U.S. Navy cruisers and destroyers equipped with Aegis Combat Systems provide the mainstay for the nation’s sea-based missile defense. Following a string of successful ballistic missile target intercepts using the Aegis system, the Navy is moving to boost the number of ballistic missile defense-capable ships in the fleet.

The Aegis Combat System provides the Navy’s cruisers and destroyers with a multi-mission capability – an integrated combination of sensors, weapons, computers, software, and displays. This system is named for the mythological shield carried by Zeus.

At the heart of the Aegis system is a powerful 4-million-watt multi-function phased array radar performing search, automatic detection, target tracking, and missile-engagement support. A family of Standard Missiles (SMs) includes a ballistic missile interceptor, the SM-3, and the new SM-6, a formidable, extremely fast, extended-range active seeker missile to engage over-the-horizon (OTH) threats.

Indeed, Aegis ships are equipped for cruise and ballistic missile defense (BMD), anti-air, antisubmarine, and anti-surface warfare, according to Rear Adm. Victor G. Guillory, USN. He is the Navy’s director of Surface Warfare, or N86. These ships also provide surface fire support for forces ashore and Tomahawk cruise missile strikes.

At the heart of the Aegis system is a powerful 4-million-watt multi-function phased array radar performing search, automatic detection, target tracking, and missile-engagement support. A family of Standard Missiles (SMs) includes a ballistic missile interceptor, the SM-3, and the new SM-6, a formidable, extremely fast, extended-range active seeker missile to engage over-the-horizon (OTH) threats, Guillory noted.

Aegis ships already operate in worldwide regions to support U.S. combat commanders with ballistic missile defense, Guillory pointed out. “Aegis, already a Navy core mission area, is transitioning into a vital missile defense capability.” A graduate of the Naval Academy, Guillory served at sea on a number of surface platforms: frigates, destroyers, and cruisers. He commanded the USS Lake Champlain (CG 57), an Aegis cruiser.

More than 27 nations possess ballistic missiles, and growing numbers operate with or pursue weapons of mass destruction warheads. Accordingly, the Navy plans to expand its Aegis-equipped BMD-capable fleet from three cruisers and 15 destroyers to 84 ships – 22 cruisers and 62 destroyers – to deter or defeat ballistic missile threats against America and its allies. The Navy will soon add three Aegis ships – two cruisers and a destroyer – to the Atlantic Fleet, bringing the total number of BMD-capable ships to 21, Guillory said. “A lot of capability has been leveraged from the Missile Defense Agency [MDA] and built upon Aegis and SM technologies.

“Eighteen ships just simply are not enough. Combatant commanders demand Aegis capabilities throughout the world, especially in areas where anti-ship cruise and ballistic missiles can fall into the hands of rogue nations or stateless groups hostile to the United States. And this threat is a growth industry,” Guillory said. Aegis modernization with a sea-based BMD capability will take place over an extended period as the vessels come into shipyards for scheduled improvements, overhaul, and maintenance. “We need to give combatant commanders options, providing a multi-mission warship with an important BMD capability.

“We have an Aegis modernization program in place to ensure that we get the full service life from these ships. As they go into yards for hull, mechanical, and electrical upgrades, they also will receive combat systems upgrades to remain relevant against the threat,” Guillory said. “The BMD capability, developed by MDA and the Navy, can be inserted into this modernization program beginning in 2012, with completion of the program in the 2020 decade. We believe this is a very efficient approach. Not only will Aegis ships have an extended service life plus the BMD capability, but the plan also assures sufficient ships will be available to meet deployment requirements.” The program was given a boost when Secretary of Defense Robert Gates announced intention of accelerating the sea-based Aegis BMD program.

The Navy plans to install new systems and components that are more capable than those being replaced. Guillory asserted that another major objective is to make the ships less expensive to operate, maintain, and modernize over the remainder of their service lives. Some changes are intended to allow the ships to operate with smaller crews, reducing annual operation and support costs. The primary contractor for Aegis is Lockheed Martin Maritime Systems & Sensors Division, Moorestown, N.J. SM technology also has evolved over the years to keep pace with the threat and grow into new missions. Raytheon Company, Tucson, Ariz., is prime contractor for the missile system.

