Of all the things that could go wrong in developing a missile defense system, Pentagon officials figured that the booster would be among the least of their worries.
They figured wrong.
Despite decades of U.S. experience building rockets to launch satellites, space shuttles and other craft -- and despite the involvement of such industry giants as Boeing Co. and Lockheed Martin Corp. -- the booster project veered far off course. Its persistent problems have led to a two-year hiatus in intercept tests and driven the Pentagon to fall back on an alternate booster design.
The troubled booster program illustrates the difficulties the Pentagon has confronted in pursuing a workable missile defense system -- and doing so within the administration's compressed timetable of deploying by the end of 2004. Interviews with many who have worked on the project or have closely observed it point to a long history of miscalculations.
Projections were overly optimistic, technical challenges were underestimated, designs were faulty, and workmanship was poor. Repeatedly over the past few years, program officials have declared the corner turned, only to acknowledge months later, with renewed frustration, that problems have persisted.
"The booster story typifies the risks we run when we think we know too much, when we're very comfortable with something," said Air Force Lt. Gen. Ronald T. Kadish, who recently left the Missile Defense Agency (MDA) after five years as director. "We didn't pay attention to the risks involved in that part of the program."
The booster's role is to carry a "kill vehicle," a 120-pound package of sensors, computers and thrusters. Once in space, the kill vehicle separates from the booster and speeds toward an enemy warhead, destroying it in a high-speed collision.
In producing the booster, Pentagon officials had hoped at the outset to save money and accelerate development by relying on commercially proven motors assembled largely from off-the-shelf components.
"Back in 1999, we thought off-the-shelf technology was kind of a slam-dunk," Kadish said in an interview.
But the missile defense mission presented some particular design challenges. In contrast with satellite shots, where the trajectories are known, the booster in a missile intercept mission must be prepared for a wide variety of flight paths, ranging from relatively flat to very lofted. The flatter trajectories, Kadish said, "require more thrust control, and that became more of a challenge than most designers appreciated."
Additionally, Pentagon officials wanted the interceptors packaged in canisters to make transporting and handling easier. That affected performance, though, and complicated maintenance and repairs.
Boeing, which already had responsibility for overseeing the entire missile defense system, won the contract in 1998 for producing the booster. Quality-control and design problems began to emerge early.
One especially nettlesome problem arose from a requirement that the interceptors might have to stay in the ground for years before being fired. This precluded use of hydraulic systems to control the boosters' nozzles, because such systems are susceptible to leakage and malfunction.
So the only option was a battery-powered system. But none had ever been produced for such a powerful booster.