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[From Aviation Week & Space Technology, Oct. 24, 1983]

U.S. STRATEGIC DEFENSE OPTIONS-STUDY URGES EXploiting of TECHNOLOGIES

(By Clarence A. Robinson, Jr.)

WASHINGTON.-The Reagan Administration's Defensive Technologies Study Team has recommended a $21.1-billion development program through Fiscal 1989 to exploit emerging technologies, including an orbital array of large, new directed-energy weapons and surveillance spacecraft. The plan is aimed at providing an effective ballistic missile defense for the U.S. and its allies against Soviet nuclear weapons attacks.

While the team's report outlined a long-term technology validation approach for ballistic missile defense, it also recommended that "certain intermediate technologies can and should be demonstrated as part of the evolutionary research and development program."

The scope of the recommended ballistic missile defense program is on the same scale as the U.S. Apollo program that resulted in six lunar landings. An immediate infusion of approximately $1.4 billion in the current fiscal year is part of the team's recommendation, with about half of that amount for directed-energy weapons development and half for surveillance, acquisition and tracking technology.

The Defensive Technologies Study Team, headed by James C. Fletcher, former administrator of the National Aeronautics and Space Administration (AW&ST July 18, p. 19), concluded that a decision to proceed with the program will require development of a Saturn 5-class booster capability (about 280,000 lb. orbital payload), and the report is expected to be a factor in President Reagan's upcoming decision on development of a space station.

"A decision to proceed with ballistic missile technology development implies a decision to proceed with heavy-lift space booster development," the Fletcher study said. "We believe a space-based system may also require a continuous manned space presence. Over 100 complex and expensive satellites with missions of highest national importance can be envisioned . . Both cost and effectiveness may justify manned systems . . . Development of a repair and refurbishment system may be the key to operational and economic viability of space-based ballistic missile defense.' The study team's report said it takes “an optimistic view of newly emerging technologies and with this viewpoint concluded that a robust, multitiered ballistic missile defense system can eventually be made to work."

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The report added that the ultimate utility, effectiveness, cost, complexity and degree of technical risk in this system will depend not only on the technology, but it also will depend on reponses by the Soviet Union to the U.S. initiative, or to arms control limitations. The new technologies that make ballistic missile defense attractive, according to the Fletcher report, are:

Directed-energy weapons-Nuclear pumped X-ray laser, neutral particle beam, visible and infrared high-energy lasers.

Precision sensors-Two-dimensional optics for search and tracking, laser imaging radar, and millimeter wave radar imaging and tracking.

Electronics systems—A billion operations a second processor for optical sensors, microminiaturized electronics, and their combination with precision sensors make small hit-to-kill guided interceptors possible.

Hypervelocity gun-Based on electromagnetic railgun technology.

The study team was chartered to delve into technology that could provide a ballistic missile defense for the nation in 15-20 years, a task assigned under National Security Studies Directive 6-83. The group called on the aid of hundreds of representatives of industry and academia from June through Oct. 1. It also based its technology findings on reviews of previous strategic studies as it sought to identify all credible approaches.

"We urge that a vigorous research and development program, broadly based but highly goal-oriented, be pursued," the report said. This program would permit informed decisions on whether to initiate, in the early 1990's an engineering validation phase leading to a deployed defensive capability after the year 2000.

"The potential exists for earlier, phased deployment against constrained [those that do not employ advanced countermeasures] threats. A detailed policy study addressing the merits of such deployment should be carried out," the report added. The most capable ballistic missile defense systems have multiple layers. Of those layers, boost-phase intercept has the greatest leverage but also is the most difficult, the report said.

In assessing the technology becoming available for ballistic missile defense, the Fletcher study team considered a system effective enough to support a strategic ini

tiative of forcing the U.S. and the Soviet Union to begin to rely on defense, not offense, as a basis for national strategic policy.

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Chief among near-term ballistic missile defense advanced technologies for terminal and midcourse phases of a layered defensive system are kinetic energy kill weapons. One of the more mature is a hypersonic interceptor, a 5,000-7,000-kg. (11,000-15,400-lb.) launch weight weapon armed with a pellet area warhead, depicted in an artist's concept. The weapon is maneuvered by rocket propulsion and terminally guided to the target. It travels at 5-6 km./sec. (3.1-3.7 mi./sec.) and has a 200-km. (124-mi.) terminal intercept range, and a 15-50-km. (9.3-31-mi.) altitude capability. Note the laser fuse and short wavelength infrared seeker.