Aegis ships include Ticonderoga-class cruisers and Arleigh Burke-class destroyers. The Navy procured 27 CG 47s that entered service between 1983 and 1994. The service intends to keep 22 of the ships in the fleet until their service life reaches 35 years. Sixty-two DDG 51s in total are scheduled to enter service, although this number may grow. Between 1985 and 2007, 52 of the destroyers were in the fleet. The 62nd ship is slated to enter service in 2011. The destroyers’ service lives also may be extended from 35 to 40 years.

“The Navy and MDA have been successful with Aegis and its Standard Missile in 14 of 18 engagements against ballistic missile targets,” Guillory said. “That number includes two engagements by our Japanese allies in 2007 and 2008. Additionally, we are also two for two with the SM-2 Block IV, which is a close-in capability against ballistic missiles flying their final endo-atmospheric trajectory, bringing the total to 16 intercepts out of 20 attempts. We are also one for one against an errant satellite, which the whole world watched.”

Authorized by the White House, an Aegis warship, the USS Lake Erie (CG 70), fired a single modified tactical SM-3, hitting a malfunctioning U.S. satellite approximately 133 nautical miles over the Pacific Ocean as it traveled in space at more than 17,000 miles per hour. “However, that is a capability the Navy does not retain and there are no plans to operate Aegis ships with continuing anti-satellite capabilities,” Guillory said.

Riding on the successful missile target intercepts and destruction of the crippled satellite, the MDA’s fiscal year 2009 budget calls for approximately $1.1 billion for Aegis BMD research and development. The Navy also contributes funding to the program and Congress recently added $56 million for sea-based missile defense. “MDA really provides the lion’s share for developing sea-based BMD, while the Navy focuses on operations and sustainment missions.

“It is often difficult for the Navy to break down the Aegis BMD portion of the budget because, as I pointed out, these are multi-mission ships. When they deploy, funding for sailors and support for the ship runs across entire mission areas, making it difficult to carve out the BMD portion of the budget,” Guillory said. He also noted that, within the context of a Presidential Decision Directive on national security, which establishes the role of theater, regional, and homeland missile defense, deployment of BMD-capable ships throughout the fleet is a priority. This capability supplements the overall BMD architecture designed to protect the nation. Sea-based missile defense is a huge part of this. Aegis BMD is designed for intercepts in the midcourse and terminal phases of ballistic missile flight.

The Aegis BMD program office reports to the director of MDA. This office is the acquisition executive for the program, and the organization operates as a field activity within the Naval Sea Systems Command, Guillory said. “Rear Adm. Alan B. Hicks, USN, is the Aegis BMD program director and works closely with N86, both in development and fielding efforts to ensure that MDA developmental programs are aligned with various yard periods and installation plans for Aegis ships.”

Guillory stated that he considers himself fortunate to have served as a young lieutenant on the first West Coast-based Aegis ship. “I don’t think anyone envisioned 30 years ago that Aegis would survive this long or that it would remain the dominant combat system for naval capability. The Navy had the vision to design and develop a system with enormous growth potential and pushed that capability hard to stay ahead of emerging threats now and throughout this period.

“Aegis has received a series of upgrades and technical advances, especially to the SPY-1 radar. Each technology upgrade provided greater discrimination capability to defend our ships against the most advanced cruise missile threats and to defend ships in company and joint forces in areas of operations,” he said.

While the admiral cannot, for security reasons, address Aegis capability against specific emerging threats such as new sea-skimming cruise missiles, he claimed that continuing technical advances will keep them ahead of the threat. “A big part of my job and what we do in N86 is to ensure that we program the upgrades necessary to keep our ships relevant against these threats.”

