Previous posts have focused on missile defense writ large and on ballistic missile defense more specifically, especially, as in the case of the AirSea Battle Concept, what Aegis ballistic missile defense (BMD) brings to the fight. But to have a more well-nuanced understanding of how all this works, it is important to understand the underlying Aegis system. This post, and the following one, will deep dive into this system including the basic Aegis system, Aegis origins, its associated missiles and launchers, the Standard Missile evolution, and the Standard Missile Three (SM-3).
The Aegis Weapon System – A Revolution in Naval Warfare
The heart of Aegis BMD – and the U.S. Navy’s fleet air defense capabilities – is the Aegis Weapon System. Consisting of the S-band AN/SPY-1 phased-array radar, the Mk 99 fire-control system, the Weapon Control System, the Command and Decision suite, and associated Standard missiles, Aegis can simultaneously detect and track hundreds of threats and friendly/neutral aircraft and engage multiple targets simultaneously. When combined with the Mk 41 Vertical Launch System (VLS), the AN/SQQ-89 underwater combat system, command-and-control, and self-defense weapons and systems, the weapon system acts as the central component of the broader Aegis Combat System.
Aegis has its origins in the Cold War struggles against the Soviet Union, when that nation’s naval, air, and missile forces called into question the Navy’s ability to prevail in a global war at sea. Aegis went a long way in answering that challenge, and also provided a tactical solution to a Navy emphasizing operations in the littoral regions of the world in the post-Soviet era.
Aegis also was engineered with a significant margin for growth, allowing the system to do things never envisioned when it was first designed and built. Ballistic missile defense is one of those unforeseen missions. Aegis BMD, nevertheless, has been able to leverage a wealth of research and development, testing and real-world operational experience with the Aegis Weapon System. Aegis Ballistic Missile Defense is currently at sea in the 3.6.1 configuration, which provides exo-atmospheric engagement capability against short-, medium- and some intermediate-range ballistic missiles with the SM-3 Block IA missile, as well as retaining its long-range early warning for BMD as a whole.
Overall, Aegis Weapon System variants are operational on board 22 Ticonderoga (CG 47)-class cruisers and 62 Arleigh Burke (DDG 51)-class destroyers. Today, 23 of these warships have BMD capability, and that number is increasing yearly. In addition, 18 foreign warships are equipped with Aegis, including four Japanese warships that have an Aegis BMD capability. These forces form the foundation for a potential global Aegis ballistic missile defense capability – one that was laid more than 40 years ago.
The need for a system such as Aegis became apparent as far back the 1950s, when U.S. Navy warships were first equipped with guided surface-to-air missiles. As we have discussed in previous posts, the Navy ultimately developed three missiles to deal with the then-prevailing jet aircraft threat – Tartar, Terrier, and Talos missiles, known as the “3-Ts.” The Navy later concluded that those missiles and their fire-control systems were not reliable enough, were susceptible to jamming, and would be overwhelmed by a large-scale enemy attack. Emerging anti-ship cruise missiles eventually added another dimension to the threat that existing systems and ships could not readily handle.
One potential solution was the Typhon system. Begun in 1957, Typhon combined a new multi-function radar and new missiles. At-sea testing proved that the system, while promising, suffered from technical, weight, and cost problems. The requirement for an advanced anti-air warfare (AAW) system, however, remained. To meet that demand, the Navy initiated development of a new Advanced Surface Missile System (ASMS) in August 1964 by asking seven contractor teams to submit conceptual designs for a new AAW system capable of dealing with contemporary and future threats. An assessment group chaired by Rear Adm. F.S. Withington evaluated the proposals against a broad set of operational criteria.
Withington’s 1965 report to the Secretary of the Navy called for the development of a new system to replace the then-current 3-T system. That recommendation received a boost in October 1967, when an Egyptian anti-ship missile sank an Israeli warship. Contracts for detailed design of ASMS were let in 1968, and a subsequent Navy decision to pair ASMS with the new Standard Missile that was under development gave the RCA firm the edge in the competition. In December 1969 the Navy awarded the company the contract to develop ASMS – soon to be renamed “Aegis.”
Then-Capt. Wayne Meyer became manager for the Aegis project office – PMO-403 in the Naval Ordnance Systems Command (NAVORD) – in early 1970. He was tasked with shepherding the development and integration of the new radars and control systems that would comprise Aegis through a series of engineering development models. In 1972, Meyer’s office also assumed responsibility for developing the SM-2 missile that would be a part of the overall Aegis package. Later, in 1974, Meyer asked for and received permission to integrate all shipboard weapons and sensors into an overarching Aegis combat system.
