Can We Nuke an Asteroid Hurtling Towards Earth?

A NASA asteroid defense expert has told Newsweek that, in the event scientists spot an asteroid coming towards us with just months to spare, blowing it to pieces would not be such an outlandish idea.

Thankfully, the scenario has only been lived out in the world of science fiction so far, but dangerous asteroid impacts are something scientists take very seriously in the real world.

This week, NASA’s Center for Near Earth Object Studies (CNEOS) has been leading a fictional scenario in which delegates at the 7th International Academy of Aeronautics (IAA) Planetary Defense Conference have been tasked with responding to an imaginary asteroid that is due to hit Earth.

The scenario imagines that scientists have discovered the asteroid, called 2021 PDC, is going to hit our planet in just six months’ time, meaning that deflecting the pretend space rock away from us is out of the question.

If this were real life, scientists would seriously consider launching a nuclear bomb at it, according to Lindley Johnson, NASA’s planetary defense officer. But it wouldn’t be an ideal option.

Johnson told Newsweek: “I call that the Hollywood solution. It is not totally out of whack.

“In fact, some of the presentations and discussions at the conference have been: Is it viable to nuke it, use a nuclear explosive device to break it up into small enough pieces that then the Earth’s atmosphere would take care of them?

“So, no, it’s not totally outlandish. But it is a scenario that we want to try to avoid getting into. First of all, the time limitations involved really put pressure on making sure everything works the first time. And the other thing is, of course, the deployment and use of nuclear devices in space is a heavily restricted thing by international treaties.”

Instead, Johnson stresses the importance of early detection—something that groups such as the CNEOS specialize in. There is also an International Asteroid Warning Network that Johnson says has signatories from at least a dozen countries around the world.

Part of the purpose for the scenario of this year’s conference is to help inform people on the importance of early detection.

“An asteroid impact is probably one of the few natural disasters that is entirely preventable if we find out about it far enough in advance and have an opportunity to do something about it,” Johnson said. “This exercise, this time, was a little different, though, in that we wanted to engage the disaster management emergency response community a little bit more.

“So we have to contemplate having to take the hit on the ground and prepare the disaster management emergency response folks with what they might have to expect as far as what the impact effects might be and what the damage might be.”

Detecting an asteroid is typically done using optical telescopes. Using these telescopes, researchers can spot the asteroids because they tend to reflect light from the Sun.

Telescopes can spot asteroids at much greater distances than radar systems can. But at the same time, optical telescopes are limited by the day-night cycle, weather, and even light pollution from the moon.

Placing optical telescopes in space is one way to get around this. But it is not as simple as having a look using Hubble, which has a very narrow field of view in order to peer into the cosmos.

“The type of telescope we need for this work has to be very wide-field of view, so that they’re able to cover the sky much more rapidly,” Johnson said. “So what we want to build is a project that we do have under formulation right now. It’s called the Near Earth Object Surveyor and it is specifically designed for this mission of detecting asteroids well away from the Earth to track them.”

Meanwhile, NASA is also working on DART—the Double Asteroid Redirection Test—due to launch in late 2021 or 2022.

Targeting the Didymos binary asteroid system, it will serve as a demonstration of technology NASA hopes will be capable of shoving an asteroid out of the way if it looks like an impact with Earth might be likely.

In any case, an asteroid impact is not a scenario that any country wants to be in, Johnson said, noting that evacuating large metropolitan areas would be “a daunting task.”

He added: “I think that scenario would be challenging for any country to contemplate having to respond to—not being able deflect it in space and having to take the hit.”