Architecting a Missile System for Navy Theater Ballistic Missile Defense

ABSTRACT While most of the theater ballistic missiles (TBM) in threat countries’ inventories are of the shorter range SCUD varieties, mid- to long-range versions are currently in development in a number of third world countries. Threat potential exists in the following three battle spaces: endo-atmosphere (0-30 km), high endo-atmosphere (30- 70 km) and exo-atmosphere (greater than 70 km). The inherent short range and low speed of endo-atmospheric threats match well with capabilities of SM-2 Block IVA, which equips the Navy with an area defense capability The exo- atmospheric TBMs are longer range and can threaten more targets which may be widely dispersed. Their higher velocities reduce response times dramatically Therefore, exo-atmospheric TBMs create the need for Standard Missile-3 (SM-3), which provides the Navy with theater wide defense Capability

Defining its area and theater wide systems as clearly endo-atmospheric and exo-atmospheric systems allows the Navy to use derivatives of the Standard Missile Block IV to take full advantage of the conditions associated with each of these operating zones. Use of an existing missile and ship system baseline also allows use of the existing interface structure to minimize cost.

To counter the endo-atmospheric TBMs, the SM-2 BLK IVA upgrades include an advanced imaging in€rared (IIR) seekm, an improved fast-reaction auto pilot and a forward lodung RE all in the same volume as the existing missile. The highly responsive SM-2 Block IVA missile, complemented with Aegis weapons systems modifications, provides capability against enemy aircraft and cruise missiles, as w d as TBMs. Standard Missile-3 (SM-3) replaces the SM-2 Block IV warhead, radar and guidance section with a boosted third stage and an advanced kinetic warhead (KW). Operation in the exo-atmospheric region permits a KW design with autonomous guidance control and divext thrusters for high maneuverabil- ity and has the capability of achieving very high interceptor velocities.

Architecting a Missile System for Navy Theater Ballistic Missile Defense

Introduction

his paper assesses the current and growing threat from theater ballistic missiles (TBMs). It then describes how the growth of the threat, along with several d t a r y and political considerations, leads to a need for a Navy theater ballistic missile defense (TBMD) ca-

pability. Navy TBMD is required to augment the Army’s layered terminal defense capability (PAC-3 and THAAD) in situations where we have limited or no forward deployed land forces. Moreover, sea-based Navy systems, because of their rapid deployability, mobility, and sustainability can often provide the first line of defense in crisis situations. Further, they can supplement in-place Army systems with additional layers of defense while providing field commanders with enhanced engagement flexibility.

The paper describes the challenges and performance benefits associated with the three basic engagement environments wherein a ballistic missile defense system can operate: the endo-atmosphere, the exo-atmosphere, and the combined endo-/exo-atmosphere. Each of these regimes has unique impacts on the performance of a TBMD system. A description of the unique challenges associated with each region and how these challenges affect interceptor design is provided. Further detail is also provided on the selection of key architectural elements of a Navy theater-wide interceptor relative to the battle space selected as well as the rationale behind the urgent need to quickly deploy a system.

The Threat Since the end of the Cold War, the threat of a Soviet conflict has been replaced by more diverse threats from smaller regional adversaries. Many aggressive third-world nations are beginning to acquire increasingly advanced weaponry and are posing serious military and political hazards to U.S. and allied interests overseas. The most widespread and rapidly growing of these advanced weapons are ballistic missiles. Ballistic missiles are now becoming a common battlefield weapon. The 1988 Iran-Iraq war, the Persian Gulf War, the civil wars in Yemen, and the recent Chinese show-of-force activities near Taiwan have demonstrated the readiness and willingness of warring factions to use ballistic missiles to further their own causes. TBMs have been used to threaten d t a r y forces, strategic military installations, and civilian population centers. The Persian Gulf War introduced the world to a new form of terrorism and taught the U.S.-led coalition forces several important lessons.

First, Iraq demonstrated that TBMs armed with conventional warheads are very effective weapons of terror. During the war, SCUD attacks on population centers greatly affected coalition military strategy, bred tension among coalition allies, and limited the military and political options. The need to protect non- combatants and international allies from TBMs in regional conflicts will become increasingly important as would-be aggressors attempt to divide defensive ah- ances through real or threatened TBM attacks.