A more specific study mission of stopping 99.9% of the attacking ballistic missile force was considered, as were unrestrained countermeasures by the USSR as a response. Prior Defense Dept. studies have shown that the level of hardness that could be achieved by the Soviet Union with ballistic missile boosters is approximately 20 kilojoules/cm.2. Present booster hardness levels are 0.4 to 2 kilojoules/cm.2.

While it is not technically credible to provide a ballistic missile defense that is 99.9% leak proof, the report said, ballistic missile defense does not have to be perfect to be worth its cost. "Rather, defense can meet the President's objectives by providing an incentive for the Soviet Union to reduce reliance on ballistic missiles and agree to arms control limitations on their numbers and capabilities."

Recent advances in technology justify another evaluation of ballistic missiles defense as a major change in strategy, according to the team's study report. "In the 1960s, there were no credible concepts for boost-phase intercept. Today, there are multiple approaches based on directed-energy concepts and kinetic energy kill mechanisms," the report said.

In the past, midcourse intercepts were hampered by lack of credible decoy discrimination, the cost per intercept and undesirable collateral nuclear weapons effects from interceptor warheads.

Inexpensive interceptors

Multispectral sensing for discrimination, launch-to-destruction tracking in midcourse, and small hit-to-kill vehicles promise inexpensive interceptors capable of overcoming midcourse limitations.

Technology available today provides the potential to discriminate between penetration aids and decoys at high altitudes. Improved interceptor technology can be coupled for boost-phase and midcourse intercepts to disrupt pattern attacks.

Robust terminal defense seems attainable, the report said, adding that computer hardware and software and signal processing capable of supporting a multilayered defense is believed to permit realization of the complex command and control systems required.

"The Soviets are believed to have a capability to widely deploy a ballistic missile defense system in a relatively short time," the report explained. “With appropriate modifications, such deployment could provide the basis for a major capability for direct ascent antisatellite operations. The Soviet Union can be expected to boost single-launch payloads of 150,000-250,000 kg. (330,693-551,155 lb.) by the end of the decade. One strategy might be to include in those launches a directed-energy weapon prototype demonstration of their technical prowess, as part of an arms control negotiating posture, or simply as a consequence of their emphasis on early operational experience and evolutionary development."

Viable option

To make a multitiered ballistic missile defense system for the U.S. a viable option, the report said that the space transportation system must be expanded to provide the capability to launch about 100 tons to medium orbits tens of times a year.

Space logistical support will require heavy-lift launch vehicles for large U.S. systems, resupply and servicing of space assets, a source of materials for shielding, and orbital transfer vehicles.

The plan mapped out by the Fletcher panel concentrates on critical technologies that "are the long poles in the tent. These include boost-phase intercept of ballistic missiles, especially those hardened against laser radiation, post-boost intercept, and handling of large threat clouds, including reentry vehicles, decoys and other material, during midcourse and high reentry altitudes.'

Other technological requirements include survivability of space-based assets for defense when threatened with nuclear weapons, or counterparts to U.S. directedenergy weapons. Inexpensive interceptors for nonnuclear midcourse and early reentry kills are necessary, along with tools for developing battle management soft

ware.

The technology limited plan proposed by the team would concentrate between now and 1986 on establishing technology needed to scale selected beam generators to the performance levels required for ballistic missile defense. This schedule will require a significant and immediate acceleration of the current neutral particle beam, excimer, free electron and nuclear-pumped X-ray laser while continuing the current infrared chemical laser program.

The plan also includes:

Expanding optical beam director programs to insure that technical feasibility and scalability of beam control system, optics, phased arrays and optical structures are demonstrated. Near-term emphasis is on resolving issues that are generic to all laser concepts as well as demonstrating technical feasibility.

Exploitation of acquisition, tracking, imaging and designation for surveillance, discrimination and midcourse interceptor technology. Existing programs would be expanded to include hybrid ground/space laser and particle-beam concepts. A separate program would be initiated to develop advanced tracking and pointing technology for the Lawrence Livermore Laboratory Excalibur bomb-pumped X-ray laser to provide feasibility and scaling demonstrations.

Increasing funding support to pursue promising innovative concepts to the point where their relevance and performance can credibly be estimated and decisions can be made to establish separate programs or integrate the technology into the mainstream concept development efforts. This would call upon a broad sector of university, industrial and laboratory communities to avoid overlooking the most useful approach.

