RIM-161 SM-3 (AEGIS Ballistic Missile Defense)

On 17 September 2009, the United States announced the cancellation of plans to deploy Ground Based Interceptors to Poland and missile tracking radar in the Czech Republic. Plans called for the replacement of these systems with SM-3 IA missiles, to be deployed by 2011. Where these missiles would be based and under who's operational control they were to be placed was initially unclear. Follow-on development of the SM-3 IIA and IIB missiles were expected to be completed by 2018 and 2020 respectively, which would then be integrated into existing defenses.

Standard Missile-3 (SM-3) is being developed as part of the US Navy's sea-based ballistic missile defense system and will provide theater-wide defense against medium and long range ballistic missiles. In 1992, the Terrier LEAP (Lightweight Exo-Atmospheric Projectile) demonstration program culminated in four flight tests and demonstrated the feasibility of theater-wide ballistic missile defense. The SM-3 KW is evolved from the MDA developed Lightweight Exo-Atmospheric Projectile (LEAP). The KW uses an Infrared (IR) sensor to detect a target in space and a Solid Divert and Attitude Control System (SDACS) for KW attitude control and divert thrust, controlled by an onboard guidance and control computer. The SM-3 is based on the SM-2 Block IV airframe and propulsion stack, but incorporates a Third Stage Rocket Motor, a GPS/INS Guidance Section and the SM-3 Kinetic Warhead.

The United States Navy and the Missile Defense Agency are developing Standard Missile-3 (SM-3) as part of the Aegis Ballistic Missile Defense System that will provide allied forces and U.S. protection from short to intermediate range ballistic missiles. The SM-3 Kinetic Warhead (KW) is designed to intercept an incoming ballistic missile outside the earth's atmosphere. Lockheed Martin Maritime Systems and Sensors develops the Aegis BMD Weapon System. The SM-3 is under development by Raytheon at its Missile Systems business unit in Tucson, Arizona.

Aegis BMD has worked closely with Japan since 1999 to design and develop advanced components for the SM-3 missile. Other prospective international participants include:

• The Joint United States and Australia MOU was signed July 2004 and provides a 25 year framework for cooperation on missile defense.
• The Joint United States/United Kingdom MOU was signed in 2003, and a U.S./UK Joint Study on potential Type 45 DDG BMD capability was initiated in 2006.
• The U.S. has provided The Netherlands Pricing & Availability data to participate in a 2006 TRACEX event. In addition, initial discussions are underway to assess the capability of Dutch systems BMD capability and may lead to integration of SM-3 onto Dutch SMART-L/APARS equipped ships.
• Germany has a BMD Liaison Officer working with the Aegis BMD staff to develop an understanding of BMD-related issues.
• High level discussions have taken place to provide South Korea and Aegis BMD capability on their KDX-III Class Aegis Destroyers.

Configuration

The Aegis BMDS builds upon the Strategic Defense Initiative Organization/Ballistic Missile Defense Organization (SDIO/ BMDO) investment in Lightweight ExoAtmospheric Projectile (LEAP) technology and the Navy's Aegis weapon system including Standard Missile and MK41 Vertical Launching System currently deployed on many U.S. Navy and international surface combatants.

The SM-3 KW is a highly modular, compact, space tested kinetic warhead designed to defend against short to intermediate range ballistic missile attacks. Raytheon has engineered two prior generations of LEAP designs starting in 1985 under contracts with SDIO and BMDO. This third generation LEAP design integrates the teamed experience of Raytheon and Boeing in KW designs and Alliant Techsystems' expertise in Solid Divert and Attitude Control. The SM-3 KW design features a large aperture wide field of view long wave infrared seeker that provides acquisition ranges greater than 300 km against typical ballistic missile threats. Seeker pointing and intercept guidance are supported by a production IFOG Inertial Measurement Unit and wooden round simplicity of the SDACS propulsion providing over 2 miles of terminal divert capability. The KW includes a fully encrypted data downlink capability for full engineering evaluation of KW performance and to support rapid kill assessment.