NAVAL ENGINEERS JOURNAL May 1997 313

Architecticg a Missile System for Navy Theater Ballistic Missile Defense

Second, the previously successful cold war deterrence policy that brought an end to the Soviet threat will not work in smaller regional conflicts. Iraq continually targeted Israel, despite the risk of escalated Israeli involve- ment, in order to disrupt the political dynamics of the coahtion. The mere presence of U.S. Patriot defensive systems was critical in deterring Israeli retaliation and avoiding further confusion while maintaining unity and co- operation among the coalition allies.

Third, despite total air superiority, coalition forces were unable to effectively locate and destroy Iraq’s mobile ballistic missile launchers. As a result of the ineffectiveness of preemptive strikes against TBMs and the allied inability to suppress the use of these weapons of terror, ballistic missile defenses wdl become increasingly vital.

While the majority of threat TBMs are of the shorter range, Soviet developed SCUD variety, several longer range missiles, such as the North Korean NO-DONG and Chinese CSS-2 versions, are in various stages of development and testing. Intelligence sources have suggested that these longer range ballistic missiles may carry larger payloads and may include nuclear, chemical and biological weapons. These TBMs wdl likely have improved guidance capability for more precise targeting and increased delivery accuracy The use of these longer range, more accurate TBMs greatly increases the number of targets put at risk of ballistic missile attack (see Figure 1).

Currently, more than twenty-five nations have or are developing nuclear, chemical and/or biological weapons. More than twenty nations have ballistic missiles that can or will carry them. In fact, Iraq’s use of TBMs carrying chemical weapons during the Gulf War has not been com- pletely disproved. Therefore, in the near future, the U.S. and our international allies will be at greater risk of strikes from hostile nations using ballistic missiles, some of which could be carrying weapons of mass destruction.

I

I G U R E 1. Threatened Capitals versus Threat Range

r4

Todax our TBM defense capability rests solely with the Patriot system and its evolving enhancements. Patriot has demonstrated terminal defensive capability against short- range TBMs that spend most of their flight time within the atmosphere. Because of the dramatic need for ex- panded area coverage, the Army and the Ballistic Missile Defense Organization (BMDO) have been developing a theater high altitude area defense (THAAD) interceptor for the past several years. The THAAD system wdl employ a powerful theater missile defense (TMD)-ground- based radar (GBR) that will improve long range surveillance and engagement capability When combined with the latest Patriot Advanced Capability Three (PAC-3) system, the Army’s THAAD/Patriot land-based architecture will provide a two-tiered, layered, terminal defensive capability

As a complement to the Army systems, Navy TMD efforts will prepare us for future conflicts where we may not have forward deployed land forces. They will also supplement and expand the “upper tier” coverage as the range of TBMs grows, while providing additional support to land- based forces as they are emplaced. Sea-based TMD will also afford the U.S. several unique tactical, strategic and financial advantages. For example, the mobility of ships enables optimal and flexible positioning of assets. It allows commanders to quickly react to changing threats and com- bat environments. Additionally, naval forces are self-sus- taining, self-defended, and ready on arrival. In many theaters, forward positioning of sea-based assets will enable defense of very large areas. For example, two Aegis ships operating in the middle of the Sea of Japan and armed with Navy theater-wide interceptors (Standard Missile Three with a lightweight exo-atmospheric projectile (LEAP)) could conceivably defend all of Japan from a North Korean balhstic missile attack.

Sea-based TBMD provides some additional unique political advantages. For example, the insertion of naval TBMD is non-intrusive and, in several scenarios, enables intercepts over international waters. Sea-based assets also reduce reliance on foreign nation support, can be forward deployed to areas of potential confkt, and estab- lish a powerful peacetime presence. In the future, Navy TBMD may be required to insert forces into hostile regions. Unlike the Gulf War, the next conflict may not allow the luxury of a six-month build-up of forces in a friendly nation.

