America’s might relies heavily on satellites—and we may be at risk of a space Pearl Harbor. Satellites are vital to U.S. military strength, tracking enemy movements and guiding bombs. Commercial satellite services—communication, navigation, and weather forecasts—generated more than $56 billion for the United States in 2004 alone. Our dependence on satellites has not gone unnoticed by other nations. The Chinese successfully tested a ground-launched satellite interceptor earlier this year, and prior to the 2003 invasion of Iraq, Iraqi forces tried to jam signals from U.S. navigation satellites by transmitting radio noise in an attempt to overwhelm GPS receivers.
The Iraqi jamming devices were quickly destroyed, but for years rumors have circulated about more-frightening antisatellite systems. America and Russia have had the technical ability to knock satellites out of the sky for decades using interceptors like the Chinese device; at the other end of the technology scale, some security experts worry that a rogue nation could use a relatively low-tech ballistic missile to launch gravel into the path of a satellite. Many reconnaissance satellites follow a north-south path—known as a polar orbit—that allows them to view the entire Earth every day. Attacking such satellites would not require precise maneuvering systems. An aggressor would just have to wait until the target passed into range overhead, and the gravel would cut into it like shrapnel.
How realistic are these different approaches? DISCOVER looked at eight ways to kill a satellite most often discussed by space watchers and ranked the threat level of each. The gravest threat is probably posed by an interceptor launched from Earth, guided to its target by a ground-based laser or radar system. The missile need not attain the velocity required to go into orbit; it needs only to reach the altitude of the satellite it is intended to destroy. Such an attack, therefore, could be mounted cheaply and quickly. “You’re firing an interceptor that costs tens of millions of dollars against a billion-dollar satellite,” says John Pike, director of GlobalSecurity.org, a defense, space, and intelligence analysis firm.
Some military advisers have proposed that the United States should deploy its own antisatellite weapons as a deterrent. But Richard Garwin, a leading expert on military technology and a critical figure in the development of the hydrogen bomb, says that would only incite a space arms race that would ultimately make our satellites more vulnerable. America should not “imply that its response to an antisatellite attack by another country would be to respond in kind,” he argues. “The primary response against an antisatellite attack should be the destruction of military facilities in the other state.”