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This is the asteroid Eros. It has a diameter of about 16.8 kilometers and also would it is in very, an extremely hard come destroy. NASA/JPL
If you to be a moviegoer in the late ’90s, ns wouldn’t blame girlfriend for thinking the best means to attend to an apocalyptic-size asteroid hurtling toward planet is to punch it come smithereens. After ~ all, that’s just how Bruce Willis conserved the world in Armageddon. Conserving the earth ought to be as straightforward as the push of a thermonuclear button, right?

Not therefore fast. Because that one, experts in planetary protection (a genuine thing) say it would certainly be a lot less complicated to just push a deadly incoming asteroid right into a more secure orbit. This is a genuine consideration because NASA is keeping its eye on around 2,000 ”potentially hazardous” objects that come in ~ 4,647,790 mile of Earth and are big enough to cause damage.

But likewise there’s this: brand-new research suggests it’s really, really complicated to pulverize one asteroid.

How tough can it it is in to destroy a 10-kilometer-wide asteroid?

Kaliat Ramesh is a professor of mechanical engineering and also material science at Johns Hopkins University. And also recently, he and also colleagues published a file in the planetary science journal Icarus that basically asked the question: What would certainly it take to break increase an asteroid? The answer to that question matters — however not so lot for what it means for the future of life on Earth. Instead, it helps us much better understand what asteroids look at like, and how castle evolve gradually as asteroids collide through one another.

First off, there’s no means to do this kind of practice without making some assumptions.

While we recognize that asteroids room mainly made up of iron and rock, us have minimal data on their surface and also interior composition. Any type of rock’s vulnerability to devastation is highly dependent on how numerous cracks, pores, and also other together deformities exist top top its surface. Yet Ramesh and his colleagues to be able to take the results of experiments on planet — experiments involving very high-speed cameras studying how rocks right here on planet fissure and crack when hit through a projectile — and extrapolate them up, accounting for the low-gravity environment of the space around an asteroid.

Smashed, fissuring rocks room a complex thing to version in a computer. Once cracks form on the surface, “you unexpectedly you gain this collective actions of cracks every trying come really fast, every one of them connecting with each other,” Ramesh says. How quickly those many cracks spread and kind helps identify the resiliency that the rock. For this reason it’s a massively facility process to predict how a collision will change or deform a absent in space.

These limitations aside, Ramesh and also his colleagues identified that, well, that going come be really hard to ruin an asteroid — close to impossible. Even if there is an asteroid hurtling toward Earth, the wouldn’t make a many sense to launch the world’s whole nuclear arsenal at it in the hopes of blowing the up.

“We would certainly estimate the it would take power equivalent to around 200 gigatons the TNT to totally disrupt one asteroid through a 20-kilometer diameter,” Ramesh says. (This is roughly dual the approximated size the the asteroid or comet that is believed to have actually killed the dinosaurs. However there is some evidence that planet has to be struck through a massive 20-kilometer asteroid in the past.)

200 gigatons that TNT (dynamite) contains about the energy equivalent of about 10 million Hiroshima-size bombs. The also about 10 times an ext energy 보다 previous estimates of what it would take to ruin an asteroid the this size. (This brand-new estimate takes into account the complicated interactions between little cracks that form on the asteroid’s surface ar upon impact, which in reality make because that a an ext impact-resistant object.)

The most powerful bomb in human development had an explosive yield of 50 megatons. You’d need the power of 4,000 that those come annihilate a 20-kilometer-wide asteroid. Yet even then, girlfriend couldn’t just launch 4,000 nuclear weapons to damage the asteroid. That power would should be ceded with a certain momentum (that is, motion confined come a particular mass). Which is to say: you’d probably need come confine the force of 4,000 that the most powerful nuclear bombs right into a projectile.

This study really isn’t around destroying asteroids. It’s around what to expect once we visit them.

The remarkable amount of energy needed is why us wouldn’t want to blow up one asteroid to conserve Earth.

But Ramesh stresses the his research study isn’t exactly about finding out just how to damage an asteroid top top a collision course v Earth. He is well conscious it would be a lot less complicated just to press an asteroid the end of the way. (Which is something NASA has actually some preliminary plan for.)

In the paper, Ramesh and also his colleagues weren’t modeling what a nuclear explosion would do to an asteroid. No, they were modeling something that happens naturally: What happens when one smaller sized asteroid slams right into a larger one, as has actually happened continually over the life expectations of the solar system?

The answer come that concern helps us recognize what asteroids could look favor if us were to explore more of them, and anticipate what can happen if we want to mine lock (possibly with the usage of explosives). Asteroids space rich sources of metals, minerals, and also even water. They may one day provide the raw ingredients to refuel spaceships without the must return come Earth.

Eventually, “humans and also robots space going to walk to an asteroid, and we desire some sense of what we’re going to see when we obtain there,” Ramesh says.

Some robots currently have. NASA’s OSIRIS-REx is at this time orbiting the asteroid 101955 Bennu, v the ultimate goal of collecting material from that surface and also returning that to planet in 2023 (a comparable Japanese mission lugged asteroid dust ago to earth in 2010). NASA’s Dawn spacecraft flew by the dwarf planets (which likewise can be believed of as very large asteroids) Ceres and also Vesta in 2012 and 2015, respectively. NASA has laid the groundwork because that an ultimate “asteroid redirect” mission. The plan: A robot spacecraft will certainly land on one asteroid, seize a boulder, and bring it into orbit approximately the moon.

Asteroids — like the ones humans could want to check out or mine sooner or later for raw materials — have been based on such collisions end the life that the solar system. By imagining how asteroids collide and are ruined (or not), we can better understand their composition and also surface features, and how castle evolve in time as an ext collisions take place. “We want to predict what we’d uncover on a surface of one asteroid if we’d go visit one,” Ramesh says.

When a huge asteroid is pummeled by a smaller one, heaviness keeps much of it with each other

One fascinating thing that happens as soon as an asteroid is hit however is not damaged is that much of the rubble that paris off ~ the collision is eventually pulled earlier toward the undamaged core that the asteroid via gravity. We could really well find asteroids that have actually this rubble loose attached in ~ the surface ar (and are thus easy to mine). Here’s an computer animation of this recollection procedure generated by the researchers’ model.

Charles El Mir/Johns Hopkins university

These calculations also aid us understand that if we were to destroy at least component of an asteroid, us could additionally be creating much more hazardous objects.

The good news is the asteroids that pose one existential hazard to life on earth only strike when every 500,000 years or more. Also the 140-meter-wide asteroids that could destroy cities and regions hit once every 10,000 years. And the hazard of even being injured from a 20-meter thing — like the one the exploded over Chelyabinsk, Russia, in 2013 and hurt nearly 1,500 human being — is tiny.

So rather of being worried about asteroids death us, we should look in ~ them in wonder. Asteroids are fascinating due to the fact that they represent the leftover structure blocks of the planets in our solar system.

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“You have actually all this body that have been roughly for a few billion years,” Ramesh says. “For us to understand the procedures that drive these things over time, that is tied into the history of whereby we come from, and also it’s additionally tied right into our future, when we acquire out right into the solar device and try to usage them.”