U.S. Conventional Prompt Global Strike Issues for 2008 and Beyond (2008) / Chapter Skim
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4 Technology Issues
4 Technology Issues
Pages 87-137
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From page 87... ...
A wide range of concepts has been proposed to meet the CPGS challenge, as illustrated in Figure 4-1. These solutions include modest modifications to existing ballistic missiles (such as the Conventional Trident Modification [CTM]
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From page 88... ...
88 FIGURE 4-1 Candidate concepts for conventional prompt global strike include ballistic missiles, boost-glide vehicles, and hypersonic cruise missiles. The range of these concepts varies from 1,000 to 3,000 nmi for forward-deployed systems to more than 10,000 nmi for land-based systems.
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From page 89... ...
. NOTE: AMaRV, advanced maneuvering reentry vehicle; E2, Enhanced Effectiveness (one of two test beds for demonstrating proof-of-principle concepts for ballistic missile delivery in CPGS and discussed in Chapter 4 in the subsection entitled "Guidance, Navigation, and Control Accuracy Issues")
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From page 90... ...
The following sections review the CPGS options and technology challenges, including the system requirements, system concepts, research and development (R&D) issues, and technology readiness time lines.
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From page 91... ...
for attack of a moving target. top is portrait size NOTE: Acronyms are defined in Appendix A
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From page 92... ...
will require compression of the time line across the entire Find, Fix, Track, Target, Engage, and Assess (F2T2EA) strike process.
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From page 93... ...
The concept of a prompt global strike capability initially evokes ideas involving strategic ballistic missiles -- either land- or sea-based -- that can deliver payloads over enemy defenses to targets 6,000 or more nautical miles away within 30 to 40 minutes of their launch. If one defines the term "global strike" to mean the ability to strike anywhere in the world without depending on basing or overflight rights, but perhaps with foresight in positioning launch platforms, one is led to look at approaches other than intercontinental ballistic delivery.
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From page 94... ...
One can see that a CPGS system operating from this area requires a range of approximately 2,500 to 3,500 nmi to reach most of the troubled regions of the area. With range requirements defined, the speed requirements for candidate concepts are shown in Figure 4-7, where the capabilities of existing conventional forces, hypersonic cruise missiles, and ballistic missiles are overlaid on lines of average Mach number (defined as the range divided by the time-to-target and stratospheric sound speed, assumed to be 968 ft/sec)
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From page 95... ...
Kennedy Space Center, Florida, and (right) Vandenberg Air Force Base, California, illustrating the need for 6,500 to 7,000 nmi to reach most parts of the world for a continental United States–based system.
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From page 96... ...
from a notional nuclear-powered guided missile submarine (SSGN) launch location in the Arabian Sea illustrating the need for a conventional prompt global strike range capability of 2,500 to 3,500 nmi when launched from an SSGN.
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From page 97... ...
-based systems, only ballistic missiles are capable of meeting a 1-hour time line. For forward-deployed systems, hypersonic cruise missiles are candidates.
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From page 98... ...
Whether or not the target lies in an area covered by a DPPDB, a principal additional challenge will often lie in intelligence efforts to find the target and verify the information indicating that a strike is warranted. In summary, the committee has evaluated technical enablers associated with finding and locating fixed, time-sensitive soft targets, as discussed in Chapter 2, and has concluded that some credible scenarios exist where a target could be found and geolocated in a time frame consistent with the CPGS mission.
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From page 99... ...
Countermeasures All approaches to targeting with CPGS will, of course, be subject to countermeasures, and some of the proposed CPGS options specifically address approaches to deal with countermeasures, such as the use of terrain to protect against attack. Continuing effort against countermeasures will be a military necessity as opponents become aware of CPGS capabilities and adopt tactics such as using terrain well, deception in locating things underground, using large underground facilities, "hiding" among civilians, jamming, decoys, and so on.
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From page 100... ...
The light-blue shaded region designated "Boost-Glide Vehicles" illustrates the range benefit of gliding reentry vehicles compared with ballistic missiles. The red data points represent subsonic cruise missiles powered by turbojet engines.
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From page 101... ...
These systems can be broadly classified as ballistic missiles, boost-glide missiles, and hypersonic cruise missiles. The committee also considered some additional ideas.
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From page 102... ...
Budget President's Budget Launch Vehicle Trident D-5 Minotaur III Minotaur III Minuteman III Two-stage Solid B-52 Class Booster Class Boostera Class Booster Rocket Booster Payload Modified Mk-4 Biconic Biconic Biconic Biconic Medium Cruise Missile Delivery (68 in.) Hypersonic Glide Hypersonic Hypersonic Re-entry Vehicle (Scram Jet with Vehicle Vehicle Glide Vehicle Glide Vehicle (96 in.)
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From page 103... ...
SOURCE: Maj. Steven Kravitsky, USAF, Headquarters, Air Force Space Command, "Prompt Global Strike Payload Development," presentation to the committee, May 11, 2007, Washington, D.C.