Threats continue to grow, both cruise and ballistic missiles, in part because they are important regional weapons in the arsenals of many powers. Missiles provide a level of prestige, coercive diplomacy, and deterrence that other weapons cannot. The worldwide trend in ballistic missile development is in maturation among existing weapons and toward a large increase in the number of countries or groups possessing these weapons. Emerging increases in range, reliability, and accuracy of these missile systems pose greater risks to U.S. forces, interests, and allies throughout the world, making Aegis’ role ever more critical.

Proliferation of missile technologies, materials, and expertise, especially by Russia, China, and North Korea, enable emerging states to accelerate development for existing programs and acquire turnkey systems with advanced capabilities. As an example, China’s development of anti-ship ballistic missiles is designed to supplement its People’s Liberation Army Ying-Ji anti-ship cruise missile family. Experts believe new terminal guidance capabilities for both the 600-kilometer (372 miles) short-range DF-15 and medium-range 2,500-kilometer (1,547 miles) DF-21 ballistic missiles could begin entering the inventory this year.

Russia developed and sold to China, and probably Iran, the Raduga Moskit anti-ship cruise missile, known by the SS-N-22 Sunburn NATO designation. The Moskit (Mosquito in English) flies at Mach 2.5 at very low altitude above the surface and executes violent terminal maneuvers to throw off defenses. Another weapon from Russia sold to China and other nations is the Mashinostroyenya Yahont, an anti-ship air-breathing ramjet-powered cruise missile that flies at Mach 2.6 to deliver a 440-pound warhead at a velocity of 2,500 feet per second a few feet above the surface.

The Navy is already addressing these threats by testing Aegis and fleet defense systems against supersonic sea-skimming target vehicles. Called Coyote, the Orbital Sciences Corporation target system integrates a four-inlet, solid-fuel ducted-rocket ramjet system to produce target speeds in excess of Mach 2.5 while flying 20 feet above the ocean’s surface.

The ability to acquire, track, and engage missiles is critical to the United States and its allies. Incoming ballistic missiles must travel across vast ocean reaches during all phases of ballistic flight. Aegis also functions as an important element of the nation’s BMD integrated sensor network capability through its long-range tracking capacity, handing off target tracks to other sea- or ground-based interceptors.

The Navy and MDA intend to continue improvements to the Aegis SPY-1 radar to keep pace with evolving threats. Planned improvements to the S-band sensor system will enhance the capability to track short-, medium-, and long-range targets. This powerful radar can acquire and track targets out to 250 miles and as far up as low Earth orbit. Additionally, the computer-controlled phased array system sends out electromagnetic energy in all directions to simultaneously track targets and engage them automatically, prioritizing by threat characteristics. Four versions of the SPY-1 radar are in service with the U.S. Navy and its allies. The SPY-1 radar provides mid-course guidance to SM interceptor missiles.

Four flat panel arrays that make up the SPY-1 radar are mounted on the ship’s superstructure, simultaneously radiating beams in all directions. This allows the system to acquire multiple targets inbound from multiple directions for full situational awareness. This fast-reaction fully automatic sensor shifts from initial target detection to first missile firing in less than 10 seconds.

Aegis sales to allied countries include Japan, with six destroyers in service; South Korea, with three destroyers under construction; Australia, with three destroyers planned; and Spain, with four frigates in service, one under construction, and another planned. Norway operates two frigates with three more under construction or planned. Norway’s ships are smaller than other Aegis ships and carry a reduced size, less powerful version of the SPY-1 radar.

Raytheon’s SM technology also is evolving to keep pace with the threat and for growth into new mission areas. The company heads a team from industry that provides missile system users around the globe with access to spares and repair services. The SM-1, which entered production in 1967, remains in use with many international navies. The more advanced SM-2’s primary role is to provide area defense against enemy aircraft and anti-ship cruise missiles. This version of the missile is deployed in several configurations – the SM-2 Block IIIA to the SM-2 Block IV extended-range missile.

