APS News


The Truth About Missile Defense: Will Science Make A Difference?

By Philip E. Coyle

In political Washington, one can get the impression that everything is "spin", that there are no real truths. In the news media different views are aired and debated, but one view is said to be no better than another, and certainly political views cannot be proven the way we learn mathematical proofs in school.

By contrast, the American Physical Society released a comprehensive study of the scientific feasibility of boost-phase missile defense. Two years in the making, the study takes no policy position on whether the United States should pursue ballistic missile defense. Also, the report only examines the technical feasibility of one approach to missile defense, namely shooting down enemy missiles in their boost-phase, that is, within the first two to four minutes after launch. Nevertheless, the APS report should be required reading for Members of Congress and other decision makers interested in missile defense, pro or con.

With scientific and mathematical rigor, the report examines those aspects of boost-phase missile defense that are feasible and those that are not. The report also identifies those aspects that while theoretically possible are so unlikely as to be fantasy.

The authors of this report, co-chaired by physicists Frederick Lamb and Daniel Kleppner, are a "Who's Who" of eminent scientists in the fields of relevance-physics, precision guidance, high power lasers, and aerodynamics-in short, "Rocket Science." The authors have bent over backward to maintain balance, spending months checking every word and sentence for proper and accurate meaning.

Critics of missile defense looking for a slam-dunk to quickly shoot down funding for the boost-phase option may be disappointed. Physicists won't say something is impossible unless it violates the basic laws of physics, and the authors stick to the facts. But proponents for missile defense should read the report carefully.

With respect to interceptors or lasers fired from platforms on land, sea, or air, the study shows that for boost-phase missile defense to work, the defender must be close to the enemy missile before launch. Also the defender must have a fast interceptor, faster than any US missile in existence.

As a result, boost-phase missile defense from such platforms is not feasible with any known technology against large countries such as China, Russia or Iran. Technically, boost-phase missile defense from land, sea or air is possible against Iraq, a smaller country than Iran, but can require basing defenders in nearby countries that might not approve, such as Syria or Turkey.

North Korea, a small narrow country, accessible to the Untied States from the sea on two sides and from South Korea on a third, is tractable for land, sea or air based boost-phase missile defenses, but even then it would take quick reaction, split-second timing, and tight operational readiness.

Proponents of space-based missile defenses may see some hope in this report since interceptors or lasers orbiting in space are not constrained by geographic boundaries. From space, boost-phase missile defense is technically possible against large countries like Russia or China so long as the orbiting defenders can reach the enemy missiles in time. Here the issue is that the world is round. Missile defense attack satellites on the wrong side of the Earth can't reach an enemy missile in time. One solution is to have enough missile defense platforms on orbit so that at least one is in the right place at the right time, that is, when an enemy missile is launched. As with land, sea or air based interceptors, space-based interceptors also must be very fast to reach enemy missiles in time. This means many platforms in space, perhaps hundreds or thousands depending on the sophistication and dispersal of the enemy threat.

In particular, the APS study explains, during the decade or more it could take the United States to develop boost-phase missile defenses against liquid fueled enemy rockets, US opponents could develop the technology of solid propellant rocket boosters. Enemy missiles using faster burning solid propellant fuel would stress the defenses even more, compress the time available for intercept to less than three minutes, and effectively negate operationally practical boost-phase missile defense from land, sea, air, or space.

With respect to missile defense weapons in space, the APS study lays out the facts about boost-phase missile defense from space in a straightforward and readable manner. Now the United States and the international community must grapple with the policy and arms control implications.

Should the United States introduce orbiting weapons with attack capabilities, and should we spend billions to place missile defense satellites in space that could be obsolete before they were fielded? And can such systems be effective, reliable and dependable even against liquid fueled enemy rockets? These are policy and engineering questions intentionally not addressed in the APS study. But apart from the policy and arms control issues raised by placing attack weapons in space, the number of satellites required and the costs of the overall system are daunting. US taxpayers will have to consider whether an arms buildup in space is worth the price.

Here the APS study provides the technical facts, not the policy answers. But for the truth about boost- phase missile defense, the APS report is unshakeable and solid. It is a report that can and should make a difference. Whether it will make a difference will depend on whether the Administration and the US Congress read this important new scientific study, and then whether they acknowledge or ignore the facts in it.

Philip E. Coyle was Assistant Secretary of Defense for Test and Evaluation from 1994 to 2001, and is a Senior Advisor at the Center for Defense Information

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Editor: Alan Chodos
Associate Editor: Jennifer Ouellette