Fielding a Theater Ballistic-Missile Defense

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Ironically, what the world did not see during the spectacular in­tercepts of Iraqi Scud missiles by U.S. Army Patriot missiles during Operation Desert Storm has had an even bigger impact on the future of ballistic-missile defense. Aegis ships—the cruiser Mobile Bay (CG-53) and others—tracked Scuds from hundreds of miles away with the precision required to support missile intercepts. But none of those ships was equipped with a missile capable of intercept­ing the high-flying ballistic threat.

As a result, the U.S. Navy con­vened an antiair warfare working group to study the possibilities of modifying existing at-sea combat systems for theater ballistic-missile defense (TBMD). At the same time, several Department of De­fense study groups, including the Defense Science Board, met to dis­cuss the future capability of the nation in general to counter ballis­tic missiles. Each study reached the same conclusion: our existing Aegis ships, with vertical launch­ing systems, SPY-1 radar, and the SM-2 Block IV variant of the Standard Missile, provided excel­lent integrated combat systems that—with some modifications— could provide a significant counter against the ballistic missile threat in a relatively short time.

Such a Navy effort is now un­derway. It includes nearly 50 cruisers and destroyers and takes advantage of ships already equipped with SPY radar, vertical launch system, and the command, control, and communication system necessary for TBMD. Repair parts, technical agencies, formal class­room training, and Navy personnel themselves are already in place and operating. The plan relies on an existing investment of more than $40 billion and accelerates development efforts to achieve real combat capability in just a few years.

Aegis/SM-2 Block IV A

Initial efforts focus on modify­ing the Aegis SPY radar and weapon-control system software to enhance tactical ballistic-missile detection, provide continuous tracking, and calculate engage­ments. Without changes to the transmitter or other hardware, SPY radar software changes can sched­ule the correct wave forms at higher altitudes in order to en­hance detection opportunities and track ballistic threats. Weapon- control software modifications will calculate the fire-control solution, predict intercept points, appoint target priorities, launch missiles, and coordinate missile uplink commands with the SPY radar.

The Aegis display and command- and-decision systems will be mod­ified to display these target tracks together with the engagement en­velopes calculated in the weapon- control system.

After extensive land-based test­ing, the new software will be ready for the final phase of com­puter program development—at- sea testing, which includes missile firings. This process will ensure that the tactical programs are de­bugged and mature upon delivery to the fleet. A planned user opera­tional evaluation system in 1997 will enhance the capability to re­spond to a crisis situation. Full initial operating capability is planned for a few years later. All 22 vertical-launch-equipped Aegis cruisers and all Arleigh Burke (DDG-51)-class Aegis destroyers (26 authorized through fiscal year 1993) could receive the Aegis/SPY radar modifications.

In order to provide an intercep­tor capable of killing ballistic mis­siles, the Standard Missile Block IV is slated to undergo modifica­tion. Currently in full-scale devel­opment, the SM-2 Block IV pro­vides a missile with the range and kinematic performance required fo^f the TBMD mission. Warhead, seeker, and fuse changes will be required. Warhead changes will capitalize on the ongoing Patriot missile design efforts intended to improve upon its Desert Storm performance. An adjunct infrared seeker is planned for the Standard to minimize miss distance during the terminal phase of the engage-

bility, and the approval of necessary requirements docu­mentation to formalize the acquisition process.

During May 1992, the House Armed Services Com­mittee was the first of the four key defense committees to endorse spending “not less than $90 million for explo­ration of promising concepts for naval TMD, including modification to the Aegis weapon system and enhance­ments to the Standard Missile interceptor.” The commit­tee also directed the organization to assess the near-term contribution and cost effectiveness of exoatmospheric ca­pabilities, including Standard missiles with kick-stag^e rocket motors and a light exoatmospheric projectiR (LEAP) hit-to-kill vehicle.

The House Appropriations Committee agreed, and stated in its report that “Navy TMD programs should be accel­erated and provided with increased budget support within SDI.” It also noted that it “strongly supports an increased role for the Navy in providing TMD. . and recognizes sea-based “advantages in mobility, flexibility, sustain­ability, and coverage.” The appropriations committee re-

^ment. Fuse improvements will ac­count for faster closing velocities between the ballistic target and the interceptor. Navy officials antici­pate that the SM-2 Block IV Stan­dard, modified as a TBMD inter­^Ceptor (now designated SM-2

Slock IV A) will retain its full ca­pability against aircraft and cruise missiles in order to provide the fleet with a multimission missile. The Aegis weapon-control system "'ill select the modes of missile op- ^emtion appropriate for the specified larget and transmit a command to launch system.

The SM-2 Block IV A and the Aegis system software modifica­tions will provide an antiballistic- missile capability similar to that provided by the most advanced up­grades planned for the Patriot sys­tem. Like Patriot, SM-2 Block IV A and Aegis will provide the lower tier of a two tiered sea-based defensive system capable of defend­ing debarkation ports, airfields, and troops ashore.

