Making Sense of Ballistic Missile Defense An Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives (2012) / Chapter Skim
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2 U.S. Boost-Phase Defense
2 U.S. Boost-Phase Defense
Pages 30-72
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From page 30... ...
Since the time from detection of a hostile launch until it completes boost is often as little as a minute and, even for slower burning liquid-fueled intercontinental ballistic missiles (ICBMs) is unlikely to exceed 250 sec, any boost-phase intercept -- accomplished kinetically or by directed energy -- must be launched after detection from a platform that is within the range and action time of the interceptor, essentially intercepting before "booster cut-off" of the hostile missile.
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From page 31... ...
, policy, time, and geography. Since the timelines for engagement in the boost-phase are extremely short, the on-site commander must have authorization from the National Command Authority to launch an interceptor immediately after a threat missile has been detected.
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From page 32... ...
missiles to enhance ballistic missile defense and as an alternative to the ABL program.2 The Office of the Under Secretary of Defense for Policy also found that a boost-phase intercept capability was required for affordability reasons. Furthermore, the ABM Treaty had recently been abrogated, making it possible to develop and deploy such a system.
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. Upon launch of a threat missile, overhead sensors would detect and report the launch directly to the KEI fire unit.
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SOURCE: Craig van Schilfgaarde, David Theisen, Steve Rowland, and Guy Reynard, Northrop Grumman Corporation, "An Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives: Northrop Grumman Perspective," presentation to the committee, July 13, 2010.
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From page 35... ...
Lynch, David Moncton, et al., 2004. Report of the American Physical Society Study Group on BoostPhase Intercept Systems for National Missile Defense: Scientific and Technical Issues, American Physical Society, College Park, Md., October 5.
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From page 36... ...
within the turret so that the beam may be directed by up to about 120 deg from the line of flight.6 The turret rotates so that any angle around the line of flight may be chosen. The ABL must be on station near the location from which the threat missiles would be launched.
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From page 37... ...
A country that is large enough can deliver an array of missile threats that are not vulnerable to surfacebased intercept in their boost phase. There may be political constraints on basing interceptors outside enemy territory, in neighboring countries.
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From page 38... ...
The primary difficulty with ABIs, like all other proposed kinetic boost-phase systems, is the need to be close enough (within about 50 km) to the target so that an interceptor with a given speed and a KKV of sufficient agility can reach and successfully home in on the accelerating booster before the boost phase ends.
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From page 39... ...
Even so, it is possible to guide a suitably maneuverable interceptor in order to hit a hostile thrusting booster, assuming the interceptor can get there in time. As noted in Chapter 1, the committee had access to classified information provided by the Missile Defense Agency on its programs of record; however, the committee chose to develop a set of notional threat missiles, notional interceptor designs, and notional sensors to explore the basic physical limitations of missile defense system performance, with the understanding that a public report was
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From page 40... ...
boost-phase defense systems against ballistic missile threats from Iran and North Korea. Figure 2-3 illustrates the dilemma for all boost-phase defense systems (i.e., the pressing intercept timelines for both solid and liquid threat booster rockets)
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From page 41... ...
Lynch, David Moncton, et al., 2004. Report of the American Physical Society Study Group on Boost-Phase Intercept Systems for National Missile Defense: Scientific and Technical Issues, 41 American Physical Society, College Park, Md., October 5, pp.
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From page 42... ...
, affected by the launch azimuth required to account for the initial missile velocity owing to Earth's tangential velocity at the launch point and also to lead the target, which moves during the flight time of the missile. When a missile is launched in an easterly direction, Earth's rotation increases the maximum range of the missile relative to its nonrotating Earth descriptor.
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From page 43... ...
for a representative two-stage liquid ICBM with a maximum nonrotating Earth range of 12,000 km that is launched from the safest location in North Korea. Figure 2-6 then shows similar contours for a representative solid propellant ICBM of the same maximum range with a maximum burn time of 180 sec.
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From page 44... ...
Up to this point, the analysis has shown the pressing time constraints for achieving boost-phase intercept against a notional ICBM -- solid or liquid propellant -- launched from Iran or North Korea toward the United States (including Alaska) and Canada.
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FIGURE 2-7 Thrust cutoff time contours for a notional two-stage liquid ICBM with a maximum nonrotating Earth range of 13,300 km that is launched from central Iran.