As highlighted above, TBMs are a current and real threat to U.S. forces and our alhes overseas. In the West- ern Pacific Theater alone, there are more than 80,000 active duty American servicemen and women. This number includes more than 20,000 marines on Okinawa, more than 15,000 sailors assigned to the forward deployed ships and support organizations of the Seventh Fleet, and the soldiers and airmen of the numerous Army and An- Force organizations protecting the Pacific Basin. Many of these servicemen and women have families stationed with them

May 1997 NAVAL ENGINEERS JOURNAL


overseas who are continually at risk from long range weapons. Rapid deployment of TBM defenses aboard naval ships at sea will significantly reduce this risk and improve the safety of these U.S. citizens and their host nation allies.

Ballistic Missile Defense-Battle Space Corn pa ri son

There are three fundamental regions in which a ballistic missile defense interceptor can operate. Each of these engagement “battle spaces” has both unique limitations as well as specific performance advantages. The peculiar characteristics of each battle space dramatically affect the design of the interceptor. As a result, detaded performance and design trade studies that balance engagement capabilities against technical limitations must be performed before an effective interceptor can be developed for each battle space.

ENDO-ATMOSPHERE The endo-atmospheric battle space, generally considered to be between zero and 30 km in altitude, is the most aerodynamically stressing of the three operating regions. Aero-thermal effects, or atmospheric heating, and dynamic pressure are the primary elements driving the design of any interceptor expected to operate in this region. Endo-atmospheric interceptors must be able to address the severe aero-thermal and aerodynamic effects on the interceptor and still be able to reliably acquire, maneuver against, and engage the high velocity and potentially maneuvering TBM target. These effects include structural stress; aero-optical distortion, refraction, jitter, and blur; jet thrust amplification; and others. Obviously, these effects have a dramatic impact on interceptor performance, controllability, and seeker design, particularly for “hit-to- kill” interceptors that require extremely accurate delivery at very high velocities.

A radio frequency (RF) seeker is generally best suited to address very low altitude atmospheric weather effects. However, an RF seeker assembly is susceptible to reflec- tive scintillation. This effect, created by the uneven sur- faces and differing reflectivities of the materials on the target body can cause the seeker to rapidly and continually traverse the target body This fluctuation in seeker tracking and target resolution makes it extremely difficult for the interceptor to select and lock-on to an aimpoint with sufficient accuracy for TBM kill. However, a high resolution imaging infrared seeker (IIR) is particularly well suited for target end-game tracking and aim point selection. IIR seekers are not susceptible to the scintdlation phenomenon and with a large, sensitive focal plane array can provjde improved angle accuracy for end-game guidance. However, the use of an IIR (or heat detecting) seeker within the atmosphere requires a window for ther-

mal protection. Currently, sapphire is the only seeker window material that can handle extreme temperatures and pressures of high speed atmospheric flight. Sapphxe is transparent only in the medium wavelength infrared band. A medium wave IIR seeker matches well with hot re- entering targets.

Operating in the endo-atmosphere also requires a very maneuverable aero-controlled interceptor. Re-entering targets are forced by atmospheric effects into intentional and or unintentional high g maneuvers, making the target’s path very unpredictable.

The requirements drivers lead to the modification of the existing SM-2 Block IV for TBMD operation within the endo-atmosphere. A RF seeker is used for midcourse flight and a medium wave IIR seeker provides improved terminal guidance. This was successfully demonstrated on 24 January 1997 with an IR guided intercept.

For protection from extreme thermal and pressure environments, the SM-2 Blk IVA sapphire window is cooled with a thm stream of Argon. To handle the target’s unpredictable flight path a very capable airframe and a fast auto pilot combine to provide very small miss distances.

SM-2 Blk IVA’s high velocity provides deep dand coverage against short range TBMs targeted at coastal high value assets. Because of the short flyout times and low apogee altitudes of short range TBMs, a sea based system regardless of operating altitude or velocity has limited inland defense Capability The SM-2 Blk IVA’s forward coverage against short range threats represents the limit of sea based inland coverage against short range TBMs.

EXO-ATMOSPH E RE The Navy maintains a unique tactical leverage, in most theaters, through sea based “forward deployment.” Being placed forward of the defended area, between the threat launch and impact point, combined with a very high velocity ex0 interceptor expands the areas. This capability is only achieved if TBM defenses are positioned to effect an ascenthidcourse (near apogee) intercept (see Figure 2).

