Can We Stop a Nuke?

From the impossible dream of a space-based shield, missile defense has come down to Earth. But will it work?

Launch of a Ground-Based Interceptor from Vandenberg Air Force Base in 2013. (Missile Defense Agency)
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Computers would feed targeting data to the interceptor missiles via fiber optic cables and satellites. These initial “weapon task plans” must arrive before the missiles blast out of their holes so that their nozzles can be pointed at the incoming warheads.

All that must happen within 16 minutes. Any later and the defense would fall to radar-guided rockets, or “terminal defenses,” fired as the warheads are falling through the atmosphere toward their intended victims. Most terminal systems, such as variants of the Patriot missile battery and the Terminal High Altitude Area Defense, are designed to target short- and medium-range theater missiles, not long-range ones.

Assuming the interceptor missiles make it into the air by their deadline, information from ground-based radars will provide the interceptors with updated information on the targets’ location as they rise to meet them. As the distance closes, the interceptors will release their kill vehicles.

By this time, the enemy missiles will have dissolved into a hail of objects streaking toward the United States at perhaps 15,000 mph. Inside that cloud of warheads, inflated Mylar decoy balloons, shaped and painted to look like real warheads, could distract the kill vehicles, if not for the guidance given by their infrared eyes and small thrusters. If all goes well, each kill vehicle will collide with an incoming warhead at about 18,000 miles per hour.

Until new sensors are created, finding the real warheads among the decoys requires a shotgun approach: “If I can’t discriminate what’s a decoy and what’s a warhead, I have to launch interceptors at both of those objects,” Obering says.

But in September 2006, the goal was to direct a single kill vehicle to a single target warhead, using upgraded tracking radar at Beale Air Force Base in California. The Beale radar was built during the cold war to bounce radar waves off incoming Soviet missiles with just enough fidelity to tell the president: “We have a missile and it’s going to impact in the New York or Chicago area,” Obering says.

During the hiatus between launches, the missile agency put engineers and software experts to work installing new computer processors and software to enable the cold war radar to track objects with greater precision. Similar work is under way at the Fylingdale early-warning radar installation in England, enabling it to track missiles that might be launched westward from Iran. New sea-based platforms will supplement the early-warning radars. The more eyes available, the better, say planners.

The Beale radar upgrades were but one of many technical goals of September’s test. An underlying goal was to restore confidence in the missile agency itself. Obering’s reputation was riding on the 55-foot-long missile streaking across the Pacific, receiving guidance (he hoped) from the radar at Beale.

As the witnesses watched, the red and blue lines of the missile flight paths closed in on each other. Suddenly, 23 minutes and 20 seconds into the test, the altitude and velocity numbers froze.

Through an audio link Obering could hear the jubilant reaction inside the fire control room at Schriever Air Force Base near Colorado Springs. “Everybody started screaming,” he says. “We knew we had achieved the intercept.”


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