This fourth upgrade of the second SM major version employs an electronic countermeasures resistant monopulse, solid-state receiver for semi-active radar terminal guidance with a digital computer. Long-range intercepts are accomplished through the use of inertial and command midcourse guidance. This version of the SM and Aegis flight profile allows the interceptor to approach the target without the need for a shipboard illuminator until the terminal engagement phase. MDA and the Navy carried out the first terminal phase interception with an SM-2 Block IV in late May 2006. The missile successfully steered to a hit-to-kill intercept of a ballistic missile target off Hawaii. This missile is scheduled to put to sea operationally in 2009. Additionally, Lockheed Martin is making modifications to the Aegis combat system to deal with the short reaction times and high closure speeds involved.

The SM-2 Block IIIB configuration incorporates a side-mounted imaging infrared seeker into a proven missile guidance system that provides a significant improvement in the terminal phase of engagements, especially against anti-ship missile threats.

SM-3 Block IA and IB missiles provide the Navy and MDA with the Aegis BMD interceptor capability. The weapons are designed to intercept and destroy short- to intermediate-range ballistic missiles in midcourse flight. MDA plans on procuring 147 SM-3 interceptors, with 38 deployed by the end of 2008 and the remainder by 2013. This high-velocity interceptor provides protection for large defended areas and multiple engagement opportunities. Throughout its flight, the missile continues to receive in-flight updates from the ship to refine the intercept guidance solution. The missile is equipped with a kinetic warhead. The SM-3 Block IB incorporates a two-color, all-reflective infrared seeker enabling longer-range acquisition and increased threat discrimination.

The MDA successfully developed and tested a multiple kill vehicle (MKV) in December 2008 for possible use on the SM-3. Both Lockheed Martin and Raytheon are developing these warheads on a dual-path basis. “While the SM-3 has planned upgrades to the missile, it operates with a unitary warhead, not an MKV. As MDA progresses, the agency will look at the technologies available and MKV could be one of the options considered at that time. However, no MKV decision has yet been made. The Navy is participating in the analysis of potential interceptor warheads, some of which could be sea-based,” Guillory said.

Another evolutionary upgrade to the SM family is the SM-6, a transformational long-range OTH system with integrated fire control capability to counter the evolving threat well into the future. This interceptor leverages the Navy’s investment in Aegis, Cooperative Engagement Capability, and Airborne Early Warning systems, Guillory explained. “It aligns the Navy with its cooperative target engagement sea power strategy. Instead of the previous capability that electronically lashes the missile to the ship after firing, the SM-6 gives us the ability to fire well beyond the radar’s range with an active and semi-active homing capability. This interceptor will take us to a new leap-ahead generation and extend our reach out from the ship.”

The SM-6 capitalizes on target cueing from the launch ship or from a remote sea-based, land-based, or airborne sensor to defeat high-density raids. This system’s operational modes include command midcourse guidance, inertial midcourse guidance, and semi-active and active homing for highly accurate target tracking. The interceptor uses both SM and Advanced Medium-Range Air-to-Air Missile (AMRAAM) signal processing and guidance and control capabilities.

SM-6 successfully passed developmental tests as an extended-range active missile. The interceptor employs extended-range technology from the SM-2 Block IV in concert with the AMRAAM active seeker to hit targets beyond the ship’s line of sight.

“Hardware programs and developmental capabilities are important; however, a critical part of what is happening today with sea-based defense in the Navy involves human BMD technical expertise. We are growing a cadre of skilled sailors much as we did in the 1960s and 1970s. Back then, it was anti-warfare talent for Aegis. Now it’s integrated air and missile defense expertise, not only at the ship level but also at the operational staff level. Nevertheless, the key to success is that individual, the sharp young sailor. The young men and women who have grown up in the information technology era are the brightest and most highly trained individuals available and they strive to serve aboard Aegis ships. Without their proficiency the system wouldn’t work. We must never forget the sailors’ fundamental value in the Aegis community,” Guillory concluded.

This article was first published in Defense: Spring 2013 Naval Edition.