New PAC-3 Missile Faces First Intercept Test in 2009

After stabilizing testing of interceptors designed to counter ballistic threats in the midcourse phase of flight, the U.S. Missile Defense Agency is now looking to bolster defenses against threats as they boost into space. Another MDA goal is to improve its ability to foil reentry vehicles in the terminal phase of flight.

These are two elements of the layered system being designed to thwart missile threats from North Korea and Iran. Some of the options for boost-phase and terminal defenses could involve modifying existing systems.

Early next year, the agency plans to begin testing its new longer-range interceptor for the Patriot Advanced Capability-3 (PAC-3) area defense system against its Scud-representative ballistic missile target.

Lockheed Martin also is exploring future missions for the new PAC-3 interceptor, including a sea-based application to protect ships from advanced ballistic, air, and cruise missile threats - including the exotic Sizzler high-speed anti-ship missile. An air-launched version is also being studied to intercept ballistic missiles as they boost.

In the traditional terminal area defense role, the Missile Segment Enhancement (MSE) is designed to double the range of today's PAC-3 interceptor. And it's supposed to engage targets at a higher altitude than is possible today, projecting potential fallout from an intercept farther from forces on the ground or population centers.

Two intercept tests are expected next year, a step forward after the program experienced failures earlier during ground trials.

The MSE interceptor will incorporate the same millimeter-wave Ka-band radio-frequency seeker, guidance unit and processor on the front end as the existing missile. But it will expand the diameter of the interceptor's back end by 1.5 in. and incorporate a new Aerojet-made motor with a second pulse. This new propulsion system and redesigned control surfaces are geared to creating a more maneuverable interceptor capable of more agile flight. This is especially useful in the endgame as the hit-to-kill missile intercepts ballistic payloads, cruise missiles and aircraft, says Mike Trotsky, vice president of air and missile defense programs for Lockheed Martin. The company also expects that the MSE will be able to increase by 50% over the existing PAC-3 weapon the altitude at which an intercept can take place. PAC-3 now engages targets about 40-60 km. (25-37 mi.) from the launch site.

MSE will "put Patriot in places where it has never been before," says Brig. Gen. Gino Dellarocco, U.S. Army program executive officer for missiles and space.

The design will use the existing PAC missile canister and foldable control fins for storage. A single MSE would stow in the same launch canister as a four-pack of smaller PAC-3 missiles.

The company is about three years into its development of the MSE, which will be fielded in U.S. systems as well as provide the interceptor capability for Italy and Germany, which are partners in the Medium Extended Air Defense System (Meads) program. The $300-million MSE development contract covers five years of work.

Meads has also been approved for sale to the Netherlands. Although the Dutch are entering the program too late for coýýdevelopment, Trotsky says there are possible opportunities for coproduction. The United Arab Emirates and Poland are also requesting the purchase of Meads.

The U.S. agreed to place Army soldiers in Poland with a PAC-3 battery as part of the larger deal to position ground-based interceptors designed to counter long-range missiles headed for Europe or the North American East Coast. PAC-3 would be able to thwart the types of ballistic missiles recently lobbed by Russia into neighboring Georgia.

Japan hopes to conduct a PAC-3 test this week. This would be the first for a foreign military sale customer.

Interest in MSE is growing around the globe as the program moves forward after experiencing problems during the last 18 months. One of the challenges in designing the new MSE motor is how the solid-rocket propellant performs in the extreme hot and cold environments that will be encountered during flight.

"We had to make some design improvements to maintain safety margins to operate [MSE] at hot and cold" temperatures, says Trotsky. They include changes to the lining that buffers the missile body from the solid-propellant storage area in the airframe.

The new motor is designed to use more propellant, and it incorporates new technology to generate additional thrust and control at altitude, he adds. The fixes were tested May 21, when MSE completed a non-intercept flight demonstration at White Sands Missile Range, N.M. During this trial, the interceptor did not carry a seeker.

The flight test early next year will pit the MSE against a short-range ballistic missile target. Like the PAC-3 interceptor, the new weapon will be optimized against ballistic targets as well as air-breathing threats such as aircraft and cruise missiles. The test program will ramp up to aircraft and missile intercepts at farther ranges.

