It’s the Missile that Hits the Target

The U.S. Navy has a long and largely successful history of shipboard Aegis ballistic missile defense development. While there are countless components to the Navy fleet – platforms, systems, sensors, weapons and people – at the end of the day, it is the defensive missile that stops the incoming aircraft, or ballistic or cruise missile.

The Navy’s defensive missile community has worked tirelessly for more than a half-century to develop the missiles Navy ships field today. Over the decades a plethora of different missiles were tested and some were fielded, with varying degrees of success. But today’s defensive missile success can ultimately be traced to the Navy’s decision to “neck down” its missiles into one family, the Standard Missile.

 

Standard Missile Evolution

Like the overall Aegis Weapon System, the basic Standard Missile has been upgraded during the past 30 years to keep pace with evolving threats. The SM-1, the first version of the Standard, entered production in 1967. Designed to replace and improve upon the Navy’s earlier Tartar and Terrier surface-to-air missiles, an improved version of the SM-1 is still used by 11 foreign navies.

The Navy, however, needed faster reaction times, longer range, greater jamming resistance, and more reliability in its primary air defense missile. Building upon the SM-1, development of the improved SM-2 began in the early 1970s. Designed to function in a demanding tactical environment, the SM-2 models feature an inertial mid-course guidance package that receives command updates from the shipboard fire control system. Several versions also have a jam-resistant monopulse receiver for semi-active radar terminal homing. The initial version of the SM-2 became operational in 1978, and an upgraded SM-2MR Block II entered service in 1983. That missile was used in conjunction with the Mk. 26 twin-arm launchers on board the early Ticonderoga-class cruisers.

The introduction of the Mk. 41 VLS on Aegis warships and SM-2’s ability to accommodate modular upgrades has allowed the missile to pace evolving air threats and maintain its effectiveness in difficult electronic countermeasures (ECM) environments. Block II was designed to have better performance against high-altitude, maneuvering threats. Block III improved missile performance against very-low altitude threats, and Block IIIA added enhanced interception capabilities against sea-skimming, higher speed missiles and crossing missile threats. Introduced into service in 1998, Block IIIB added an infrared guidance mode to improve performance in heavy ECM environments. Today, the SM-2 Block IIIB remains the U.S. Navy’s mainstay against air threats.

The Navy began the development of the SM-2 Block IV in 1987. This variant featured major enhancements in the areas of guidance, target detection, altitude, velocity, jamming resistance and missile control, as well as a blast-fragmentation warhead. Another aspect of the Block IV design was the thrust vector-control booster, which gave Aegis warships the ability to engage extremely high-altitude targets – a key consideration in the Navy’s later ballistic missile defense effort. Technical and contractual problems delayed testing on the Block IV until 1992, however, and the missile did not achieve initial operational capability until 1999.

As the Block IV program struggled forward, the Navy already was at work on the SM-2 Block IVA missile, which ultimately would become part of its sea-based terminal defense capability against ballistic missiles. The Block IVA upgrade added dual-mode, radio frequency/infrared guidance; an upgraded ordnance package; and autopilot-control enhancements to provide ballistic missile engagement capability, in addition to enhancing the missile’s basic anti-air warfare (AAW) performance. But facing cost and schedule problems, the Department of Defense terminated the Block IVA program in December 2001.

The basic missile design was sound, however, and in May 2006 a modified version was successfully tested in the sea-based terminal missile defense role. That led the Navy to continue modifying existing Block IV missiles for the BMD mission. The SM-2 Block IVA thus became a key, albeit temporary, part of the Navy’s “lower tier” terminal ballistic missile defense system. Meanwhile, the SM-3 had established itself as a key U.S. weapon for conducting upper-tier, exo-atmospheric engagements of short-, medium-, and later, intermediate-range ballistic missiles.