To provide a higher-altitude, longer-range inter­ceptor, the Navy plans to build upon the ongoing Strategic Defense Initiative Organi­zation (SDIO) technology effort to develop a light­weight exoatmos­pheric projectile (LEAP). Like other ongoing in­terceptor efforts, this projectile emphasizes a kinetic kill vehicle. As ballistic missiles fired from longer ranges reenter the atmosphere, their increased speed makes existing fragmentation war­head technology less effective. The hit-to-kill concept strives to smash the mass of the kinetic kill vehicle into the target at high speed, while the inbound ballistic missile is still in the upper atmosphere. Homing accuracy comes from an infrared seeker and miniaturized rocket mo­tors to divert or adjust the position of the kill vehicle before intercept. The SDIO technology effort has fo­cused on reducing the size and weight of these vehicles and im­proving their performance to make them suitable for use on board Standard Missile-sized launch vehi­cles. Some of the nation's key de­fense contractors are involved with the LEAP work, including three of the biggest aerospace defense firms: Rockwell International, Hughes, and Boeing. All three con­tractors have built and tested LEAP vehicles. Upper atmosphere flight tests are ongoing.

The Navy Standard missile is an attractive LEAP launch vehicle.

The SDIO has started a Navy LEAP flight-test program in order to gain a better understanding of it. The Phase I flight test program will use SM-2 Block II (Terrier) launch vehicles to propel the LEAP and a “kick stage” rocket motor into the exoatmosphere. In September 1992, the USS Richmond K. Turner (CG-20) validated the concept of the Standard Missile launch vehicle by sending up a Terrier round with a payload built to the dimensions and weight of a real LEAP.

Phase II of the Navy LEAP flight-test program, currently sched­uled to begin in 1995, will use the SM-2 Block IV Standard as the launch vehicle.

While LEAP is a potential upper-tier sea-based interceptor with great promise, the SDIO is working with the Army and Navy

Port “strongly supports aggressive exploration of promis­ing concepts for Naval TMD” because of relative cost ^effectiveness of naval systems and upgrades that can be fielded more quickly.”                               _

Subsequently, all four congressional defense commit­tees formally approved initiation of Navy TMD at not less than $90 million in fiscal year 1993. The appropriations hill provided full funding.

Support for Navy TBMD has been embraced quickly by industry teams, who see this new initiative as capital­izing on existing production-line investments by modify­ing existing weapon systems and missiles. It keeps engi­neering teams together and goes a long way toward pre­serving defense-related jobs. Navy TBMD enjoys strong, wide-based support throughout the Department of Defense, Congress, and within the defense community at large. Al­lied navies in Europe and the Western Pa­cific already are expressing interest in coming involved.

Saddam Hussein’s use of Scud missiles in the Gulf War woke up national political and military planners. Future

SM-2 Block IVA for TBMD Common Missile for ATBM / ASCM Defense

to ensure that ultimately the best interceptor becomes incorpo­rated into the Aegis weapon sys­tem. Another sea-based upper- tier candidate is the Army’s the­ater high-altitude area defense (THAAD) mis­sile. Like LEAP,

THAAD uses hit to kill technol­ogy to destroy ballistic missiles.

Cost and opera­tional analyses are evaluating all the sea-based, upper-tier options.

Long-Range Ballistic-Missile Targeting

We could target long-range exoatmospheric interceptors in a variety of ways. Sensor netting, which employs computers to compare, correlate, and fuse the data from different sensors with different angles on the target, has great promise. The Navy already has developed one such system called cooperative engagement. Through a high-speed data net­work, it shares radar measurement data between different units, a ca­pability more important than shar­ing track positional data, like Link 11. Cooperative engage­ment, or systems like it, could en­hance theater ballistic-missile de­fense by giving all shooters (Aegis ships, Patriot units, and

THAAD) the benefit of a com­posite, multisensor detection and tracking system. For example, during Desert Storm, ships tracked Scuds from a side aspect, detecting a large target. Mean­while, the Patriot radars worked hard to acquire a much smaller head-on aspect target. Should a sensor netting system such as co­operative engagement become a part of the TBMD architecture, all shooters would reap the bene­fits of an apparently much larger target through sensor netting and cueing. Cueing is one sensor “telling” another sensor where to “look” through the data network. The SDIO and the Navy plan to conduct Aegis-to-Patriot cuing experiments in the near term. Al­ternatives to sensor netting, in­cluding a plan to double the range of the SPY radar on board

Aegis ships, are still viable options.

Other assets that may assist in long-range tar­geting include national space- based sensors, such as the de­fense support program satellites and aircraft- mounted sensors. Although they are still in early stages, infrared seekers install­ed on board AWACS, E-2, or P-3 type aircraft, will enhance the theater comman­der’s'ability to make early TBM detec­tions—and turn early warning into targeting.

These complementary efforts, an area-defense capability built upon the SM-2 Block IV A, a greater theater capability built upon THAAD, LEAP, or some other variant, and continued work to develop sensor netting and im­prove satellite and airborne target­ing support, can provide a layered defense of land targets from Aegis ships at sea. Such a multitiered system could give the nation much greater flexibility in deploy­ing a theater ballistic-missile de­fense capability during the current decade and beyond.

Commander Carey is currently the Navy program integration officer in the Strategic Defense Initiative Organization.

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