Several NATO nations, as well as the United Arab Emirates, are ordering an additional 186 RIM-162 Evolved Sea Sparrow Missiles (ESSM) and 77 storage containers. This eleven year old system has been very popular because of its low cost (about $400,000 each), simplicity and effectiveness..
ESSM is a modified version of the standard Sea Sparrow shipboard antiaircraft missile, which has been around since the late 1970. It was based on the Sparrow, radar guided air-to-air missile. Actually, the ESSM shares little more than the name with its predecessor (the Sea Sparrow). Even its shape is quite different. Essentially, a new missile, ESSM can handle aircraft, supersonic anti-ship missiles and fast surface craft.
ESSM is 12 feet (3.66m) long, has a diameter of 10 inches (254mm) and weighs 620lbs. (280 Kg). It carries an 86lb (39kg) blast fragmentation warhead, has a range of 50 kilometers, and a top speed of 4,210 kilometers an hour. Guidance is provided by the firing ships radar keeping the missile informed where the target is, until the missile is very close, and can use its own guidance system (which homes in on radar signals reflected off the target).
ESSM is most popular as a quad-pack (four missiles in storage containers, fitting inside a single Mark 41 Vertical Launch Systems cell) as opposed to a single larger SM-2 Standard missile. -- Mike Perry