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10 Things That Would Likely Happen If We Nuked an Asteroid  

Kellen Perry
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Let’s say an asteroid large enough to do some significant damage to Earth is headed our way and will make impact in, say, six months. What's the plan? Can we blow up asteroids? Better yet: what if we nuked an asteroid? Is that a thing?

It’s totally a thing. Some of the brightest minds in the world have studied what would happen if we blew up an asteroid, and the answer is... complicated. There are a lot of factors to consider: the size of the asteroid, how far away it is, what the asteroid is made of, etc. But rest assured: using a nuclear weapon to blow up and/or deflect an asteroid is something that NASA has spent a lot of time investigating.

What would actually happen if we nuked an asteroid? Why is it so complicated, exactly? Read on to find out!

We Have the Technology!
We Have the Technology! is listed (or ranked) 1 on the list 10 Things That Would Likely Happen If We Nuked an Asteroid
Photo: Dave_Darroch/flickr/CC-BY-NC-ND 2.0

Let’s say that everyone agreed that nuking an asteroid was a-okay and it’s something that we have to do to save humanity. Do we have the means? Yep!

Dave Dearborn, physicist at the Lawrence Livermore National Laboratory—and “one of the most experienced nuclear weapons designers on Earth”—tells Popular Mechanics that the US has what it needs in its stockpile of nuke-related tech to handle “objects up to kilometers in size.” In the terrifying event of something larger than that heading our way, Dearborn says we don’t have the technology just lying around, but “we know what to build.”

Bottom line: “Getting a nuke into space isn't difficult.”

It Could Be Our Only Hope
It Could Be Our Only Hope is listed (or ranked) 2 on the list 10 Things That Would Likely Happen If We Nuked an Asteroid
Photo:  Don Davis/via Wikimedia/Public Domain

We have the means to launch a nuke into an asteroid, but will we ever really have a good reason to actually do it? If the asteroid was large enough to justify it and we only had a warning time of a few years or so (yes: years), then it is “generally accepted” that “only the nuclear bomb approach would work,” according to Keith A. Holsapple of the University of Washington in his study, “The Deflection of Menacing Rubble Pile Asteroids.”

Los Alamos National Laboratory astrophysicist Robert Weaver is among those that generally accept the nuclear option could be our last hope—under certain desperate circumstances. Weaver thinks nuclear is the only practical option if we only have as little as, say, a six-month lead time. “From my perspective, the nuclear option is for the surprise asteroid or comet that we haven’t seen before,” he told the journal National Security Science in 2013, “one that basically comes out of nowhere and gives us just a few months to respond.”

Weaver says non-nuclear options to deflect the asteroid, while possibly effective, would take a decade of planning and development and would have to be deployed years in advance of the collision. Nukes it is, then!

It Wouldn't Be a Manned Mission
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So we’ve decided to send a nuclear weapon to destroy an asteroid. We’re positive this is a good idea. A zillion people on Twitter make Armageddon jokes. The snobs make Deep Impact jokes. The scientists, meanwhile, counter to popular imagination, will likely be prepping an unmanned mission using something called an HAIV (or Hypervelocity Asteroid Intercept Vehicle, if you’re nasty).

The HAIV is comprised of two detachable parts: a leader craft and a follower craft. Instruments on the leader, if all goes according to plan, detect the perfect impact point on the asteroid roughly two hours before the big boom. About one minute before impact, the leader separates from the nuke-packed follower at high speed and touches the surface, sending a signal to the follower to begin the detonation sequence. The leader then crashes into the asteroid, creating a crater for the nuke to nest in. A millisecond later, the nuke detonates in the crater.

No plucky team of snarky underdog a**holes necessary!

It Just Might Work!
It Just Might Work! is listed (or ranked) 4 on the list 10 Things That Would Likely Happen If We Nuked an Asteroid
Photo:  Uropean Southern Observatory/via BY 4.0

Yes, a lot could go wrong when you’re sending a nuclear weapon into space to kill a giant rock. But let’s focus on the positives. Could this actually work?

Possibly! Based on supercomputer simulations, a nuclear blast striking the Itokawa asteroid—“a quarter of a mile long and about half as wide” cluster of granite rocks resembling an ugly potato (pictured)—would effectively swat it away from our planet, also sending its many fragments soaring safely away from our lawns and faces. The blast would only propel Itokawa in the desired direction, however, if we hit it in a direction perpendicular to its motion. We couldn’t just launch a nuke straight at it.

Bong Wie, director of the Asteroid Deflection Research Center at Iowa State University, is also confident that his HAIV-delivered nuke could safely deflect “99 percent or more” of an asteroid’s pieces away from us, with those remaining burning up safely in the atmosphere.

Needless to say, there are naysayers. But what could actually go wrong?