The critical element required to take full advantage of the Navy’s unique leverage of forward deployment is a very high velocity interceptor operating throughout the entire exo-atmospheric battle space. The exo-atmospheric battle space (greater than 70 km) is the most technologically flexible region for improved interceptor and system performance. The required very high interceptor velocities are most easily achievable in the vacuum of space employing a lightweight divert controlled kinetic warhead.

For economy and near-term deployment the Navy’s interceptor must volumetrically fit within the existing Mk- 41 Vertical Launch System (VLS). SM-3 capitalizes on existing propulsion (Mk 72 booster and Mk 104 rocket motor), that has already been integrated with the Aegis Weapon System and VLS, while optimizing the remaining space to achieve kinematic performance. The use of a lightweight, high g kinetic kill warhead allows room for a


Architecting a Missile System lor Navy Theater Ballistic Missile Defense

I I F I G U R E 2. AscenffNear Apogee Intercept Capability

third stage rocket motor (TSRM) which is used to achieve high intercept velocities. This velocity provides the kinematic capability required to cover the large defended areas of the theater wide mission.

Exo-atmospheric kill vehicle operation provides other unique performance advantages allowing for a lightweight design. In space, TBMs follow a non-maneuvering, predictable ballistic path. Given this predictable target path and the absence of atmospheric constraints, an exo- atmospheric kinetic kill vehicle (also called kinetic warhead (KW)) can easily maneuver into the target’s path destroy- ing it with h e t i c energy. Without the limitations of atmospheric operation, an exo-atmospheric lull vehicle can employ an uncovered large aperture long wave IR (LWIR) seeker for the longer acquisition ranges and higher sensi- tivity required to intercept cool TBMs in the exo-atmosphere. A LWIR seeker is optimized against the h a r e d signatures of cool theater wide exo-atmospheric TBMs (see Figure 3).

An exo-atmospheric space kdl vehicle can be optimized with increased divert capability for intercept margin and high density lethal mass for lethality An interceptor that only operates in the exo-atmosphere is by definition a space vehicle that can capitalize on the unique advantages of space operation. Lack of atmospheric effects hke drag or pressure simp& the thermal protection and airframe requirements of an exo-atmospheric system. Exo-atmospheric operation in the vacuum of space allows for a very agde kill vehicle design. This high degree of aghty combined with a minimized volume for electronics and maximized divert propulsioddense lethal mass makes a dedi- cated exo-atmospheric kill vehicle a precision guided lethal interceptor.

A divert propulsion system designed for operation in ex0 space is considerably smaller than one designed for

endo operation. An ex0 divert and attitude control system (DACS) requires about one-fifth of the lateral velocity and thrust of a comparable system providmg the same intercept capability within the endo-atmosphere. Operating in the absence of atmospheric and drag effects allows the design of a smaller system that still maintains the required divert complexity but can be packaged into a smaller volume to fit w i t h the Standard Missile.

Exo-atmospheric ascent or midcourse intercepts elimi- nate or greatly reduce potential nuclear, biological or chemical (NBC) fallout on the targeted area. One issue under examination is that early intercepts in the vacuum of space increase the dispersion of NBC contaminants to less than lethal doses. Industry and government analysis is being conducted to determine the effects of re-entry physics, ultraviolet radiation and temperature on biological elements, containers and fuzing/dispersion mechanisms. In addition, the high closure rates achieved during exo- atmospheric intercepts go beyond the effects of purely mechanical collisions. At these very high closure rates

Signature Relative to Temperature vs. Wavelength 0.014

’ 0.01

0.006 I

0.002

0 0 5 10 15 2c

Wavelength (pn)

F I G U R E 3. TBM Signature Comparison

376 May 1997 NAVAL E N G I N E E R S J O U R N A L


kinetic intercepts produce plasma effects that can sub- stantially increase the levels of damage to the intercepted target.

