"The single biggest element in the program is space-based sensors," he said. The sensors would provide the information needed to launch and direct anti-ballistic missiles and track Soviet warheads. That research accounts for about 40% of his agency's budget. If the hardware to do the job were added, "about 50% of the program would be going into surveillance," he said.
He said such a system would involve "tens of millions of detectors in space."
One point both men agreed on is that the kind of anti-missile defense system envisioned by the Reagan Administration would involve possibly hundreds of orbiting platforms. While those platforms would serve many different functions, Yonas seemed to rule out lasers as one of them.
Giant space-based lasers would require enormous amounts of electrical power in orbit, plus they would be difficult to protect.
Yonas said that the newest approach--bouncing the beams off orbiting mirrors--will be tested "in about a month in Hawaii," apparently a reference to an experiment with the space shuttle Discovery. A laser beam, fired from the Hawaiian island of Maui, will be aimed at a small reflector on the shuttle.
Garwin challenged the idea of using mirrors, saying, "They are all vulnerable, and that's why we shouldn't do it."
Vulnerability, he said, threatens "Star Wars" at every turn.
"Satellites," for example, "are costly to put up and cheap to shoot down," and any anti-missile system would depend on hundreds--if not thousands--of satellites.
He said development of such a system would be far more unpredictable than sending astronauts to the moon.
"The moon didn't shoot back or jump out of the way," he said.