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Figure 2-10 shows an example of a coplanar, or head-on, engagement for the notional 6 km/sec interceptor against a North Korean liquid ICBM that was modeled and then used like the preceding construction example to determine the general case of engagement at any aspect angle.12 The interceptor fly-out contour times are referenced to the 11 See David K Barton, Roger Falcone, Daniel Kleppner, Frederick K
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From page 47... ...
Lynch, David Moncton, et al., 2004, Report of the American Physical Society Study Group on Boost-Phase Intercept Systems for National Missile Defense: Scientific and Technical Issues, American Physical Society, College Park, Md., October 5. 6 km/sec Two-Stage 70 sec Interceptor vs 250 sec Liquid ICBM - North Korea to Alaska 400 Interceptor Fly-out Times from Threat Launch +65 sec 190s 215s 240s 265s 165s 300 200 Threat Burnout @250 sec 5 sec Time Intervals Shown Would Impact on Eastern 100 Canada or U.S.
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From page 48... ...
to the earliest point at which a kinetic interceptor with a given fly-out velocity could engage a hostile missile. A view over the North Korean launch point in Figure 2-11 shows the azimuth and boost ground tracks to various parts of the United States (noted at the top of the figure)
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From page 49... ...
Figure 2-12 shows where these same boost-phase defense systems would need to be emplaced in order to kinetically engage liquid-propellant ICBMs aimed at America; Figure 2-13 shows this information for solid-propellant ICBMs. In both Figures 2-12 and 2-13, the launch point for the notional ICBMs launched from North Korea was chosen to make intercepts and attacks on the launch site the most difficult -- that is to say, the safest locations, as shown in FIGURE 2-12 Notional interceptor ranges to kinetically engage a liquid-propellant ICBM launched from North Korea.
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From page 50... ...
the 6 km/sec interceptor, if based on a ship, can engage the more easterly liquid ICBM trajectories, but to engage the more western trajectories headed to eastern North America it would have to be so close to the North Korean coast as to be highly vulnerable to attack. Engaging notional solid-propellant threats from North Korea is even more constrained, as shown in Figure 2-13.
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From page 51... ...
One can conclude then that, until otherwise demonstrated, no airborne or Aegis VLS-based interceptor could be used for boost-phase defense against notional ICBMs aimed at the United States, even against a country that is as small as North Korea and that is accessible by sea, unless those interceptors are based on or over neighboring territory or over the threat country itself. However, a possible application limited by the interceptor fly-out envelope and on-station endurance is the engagement of notional longer range missiles launched from North Korea against Hawaii or other Pacific Ocean targets where the boost trajectories are headed toward international waters or allied territories and where boost-phase interceptors can be stationed.
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From page 52... ...
No effective boost-phase defense of Europe or the Middle East is possible because of the shorter burn times associated with medium- and intermediate-range ballistic missiles and the fact that Iran could arrange to launch the attack from locations such that no boost-phase interceptor could be in range from outside Iranian airspace. There has been some discussion of the use of stealthy aircraft or unmanned aerial vehicles (UAVs)
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From page 53... ...
FIGURE 2-16 Notional boost-phase engagement of solid ICBMs launched from Iran.
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From page 54... ...
In reality, atmospheric effects will substantially disturb the propagation of the beam to a degree that increases rapidly with the distance traveled through the atmosphere. Much has been accomplished, however, in developing pointing and tracking capabilities and adaptive optics to maintain beam quality.
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When a laser such as the ABL (now renamed the airborne laser test bed (ALTB)
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From page 56... ...
For various reasons, one of which was the ABM Treaty, the ABL was designed for use against short-range theater missiles, not long-range missiles like ICBMs. Because the long-range missiles burn longer and burn out at higher altitudes, more of the optical path goes through less of the turbulent atmosphere.
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Clearly it would be very important to establish air supremacy over the enemy territory where the ABLs would fly. The ABLs are very high-value assets, and they would be high-priority targets for an enemy attack.
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From page 58... ...
Like all other proposed boost-phase defense systems, they must get from their orbital bases to the threat missile just as fast, with the same very short decision times, and to be close enough to do so. If the interceptors are to be constantly in a position to intercept, many platforms would be needed that must obey the laws of orbital mechanics.
