Little Room for Error in Catching a Missile

The first line of defense in America’s next antimissile system fails or succeeds in a window of 90 seconds.

That’s all the time there is, designers estimate, for a satellite to detect the flash of an enemy launch, determine that it is real and send off a counter-missile from the ground.

It all happens too fast to include a human in the loop.

“Time is of the essence,” said Craig van Schilfgaarde, the Northrop Grumman Corp. engineer in charge of the project.

Known as “boost-phase” interception, it is designed to be the first “layer” of defense, firing rockets at enemy missiles just after launch, when they are most vulnerable.

The military has already deployed parts of the two other layers in the missile defense system -- one targeting missiles as they cruise through space in midflight and the other aimed at descending warheads when they are just above their targets.

The three layers are the cornerstone of President Bush’s plan to defend the country against rogue nations, such as North Korea and Iran, that are gradually developing the ability to produce weapons with global reach.

But the system has already faced serious problems.

The midcourse missile failed a test Dec. 15 when it shut down before leaving its silo at the Ronald Reagan Test Site at Kwajalein Atoll in the central Pacific Ocean. It was the second failure in a major test in two years.

On Dec. 17, the Pentagon announced it was dropping plans to activate the existing pieces of the missile defense system this year because it had not completed full “shakedown” testing.

The boost phase reaches into an even more complex realm of design, in part because of the speed with which it must identify and destroy an enemy missile.

The payoff could be big. Terry Little, executive director of the government’s Missile Defense Agency, said the boost-phase interceptors could destroy 80% to 90% of enemy ICBMs, leaving the other layers to take care of the rest.

But a recent Congressional Budget Office technical report suggested that the boost-phase system, scheduled for deployment in 2011, would press the far edge of what was physically possible in an antimissile system.

Philip Coyle, who headed the Pentagon’s testing office during the Clinton administration, said the design of the boost-phase system was already buckling under its own complexity.

“The [congressional] analysis confirmed that boost-phase missile defense isn’t practicable,” Coyle said. “You can’t fool mother nature.”

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Today’s missile defense programs were inspired by President Reagan’s promise to end “nuclear blackmail” with his Strategic Defense Initiative, a plan to shield the nation against an all-out nuclear attack using satellite-fired interceptors.

Dubbed “Star Wars” by opponents in Congress, Reagan’s program fell victim to technical dead-ends, cost overruns and concerns that it would violate the 1972 Anti-Ballistic Missile Treaty, which banned nationwide missile defense systems.

Missile defense languished until 2002, when Bush withdrew from the treaty, which he considered a Cold War-era anachronism.

Instead of trying to defend against all-out nuclear attack by a major power, today’s plan targets the less-advanced arsenals of emerging nuclear states.

The entire system is budgeted at about $50 billion over the next five years and is likely to cost several times that amount to build, deploy and maintain.

In July, the Missile Defense Agency began deploying the midcourse interceptors in Alaska. A second battery is scheduled for deployment next year at Vandenberg Air Force Base in Santa Barbara County.

Mobile Patriot antimissile systems, a key part of the descent layer (also known as the terminal layer), have been deployed.

A year ago, Northrop won a $4.5-billion contract to develop the boost-phase interceptors. Congress has approved $348 million for the current fiscal year.

Boost defense “would never be able to handle every situation that anybody could conceive of,” said Little of the Missile Defense Agency. “But we could handle enough that we could look at ourselves as an 80% or 90% solution.”

The allure of striking enemy missiles in the boost phase is that they are easily identified by their plumes just after launch and, because they are ascending, cannot use their full bag of tricks to dodge and deceive.

So far, the only part of the boost-phase system that has been built is a single camouflaged launcher with dual launch tubes. The 30-foot-long trailer is parked beside a pile of scrap metal outside a Northrop warehouse near Baltimore.

Little said that the system would not need the technical leaps that Star Wars required.

“The technology is in hand,” he said. “It does not hinge on any kind of a technology breakthrough.”

The trick is getting the pieces to work together -- all in the space of a few minutes at most.

To destroy a missile in the boost-phase requires an unprecedented coordination of space-based sensors, signal-analysis computers, interceptor agility and enough sheer thrust to lift a 10-ton object to about 20 times the speed of sound in less than a minute.

Each interceptor consists of a two-stage booster, followed by a liquid-fuel rocket that steers the kill vehicle on the last leg of its journey to the target. It would travel at about 13,400 mph.

After infrared sensors on satellites detect the enemy launch, interceptors would be directed to the target by terrestrial command stations that constantly update the target’s flight path. Onboard sensors would take over at close range.

The interceptor’s goal is to strike the enemy missile before the warhead separates from its rocket, usually at an altitude below 300 miles.

