Raytheon's Bill Carpenter, left, and Chuck La Due with a full-scale model of the "exoatmospheric kill vehicle," developed to destroy incoming missiles. (Raytheon Co. Photo)

TUCSON – Sleek, it isn't.

Propped on a metal stand in a brightly lit workshop here beneath the Arizona desert, the military's most controversial new weapon hardly looks like the silver bullet that can stop an enemy missile from obliterating Washington or some other U.S. city.

With a long, cylindrical canister on its front end holding lenses and panels of sensors, and a jumble of thrusters, fuel tanks, plumbing tubes and wiring all exposed at the rear, the device has the makeshift appearance of a jet-propelled telescope. Just 55 inches long and weighing 120 pounds, it is small and light enough to fit in the back of a pickup truck.

"It may look kind of messy, certainly in contrast with atmospheric missiles, which have aerodynamically sleek systems," acknowledged Bill Carpenter, who manages the program for Raytheon Co.

But in the vacuum of space, where the interceptor is designed to soar atop a rocket, then break free and home in on an enemy warhead, streamlined looks aren't important. Results are.

A first intercept attempt in October scored a solid hit and has given the Pentagon fresh confidence that it is on the right track with the "exoatmospheric kill vehicle," or EKV, following a history of failures with earlier prototypes. At the same time, critics argue that the test was simplified and carefully choreographed to ensure success. They also say that technical glitches during the test have only reinforced their doubts about the weapon's feasibility.

After a crucial second flight test over the Pacific Ocean this Tuesday and a third intercept attempt slated for April, President Clinton is due to decide this summer – in the middle of the political convention season – whether to commit to a five-year deployment plan and authorize construction of interceptor silos in Alaska.

The quickening prospect that the United States might field a national antimissile system, after years of contentious debate and aborted experiments, has emerged as a key defense issue in the 2000 presidential campaign.

Republican front-runner George W. Bush says he would deploy a national shield even over Russian objections. Same for John McCain, the Arizona senator also vying for the Republican nomination.

On the Democratic side, Vice President Gore has been more circumspect, conditioning his support for a protective antimissile umbrella on further testing and the outcome of talks with Russia on amending the 1972 Anti-Ballistic Missile Treaty. Former senator Bill Bradley (D-N.J.) is the most skeptical of the leading candidates, calling for more research and voicing concern about the diplomatic implications of fielding a national system.

Evidence that North Korea and Iran are moving to acquire ocean-spanning missiles is lending a sense of urgency to the development effort. But whether an antimissile system would offer the best defense still is a matter of sharp debate among scientists and arms control experts.

Doubts About Reliability

"They're moving too fast, heading for a deployment decision based on primitive, simple developmental tests," said Joseph Cirincione, director of the Non-Proliferation Project at the Carnegie Endowment for International Peace. "That's not the normal way to proceed with a weapon system. We've done it with some other programs, like bombers, and paid the price with years of very expensive fixes. But these interceptors are supposed to work the first time."

Critics warn that building a shield against missiles could ignite a new arms race with Russia and China as well as roil relations with European allies. They also predict that the cost of constructing an antimissile system will run much higher than officially forecast. When Clinton submits his fiscal 2001 budget to Congress next month, it will reflect an increase of $2.2 billion for the system over the next five years, a 20 percent jump over the $10.5 billion price tag projected just one year ago.

Perhaps most of all, critics harbor doubts that the system can work reliably and effectively. Efforts to hit a missile with another missile, they argue, are prone to malfunction and vulnerable to deceptive actions by adversaries. As a recent case in point, they cite last October's flight test, which, while ending in an intercept, got there in a roundabout way.

During the test, the EKV failed at first to locate its intended target. One reason for this, officials said, was that the interceptor drifted slightly off course due either to a navigational problem – an incorrect star map had been loaded into the EKV's computer – or an uneven burn rate in the decades-old Minuteman rocket that boosted the EKV into space.

