The ever-evolving "Star Wars" space-based defense program is now staking its future on an embryonic technology known as "Brilliant Pebbles," swarms of new mini-missiles designed to detect, track and pulverize incoming Soviet nuclear missiles in flight.
The new scheme marks a radical departure from previous "Star Wars" designs and represents, some officials say, the last hope for the costly and controversial anti-missile program, which is formally known as the Strategic Defense Initiative or SDI.
Brilliant Pebbles was endorsed by Defense Secretary Dick Cheney this week as the centerpiece of Pentagon anti-missile research. He indicated that if two years of intensive research on the new concept fail to yield results, the entire "Star Wars" program would be delayed and would have to be re-evaluated.
Critics immediately assailed the idea as unaffordable and technically impossible, charges they have leveled at all previous "Star Wars" proposals.
The Brilliant Pebbles idea, devised by weapons scientists at California's Lawrence Livermore National Laboratory, would place thousands of miniature interceptor rockets encased in solar-powered "life jackets" in space awaiting orders to blast enemy missiles as they arc toward the United States.
The three-foot-long, 100-pound rockets would be guided by an electronic "brain" with the capacity of a Cray supercomputer shrunk to the size of a deck of cards. The rockets would hurl 10-pound, non-explosive projectiles--the "pebbles"--into thin-skinned ballistic missiles at ultra-high velocity.
Pentagon officials estimate that the Brilliant Pebbles interceptors can be built for less than $500,000 each because of dramatic advances in sensors, computers, guidance systems and thruster rockets.
Lt. Gen. James A. Abrahamson, who recently retired as director of the "Star Wars" program, estimated that a Brilliant Pebbles system could be deployed in space for $25 billion, compared to $69 billion for last year's model, known as the space-based interceptor (SBI).
Cheney and President Bush are intrigued with the concept, which offers the elusive promise of an affordable and survivable space-based missile defense.
Program in Jeopardy
But if Brilliant Pebbles fails to meet their expectations, officials concede, the whole "Star Wars" program--on which nearly $18 billion has been spent already--could be in jeopardy.
Cheney told Congress last week that if the Brilliant Pebbles concept does not work out after an aggressive research and testing schedule, the entire SDI program will be pushed back two years, meaning that the first deployment of a system would not take place until after the turn of the century.
Democrats in Congress have already grown impatient with the cost and the apparent slow progress of the "Star Wars" program. Failure of yet another scheme could doom the cherished project of former President Ronald Reagan.
"Every year or so, there's a big new idea that turns the program around. For a program that's spent $17 billion already, this is a bit disturbing. This program appears to have very shallow roots," said Bruce McDonald, an aide to Sen. Dale Bumpers (D-Ark.), an influential SDI critic.
Brilliant Pebbles is a refinement of an older concept known as "smart rocks," which were larger non-explosive projectiles carried aboard rockets. Pebbles are smaller and have much more advanced targeting and guidance systems, according to the system's designers.
But Brilliant Pebbles still faces grave technical challenges. Although early tests of the rocket propulsion and maneuvering systems have been encouraging, the sensor "eyes" and computer "brain" of the missile remain on the drawing board.
Any space-based anti-missile system confronts a difficult technological task--to identify ballistic missiles in the very early stages of flight, to pick out the rocket body from its large plume of fire, to track and then home in on the target before the weapons-carrying "bus" separates and releases the nuclear warheads.
SDI officials claim rapid progress in these tasks and say that advances in miniaturization have shrunk the sensors and computers to remarkable compactness. In addition, the cost of these systems has come down so that the missiles can be built in quantity and deployed for less than $500,000 each.
"The issue is mass production," said Charles J. Infosino, who oversees the Brilliant Pebbles program for the Pentagon's Strategic Defense Initiative Office. "We're attempting to build Fords on an assembly line. . . .
"The problem now is reliability. But if we have thousands of them up there, so what if we lose a few?"
Infosino noted that with between 5,000 and 10,000 Brilliant Pebbles in space, none is an attractive target for Soviet countermeasures. The old space-based interceptor system, which housed 10 or more larger interceptor rockets in big solar-powered "garages," would offer easier targets for Soviet anti-satellite weapons.
Another advantage, according to Pebbles proponents, would be eliminating big communications and guidance satellites that previous SDI designs required.
"Each Pebble carries so much prior knowledge and detailed battle strategy and tactics, computes so swiftly and sees so well that it can perform its purely defensive mission with no external supervision or coaching," Lowell L. Wood, a senior staff physicist at Livermore Laboratory and father of the Brilliant Pebbles concept, wrote last year.
Pure fantasy, replied Marc Rotenberg, a computer analyst and spokesman for Computer Professionals for Social Responsibility, a Palo Alto-based organization critical of "Star Wars."
"In 10 years, we may well have Crays the size of cigarette boxes. But the more subtle and significant problem is what happens to the software--the programming," Rotenberg said.
He argued that the tolerance for software errors is extremely small, because once the Pebbles are given the go signal, the interceptors are to act without further human guidance. A miscalculation by an errant Pebble could cause not only loss of human life but massive economic damage if communications satellites are destroyed, Rotenberg said.
'BRILLIANT PEBBLES'--The latest twist in "Star Wars" technology is "Brilliant Pebbles," mini-missiles that would detect, track and intercept incoming Soviet nuclear missiles. The plan calls for stationing thousands of the interceptors in space.
Source: Department of Defense.