The Science of Missile Defense
School of Public Affairs, University of Maryland
About the Lecture
The desirability and feasibility of constructing a national missile defense (NMD) for the United States have been debated since the advent of long-range ballistic missiles over forty years ago. Despite monumental political changes and remarkable technical progress during this time, the basic arguments against NMD remain unchanged: relatively simple countermeasures can defeat the systems under development, and deploying NMD could trigger reactions by Russia and China that would, on balance, decrease U.S. security. I will review the history and the current status of NMD programs and critique arguments for and against deploying NMD.
About the Speaker
Steve Fetter is a professor in the School of Public Affairs at the University of Maryland, College Park, and associate director of the Joint Global Change Research Institute. A physicist by training, his research interests include arms control and nonproliferation, nuclear power and the health effects of radiation, and climate change and energy supply.
Prof. Fetter is chairman of the Federation of American Scientists Fund and treasurer of the Arms Control Association. He serves on the National Academy of Sciences’ Committee on International Security and Arms Control, the Executive Committee of the American Physical Society's Forum on Physics and Society, the Department of Energy's Nuclear Energy Research Advisory Committee, the board of directors of the Sustainable Energy Institute, and the Board of Editors of Science and Global Security. He is a fellow of the American Physical Society and recipient of their Joseph A. Burton Forum Award.
In 1993-94, Fetter was special assistant to the Assistant Secretary of Defense for International Security Policy, for which he received an award for outstanding public service. He has been a Council on Foreign Relations international affairs fellow at the State Department and a visiting fellow at Stanford’s Center for International Security and Arms Control, Harvard’s Center for Science and International Affairs, MIT’s Plasma Fusion Center, and Lawrence Livermore National Laboratory. He received a Ph.D. in energy and resources from the University of California, Berkeley, and a S.B. in physics from MIT.
His articles have appeared in Science, Nature, Scientific American, International Security, Science and Global Security, Bulletin of the Atomic Scientists, and Arms Control Today. He has contributed chapters to more than a dozen edited volumes, is author of Toward a Comprehensive Test Ban, and coauthor of The Future of U.S. Nuclear Weapons Policy and The Nuclear Turning Point.
President McDiarmid called the 2136th meeting to order at 8:17 p.m. on November 9, 2001. The Recording Secretary read the minutes of the 2135th meeting and they were approved.
The speaker for the 2136th meeting was Mr. Steve Fetter. The title of his presentation was “The Science of Missile Defense”.
It is difficult to speak about the science of missile defense without also talking about the politics. The desirability and feasibility of constructing a national missile defense (NMD) have been debated since nuclear-armed, long-range ballistic missiles were deployed over forty years ago. The original US missile defense plans began with the Nike system, followed by the Sentinel and Safeguard systems. These missile interceptor systems depended on radar capable of tracking objects at great distances and guiding the intercepting missiles. Phased array radar was one of the technical developments of these programs. The interceptors required high acceleration rockets, the Sprint and Spartan, and carried 5 megaton nuclear warheads because they were not accurate enough to rely on inertial impact. In the late 1960's President Johnson proposed a “thin defense” that would be effective against a threat from China. Eventually, it was operationally deployed to protect Minuteman silos for nine months, but was judged to be too easily defeated by simple countermeasures. The Anti-Ballistic Missile (ABM) Treaty was ratified in 1972 to limit ABM deployment to small systems in North Dakota for the US and around Moscow for the Soviet Union. In 1983, President Reagan proposed the “Star Wars” Strategic Defense Initiative (SDI), but no missile defense system was ever proposed for construction. During the Gulf War in 1991, Iraqi Scud missiles were countered by US-designed Patriot missiles launched by Israel and by the United States in Saudi Arabia. Analysis after the war showed that the system had not been 90% effective as reported by the Defense Department at the time, but had intercepted only one or two of the 79 documented Scud launches.
President Clinton shifted funding for planning from an SDI to a theater missile defense system. Congressional Republicans in 1995 proposed an alternative, more comprehensive NMD system to be built in 2003. In 1996, President Clinton opened talks with Russia on additional limitation of nuclear missiles and on the development of missile defense systems. In 1998, the Rumsfeld Report dealt with the possible use of a missile defense system against rising threats from rogue states. Soon after, North Korea launched a multi-stage rocket beyond Japan.
There are three phases in which missiles defense systems may attempt to find and destroy targets: boost phase while thrust rockets are firing, ballistic phase while warheads are traveling outside the atmosphere, and reentry phase while warheads are falling through the atmosphere. Satellites in geosynchronous orbit may detect hot flashes of missile launches. Low orbit satellites may track IR emissions of the boost rockets and thermally warm nuclear warheads. Radar may also detect warheads in the ballistic phase and send homing signals for missile interceptors designed for inertial impact. The interceptors may carry IR and other detectors.
Hit-to-kill interception systems have had 22 tests, with only 6 hits scored. The most recent problems have been due to quality control of these complex integrated systems. There have been charges that the tests were unrealistic because there were either no or only one balloon decoy, because there was one target and one interceptor, not many-to-many, and because the target carried and broadcast GPS signals to confirm the tracking. Nevertheless, there has been remarkable technical progress, and reliable hit-to-kill systems could be realized within a few years. The problem is that, even if the proposed system works as designed, it is unlikely to be effective against a real adversary.
Relatively simple countermeasures could defeat the NMD systems under development. Four effective counter-measures would be the use of biological submunitions, balloon decoys, nuclear warheads hidden inside balloons, and cooled nuclear warheads. One hundred biological bomblets, each with a 2 kg payload, could be launched on one missile and deliver enough anthrax spores to cause 100,000 deaths in a metropolitan area, such as Washington. If such bomblets were released after boost phase, they would overwhelm almost any conceivable interceptor system. Nuclear warheads can't be subdivided, but they can be disguised to look like decoy balloons, and an inertial hit on a balloon containing a warhead might not kill the warhead. Warheads might also be cooled by liquid nitrogen so it would not have a detectable IR signature.
What would work against these counter-measures? Certainly, there could be improved discrimination of targets by watching as decoys are deployed after boost, or by using lasers to push empty balloons. The use of nuclear-armed interceptors would probably be effective, but politically unacceptable. A defense targeting the boost phase when the targets are most vulnerable would be capable of destroying all of the warheads along with any countermeasures. However, the surveillance area for such a system would be much larger. The defense system would have to be close to the launch in place and time, so a large number of expensive interceptors would be required. An NMD against Russia or China would most likely not be effective. An NMD system against North Korea, Iraq or Iran probably would be effective since the distance of the launch can be 500-700 km from the interceptors.
Defending against delivery modes other than ICBM's, such as short range cruise missiles launched from ships or planes, or covert delivery, is highly problematic, with the added complication that the identity of the attacker is no longer certain. ICBM systems are very expensive and increasingly visible, so adversaries are less likely to deploy such systems in the future. Russia and China both oppose U.S. deployment of an NMD. Obviously, they want to deter the US from threats to their interests and would not want the US to think and behave as though it were invulnerable. Deploying NMD could trigger reactions by Russia and China that would, on balance, decrease U.S. security.
Mr. Fetter kindly answered questions from the floor. President McDiarmid thanked Mr. Fetter for the society, and welcomed him to its membership. The President made announcements about election business, membership, the next meeting, parking, and refreshments, and adjourned the 2136th meeting to the social hour at 9:33 p.m.
John S. Garavelli