It may sound like a good idea. It really isn’t. In 1983, President Ronald Reagan proposed a military system, later dubbed “Star Wars,” that promised to protect the United States from nuclear attack. The basic idea was to use weapons based in space to knock down incoming intercontinental ballistic missiles (ICBMs).
Politicians have called for “space-based missile defense” for years. Unfortunately, it’s not a very good idea.
Reagan’s plan didn’t materialize, but the idea never went away. In 2018—against the Department of Defense’s wishes—Congress passed a bill calling for the Pentagon to start building space-based interceptors.
Unfortunately, it’s a terrible plan. Space-based missile defense is an ineffectual defense at best, and a very dangerous provocation at worst.
Understanding why space-based missile defense is a bad idea requires basic knowledge of how it works—and what it can and can’t do.