Missile Test Failure Points to Bigger Problem

WASHINGTON â€”  The embarrassing failure of a missile interceptor to smash a mock warhead high over the Pacific Ocean has resurrected an uncomfortable question: Can America’s rocket scientists really make a “bullet hit a bulletâ€� at 15,000 miles per hour?

Despite Tuesday’s high-profile setback, experts on both sides of the issue say there is little question that before long the Pentagon’s anti-missile warriors will be able to reliably pick off a single warhead streaking toward the United States.

The real question, they say, is different: Will America’s missile defenders be able to knock down a fusillade of incoming warheads that have been scattered, along with a complement of decoys, across the vast vault of the sky?

With President Clinton set to decide this summer whether to give a controversial national missile shield the go-ahead, the answer is far from clear and the technological challenges are formidable.

After nearly 50 years and $120 billion worth of anti-missile research, U.S. scientists now know how to build advanced radars and heat sensors that can identify small objects thousands of miles away. They have developed interceptors that can reach incoming warheads more than 1,000 miles away in less than 15 minutes, making it possible to protect most of the U.S. mainland from one site in the Midwest. And they have designed command-and-control computers capable of synchronizing a defense against hundreds--perhaps thousands--of flying objects.

Yet Pentagon officials and outside experts acknowledge that making these parts work together so flawlessly that no warhead can slip through and flatten, say, Cleveland, remains a daunting challenge.

“All of the component technologies are at the ragged edge of feasibility,� said Richard Mesic, a Rand Corp. defense expert, expressing his own views and not those of his employer. “So an enthusiast might see it all as feasible, and a skeptic might focus on the fact that it has yet to be proven.�

But for now, he added, it only takes a slight deviation to make the system fail.

The missile defense system, proposed for deployment from 2005 to 2007, is supposed to work like this:

When a missile is fired at the United States, it is detected by infrared sensors on satellites and a network of early-warning radars on the ground. Information on its location and trajectory is sent to a “battle management� center in Colorado and then to operators of a huge interceptor-missile range likely to be located in Alaska.

When the incoming warhead, now separated from its booster rocket, reaches the upper atmosphere, an “X-band� radar facility in Alaska will begin tracking it, picking up more precise information on its speed and course.

Within minutes, the battle management center begins firing, at intervals, up to four interceptor missiles carrying smart “kill vehicles.� When they reach the upper atmosphere, the booster rocket breaks away and the kill vehicle heads for the approaching warhead.

The kill vehicle carries two heat sensors and an electro-optical eye that help it find the warhead. Small rocket thrusters enable it to maneuver. If all goes as planned, the craft can distinguish the warhead from any nearby decoys and ram it head-on, reducing it to a shower of tiny particles.

A closer look at the system’s key components shows just how far scientists have come, and the job that lies ahead.

Heat-detecting sensors--In its initial deployment, the system will rely on a network of five Defense Support Program satellites to detect enemy missiles. These sensors, which register the intense heat of a missile’s engines a hemisphere away, have been upgraded five times since their introduction in the 1970s.

But far more capable--and crucial to the success of the whole concept--is the next-generation infrared sensor system that will replace the support satellites after they become operational.

The Space Based Infrared System, or SBIRS (pronounced “sibbers�), would be a network of sophisticated high- and low-altitude satellites designed to simultaneously track hundreds, perhaps thousands, of warheads and other objects. While the current generation of infrared sensors can pinpoint a missile’s location to within about 10 miles, these will be able to track them to an area the size of a football stadium.

The potential ability to track huge numbers of flying objects has alarmed the Russians, who can imagine the United States someday expanding the system to protect against Russia’s arsenal of 4,500 warheads.

Unlike earlier sensors, SBIRS will allow the defenders to track missiles through their entire flights. The key is the capacity of SBIRS’ lower-altitude satellites to “see� warheads after their rocket engines burn out when they are cooler and far harder to find in the cold void of space.

With this additional accuracy, the missile defenders gain precious additional minutes to distinguish warheads from decoys. They can start firing off interceptor missiles much earlier in the attack, increasing the odds of success.

Yet SBIRS is a highly complex and fragile system, especially its two dozen low-altitude satellites. Already, the government scrapped one testing program because of its high cost and decided not to replace it.

Advanced radars--The first radars to spot an attack will be the successors to the early-warning network dating to the time of President Kennedy. They were originally designed to detect clusters of objects at great distances without providing much detail. In their upgraded form, they will be able to track not just clusters but individual objects at distances of more than 2,000 miles.

Far more sophisticated are the new X-band radars, which use very-high-frequency radar waves to gather highly detailed information at distances of more than 1,000 miles.

Yet it is tough to work with higher-frequency radar. In the first four flight tests, defense officials still have not tested whether this radar can use information it has received to guide an interceptor missile.

“Battle manager� system--While the Patriot anti-missile systems used in the Persian Gulf War never had to contend with more than a few dozen flying objects at once, the new system will be designed to keep track of many hundreds or more, sorting weapons from decoys and making sure that interceptors are taking care of each one.

Twenty years ago, this job “was seen as a profound challenge,� but with advances in computing and other technologies “today it’s not seen as such,� said John Pike, space analyst for the Federation of American Scientists.

Still, the job is huge, and testing of the system remains at an early stage.

Interceptor missile--The Safeguard anti-missile interceptor of the early 1970s could reach targets a couple of hundred miles away and had a nuclear-armed kill vehicle that weighed as much as a small car. The new system has a range of more than 1,000 miles, enabling it, theoretically, to shield much of the country if based in the Midwest. And it has been compacted to 121 pounds.

To be sure, the new kill vehicle looked like a dunce last week when its two heat sensors blinked off six seconds from impact, causing it to miss its target. But Oct. 2, the craft showed its smarts: It overcame a navigation glitch by homing in on a decoy balloon, then at the last moment picked out the correct target and pulverized it.

These days, the key arguments about the system’s capabilities focus on what will happen if rogue regimes launch multiple warheads, with decoys that have misleading heat and radar signatures.

Experts fear that Russia and China may be willing to pass on their knowledge of decoys, either to make money or to offset the perceived geopolitical dominance of the United States.

Attackers could, for instance, disguise a warhead by releasing a cluster of metallic Mylar balloons and putting the weapon inside one of them. Using small heaters or cooling substances, they could disguise the warhead’s temperature.

Scientists at the missile defense program and its contractors believe that such theories are far-fetched. They contend that by collating data from radar, light and heat sensors, they can pick out any decoy.

Many outside analysts, however, will not be convinced without more testing. In a June 1998 report, the General Accounting Office noted that a limited testing schedule, particularly testing the system against multiple targets, increases the risks in any deployment decision.

“The answer is, right now, nobody knows,� said one congressional analyst, who asked to remain unidentified. “If they try to tell you otherwise, don’t believe them.