The SM-3 interceptor, detailed in a following section, incorporates a lightweight exo-atmospheric projectile (LEAP) kinetic warhead (KW). The Ballistic Missile De- fense Organization (BMDO) has developed the enabling kill vehicle technologies that have been incorporated into LEAP for optimized operation in the exo-atmosphere. It employs a solid divert propulsion system that provides sigdcant safety and handling advantages compared to a hypergolic liquid system, and permits "wooden round" operation whde maintaining the required divert performance. It utilizes a large aperture long wave IIR (LWIR) seeker that has been designed to operate in the most optimum waveband for cool exo-atmospheric threats with miniatur- ized electronics. This permits optimized lethal mass and divert propulsion for increased lethality and intercept margin.

HIGH ENDO-ATMOSPHERE The third potential operating region for ballistic missile defense is a combination of the previous two and poses the most technically demanding requirements. The high endo-atmospheric battle space, between 30 and 70 km, includes the stressing aerodynamic requirements of operating in the endo-atmosphere while requiring l i t e d low altitude exo-atmosphere operation. An interceptor operating in this battle space must incorporate a rigid aerodynamically controlled airframe for endo-atmospheric control and thermal protection and a divert propulsion system for low exo-atmospheric control in the absence of atmosphere. This drives the interceptor design to a very large kill vehicle that must contain aero and divert control ability as well as an airframe that can provide atmospheric thermal and pressure protection. These demanding requirements greatly limit the achievable maximum interceptor velocity in a volumetrically constrained system like the Mk-41 VLS. Without the very high interceptor velocities provided by a purely exo-atmospheric interceptor, theater wide defended areas are greatly reduced (see Figure 4).

Endo-atmospheric operation drives the interceptor to an aero dynamic design (pointy nose) that must employ a seeker window for thermal and pressure protection. As previously mentioned, the best window material that can meet these requirements is sapphire. The use of a sapphire window limits the design to a small aperture medium wave IIR (MWIR) seeker that may be optimized for the endo-atmosphere but has very limited to no capability against cool exo-atmospheric targets. While closely matching hot re-entering targets, a medium wave IIR seeker provides short acquisition ranges against cool ex0 targets forcing a very limited time line for acquisition, track, divert, discrimination, smart aimpoint and intercept (see Figure 5).

N A V A L E N G I N E E R S J O U R N A L May 1997

F I G U R E 4. Defended Area versus Missile Burnout Velocity

The amount of divert required for low exo-atmospheric intercepts forces the KW design to employ a very large high g divert propulsion system. Unfortunately, current solid propulsion technology cannot meet low exo-atmospheric divert requirements for a large KW design without employing the use of a very large system. This impedes shipboard integration within a volumetrically limited system like the VLS. As a result, this hitation forces the use of a hypergolic liquid divert propulsion system that poses serious safety risks for shipboard use. Hypergolic liquid propulsion systems would require continuous moni- toring and safety equipment and pose increased reliability and shelf life risks due to complicated plumbing.

F I G U R E 5. Benefits of Longer Seeker Acquisition Range

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Archi!ecting a Missile System for Navy Theater Ballistic Missile Defense

SM-3 Architecture and Design Drivers As discussed above, interceptor velocity is a critical performance factor for the exo-atmospheric region. There- fore, the selection of the SM-3 architecture for the Aegis LEAP Interceptor Program was driven by the goal of max- imizing interceptor velocity while meeting the following requirements: 1) Aegis Weapon System (AWS) compatibility with the goal of minimizing AWS modifications, 2) maximize probability of intercept, and 3) develop a missile that would require minimal modifications to transition to a User Operational Evaluation System (UOES). To achieve a near-term capability and reduce cost as well as risk it was decided to: 1) use existing qualified SM-2 Block IV hardware where possible, and 2) use the Terrier LEAP and SM-2 Block IV functional architectures with mmnal modifications. The main modifications to the Terrier LEAP and SM-2 Block IV functional architectures were the deletion of functions not required for the SM-3 mission.

An SM-3 for the ALI program is shown in Figure 6. The selection of key architectural elements of a Navy theater-wide interceptor relative to the exo-atmosphere battle space is described in the following paragraphs.