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From page 104... ...
missile for 2 of the 24 missile tubes on each SSBN. Each missile would nominally carry four modified Mk4 reentry vehicles. The proposed deployment on the existing SSBN fleet allows the existing infrastructure of crews and training to be used, thus minimizing the costs of deploying the system and giving high confidence in its reliability.
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From page 105... ...
Figure 4-9 The prompt global strike (PGS) baseline system is the Conventional Trident Modification (CTM)
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From page 106... ...
both kinds of weapons would be carried on the same submarine platform, and (2) prompt global strikes may often allow little time for second checks.
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From page 107... ...
A Committee-Proposed Additional CPGS Option: The CTM-2 CTM as proposed is constrained to small conventional payloads primarily for missions against fixed soft targets. Another possibility discussed by the committee is a two-stage Trident configuration (CTM-2)
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From page 108... ...
. Submarine-Launched Global Strike Missile For the longer-term CPGS role, the Navy proposes a small new, singlewarhead, two-stage missile known as the Submarine-Launched Global Strike Missile, or SLGSM.
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From page 109... ...
The system requires the development of a new missile, including new solid-propellant booster motors and scaled derivatives of existing reentry vehicles. Rocket motor technology consistent with a shorter-range submarine-launched, intermediate-range ballistic missile (SLIRBM)
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From page 110... ...
and Submarine-Launched Global Strike Missile (SLGSM) reentry bodies to the tested Enhanced Effectiveness (E2)
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From page 111... ...
38 ft (3) h 2 Stg 38" x FIGURE 4-12 Payload versus ballistic range capability for notional two- and three-stage Submarine-Launched Global Strike Missile (SLGSM)
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From page 112... ...
These concepts can be divided into conventional ballistic missiles and boost-glide missiles, which can be CONUS-based or forward-deployed. This section discusses current Service programs, alternative concepts under active study, and other possible system concepts that come immediately to mind but are not being pursued, together with the reasons why.
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From page 113... ...
The reader is also referred to Appendix G for additional details on the characteristics of the boost-glide trajectory. CONUS-Based Boost-Glide Vehicle: Conventional Strike Missile The primary concept for a CONUS-based Conventional Strike Missile is based on a modified ballistic launch vehicle together with a scaled version of the advanced maneuvering reentry vehicle (AMaRV)
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From page 114... ...
SOURCE: Maj. Steven Kravitsky, USAF, Headquarters, Air Force Space Command, "Prompt Global Strike Payload Develop color ment," presentation to the committee, May 11, 2007, Washington, D.C.
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From page 115... ...
While a ballistic reentry body typically spends less than 60 seconds in the oxidative hypersonic environment, the first version of CSM is proposed to fly in it for about 800 seconds, stressing current technology. A planned second version of CSM would increase the maximum glide range to 9,000 nmi, which would require the development of new thermal protection technology to operate for up to 3,000 seconds in the stressing hypersonic environment.
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From page 116... ...
Army officials informed the committee that technology developed in this effort would flow into the Air Force's CSM program. Hypersonic Cruise Missiles In addition to ballistic and boost-glide missiles, hypersonic cruise missiles launched from submarines, surface ships, or aircraft potentially offer capability for the CPGS mission. In concept, these systems consist of two stages: the firststage rocket-powered and the second stage powered by an air-breathing ramjet or scramjet (i.e., supersonic combustion ramjet)
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From page 117... ...
hypersonic cruise missiles. The solid curves are based on flight- or laboratorydemonstrated aerodynamic and propulsion technology.
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From page 118... ...
Thermal management issues associated with hypersonic cruise missiles are quite different from those involving ballistic or boost-glide systems. Operating at a maximum speed of Mach 6, the heat transfer to the external air vehicle is substantially lower than that of reentry vehicles, and metallic structures can be used.
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From page 119... ...
Ballistic missile reentry vehicles are typically designed with a high β so that the reentry vehicle plunges into the deep atmosphere at high speeds. This makes defense very difficult (which was an early consideration in the development of ballistic missiles)
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From page 120... ...
For CONUS-based global range systems that reenter at 7.9 km/sec, 30.7 MJ/kg of kinetic energy must be dissipated if the impact speed is limited to 1 km/sec. For high-β reentry vehicles, the slender aerodynamic shapes result in minimal heating of the atmosphere, with most of this dissipated energy entering the vehicle prior to being released as radiation cooling or ablation products.
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From page 121... ...
Obtaining this increased delivery accuracy is a key technological challenge in developing a conventional prompt global strike capability. Obtaining high delivery accuracy for a ballistic missile requires that the reentry vehicle be steerable.
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From page 122... ...
The proposed CPGS ballistic delivery systems build on these earlier results, as illustrated in Figure 4-2. As has been discussed, the simplest proposal is the CTM, which builds on the E2 results to allow fine control of targeting around the normal ballistic reentry trajectory.