The interceptors gain speed and agility because they don’t have to haul a heavy explosive warhead. Instead, they are designed to destroy their target with the force of collision.

This “kinetic” attack -- described as hitting a bullet with a bullet -- demands uncanny accuracy.

“What is the precision required? I would characterize it as within less than a meter” over hundreds of miles traveled, he said.

To catch an ICBM streaking across the sky, interceptors would be placed about 600 miles back from the target’s launch site on land or sea.

The military also is developing an airborne laser to shoot down ICBMs as they ascend.

“These guys are very, very immature in their development,” said Northrop’s Van Schilfgaarde, referring to the missile programs of North Korea and Iran. Even if their technology improves, he said, “we have tremendous flexibility.”

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Even before it has gotten off the drawing boards, the boost-phase system has drawn criticism from a variety of scientists and engineers, who see it as technological hubris.

It’s a needlessly costly and complicated system for a threat that could, for example, be more easily neutralized with preemptive strikes, said Theodore A. Postol, a missile expert at MIT.

The agency’s boost-phase plan faces a conundrum that has plagued missile defense since World War II: Technology advances tend to favor offense over defense.

The Missile Defense Agency said that 27 nations, including several with unstable governments, have ballistic missiles. No rogue nation can deliver a nuclear or chemical warhead to the United States, but each is striving to improve its technology. And proliferation is accelerating.

The technical challenges of boost-phase defense are best captured in the problem of Yazd, an ancient city of about 500,000 in the geographic center of Iran.

To down a missile launched from Yazd and other potential Iranian launch sites, up to seven interceptor batteries would be needed in such areas as Iraq, Turkmenistan and the Gulf of Oman -- areas that might be hard to reach or secure.

“If you can’t get in close, you don’t have a boost-phase capability,” Van Schilfgaarde acknowledged.

The Congressional Budget Office report said that defending against missiles from large countries might require interceptors that travel up to 22,000 mph -- beyond today’s technology.

One of the most complex parts of the boost-phase interception is its sensing and targeting system. Launch commands would have to be automated because the launch window would close long before a human being could evaluate sensor data, particularly if several ICBMs were fired at once.

Yet spy satellites that would direct the action are far from foolproof.

“Sensors are subject to huge [signal] noise problems, so you have to be careful not to launch too soon,” said David Mosher, an antimissile expert with the Rand Corp. in Arlington, Va.

“Even bonfires are a problem,” said Coyle, the Clinton Pentagon official. “If you make them hot enough with chemicals, to our satellites at first glance they look like a rocket going off.”

Bigger doubts involve interceptor accuracy.

Midcourse missiles, which use a similar kinetic attack, have a spotty record. They have hit targets in five of nine tests; succeeding only under what Coyle regards as rigged conditions. During the recent test in Alaska, the rocket failed to leave its silo.

Even against slower-moving short- and medium-range rockets, antimissile systems have been troubled. Patriot interceptors failed to hit nearly all of their targets during the 1991 Persian Gulf War, according to a congressional investigation and an analysis by outside scientists. In the Iraq war, Patriots mistakenly downed two coalition aircraft.

For boost phase, a glancing blow could prove worse than a simple miss. If the interceptor hits the missile body -- an error of a couple of feet over hundreds of miles traveled to the target -- an Iranian weapon aimed at San Francisco, for example, could end up in Russia.

The Missile Defense Agency regards the risk as unfortunate but acceptable.

“Everything else being equal, a warhead not hitting its intended target is a good thing,” Little said. As bad as it would be to destroy another populated area, he added, “what’s the alternative? It’s worse.”

The interceptors could also be mistaken as hostile missiles by nearby nations.

“The interceptor trajectories from North Korea are generally to the northwest,” noted a critical 2003 report from the American Physical Society, a leading scientific organization. “An interceptor fired in defense runs the risk of triggering retaliatory action by China or Russia.”

Little said critics’ concerns and a funding cut by Congress prompted his agency to restructure the development program for the boost-phase missiles.

Now a preliminary system will be produced before full development. If Northrop can’t demonstrate that the components work within three more years, the agency may rethink or cancel the contract.

But the alternatives are also problematic.

Some advocates of missile defense in Congress insist that only a space-based system -- a new Star Wars -- could provide sure global coverage.

But an orbital defense would pose even more formidable technical challenges and cost up to $224 billion, the congressional report said.

To mount a credible orbital system against North Korea and Iran, up to 10,909 interceptors, together weighing more than 1,000 metric tons, would be needed, the congressional report said. That would be more than twice the projected weight of the completed International Space Station, the largest space assembly in history.