SELECTION OF SM-3 PROPULSION The SM-3 design uses three motors to achieve its high velocity The first and second stage motors are the existing SM-2 Block IV propulsion stack; Mk 72 Booster and Mk 104 Dual Thrust Rocket Motor (DTRM). A thn-d stage rocket motor (TSRM) was added to achieve higher velocities, leading to greater defended areas, and provide the opportunity for error correction later in flight when increased targeting accuracy is available.

The use of the existing first and second stage motors (see Figure 7) greatly reduces development risk and cost as well as increasing the probability of intercept. These elements have successfully completed qualification testing for shipboard use as well as at-sea DT/OT testing including more than twenty live firings. These elements, including the steering control section, will be used with no hardware changes.

In addition, the use of an architecture of three separate motors allows each to be tailored for its specific flight regime. This follows the design practices of space vehi- cles. The Mk 72 is designed to provide for egress from the VLS and is then dropped off, reducing missile weight. The second stage motor is used to provide the kinematic capability to exit the atmosphere and it is also separated from the missile, again reducing missile weight. The TSRM is then used in the exo-atmosphere, where its velocity is maximized since it does not face the aero environments that the first two stages must deal with.

The selection of a dual-pulse TSRM was driven by the need for mission flexibility The two pulses can be ignited independently and on command for maximum time h e

F I G U R E 6. SM-3 for AEGIS LEAP Intercept Program

flexibility The first pulse provides for third stage divert maneuvering while the second pulse can be used to cor- rect for relative position errors that may propagate during long midcourse coast periods. For shorter range engage- ments the second pulse may not be needed or desired.

GUIDANCE SECTION The guidance section contains the functionality that is required for the mission, but not needed onboard the KW during end game. Leaving these elements on the third stage provides more room in the fourth stage, the KW, for high density lethal mass and maximized divert propulsion for increased intercept margin.

The functions allocated to the guidance section include: 1) power for the long-range flyout (batteries, power changeover and control, and event initiation; 2) AWS com- munications (transceiver, receiver, encoding and decoding functions); 3) telemetry; 4) flight termination electronics including Master Arm, and 5) GPS Aided Inertial Navi- gation (GAINS).

GAINS is used to provide increased guidance accuracy during midcourse missile flyout. This greatly reduces required KW handover accuracies and provides increased margin for intercept. GPS guidance provides very precise

1 - F I G U R E 7. SM-3 1st and 2nd Stage

May 1997 NAVAL ENGINEERS JOURNAL

Architecting a Missile System lor Navy Theater Ballistic Missile Defense

position, velocity and attitude knowledge on-board the missile to ensure that the missile can be delivered into the proper “error basket” and that the KW can be pointed precisely enough to rapidly acquire the target as is required for long-range intercepts of high speed TBMs. In- ertial measurement units (IMUs) tend to drift over time during flight, whereas GPS does not. GPS is not required, however updating the IMU with the precise GPS state estimations helps to remove errors caused by tilt, drift, random walk, and system noise. The GPS data will not be used independently GPS information will be combined with radar updates to provide the missile with the highest possible missile state accuracy To ensure a high probability of intercept success SM-3 has also been designed to be capable of operating if GPS data is not available.

KIN ETlC WARHEAD Given the fixed volume constraint of the Mk-41 VLS, and the need to allocate a majority of this volume for propulsion to achieve high intercept velocities, a small lightweight KW was required to minimize AWS changes. The KW is shown in Figure 8.

To minimize risk and achieve a near-term capability the KW architecture leveraged heavily on the previous LEAP Program efforts. The LEAP program started in 1986 and more than $400 d o n was invested to build a hit-to-kill vehicle sized for tactical missile applications.

As discussed previously, a LWIR seeker provides advantages in the exo-atmospheric region. Therefore the KW employs a long wave body fixed imaging infrared seeker that is optimized for operation against cool exo- atmospheric ballistic missile targets. Several space flight tests have proven seeker acquisition and track. In addition, ground testing in 1995 proved the feasibility of an increased field of view LWIR seeker.

For ship compatibility and to minimize AWS modifications a high g solid divert propulsion system with increased intercept margin was selected. This is an evolution of the solid divert system that was hover tested in 1994.