The SM-3 evolves from the proven SM-2 Block IV design. SM-3 uses the same booster and dual thrust rocket motor as the Block IV missile for the first and second stages and the same steering control section and midcourse missile guidance for maneuvering in the atmosphere. To support the extended range of an exo-atmospheric intercept, additional missile thrust is provided in a new third stage for the SM-3 missile, containing a dual pulse rocket motor for the early exo-atmospheric phase of flight and a Lightweight Exo-Atmospheric Projectile (LEAP) Kinetic Warhead (KW) for the intercept phase. Upon second stage separation, the first pulse burn of the Third Stage Rocket Motor (TSRM) provides the axial thrust to maintain the missile's trajectory into the exo-atmosphere. Upon entering the exo-atmosphere, the third stage coasts. The TSRM's attitude control system maneuvers the third stage to eject the nosecone, exposing the KW's Infrared (IR) seeker. If the third stage requires a course correction for an intercept, the rocket motor begins the second pulse burn. Upon completion of the second pulse burn, the IR seeker is calibrated and the KW ejects. The KW possesses its own attitude control system and guidance commands are acted upon by a solid divert propulsion system. The IR seeker acquires the target. Tracking information is continuously transmitted to the guidance assembly which controls the divert propulsion system.

Aegis BMD is capable of using data from space-based sensors or cues from other elements of the BMDS, however external cues and sensor data is not required for Aegis BMD. The system is designed to be capable of autonomous (self-contained) operations for detection, tracking, and engagement of ballistic missile targets or reporting ballistic missile track data to other elements of the BMDS.

The KW does not carry any high explosive. Hit-to-Kill technology relies on the kinetic energy released in high-speed collisions, such as between the KW and the target. The energy from the impact has been calculated to be in excess of 125 megajoules, which is equivalent to the force released when a ten ton truck traveling at 600 miles per hour hits a wall.

Discrimination algorithms enable defense systems to compare objects in a target scene to determine which to intercept. Increasingly complex threats with separated target elements, countermeasures, and debris, require advanced signal processing and discrimination algorithms to identify object features needed to provide robust target selection. SM-3 has flown and demonstrated fundamental discrimination capability for unitary threats.

Computer program design upgrades are in work to expand the current selection accuracy and add capability against more stressing unitary and separating target scenes using target features observed by the Aegis radar system and the KW LWIR seeker to optimize selection confidence. Leveraging off discrimination architecture used across Raytheon's missile programs, SM-3 continues to evolve an integrated discrimination design for insertion with the current seeker design and each of the sensing and signal processor upgrades available to counter advancing threats.

Raytheon is working closely with the Navy to ensure that SM-3, based on legacy Standard tactical missile designs, stands ready to provide immediate emergency Aegis BMD capability against preponderant threats. The SM-3 Block I KW configuration features a single color LWIR seeker, a solid DACS propulsion, target identification and discrimination, and lethal intercept accuracy.

Existing solutions for early intercept consist of a single ship identifying a threat such as a missile, tracking the threat with its local radar, and then engaging the threat. This single ship solution relies entirely on local radar and is not able to provide effective early intercept performance for intermediate or longer range threats.

A single ship solution that is supplemented by offboard Electro-Optical/Infra red track reports (such as from an Overhead Persistent Infrared (OPIR) sensor, an overhead non-imaging infrared (ONIR) sensor, or even land-based sensors) to provide initial threat detection has also been considered. But while the supplemental sensors can provide earlier threat detection capability relative to shipboard radar alone, these supplemental sensors have little or no tracking capability after threat burnout because the threat's heat signal dissipates rapidly after burnout. Thus, while a single ship solution using supplemental sensors could launch a countermeasure based on the data from the supplemental sensors before acquisition of the threat by the ship's local radar, the ship's local radar must pick up the threat after launch to close the fire control loop so that the countermeasure can be guided to intercept the threat.

Placement of the ship when using a single ship solution supplemented by sensors is problematic because there is no optimal single ship placement for both threat acquisition and missile intercept. While it is advantageous to be as close as possible to the threat for timely detection, the relative missile/threat geometries resulting from a closer ship placement results in tail chase engagements where the anti-missile weapons (e.g. RIM-161 Standard Missile 3 (SM-3)) must "catch up" with the threat, resulting in limited engagement opportunities. When the ship is placed farther away from the launch point of the ballistic threat to provide better intercept geometry, the ship's radar is also farther away which results in a limited detection capability to detect the threat prior to burnout when the supplemental sensors cease to provide data.