So the EKV aimed itself instead at a decoy balloon meant to simulate the kind of measures an enemy might toss up to confuse U.S. interceptors. Only late in its flight did the EKV find the right target – a mock warhead – and ram into it.

Critics questioned whether the interceptor would ever have found the target had there been no decoy balloon. "They don't know if the hit was a success or a lucky shot," said Tom Collina, director of the Arms Control and International Security Program at the Union of Concerned Scientists.

But Defense Department officials, discussing the test glitches publicly for the first time last week, insisted the EKV's ability to overcome them was even better proof of the weapon's viability. "I remind you to keep one thing in mind: The test succeeded. The target was hit," Pentagon spokesman Kenneth Bacon said.

Here on the outskirts of Tucson, home of Raytheon's Missile Systems unit, the engineers and technicians dress casually in open-neck shirts, eschewing jackets or ties, but speak with intensity and confidence about their prized project, the EKV.

A poster in a stairwell leading to the EKV laboratory depicts an interceptor arcing across the sky. The caption reads: "It's not magic, it's discrimination."

Finding the Right Target

Discrimination – that is, getting the EKV to distinguish a warhead from decoys and chaff thrown up to sow confusion – has posed the last major technological stumbling block to the limited missile defense system that the Clinton administration has in mind. Raytheon officials credit advances in infrared seekers and computer processing technology for improving the EKV's ability to identify the right target.

Discrimination works this way: After detecting an object in space, the EKV's sensors measure its heat and light intensity, as well as its movement and position relative to any neighboring objects. Onboard computing chips – with processing power equivalent to a mainframe – analyze the information in milliseconds, checking it against preprogrammed profiles of enemy warheads compiled by U.S. intelligence agencies.

Traveling at speeds that can exceed 14,000 mph through the subzero temperatures of space, the EKV then selects the target and maneuvers itself into a collision, hitting within centimeters of a predetermined point on the warhead to ensure obliteration.

The Pentagon plans initially to deploy 100 land-based interceptors, enough to knock down a handful of missiles fired by a "rogue state" such as North Korea or Iran. This represents a far less ambitious undertaking than President Ronald Reagan's vision of a vast "Star Wars" system involving thousands of space-based lasers and interceptors to ward off a massive attack.

But even the limited approach has many moving parts that make it – in the words of the Pentagon's acquisition chief, Jacques Gansler – the most complex weapon ever developed.

In addition to the EKV, military satellites will play a role in detecting launches; ground-based radars in Alaska, California, Massachusetts, Britain and Greenland will track incoming warheads; and a specially designed battle management center in Colorado Springs will process the information, determine possible intercept points and issue launch and guidance commands to the interceptors.

The system's complexity increases the likelihood of something going wrong and, critics say, decreases its reliability. It also could prove obsolete, according to its detractors, given the potential for decoys and other countermeasures to throw an EKV off target.

"What advocates of the system want you to believe is that adversaries will be smart enough to build intercontinental ballistic missiles and nuclear warheads but not smart enough to figure out ways of foiling the EKV," said Ted Postol, a professor of science, technology and national security policy at the Massachusetts Institute of Technology. "That doesn't sound plausible."

Much of the debate about the system's effectiveness revolves around decoys. Specialists such as Postol, his MIT colleague George Lewis and John Pike of the Federation of American Scientists in Washington argue that the system can be readily defeated by, for instance, dispersing lightweight warhead replicas alongside the real thing.

Even easier and more effective than making a decoy look like a warhead, these critics contend, would be to make a warhead look like a decoy by wrapping it in a metal-coated Mylar balloon. Alternatively, the warhead might be disguised by placing it in a shroud cooled by liquid nitrogen, rendering it invisible to an infrared homing interceptor.

Confidence and Concerns

Raytheon and Pentagon officials dismiss some of these scenarios as unrealistic and others as posing little problem for the EKV. They say the universe of countermeasures is known, and the interceptor will be programmed to avoid being fooled.

