If an asteroid capable of destroying our planet were hurtling toward us, blowing it up with a nuclear weapon might be the best option. Or at least the best option based on a Bruce Willis movie ("Armageddon"). But why would the United States use an outdated nuclear weapon on such a crucial mission? A recent audit of the National Nuclear Security Administration revealed a policy to not dismantle some old warheads while we study whether they could be used this way.
The asteroid danger is real, but very rare. Huge asteroids hit the planet about once every 100 million years, and some scientists think a 6-mile-wide one may have killed off the dinosaurs. The United States probably wouldn't need many of its 4,800 nuclear warheads to fend off an asteroid. And if the need ever came up, shouldn't we use newer and presumably better ones?
Take the old warheads apart. Our military losing weapons is a disaster that happens a lot more than every 100 million years.