The United States currently accounts for nearly half of all global military expenditures.  There is reason to believe that the armed forces will need to make do with less money in the future.  But the core missions of the military won't go away, so the search is on for more cost-effective solutions to security challenges.  Raytheon has come up with a low-cost approach to missile defense -- arguably the single most important mission the military has -- that is so elegant and compelling that it could serve as a model for other cost-saving breakthroughs.

What the Massachusetts-based company has done is adapt an air-to-air missile already in widespread use so that it can intercept ballistic missiles in the most vulnerable phase of their trajectory, before they have released multiple warheads or countermeasures to assist in penetrating defenses.  That initial phase of a missile's trajectory is called the boost/ascent phase, because it is the period when rocket motors are firing or immediately after they shut off, as the payload is rising rapidly into space. 

At that stage in its flight, a ballistic missile is relatively fragile and easy to spot because of the huge exhaust plume it generates.  Missile defense experts have long known that boost/ascent was the optimum time to attempt intercept of a hostile missile, since a single strike can destroy all of its warheads while minimizing the challenge presented to defenders later in the trajectory.  In the later stages, when the payload is coasting through space or undergoing re-entry, warheads are harder to sort out from surrounding debris and track, especially if the attacker is smart enough to disguise them.

The reason missile defense planners typically focus on intercepting attackers in those later phases is because of the difficulty of getting close enough to a launching missile to hit it during the few minutes before it reaches space and releases its warheads.  But by adapting an air-launched missile already in use on supersonic fighters for the boost/ascent phase intercept mission, Raytheon has crafted an affordable, low-risk complement to the bigger and more costly systems that are required to intercept fast-moving ballistic bodies in the later stages of their trajectory.

The interceptor for the Raytheon system -- called “Network Centric Airborne Defense Element” or NCADE -- would be carried close to the enemy launch site on its host aircraft, and then released at high altitude to attack the rising missile.  By netting together sensor inputs from a variety of existing systems such as Aegis destroyers and JSTARS radar planes, the aircraft could be vectored to the best release point for its interceptor.  The interceptor would then use a heat-seeking sensor in its nose adapted from another existing air-to-air missile to achieve impact kill of its target.

NCADE could also be launched from a loitering unmanned aircraft such as the Air Force's Reaper.  In fact, it could be launched from a wide range of aircraft, because it has the same external configuration as the air-to-air missile on which it is based, despite the introduction of a new seeker and second propulsion stage.  That means no expensive aircraft modifications or new infrastructure would be required.  The interceptor would cost less than a million dollars per copy to produce, and could be ready for use in a few years.  It may not be the answer to all of America's missile defense needs, but it is the least expensive, highest leverage solution to a major threat that anyone has proposed in a long time.