Over the past decade much has been invested in developing all of the critical kill vehicle components required for a highly accurate, lightweight vehicle including: miniatur- ized electronics for maximized divert and lethality, precision IMUs for high guidance accuracy, and s u e d and

F I G U R E 8. SM-3 Kinetic Warhead

experienced teams for low risk missile integration and hardwarelsoftware performance.

Conclusion The United States urgently needs naval ballistic missile defense. There is no other way to provide defense against this growing threat in the crucial, initial stages of a crisis. It is important to ensure that the U. S. has a forcible entry capability in the face of today’s threat, which can protect overseas ports and airfields in order to ensure the safe entry for air- and sealift operations, essential to our national strategy.

Since there is a sound technical basis for the development plan and a solid Aegis and Standard Missile infra- structure in place, naval TBMD can be at sea in the near- term. This evolutionary development builds on the very successful Aegis, Standard Missile and LEAP engineering legacy

There is no silver bullet for ballistic missile defense. A two tiered system provides defense in depth, multiple shot opportunities, and capability against MW, cruise missiles, low altitude endo-atmospheric and exo-atmospheric TBM intercepts. SM-2 BLK IVA and SM-3 maximize the Navy’s firepower while minimizing interceptor complexity (risk) and the required number of VLS cells aboard Aegis ships. ++ Anant Patel is senior project engineer for the Standard Missile LEAP Program (designated SM-X) in the Standard Missile1 Vertical Launch System Program Office (PMS 422) of the Nay’s Program Executive Office for Theater Air Defnse (PEO T D ) . He is responsible for the integration and test of the SM-X missile including the third stage rocket motor (TSRM) and the kinetic warhead (KW) assemblies. He received his bachelor of science in electrical engineering from the University of Pittsburgh, in 1985. Prior to joining PMS 422, he was the project engineer for the shipboard targeting system used during the Terrier LEAP technology demonstration program. He was also the project manager fm the installation and integration of the new threat u p g r d (NTU) and cooperative engagement cwbilities (CEC) aboard USS K i d (DDG 993), the first ship to receive CEC during its development test phase. Mr Patel‘s other assignments as NTU devehpvnent lead engineer included providing development and technical direction for mod$cations to the NTU engagement system for Standard Missile 11 and IIIIIIIA compatibility. Kathrin Kjos is the program development team leade~fov Hughes Missile Systems Cmpany. She worked on the initial flight demonstration phase of the program integrating the kill vehicle and advanced solid axial stage into the SM2 Block 111 ER missile and served as co-chair of the System Safety Working Group. She has thirteen years of experi‘ence in systems engineering. Previous experience includes missile systems engineering for the Advanced Air-to-Air Missile (AAAM) as well as for laser and radar surveillance systems. She has a bachelor of science degree in chemical engineering from the Illinois Institute of Ech- nology, a master of science degree in systems engineering from the University of Southern California, and is current& a doctoral candiihte in systems architecting at the University of Solsthem C a l i h i a .


Architecting a Missile System far Navy Theater Ballistic Missile Defense

Felix Sasso is a member of technical staff 11 at Hughes Missile System Company. He has three years of experience in operations research and weapon systems analysis. He is currently serving as lead operations research analyst for both the SM-X (Nay theater widt.) and SM2 Block IVA (area defense) programs. His p ~ v i o u s experience at HMSC includes serving as lead design engineer responsible for aheloping a system level force on force ballistic missile defense simulation, ITADS. I1;4DS was the primay analysis tool used for the system pe&mnnce analysis shown in this papm Mx Sasso has also worked on several other ballistic missile defense programs including the exo-atmosph& kill vehicle for national missile defense, an air launched boost phase kinetic kill vehicle, and several Standard Missile uariants for muise missile and anti-air waqare shig self-d&nse. He holds a bachelor of science degree in electrical engineering from the University of California, Los Angeles and is currently pursuing a mash‘s degree in business fm the University of Arizona.

