With the threat of enemy missile attacks on the U.S. and our allies ever present, the need for interception capabilities grows. To that end, the Pentagon's Ballistic Missile Defense System has a new star player: The Kinetic Energy Interceptor.

Killer Features:

• Ground based launcher is mobile (truck transportable)
• Italy-based launcher could shield Western Europe; Virginia based launcher could defend Atlantic coast
• Top speed will be in excess of 12,000 mph
• Can be submarine launched from modified Ohio-class SSBN submarines
  

The mandate of the Missile Defense Agency (MDA) is simple: Protect America and her allies from the threat of Theater and Intercontinental Ballistic Missiles. Getting the job done, on the other hand, is not quite that easy, especially in an age where enemy missiles could be launched from conceivably anywhere. To provide as much coverage as possible, in addition to developing high energy systems such as the Airborne Laser (ABL), the MDA is researching a number of ground and sea-based approaches, one of which is a direct attack kinetic energy interceptor (KEI). This projectile has one purpose: Track incoming missile threats, and destroy them with a non-explosive kinetic energy warhead.

A View to a Kill

The KEI system, as being developed by Northrop Grumman and Raytheon on a joint contract, features a mobile land-based launcher built by Northrop Grumman and subcontractor SEI; a Raytheon-built interceptor that will be faster and more agile than any other interceptor to date; a HMMWV that will house the command and control battle management and communications system; and satellite receivers to process the signal that a hostile missile has been launched. The equipment is highly mobile and can be easily loaded onto a C-17 aircraft and transported worldwide.

At approximately 12 meters long and 1 meter wide, the KEI interceptor is twice the size the RIM-161A Standard Missile-3 (SM-3), which currently provides allied forces and U.S. protection from short to intermediate range ballistic missiles. The KEI attacks its targets at a maximum speed of 12,000 mph, more than twice the speed of the SM-3. Its premise is logical: destroy enemy missiles in their most vulnerable stage -- the "boost" phase of flight, before reentry vehicles, decoys or countermeasures can be deployed.

In for the kill: The Exoatmospheric Kill Vehicle within the KEI projectile seeks out and demolishes enemy missiles.

When a threat has been detected, the KEI projectile is launched toward its target. The first and second stages of the booster will burn together in 60 seconds, giving the projectile a speed of 6 kilometers per second. Finally, the projectile adjusts its trajectory and ejects the Exoatmospheric Kill Vehicle, a device that is used to destroy enemy missiles outside the atmosphere. The Kill Vehicle uses an infrared seeker to detect and discriminate the reentry vehicle from other objects. Then the "hit-to-kill" concept is carried out, as the Kill Vehicle collides with the incoming warhead, completely pulverizing it.

Larger Engagement Area

The challenges involved in the KEI program are manifold. In order to catch the missiles it is supposed to destroy, the KEI needs to be fast -- really, really fast. This is accomplished by making the KEI small and light and packing it with solid rocket fuel. Unfortunately, the tradeoff is that by doing so you limit the missile to "boost" phase interceptions. For most theater missiles, this is around 3 minutes (180 seconds), not a very large launch window.

Due to this, the defending KEI battery was initially intended to be stationed relatively close to enemy threat launch platforms (500-1,500 km), which would cut down on their effectiveness against missiles launched from countries with large land masses, such as Iran and China, or from blue-water launches from open ocean. On the other hand, target missile tracking during the boost phase is easier, since the missile is accelerating linearly, and decoys, such as flares and chaff bundles, would be less effective.

So it looked as KEI would be locked down in its "boost phase" role, but conditions change. But MDA's decision to build a highly flexible kill vehicle for the KEI - which would be effective in other phases of the missile defense regime - helped convince agency officials that the missile could be a capable performer in the ascent and mid-course phases of a missile attack.

Photo of the KEI Launcher.

Upgrading the KEI to a "mid-course" interceptor would enlarge the KEI's engagement window considerably. During the mid-course phase, the threat missile is no longer accelerating, and is arcing ballistically through its apogee towards the target. This phase can last as long as 1200 seconds, which would give an "assent" or "mid-course" capable KEI 20 minutes to engage the target.

It all adds up to a large engagement area for the KEI. For example, a single battery of 10 missiles based in Italy could protect all of western Europe against Middle East missile threats. One battery based in Norfolk, Va., could protect the East Coast of the United States from a launch 300 to 1,500 kilometers off the coast. This is in opposition to KEI's critics, who have stated that the weapon is essentially a one-country missile intended to defend against an attack by North Korea.

Challenges Ahead

One caveat to the "mid-course" approach is that the missile would need to be significantly larger than the current 12 meters long and 1 meter wide. While this is not an issue for sub-launched, or ground-based interceptors, the size makes their use aboard guided missile cruisers and destroyers problematic (the largest missile currently launched from the Ticonderoga cruisers and Arleigh Burke destroyers is the SM-3 missile, which is 6.5 meters long, and has a finspan of 1.5 meters.

KEI Command Center: C2BMC Shelter with Interceptor Communication Antenna.

Another challenge facing the KEI is actually hitting the target. While anti aircraft missile interception technology has been around for some 40 years, the precision needed to intercept a ballistic missile is significantly higher. The greatest challenge in this equation is the data processing limitations in the guidance system. With a closing speed as high as 37,000 meters per hour (22,000 miles per hour), a target missile can literally move hundreds of feet between the computational cycles of the interceptor's course correction software. As if that wasn't enough, the engagement solution can be further complicated by the use of decoys, such as flares and chaff, to spoof the KEI's sensors and have it attack the wrong target.

"If it's an elaborate countermeasure, then we will have to get more sophisticated," says Larry Little, program director of the Missile Defense Agency's KEI office. Getting around this problem could be accomplished with smaller, terminally launched seeker warheads, carried aloft by a booster, which would attack all targets in the missile path, rather than try and discriminate between target and decoy. Still another option is to adopt a different tactic. "You don't necessarily discriminate, you just shoot everything that is up there," Little said.

Despite these challenges, a Northrop-Grumman/Raytheon team is confident that they can meet the goals set by the MDA. Granted $4 billion over the next 8 years, the team is developing a "multi-window" KEI missile using technology developed for the fielded SM-3 missile interceptor. They are expected to have a prototype Ground launched system ready for evaluation by 2010, with a sea-based system ready by 2013. Initial elements of the missile defense system, comprising two destroyers armed with SM-3 air defense missiles, are to be deployed in September.