 

The SM-3 and Aegis BMD

Today, progressive, “spiral” upgrades to the SM-3 missile are occurring in unison with the enhancements to the Aegis Weapon System. The Aegis BMD 3.6.1 and SM-3 Block IA combination are currently in fleet service as part of the Phased Adaptive Approach (PAA) Phase 1 architecture, providing a robust, “baseline” BMD capability. The Block IB variant is the next upgrade, entering service at sea and on land in conjunction with Aegis BMD 4.0.1 as the interceptor element of PAA Phase 2.

Equipped with an improved, two-color seeker, an advanced signal processor, and the Throttleable Divert Attitude Control System, the Block IB will have improved on-board target discrimination capabilities. The missile’s coverage will be further expanded by its ability to launch on remote sensor data – a capability already inherent in the Block IA, as demonstrated in 2011 flight-testing. The Block IB upgrade also will enhance Aegis BMD’s capacity to handle multiple-missile raids.

The Missile Defense Agency and Navy acquired 24 IBs for developmental testing, and the first intercept test for the Block IB missile. That test, FTM-16, ultimately proved to be unsuccessful, necessitating a Navy/MDA failure review board to determine the root cause and implement any required fixes. A low-rate initial production contract commences in 2012, with the aim of having the Block IB in full-rate production 10-12 months after that.

More missile improvements will follow. Entering service later in the decade in conjunction with Aegis BMD 5.1 and as part of PAA Phase 2, the SM-3 Block IIA will provide greater regional coverage against intermediate range ballistic missiles (IRBMs). This version features a higher burnout velocity; a more advanced seeker better able to discriminate between warheads and decoys; engage-on-remote capability; and nearly double the range of earlier SM-3 interceptors.  The kinetic warhead and second and third stages of the Block IIA all will be larger than those of the Block IB, which will make the Block IIA the largest SM-3 variant compatible with the Mk. 41 VLS. Currently in co-development with Japan, flight-testing of the Block IIA is scheduled for 2014 and initial-use certification in 2018.

Progressing even further, the SM-3 Block IIB – in 2013 in the concept and planning stage – will have an even higher burnout velocity and greater divert capability. This will give the SM-3 variant some boost-phase intercept capability against long-range missiles, including ICBMs, and permit it to defend a greater area than its predecessors. As a larger missile, the SM-3 Block IIB will require modifications to the vertical launch systems on board BMD-equipped Aegis warships. This version of the Standard Missile is scheduled to enter service around 2020 as part of PAA Phase 4. However, there is some speculation that, if the Iranian ICBM threat becomes compelling in the nearer-term, development of the SM-3 IIB would need to be accelerated.

The SM-3 is not the final Standard Missile variant: The SM-6, which currently is in low-rate initial production, combines an SM-2 Block IV airframe and the active seeker from the AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM), and is the Navy’s next-generation extended range anti-air warfare interceptor. This will increase the ability of Aegis warships to engage air targets beyond their radar horizon and reduces Aegis Weapon System’s reliance on radar illuminators. A variant also may play a role in future sea-based terminal ballistic missile defenses.

Finally, a note on this almost dizzying array of terminology. The planned succession of blocks accords perfectly with the long-standing Aegis philosophy of building a little, testing, and then learning before building some more. Blocks alternate changes in missile airframe and kinematics with changes in the kinetic warhead (including its own maneuvering propulsion). Thus the Roman numbers indicate airframe and kinematics, the transition from Block I to Block II indicating the shift from an airframe based on the earlier series of Standard Missiles to a new airframe which completely fills the available space in a vertical launcher canister, and which takes advantage of some weight reduction in the canister itself. The letters refer to the kinetic warhead, with its seeker and its signal processor.  Meanwhile the Aegis system in which the missile is embedded also benefits from block upgrades as its own sensors are improved.

The focus of this post has been on missile development and testing of various variants of the U.S. Navy’s Standard Missile family. But it is fair to ask, has all this development and testing led anywhere, in other words, has the Standard Missile yet been put to the test and used in a challenging operational scenario.  The answer is yes, and the next post will examine that success in Operation Burnt Frost.