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RIM-162 Evolved Sea Sparrow Missile (ESSM)

The Evolved Sea Sparrow Missile (ESSM) is a short range missile intended to provide self-protection for surface ships. It will provide each ship with the capability to engage a variety of antiship cruise missiles (ASCMs) and aircraft to support self defense. ESSM is a coordinated effort with numerous nations in the North Atlantic Treaty Organization (NATO). This coordinated effort allows all NATO countries to have the same self defense capability and at the same time, reduce the cost to each country associated with developing and testing new systems.

Evolved Sea Sparrow Missile is an improved version of the RIM-7 missile with a new rocket motor, associated tail control section, new warhead, and guidance upgrades. A faster missile with an improved payload and range, the ESSM will have enhanced capability to destroy next generation anti-ship cruise missiles. It will be more capable against low observable highly maneuverable missiles, have longer range, and can make flight corrections via radar and midcourse uplinks.

The ESSM is an international cooperative effort being designed to operate with current and future fire control systems and with the capability of being fired from three existing missile launchers. On Aegis ships, ESSM will be launched from the MK 41 Vertical Launch System, requiring a thrust vector control system on the ESSM rocket. On non-Aegis ships (aircraft carriers, amphibious assault ships, other surface combatants), it will be fired from other launch systems.

ESSM uses an 8 inch diameter forebody that includes a modified guidance section from the in-service RIM-7P Sea Sparrow. The guidance section, which includes a radome-protected antenna for semiactive homing, attaches to a new warhead section. The forebody is attached to a new 10 inch diameter rocket motor which provides higher thrust for longer duration than predecessor Sea Sparrow missiles. ESSM will use skid-to-turn steering (tail control) whereas earlier Sea Sparrows were wing-controlled. ESSM will retain capability of the RIM-7P missile but will also have capability against maneuvering anti-ship missiles.

The new RIM-7P software features advanced guidance algorithims that enable Seasparrow to counter the most formidable threats. The missile's Improved Low Altitude Guidance (LAG) mode makes the RIM-7P exceptionally effective against very low altitude threats, such as sea skimming cruise missiles. In addition, the missile has proven to be highly effective in stressing Electronic Attack (EA) environments.

A Jet Vane Control (JVC) unit allows the RIM-7P to be vertically launched. The JVC unit rotates the missile immediately after it has cleared a ship's superstructure, cancels the missile's initial upward velocity, and controls transition to the initial intercept path. Once the seeker is pointing toward a target, the JVC is jettisoned. Vertical launch capability provides quick-reaction, 360-degree defense and eliminates trainable firing restrictions and time consuming slew requirements.

In December 1997, an ESSM blast test vehicle was successfully fired from an industry developed prototype that utilized a MK 41 Vertical Launching System Quad Pack cannister. In March 1998, a test firing that utilized a MK 48 Guided Vertical Launching System was successfully conducted. In mid-1998, however, the program began experiencing technical problems. The technical problems involved the new digital autopilot software and the control actuator assembly in the missile. The autopilot software had to be redesigned causing a program delay of about nine months. Concurrently, efforts were expended to modify the control actuator assembly. Collectively, both problems resulted in a program delay of 13 months and a US cost growth of about $22 million.

In November 1999, the ESSM program conducted a test firing that did not achieve all required objectives. Upon investigation, the program office learned that a control actuator assembly was missing a critical component. During the next scheduled test firing in March 2000, the test firing was successful, accomplishing all remaining controlled test vehicle objectives and initial guided test vehicle objectives.

In Sept 2002 the first production Evolved Sea Sparrow Missile (ESSM) was delivered to the U.S. Navy by the Raytheon Company. The final phase of the missile's flight test program is scheduled for early spring 2003, when performance with the AEGIS Fire Control System of the U.S. Navy's Arleigh Burke-class guided missile destroyers will be verified.

On January 12, 2004 the Honorable John J. Young, Assistant Secretary of the Navy for Research and Development, approved the Evolved SEASPARROW Missile (ESSM) to enter into full rate production. The ESSM is now being manufactured with the first U.S. rounds destined for the Aegis DDG community. USS Chaffee (DDG-90) was the first ship to receive tactical rounds in February and the USS McCampbell (DDG-85) will load out in March. Soon ESSM will also be employed aboard converted Aegis cruiser, CVs, and CVNs.

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