The Missile Defense Agency is growing concerned about new short- and medium-range missiles, especially those being developed by Iran. Recently, Iran conducted "launches of several short- and medium-range ballistic missiles capable of striking Israel and U.S. bases in the Middle East," said U.S. Air Force Lt. Gen. Henry (Trey) Obering, the MDA director, in July.

The intercept trajectory for MSE and PAC-3 can be tailored depending on the threat. "While there are times when the MSE missile would arc up and descend on its target, this is not a "fixed" trajectory," say Lockheed Martin officials. The missile guidance system will optimize its trajectory to preserve the most maneuverability in the endgame.

The seeker is capable of discerning ballistic and air-breathing targets in the presence of clutter, rain, multipath effects and countermeasures so is not a factor in optimizing the trajectory shape. "The differences depend on environment, and speed and type of target," says Trotsky.

However, the test schedule won't be firm until the MDA hammers out its Fiscal 2010 budget request, which is due to Congress in February. No plans exist now to test MSE against a salvo of incoming missiles, a more realistic representation of a true threat.

Depending on the test schedule, Trotsky says MSE could be ready for deployment between Fiscal 2010 and 2012. While Lockheed Martin is leading the MSE development, Raytheon is the PAC-3 system integrator. A typical fire unit includes a radar, engagement control station and 8-16 launchers.

Meanwhile, Lockheed Martin is designing MSE variants for an air-launch boost-phase interceptor and a sea-based hit-to-kill terminal defense system. The air-launched MSE would be pitted against Raytheon's modified advanced medium-range air-to-air missile (Amraam), the Network-Centric Airborne Defense Element (NCADE). The MDA is considering a competition for the capability. Funding is expected in the Fiscal 2010 budget request.

The air-launched MSE would be housed inside a pod under the wing of an aircraft. Upon launch, a clamshell door on the pod would open, the weapon would drop and ignite, engaging the target. The mission set includes homeland defense against a boosting target; in one scenario, a cruise or ballistic missile would be launched from a ship offshore.

Intercepting a boosting ballistic missile is generally easier because the target is traveling in a straighter trajectory and is slower than in the terminal phase. Lockheed Martin is working with Boeing in its design lab to begin integrating the air-launched MSE onto the F-15C, which is used for combat air patrols in North America. The company is also beginning to explore integration onto the F-35 Joint Strike Fighter and F-22.

As for Raytheon, it has experience integrating the Amraam onto aircraft, and is focusing its efforts on pulling together the right components - including the first stage from Amraam, a new second stage and a passive imaging infrared seeker from the AIM-9X. Raytheon also notes that its system would interface with all fighters already capable of launching an Amraam. The company conducted a seeker characterization test in December 2007. Flight trials await funding from the MDA, which is expected in the Fiscal 2010 budget. The company is now working on a $10-million MDA contract to continue refining the NCADE.

The MSE interceptor is also a candidate for the MDA's upcoming competition for a Sea-Based Terminal Defense. This system is envisioned as dual-use, destroying air-breathing and ballistic missile threats to ships. Its increased agility is also designed to counter the notorious "Threat D," or Sizzler, an exotic high-speed cruise missile for which the U.S. Navy doesn't yet have a suitable countermeasure (see p. 51).

The MDA has budgeted nearly $500 million through Fiscal 2013 to develop this weapon. A request for proposals for this competition is expected by the end of the fall, according to Obering.

Trotsky says the PAC-3 MSE would need few modifications to handle the mission. One is the addition of a safety clamp to restrain the weapon in a vertical-launch system on board Navy ships. Also, software work is needed to integrate the missile into the overall Aegis ship architecture.

"One question that MDA will want to answer in this competition is which missile has growth potential for today and current evolving threats," he says.

The competitor to the sea-based MSE is expected to be the Raytheon SM-6, an upgrade to the Standard Missile.

[Source: By Amy Butler, Aviation Week, Washington, 12Sep08]

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