The Aegis team deployed the first development model at a land-based site in Moorestown, N.J., and completed initial land-based testing there by October 1973. The model was then installed in the Navy test ship Norton Sound (AVM 1) for at-sea evaluation. Those testing efforts, which began in late 1974 and ran until 1977, proved conclusively that the anti-warfare capabilities resident in Aegis far exceeded any other system in the fleet. Meanwhile, a successor engineering development model featuring improved performance and reduced weight was introduced in 1976.
When NAVORD was merged with the Naval Ship System Command to become the Naval Sea Systems Command (NAVSEA) in 1974, the Aegis Project Office became PMS-403. In addition to retaining command of that office, Meyer (a rear admiral as of 1975) also became director of the Surface Combat Systems Division. That move provided him with a platform to ensure smooth integration of both Aegis and the ships that ultimately would carry the system. In this way, the Aegis program avoided many of the ship-combat system integration problems that had dogged the Navy in the 1960s and 1970s.
As combat system engineering progressed toward deployment, the Navy established the Aegis Shipbuilding Project (PMS 400) – which combined PMS-403 with two other offices – under Meyer in January 1977. In October, Congress appropriated funds for the first Aegis warship, DDG 47, which was later re-designated CG 47. In 1978, the Navy awarded a ship construction contract to Litton Ingalls shipbuilding division in Pascagoula, Miss., and a production contract to RCA for an Aegis combat system.
Missiles and Launcher
The SM-3 RIM-161 is a ship-based missile system used by the U.S. Navy to intercept ballistic missiles as a part of the Aegis BMD system. The SM-3 is primarily used and tested by the Navy, but is also currently used by the Japan Maritime Self-Defense Force and may, in the future, be used by other navies. The SM-3 has shown the best results of any anti-missile system developed by the United States, and as the Missile Defense Agency’s 2011 program update noted, “The SM-3 1A currently deployed on Aegis ships has proven to be a highly reliable interceptor. Aegis, using the current 3.6.1 Aegis Weapon System and the SM-3 1A, has more than twice the exo-atmospheric engagement range of THAAD.”
To accomplish a ballistic missile intercept, an Aegis warship’s SPY-1 radar detects and tracks the target, and the Aegis weapon control system calculates a fire-control solution. When the missile is ordered to launch, a Mk. 72 solid-fuel rocket booster launches the SM-3 out of the ship’s Mk. 41 VLS. The missile then establishes communication with the launching ship. Once the booster burns out, it detaches, and the Mk. 104 solid-fuel dual-thrust rocket motor (DTRM) takes over propulsion through the atmosphere. The missile continues to receive mid-course guidance information from the launching ship and is aided by GPS data. The Mk. 136 solid-fueled third-stage rocket motor (TSRM) fires after the second stage burns out. It takes the missile above the atmosphere. The TSRM is pulse fired and provides propulsion for the SM-3 until 30 seconds prior to intercept.
At that point the third stage separates, and the kill vehicle begins to search for the target using pointing data from the launching ship. The Solid Divert and Attitude Control System (SDACS) allows the kinetic warhead (KW) to maneuver in the final phase of the engagement. The KW’s sensors identify the target, attempt to identify the most lethal part of the target, and steer the KW to that point. When the KW intercepts the target, it results in 130 mega joules (96,000,000 foot-pounds) of kinetic energy at the point of impact.
Mk. 41 Vertical Launching Systems used to launch the SM-3 and other weapons are found on all Aegis warships. First introduced in the mid-1980s, the Mk. 41 currently is available in three sizes, although only the 25-foot long Strike variant is capable of launching large missiles such as the SM-3 or the Tomahawk land-attack missile. Ticonderoga-class cruisers are fitted with two 61-cell VLS modules, while Burke-class ships have a 61-cell module forward and a 29-cell module aft, for a total of 90 cells compared to 122 in the cruisers.
The Mk. 41 launchers, like the missiles they support, have been continuously improved since fleet introduction. These changes – mainly consisting of electronic and software upgrades – have not altered the system’s mechanical structure. The Baseline VII upgrade introduced in 2004 featured COTS processors, a real-time operating system, C++-format programming, Ethernet communications, and fiber optics. In addition to introducing the open-architecture computing environment (and thus economically facilitating future upgrades), this improvement permits Evolved Sea Sparrow Missiles to be launched from the Mk. 41. The VLS Baseline VII is currently fielded in the Aegis destroyer USS Pinckney (DDG 91) and later destroyers, and will be back fitted into previous Aegis destroyers and CG 47 cruisers as part of the Cruiser and Destroyer Modernization Program.
With this look at the Aegis weapons system’s origins, core components, and missiles and launchers, we will examine the missile itself in the next post.