"Some of the postulated countermeasures that I've heard about are absurd," Carpenter said. "They are things that our best people at the national laboratories have not been able to do. So I don't know how you can postulate a developing country doing them."

Carpenter said his most serious concern is not a deception measure but the potential effect of a nuclear explosion on EKVs in flight. Radiation from a nuclear blast in space – set off either intentionally by an adversary or as a result of an intercept – could disrupt the electronics inside EKVs that are chasing other missiles.

To guard against this possibility, EKVs are being hardened with tungsten, and their electronic systems rigged to shut down momentarily in the event of a blast.

For all their expressed confidence, however, officials at Raytheon and the Pentagon acknowledge that the interceptors cannot be expected to hit targets 100 percent of the time. The Defense Department's contract with Raytheon requires each EKV to have a success probability of about 90 percent.

To increase the chances that the system will prevent even a single missile tipped with a nuclear warhead or germ warfare agents from slipping through, the Pentagon plans to fire three or four interceptors at each incoming missile in the event of an attack. With an initial 100 interceptors, the U.S. shield thus could handle about 25 or 30 missiles.

In a second deployment phase, the Pentagon plans to base another 100 or so interceptors at a second launch site somewhere in the continental United States, enabling the system to destroy a volley of up to several dozen incoming missiles.

These numbers help explain how the United States can insist to the Russians, who have more than 5,000 nuclear missiles, that the system would pose no real threat to them.

"The thing we can't defend against is a massive attack," Carpenter said. "The Russians could clearly overwhelm the system."

Accelerated Development

However quarrelsome the dispute over the system's effectiveness, there is consensus on at least one point: The weapon is being developed uncommonly fast.

For much of the 1990s, the Pentagon ran separate development programs for the EKV, ground-based radar and battle management systems. In 1998, it hired Boeing Co. to coordinate the effort and pull the elements together into a coherent whole.

"The Defense Department generally takes 10 to 14 years to invent something," said Lt. Gen. Ronald Kadish, who heads the Pentagon's Ballistic Missile Defense Organization. "Right now, we're capitalizing on a lot of investment made in past years, but we're essentially going from program start-up to deployment in about half the usual time."

Such acceleration has led to problems. A recent report by a panel of outside experts, commissioned by the Pentagon and headed by retired Air Force Gen. Larry Welch, concluded that the program is plagued by inadequate testing and management lapses as well as hardware shortages.

Lacking spare parts for both testing and backup, Raytheon officials have had to conduct experimental tests on the same EKV models designated for flight trials. This has placed unusually heavy stresses on the flight models, raising the risk of fatigue and failure.

"We have beat the flight hardware up much more than we would normally do, banging on it, smacking it, running multiple cool-downs that have caused significant thermal stresses," Carpenter said.

One of the most nerve-racking moments for Carpenter came last summer, when engineers sought to measure how the EKV's inertial measurement unit, which helps guide the vehicle, would withstand the shock of the thrusters firing. To simulate the stress, they decided to ram the IMU with a steel ball – again and again.

"The engineering community got into this enormous argument" over the heights from which to drop the steel ball, Carpenter recalled. "They dropped it everywhere from three feet up to six feet. They did it until the program manager told them they weren't going to do it again. . . . We must have dropped that damn ball 40 or 50 times."

The part never broke, either during the ground test or, later, in the October flight test. But Carpenter recounted the episode as an example of the strains under which the whole program is operating.

Senior Defense Department officials say they have taken steps to remedy such concerns, authorizing the purchase of additional spare parts and seeking more money for additional ground testing and simulation. Indeed, while the October flight test was delayed several months as engineers encountered various problems, the countdown for Tuesday's trial is proceeding more smoothly, officials said.

But meeting the proposed deployment date of 2005 is still considered – by experts both inside and outside the Pentagon – a highly risky proposition.

"What high risk means is that any failures or slips must be dealt with very quickly," Kadish said. "We may end up having to slip schedule in the end, but we're doing everything we can to prevent that from happening."