No, We Can't Just Nuke Incoming Asteroids
And why they're more dangerous than you think
Michael Bay’s blockbuster movie Armageddon is about a team of blue-collar workers sent on a mission to fly to a massive incoming asteroid and destroy it with a nuclear bomb before it hits Earth and kills everyone. The concept looked pretty damn awesome on screen, and the movie made like a bajillion dollars, but it also made us ask ourselves a question: is that how humanity would handle an incoming asteroid in real-life?
That question is more complicated than you’d think, however, right off the bat, the answer is a deafening no. See, nuking asteroids, regardless of how heroic Bruce Willis makes it look with multi-million dollar cameras and lighting setups, creates more problems than it solves.
The first of which is also the most common “let’s-nuke-the-asteroid” counter-argument: wouldn’t the asteroid just break up into a million little pieces? Short answer, yes, long answer, no. See, it is true that we could disintegrate an asteroid with nukes, but the issue is that gravity is kind of a pain to deal with. Scientists have run dozens of simulations of exploding asteroids and have discovered that all of the pieces would basically reassemble themselves under the force of gravity.
This happens all the time in space when two asteroids smash directly into each other. The bigger asteroid has more gravitational force, therefore gravity keeps it all glued together. So what you’d actually get is a very brief moment of celebration after nuking the asteroid, right before it comes back together and kills everyone.
Another issue is that asteroids can take a pretty big beating without losing steam. To theoretically blow up an asteroid, you need a lot of power. Just one nuke won’t do it. Scientists estimate that you would need 4,000 50 megaton nuclear bombs (50 megatons is about the same yield as Tsar Bomba, the most powerful nuclear weapon ever created and tested) to even make a dent in an asteroid. As you can imagine, we don’t exactly have any feasible way of delivering a payload of that size to a very fast-moving and imprecise target like an asteroid. The technology simply isn’t there to produce a projectile of that much raw energy, at least in our current moment.
Asteroids are also not one-size, or one-cluster, fits all. There are various factors involved in asteroid composition, such as low-gravity environments around asteroids, deformities, and so on that make it inadvisable to approach handling them with a singular tactic. Maybe there will come a day when we’re nuking asteroids, but that will probably be part of a multi-pronged strategy of deflection.
Hopefully, we as a species -- or the eggheads at SpaceX -- will figure this out all before we’re forced to call Bruce Willis.