(6 of 10)
Some areas, including PAR sites that must be kept intact to maintain defenses, would also be protected by Sprints. These sharp-nosed, two-stage missiles, with a payload of a few kilotons (equal to thousands of tons of TNT instead of Spartan's millions), are aimed at warheads that have eluded Spartan. By this time the attacking vehicle has passed into the atmosphere and is traveling at about 18,000 miles per hour. To kill it before it explodes near the earth, Sprint must travel at fantastic speed. Its exact acceleration ability is secret, but the Army talks of Sprint's climbing 50,000 ft. "in two heartbeats." Sprint would make its interception between 25 and 40 miles from its launch site, relying primarily on the blast and heat effects of its own detonation to incapacitate the aggressor weapon's innards. As with the Spartan, its purpose is not to blow up the opposing RV (reentry vehicle)—which would dump much lethal fallout on the territory below—but to detonate close enough to defuse the warhead. Sprint's own bang, however, would cause a degree of radioactivity.
The entire scenario, of course, is theoretical. Dr. Jerome Wiesner of M.I.T., who was John Kennedy's science adviser, notes that Sentinel is "untestable" under anything approaching simulated combat conditions. The warheads have been detonated in underground explosions, to be sure, and the missiles that carry them have been launched, but the 1963 nuclear Test-Ban Treaty prohibits nuclear explosions in space. Even without this veto, it would be fantastically difficult to stage a realistic war game featuring ABM.
The Buts Mount
"We lack vital data about the attacking missiles and about ABM performance," says Wiesner, who calls Sentinel "that Edsel of ABM's." "So we just pick some numbers that seem rational and we use them to make whatever point serves our purpose." Ted Kennedy quotes the Budget Bureau's Richard Stubbing, who evaluated $40 billion worth of aircraft and missile projects initiated since 1955 and concluded that "less than 40% of the effort produced systems with acceptable electronic performance." The implication, of course, is that if technology cannot perfect relatively simple devices, it seems highly improbable that the infinitely complex ABM will work any better.
Some critics, notably Cornell Physicist Hans Bethe, a Nobel prizewinner, and Dr. J. P. Ruina, former director of the Pentagon's Advanced Research Projects Agency, are more lenient. In testimony last week before the Senate Disarmament Subcommittee, they did not attack Sentinel's basic hardware. Bethe, in fact, called the components "well designed" and said he went along with the idea that Sprints should be used to protect Minuteman sites. Both Ruina and Bethe, however, were particularly critical of Spartan's role.
Like McNamara and others, Bethe has long doubted that any defense system can effectively discriminate between real warheads and a variety of decoys and "penetration aids" that the offense is likely to use. Spartan, operating in space, faces a handicap in this area because it is only after the real birds