Bart R. Olson THIOKOL CORPORATIONiELKTON DLV OPERATIONS

he Navy Program Executive Office (PEO) for

of Standard Missile-3 Aegis LEAP Intercept (SM-3 ALI) flight tests to demonstrate the feasibility of Wide Area Theater Missile Defense interceptor missions leveraging existing Aegis shipboard systems. These tests will incorporate several unique propulsion upgrades to achieve critical flight test objectives. The propulsion upgrades include a Solid Divert and Attitude Control System (DACS) that is incorporated into the SM-3 ALI kinetic warhead (KW). The solid DACS is an extension and scaleup of LEAP propulsion technologies successfully demonstrated in hover tests. Another critical propulsion upgrade for the SM-3 ALI flight test program is the third stage rocket motor (TSRM). The TSRM adds a third axial propulsion stage to the existing SM-2 Block IV propulsion stack. The TSRM is unique in that it incorporates composite structures, dual-pulse solid-propellant technology, along with omniaxis thrust vector control (TVC), safe-and-arm (S&A) devices, flight-termination system (FTS), as well as a unique hybrid pitch/yaw/roll attitude control system (ACS), cableskonnectors, and skirthterstage structures. The design is based on concepts demonstrated on the Advanced Solid Axial Stage (ASAS) and ACS built for the Navy Terrier LEAP flight demonstration program.

T Theater Air Defense (TAD) is preparing for a series

Solid DACS Technology Base Solid propellant control system technology was originally developed for ballistic missile post-boost control and has evolved into an important element of ballistic missile defense. As an antiballistic missile KW subsystem, the

Scott D. Robinson is a seniaV test and evaluation (T&E) engineer for N a y Theater- Wide Defense Programs at Standard Missile Company. He is the lead T&E engineer for SM-X and has been involved with the program since its incetion. Begin- ning in 1990, Mx Robinson spearheaded the effort to integrate BMDOs lightweight em-atmospheric Projectile (LEAP) technologies with N a y Standard Missile anti-air warfare systems for the perfomu2.nce of ballistic missile defense. During the initial flight demonstration phase of the program involving the use of SM2 Bbck 111 E R missiles and the Ter~ier NTU Weapon System, Mx Robinson served as co-chairman ofthe System Safty Working Group and T&E Steering Committee. For approxi- mately six years prior to joining Standard Missile Company in March 1996, M?: Robinson prmided scienttjtc, engineering and technical assistance to BMDOS Technology Readiness Director- ate. He is a fmmer captain in the US. Army Signal Corps and holds a bachelor of scinece in engineering science (physics concentration) from the University of Virginia.

DACS provides propulsion for target acquisition pointing, cross-range maneuvering, and end-game error correction. Energy management through multiple propellant pulses and high-response hot-gas valving have been key technologies for DACS maturation. Solid propulsion DACS is ide- ally suited to this mission by offering performance capability, a “wooden round,” and by avoiding an enormity of safety and logistics issues associated with shipboard use of hypergolic fuels.

The bulk of the solid DACS technology base was developed in conjunction with the Navy LEAP program funded by BMDO for Theater Ballistic Missile Defense (TBMD) applications. The major components/subassemblies of a solid DACS are the gas generator, main thrust assembly, attitude control assembly, and structural interstage components. LEAP DACS system tests history includes structural evaluation tests, flightweight valve/gas generator tests, and four full-up DACS finngs including a controllability unit (CU-11, a strap-down system integration test (SIT), and the two hovered units (H1 and H2). LEAP DACS system-level testing is summarized in Table 1 of this commentary

SM-3 DACS Design Development The SM-3 DACS mission requirements dnve a three-pulse gas generator design for higher total impulse and average thrust levels. While the physical envelope diameter increased by a factor of 2 over the LEAP DACS, the available length remained essentially unchanged. This resulted in an oblate spheroid gas generator case configuration as shown in Figure 1 of this commentary Within this case, the propellant grains are arranged concentrically around a carbon-carbon central tube that transfers gas to both valve subassemblies. Aside from larger thruster nozzles, the main thrust assembly (MTA) and attitude control assembly (ACA) are very s d a r to their LEAP DACS prede- cessors. Internal gas generator pressure for the SM-3

380 May 1997 NAVAL ENGINEERS JOURNAL

Documents

Architecting a Missile System for Navy Theater Ballistic Missile Defense