The program schedule recommended by the Fletcher group brings all candidate concepts to at least the level of feasibility demonstrations in 1986-1987. At this point, the feasibility outcomes are combined with the assessment of achievable target hardening to select the most promising concepts for scaling demonstrations.

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Three priority areas

The study team's report establishes three technology development areas by priority. The highest of these priorities includes lethality.

"An assessment of the vulnerability of responsively hardened targets to lasers, particle-beam and X-ray weapons is the single most important issue in determining whether there is a feasible concept for development and ultimate deployment. We must postulate that the threat will be hardened to the maximum practical extent."

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Porcupine satellite defense system proposed by the Defensive Technologies Study Team depicted in drawing above is a self-contained, 20,000-kg. (44,100-lb.) system armed with 50 kill vehicles. The kill vehicle is a 150-kg. (330-lb.) mass vehicle to deliver 6 km./sec. (3.7 mi./sec.) velocity with a 5-kg. (11-lb.) terminal stage. Note the laser radar sensor and the passive surveillance system. The team's report said that conventional technology as well as directed-energy weapons are required for defense of space platforms with firing rates of 0.1-1/sec., and from 50-500 engagements per platform.

The technology in the first priority is that with elements that have broad application, high leverage on research and development costs, and are vital to defining early program scope and direciton. These are:

Nuclear-driven X-ray lasers.

Large, deployable space optics.

Acquisition, pointing and tracking.

Atmospheric compensation for ground-based short wavelength lasers.

The second priority in technology development proposed by the study team includes major elements that are more specific to a limited aspect of directed-energy weapons that are necessary for fundamental feasibility. There are:

Neutral particle-beam weapons technology.

Excimer and free electron lasers.

Chemical infrared laser technology.

New and innovative concepts.

This second priority category is concerned with demonstrating the feasibility of generating the required high-brightness beams with appropriate efficiencies to insure the optional approaches are well characterized. It also includes nucleardriven particle and microwave beam technology. The third technological priority proposed by the report includes major efforts involving integration of technology building blocks and investigation of scaling. These are:

Space demonstration to acquisition, pointing and tracking.
Cylindrical 2-megawatt chemical infrared laser.

Neutral particle-beam accelerator at 100 MeV.
Single-pulse megajoule excimer laser.

Free electron and excimer laser at 1 megawatt.

New nuclear weapon/beam concepts.

Nuclear reactor power systems and power conditioning technology.

The technologies proposed for development by the report are predicated on providing the capability to defend the U.S. effectively against a near simultaneous launch of 1,000 ballistic missiles by the USSR, armed with 10,000 reentry vehicles each carrying a nuclear weapon.

The nuclear-pumped X-ray laser is a high-interest technology as a potential capability for handling a massive salvo launch threat. It also is of interest to determine against U.S. defensive systems.

A major goal, according to the study report, is early resolution of technical feasibility issues in defining laser physics and verifying performance scaling in a series of underground tests. Critical X-ray laser device issues include demonstration of high efficiency and low beam divergence.

"Decisions on the value of this concept are based on demonstration of energy scaling, the fabrication of laser rod bundles, and pointing of multiple rods at multiple targets with accuracy consistent with beam-divergence," the report said.

New technologies and concepts emerging from the defensive technologies study include:

Surveillance, acquisition and tracking-A 60-GHz. geostationary imaging radar, laser imaging radar, long-wavelength infrared passive search system and airborne optical system.

Kinetic interceptors-Exoatmospheric nonnuclear kill, high endoatmospheric nonnuclear kill and hypervelocity guns.

Space asset survivability.

The airborne optical system is considered one of the highest priorities, especially for application on both theater and intercontinental ballistic missile defense. The long-endurance aerial platform carrying acquisition, discrimination, tracking and fire control equipment would cover a defense radius of 750 km. (466 mi.). It would carry aloft long wavelength infrared sensors and laser ranging equipment to provide detection at a range of 1,600 km. (994 mi.). As an important adjunct to a midcourse or terminal layer of the defense, the airborne system would observe interaction with the atmosphere for discrimination.

Field of view

The 60-GHz. geostationary imaging radar would operate in space at a 40,000-km. (24,840-mi.) altitude. The number of elements in the radar would be 2.3 x 107, and the antenna diameter would be 115 meters. The field of view would be 6 deg. x 12 deg., with a target area coverage of 4,000 × 8,000 km. (2,484 × 4,968 mi.).

Another surveillance technology included in the study is the midcourse surveillance discrimination and tracking system, a multisensor platform operating at a

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