New Issue: Science’s Impossible Questions. Read Now

Test Drive

Will a planned defense shield defeat real missiles?

Join Our Community of Science Lovers!

Perhaps as early as this month, President George W. Bush is expected to declare that a handful of prototype missiles in California and Alaska are ready to protect the U.S. from long-range missile attacks. The Pentagon calls the system a "test bed," one that still needs more sophisticated radar, interceptors and space-based lasers to realize Ronald Reagan's dream of a "Star Wars" antimissile program. The Defense Department, however, maintains that it can defeat North Korea's small arsenal of long-range missiles--a claim that may be hard to swallow given the limited number of tests done so far.

The ground-based midcourse defense system, as it is called, will start off with no more than 10 "hit-to-kill" interceptors designed to collide directly with incoming missiles in space. To date, the program has intercepted target missiles in five of eight heavily scripted tests.

But critics say those trials prove little. The Union of Concerned Scientists, in a report released earlier this year, concluded that the initial system ¿will be ineffective against a real attack¿ and also slammed the administration for ¿irresponsible exaggerations¿ about its abilities. In June opponents in Congress tried unsuccessfully to postpone deployment on grounds that the system should be tested further. During a Senate debate, Senator Barbara Boxer of California likened the plan to the Wizard of Oz, who ¿was scary, but when you pull back the curtain, it was just some little guy,¿ she said.


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


The Pentagon's Missile Defense Agency (MDA) has long held that live tests, which are costly, difficult to plan, and limited by range and safety concerns, are not the only means of proving the system's efficacy. According to the Pentagon, sophisticated modeling, simulations and exercises can offset the paucity of real intercepts. In April, Air Force Lt. Gen. Ronald Kadish, then head of the MDA, told Congress: ¿We use models and simulations, and not flight tests, as the primary verification tools.¿

But the Center for Defense Information's Philip Coyle, the Pentagon's top tester during the Clinton administration, argues that such technology ¿simply doesn't capture the basic physics and the variables in a missile defense engagement.¿ His successor under Bush, Thomas Christie, told Congress in March that such virtual assessment is ¿not a good substitute for integrated system testing.¿ And the Pentagon's Defense Science Board, a high-level advisory group, concluded in a May report that the MDA's current models and simulations are ¿legacy¿ items that are ¿not well designed to fit together.¿ As a result, Coyle says, the military will be ¿operating blind¿ once the program is up and running. The science board also stated that the MDA models of the system's ability to discriminate between actual targets and decoys are ¿oversimplified.¿

Richard Matlock, named the MDA's first director of modeling and simulation after the science board report was released, says current models ¿do a very good job at predicting the performance of system components.¿ But the report did confirm the need to enhance those models as missile defense evolves, he remarks. According to the MDA, an aggressive evaluation program will occur over the next few years as the test bed is upgraded. ¿We will constantly improve our capabilities through operationally realistic testing,¿ an MDA spokesman comments. ¿We can't operationally test the system until we put it into place.¿

That will happen shortly before voters decide between Bush and presidential candidate Senator John Kerry of Massachusetts, who says missile defense research is important but believes the Bush approach has not been sufficiently tested. The Pentagon asserts that the timing of the deployment is a coincidence, but opponents are skeptical. ¿I believe that's a big part of the push for deployment this year,¿ Coyle says.


Daniel G. Dupont edits InsideDefense.com, an online news service. He wrote about the threat of high-altitude nuclear explosions in the June issue.

Subscribe to Support Independent Journalism

Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.

When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.

Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber

Thank you,

Jeanna Bryner, Editor in Chief, Scientific American

Subscribe