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From page 123... ...
. JASON Study for STRATCOM on Prompt Global Conventional Strike," JSR-05-450, July 29, " 2005, presentation to the Defense Science Board, January 2007, Washington, D.C.
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From page 124... ...
If the dispensing occurs at hypersonic speeds, additional thermal protection will likely be required for the munition. As an alternative to a high-speed dispensing, the reentry vehicle may slow to low speeds, at which the challenges associated with dispensing munitions have largely been solved.
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From page 125... ...
Air-Breathing Propulsion Hypersonic cruise missiles require the development of air-breathing engines such as ramjets or scramjets. Ramjet engines are capable of powering the missile to speeds up to approximately Mach 4.
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From page 126... ...
As a practical matter, boost-glide missiles or hypersonic cruise missiles must be given a steady stream of reports in order to intercept the right moving target. Brought into the vicinity of the right target by the in-flight targeting updates, the boost-glide missile or hypersonic cruise missile can dispense a seeker-guided weapon (subject to the technical constraints of real systems as discussed below in the subsection "Mobile Targets")
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From page 127... ...
Fixed Soft Targets Most fixed soft targets are susceptible to attack by unitary blast-fragmentation or kinetic energy warheads. As previously noted, the initial CTM would carry up to four reentry vehicles equipped with advanced navigation, guidance, and control capabilities.
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From page 128... ...
The results indicate that in most cases, a single CTM KEP will have a high kill probability against fixed soft targets if target geolocation accuracy and guidance, navigation, and control accuracy are as predicted. Current plans call for high-speed sled tests of the KEP warhead and for continued modeling of the effectiveness of the KEP warhead against classes 12 APT Terry J
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From page 129... ...
Some of the difficult issues in addressing mobile targets are described below in the subsection "Mobile Targets." Fixed Hard Targets Hardened targets include above-ground hardened structures, shallow underground structures, and deeply buried targets. The issue of lethality against hard
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From page 130... ...
Currently, penetrating warheads are limited by structural considerations to impact speeds of approximately 3,000 ft/sec, which sets the upper limit to the capability to penetrate hardened structures. Reducing reentry vehicles speeds to this level also creates technical issues of thermal protection and guidance, navigation, and control, as discussed above.
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From page 131... ...
permit human control of the UAV, including authorizing it to attack. In this report, it is assumed that CSM-2 and the hypersonic cruise missile could deploy a 2,000 lb UAV capable of the same functions, although it would have less payload and/or range (or loiter time)
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From page 132... ...
What makes this concept potentially better than any existing capability is that the camera is very close to the scene, the photo sequence enables a direct comparison of "immediately before" with "immediately after," taking time for photo compression and communication after the strike should enable a high-quality image, and the commander has the photos quickly. Any CPGS option could, in principle, incorporate this concept, as could any weapon system capable of carrying and releasing the BDA device.
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From page 133... ...
The committee believes that there are significant technical risks in the operation of existing reentry vehicles in this new flight mode with an extended glide range and that these risks can only be mitigated through system-level demonstration testing. Very long range glide segments will require the development of new thermal protection systems.
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From page 134... ...
MK-4 RB E2 and LETB 134 CTM GN&C accuracy Sea-launched KEP effectiveness Corona/Apollo ballistic CTM-2 with missiles deployed UAV CTM-2 RV scaling MK-500 RB Lethality Assessment SLGSM Medium lift-to-drag shape Sea-launched Intermediate TPS boost-glide missile FALCON 3600 s TPS 3000 s TPS Hypersonic L/D High lift-to-drag AMaRV In-flight CSM-2 Communications CONUS-based boost-glide CSM-1 800 s TPS missile GN&C accuracy SWERVe Forward-deployed AHW boost-glide Advanced TPS GN&C accuracy missile ASALM X-51 Mach 4 Missile Mach 6 Missile HyFLY Sea- or air X-43 A/B propulsion launched hypersonic Thermal management missile GN&C accuracy 1970 1980 1990 2000 2005 2010 2015 2020 2025 Year FIGURE 4-16 Technology development time lines illustrating a legacy to all proposed conventional prompt global strike systems. The time lines for future technologies are based on an assumption that investments will continue to be made in critical research and development activities.
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From page 135... ...
Although not all recommendations in that report were implemented, the technology readiness of hypersonic cruise missiles is such that this type of capability can be deployed in about 2020. Summary The desire for conventional prompt global strike capabilities with the fewest constraints has led to proposals based on ballistic and hypersonic delivery systems.
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From page 136... ...
Recommendation 2.3. The baseline CTM system concept should include the development and use of reentry vehicles capable of vertical impact to allow the attack of targets in urban or mountainous environments.
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From page 137... ...
OSD should fund the technical evaluation of system concepts to address the attack of moving targets and incorporation of battle damage assessment, including the dispensing of unmanned aerial vehicles from ballistic missiles or boost-glide vehicles.
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