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From page 59... ...
Lynch, David Moncton, et al., 2004, Report of the American Physical Society Study Group on Boost-Phase Intercept Systems for National Missile Defense: Scientific and Technical Issues, American Physical Society, College Park, Md., October 5, p.
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From page 60... ...
Consider, then, what would be required to deal with a simultaneous salvo of threat launches, a tactic that both North Korea and Iran have been practicing. Unless the constellation is populated sufficiently to handle salvos, there will be much leakage.
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From page 61... ...
Potential Scenarios for Intercepting Hostile Missiles in the Boost Phase of Flight One can envision scenarios in which intercepting hostile missiles in their boost phase of flight appears practical. Here are three such scenarios; however, it is important to note that none of the scenarios involves developing new systems such as ABL or KEI.
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From page 62... ...
Countering Ship-Based Theater Ballistic Missiles Launched with Early Deployed Submunitions Against CONUS, Deployed Forces, U.S. Allies, Partners, or Host Nations Some observers consider the possibility of attacks by short-range ballistic missiles launched from ships near U.S.
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From page 63... ...
bases on Guam or the Japanese homeland, are so close to North Korea that a ballistic missile aimed at them would have too short a burn time (and too low a burnout altitude) for a boost-phase intercept to be feasible from an Aegis inteceptor on board a ship in the Sea of Japan.
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From page 64... ...
Kinetic Energy Interceptor The KEI program was terminated after cost and schedule problems delayed flight testing of the vehicle. Both stages of the booster had been ground tested and were deemed ready for flight test, and simulations using some actual tactical warning and attack assessment (TWAA)
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From page 65... ...
There are logical applications that were identified by the Defense Science Board in an unclassified report that do not entail such short reaction times, going in harm's way, endurance on station, or atmospheric problems at low elevation angles.25 Specifically, the single existing ABL could serve as an emergency antisatellite (ASAT) device.
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From page 66... ...
Boost-phase defense of allies or deployed forces against shorter than intercontinental range attacks requires even closer stationing than for longer range threats, because shorter boost times and lower altitudes at burnout -- which are the determinants of the windows for boost-phase intercept and of the proximity requirement for both kinetic and laser intercept -- are even more demanding. Only in highly favorable geographic situations, e.g., trajectories from North Korea to Hawaii and some other Pacific Ocean targets, is it likely that boost-phase interceptor platforms could be located so as to overcome the time, distance, and altitude constraints.
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From page 67... ...
The dwell time relative to the short duration of an engagement also limits the raid handling capability of any laser ballistic missile defense system. The net effect of these time, altitude, and range constraints is that both kinetic and laser boost-phase interceptors must be ready to engage from within a few hundred kilometers of the intercept point.
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From page 68... ...
Other Issues A significant technical limitation of boost-phase intercept, in addition to those presented by the short powered flight of the target, arises from the fact that ballistic missiles are accelerating nonuniformly during powered flight, not to mention almost discontinuously at staging events. This further complicates predicting the target's future location, which for kinetic-kill intercepts increases the divert requirements for the kinetic-kill vehicle.
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From page 69... ...
Even leaving aside how such proximity would expose the interceptor platforms to attack, this range-determined constraint makes boost-phase intercept operationally infeasible, because, except in a few cases, it would not be realistic to count on a boost-phase intercept platform being close enough to effect intercept. • In particular, Iran is too large geographically (and its northern neighbors 26 Additional discussion on decoys and countermeasures is provided in the classified annex (Appendix J)
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From page 70... ...
So far, there is no sign that North Korea is working on solid-propellant rockets for longer range missiles, but it could shift toward solid propellant, possibly with assistance from Iran, with which it has significant cooperation. The question becomes, Should the United States invest in a boost-phase system with some capability against liquid-fuel North Korean ICBMs if that country might shift to solid-fuel rockets before or soon after the system becomes operational?
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From page 71... ...
Shorter range missiles with their shorter burn times and lower burnout altitudes cannot be engaged by spacebased boost-phase intercepts. • The total life-cycle cost of placing and sustaining the constellation in orbit is at least an order of magnitude greater than that of any other alternative and impractical for that reason alone.
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From page 72... ...
. The limited ranges of which a system would be capable do not allow boost-phase intercepts from outside the territory of even a small country such as North Korea.
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