The Government Says We Should Use Nukes to Deflect Asteroids

Caroline Delbert
·3 min read
  • A new paper explains why detonating nuclear weapons is the only way to deflect an asteroid.

  • We can disrupt (blow up) or deflect (redirect) asteroids.

  • Scientists say deflection is safer and more elegant, leaving less of a mess.

In a plot straight out of a 1990s action flick, scientists from the U.S. Department of Energy-funded Lawrence Livermore National Laboratory and the U.S. Air Force are studying the ways humans could detonate nuclear weapons to deflect an asteroid hurtling toward Earth.

➡ Science is badass. Let’s nerd out over it together.

“In the future, a hazardous asteroid will find itself on a collision course with Earth,” the researchers write in their new study, published in Acta Astronautica.

Relatively speaking, an asteroid doesn’t have to be huge in order to cause serious destruction. The simulated one in this study was 300 meters in diameter, or about 1,000 feet. That’s six Olympic-length swimming pools. It’s not rogue planet big, but it would still take out several big city blocks with the initial impact alone.

An asteroid this size is hardly hypothetical; as of October 2020, scientists have discovered 9,336 near-Earth object/asteroids (NEO/NEA) with diameters greater than 140 meters. Of those, scientists have classified 2,122 as potentially hazardous objects (PHOs). So, the risk here isn’t astronomically low—it’s much more, well, down to Earth.

NASA has found nuclear weapons are “10 [to] 100 times more effective” at moving asteroids out of a collision course with Earth than non-nuclear options, the scientists say. Here’s why: The energy density of nuclear devices is many, many times higher that of regular materials. This gives the nukes the right amount of force to push near-Earth asteroids out of the way.

There are two ways to move an asteroid off: disruption and deflection. In their study, the scientists ran computer simulations to see which strategies could best bounce the 300-meter asteroid away from its path toward Earth.

Disruption is the Armageddon solution: strike the asteroid directly in order to shatter it into much less harmful pieces. Deflection, on the other hand, is the more “elegant” solution, the researchers say. This involves simply redirecting the entire asteroid so it won’t hit Earth, removing the remaining variable that a shattered asteroid leaves behind: where all the pieces will end up.

When we blow up a nuke near an asteroid, what happens is pretty simple:

“Detonating a nuclear device above an asteroid irradiates a certain surface area. [T]he material near the surface is nearly-instantly melted. Subsequently, this small amount of superheated material expands away from the asteroid as “blow-off,” inducing a pressure wave in the remaining asteroid. [A] rocket-like exhaust momentum impulse is imparted, and the asteroid’s original velocity is changed, deflecting the asteroid.”

After the scientists detonated the nuke in the simulations to change the strength of its released neutron energy, it had up to a 70 percent impact on deflection performance.

So, if we ever do this in the real world, the nuclear device will partially liquefy the asteroid’s surface, creating a violent reaction that alters the asteroid’s trajectory. The researchers say it must be a neutron-based nuclear device rather than X-ray device in order to be as effective as possible. And while we hope to never have to use such a thing, it’s definitely better to know in advance that we could.

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