How do you hit a bullet with a bullet?

Next-generation Patriot missile ups the ante for accuracy: A direct hit from one missile to another

BY DIANE STRATMAN

Although the easing of tension between superpowers in the late 1980s and early ’90s reduced the likelihood of massive global conflict, a different kind of threat exists today—the availability of sophisticated missile technology in many smaller countries. Unfortunately, this missile technology has proliferated and is in the hands of some who are prepared to use it.

Among the champions of missile defense is the Patriot missile system—designed to detect, target and then destroy an incoming missile that may be no more than 10 to 20 feet long and is typically flying at three to five times the speed of sound. The latest version of Patriot does what scientists once said was impossible—hit a missile with another missile, or as some describe it: “hit a bullet with a bullet.”

The Patriot anti-missile system demonstrated a degree of effectiveness in destroying Scud missiles launched at Saudi Arabia and Israel during the first Gulf War in 1991. This was the first combat use of the Patriot and the first time an air defense system destroyed a hostile tactical ballistic missile. In 1997, the U.S. Ballistic Missile Defense Organization, now the Missile Defense Agency, undertook development of the next-generation Patriot Advanced Capability-3 missile, designed to intercept and destroy tactical ballistic missiles, aircraft and cruise missiles under all battlefield conditions.

Both PAC-2 and PAC-3 missiles are single-stage solid rockets. The older PAC-2 is 17 feet long, weighs almost 2,000 pounds, carries a 200-pound fragmentation bomb, flies at Mach 5 and is supersonic within a second after launch. The PAC-2 flies straight toward the incoming missile and then explodes when it senses the point of nearest approach. The explosion will either destroy the incoming missile with fragments from the fragmentation bomb, or knock the incoming missile off course so it misses the target.

The PAC-3 missile, unlike PAC-2, is designed to actually hit the incoming target so that the target is destroyed. This head-on collision between the interceptor and the threat missile releases massive amounts of kinetic energy, which greatly increases the probability of destroying the threat warhead and its contents. These warheads potentially include chemical and biological agents. This is called “hit to kill” technology.

The biggest difference between the PAC-2 and the PAC-3—and the thing that enables PAC-3 to actually hit a target head-on—is its built-in radar transmitter and guidance computer. Once launched, the PAC-3 turns on its radar, finds the target and, using the missile’s increased agility, guides itself in for a direct hit.

The achievement is even greater than hitting a bullet with a bullet: Both the incoming target missile and the outbound PAC-3 missile are traveling much faster than a typical bullet, closing on one another at a combined speed of up to Mach 10, or two miles (3.2 kilometers) per second. At that speed there is no room for error—if the missile miscalculates by even 1/100th of a second, it will be off by more than 100 feet (30 meters).

Boeing’s role in the Patriot missile program has been the development and production of the seeker for the PAC-3 Missile—the “eyes” of the missile that guide it to the target and destroy it on impact. The seeker provides active guidance data to the missile, which enables it to acquire the target shortly before intercept, select the optimal aim point and initiate terminal, or final course, guidance to ensure target kill.

The PAC-3 seeker is the culmination of more than 20 years of technical evolution through technology demonstrations, flight test programs and finally the engineering and manufacturing development program. What began as a technology study by a handful of Anaheim, Calif., engineers and technologists has resulted in the only proven and fielded terminal missile defense product in the U.S. Army’s inventory.

A team of 100 Boeing employees produces the seeker at the company’s Huntsville, Ala., facility. The facility’s production area includes a high-reliability electronics assembly area, an anechoic (echo-free) test chamber for calibration and acceptance testing, and an area in which to conduct environmental stress screening. Another 40 Boeing employees produce and test circuit card assemblies in El Paso, Texas. The Boeing program office, led by Ron Eckels, is based in Anaheim, as is the design authority for the seeker. The design team provides design support to production personnel and tracks state-of-the-art technologies being made available by the evolving electronics industry.

Operating two shifts Monday through Friday and one shift on weekends, the PAC-3 team at Huntsville has delivered 234 seekers in support of PAC-3 Army contracts. Currently, Boeing is under contract to build 100 seekers by February 2005 and recently received a contract to deliver an additional 159 seekers between then and February 2006. Beyond that the PAC-3 future is bright with proposals submitted for up to 624 additional seeker deliveries between 2006 and 2008.

“The PAC-3 team is up to the challenge,” said Debra Rub, vice president, Air and Missile Defense Systems. “Their production rates have been outstanding. They are top-notch performers and can be proud of the role they play in protecting U.S. armed forces, our assets, our allies and our freedom.”

Just ask them. “The ultimate reward of my work is knowing that when a soldier has to fire a PAC-3, it’s going to perform,” Integration tester Doug Alston said. “Lives are on the line, and it makes me feel good knowing that the system is going to do what it’s supposed to do.” Alston is one of 50 employees who moved to Huntsville from Duluth, Ga., in 1999 in order to remain on the PAC-3 production team. The production work was moved to Huntsville as part of Boeing’s consolidation strategy following the company’s acquisition of the defense and space units of Rockwell and the merger with McDonnell Douglas.

Assembler Andrea Smith added: “I have a feeling of tremendous accomplishment knowing that we are building something that has proven itself 100 percent in terms of saving lives.”

To technician David Yielding, the significance of the PAC-3 program was underscored during a visit to the Huntsville facility by U.S. Army Capt. Aaron Montgomery and his battalion commander, Lt. Col. Rod Burke, a few months after the beginning of Operation Iraqi Freedom. Montgomery fired the first PAC-3 during Operation Iraqi Freedom. The missile he fired destroyed an Iraqi ballistic missile headed for the Coalition Force Land Component where thousands of coalition service members were stationed. “Talking face-to-face with the soldier who actually fired the missile and hearing him tell us the PAC-3 saved thousands of lives really brings homes the importance of the work we’re doing,” Yielding said.

“It is impossible to calculate the number of lives that you saved,” Burke said to the PAC-3 team at Huntsville. “When my battalion left for the war, I made a commitment to bring all my soldiers back safely—the PAC-3 seeker that you built made that possible. My soldiers thank you, I thank you, and our families thank you.”

diane.l.stratman@boeing.com