Third shot Maine 1,481 1,716 12.1 18.5 Fourth shot Maine 1,746 1,849 11.7 50.3 If Azerbaijan, Fylingdales, and Thule are all out, then Cape Cod is left to provide the tracking data necessary for a two-shot SLS engagement very similar to the one just discussed. FINAL COMMENTS Chapter 5 is intended to recommend the path forward for the United States to develop the most effective BMD capability—particularly for homeland defense— taking into account the surrounding operational, technical, and cost issues. This will take time, money, and careful testing, but unless this is done, the system will not be able to work against any but the most primitive attacks. The recommended path forward, GMD-E, involves a smaller, shorter burn interceptor configuration building on development work already done by MDA under the KEI program but with a different front end. The heavier, more capable KV with a larger onboard sensor provides the capabilities absent in the current GMD system but responsive

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RECOMMENDED PATH FORWARD 173 to the recommended CONOPS discussed earlier. This evolved GBI would first be deployed at a new third site in the northeast United States along with five additional X-band radars using doubled THAAD AN/TPY-2 radars integrated together at each early warning system (EWS) site and at Grand Forks, North Dakota. At a later time, the more capable interceptor would be retrofitted into the silos at FGA, with the existing GBIs diverted to the targets program supporting future operational flight tests. As discussed throughout this report, missile defense is at a critical point. The title of this report, Making Sense of Ballistic Missile Defense: An Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives, underscores this critical point and the objectives put forth by both the current and previous administrations. While the current administration will need to consider the 20-yr LCCs associated with present and proposed BMD systems as discussed and assessed throughout this report, it will also need to be mindful of the funding wedge for the next 5 years. Figure 5-22 displays the MDA cummulative annual funding wedge for the FY 2012 future years defense plan (FYDP) submitted by DOD to the Congress. Here, the cumulative total obligation authority (TOA) from FY 2010 through FY 2016 is about $45 billion. It includes approximately $1.3 billion for the precision tracking and surveillance system (PTSS); $1.6 billion for BMC3; and $500 million for advanced technology. FIGURE 5-22  MDA funding wedge for FYDP submitted to Congress in FY 2011. The activities with an asterisk include funds for PAA Phases I through III.

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174 MAKING SENSE OF BALLISTIC MISSILE DEFENSE Based on Figure 5-22 and the results presented in this report, the committee concludes as follows with respect to the immediate future: 1. The current homeland defense plan, which consists of GMD augmented by early intercept capabilities from Europe, is very expensive and has limited effectiveness. 2. PTSS costs four times as much to acquire and four to five times as much over its 20-yr life cycle as the X-band radar suite recommended and it offers less value. 3. GMD-E has substantially lower LCC and provides the most effective capabilities. It can be implemented within the same TOA over the next 5 years with an initial operational capability of FY 2019 provided some low pay-off programs are terminated and others are not started. 4. GMD-E’s predicted capability for SLS over most of North America relieves the requirement, necessitated by current GMD limitations, for early in- tercepts from Europe against threats from the Middle East toward North America. This decoupling allows independent decisions for the later phase of European defense or any other new task.