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Environment
Every other Friday, the Outside/In team answers a listener question about the natural world. Got a question of your own? The Outside/In team is here to answer your questions. Call 844-GO-OTTER to leave us a message.

Outside/In[box]: Would the hare-brained scheme from 'Don't Look Up' actually work?

 A composite image of Comet 67P
ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
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A composite image of Comet 67P

Every other Friday on Morning Edition, the Outside/In team answers a question from a listener about the natural world.

This week, we answer a question posed by John Gage on Twitter:

“In the movie "Don't Look Up", the business tycoon wanted to split the asteroid into a couple dozen pieces and retrieve them after they landed in the ocean. Would the consequences to us of a large asteroid hit be any less if it were broken up like that?”

Don’t Look Up is a star-studded dark comedy from Netflix, and scientists were talking about it even before it was released to the public during the 2021 holiday season. Why? Because the massive comet hurtling towards Earth in the movie is clearly a metaphor for climate change.

Heads-up: John’s question addresses the plot directly, so we’ll have to spoil a few things to properly answer it.

In the movie, a PhD student (Jennifer Lawrence) discovers a 9-kilometer wide comet that will smash into the Earth in about six months. As one character describes it, this comet is a “planet-killer” on par with the one that wiped out the dinosaurs.

The PhD student and her advisor (Leonardo DiCaprio) are rushed to the White House to explain the threat. Initially, a plan is devised to knock the comet off course, but that plan is swept aside when billionaire tech tycoon Peter Isherwell discovers that the meteor is rich with rare-earth minerals used in electronic devices like cell phones.

Isherwell hatches a hare-brained scheme to blow the meteor up into thirty separate pieces and steer them into the oceans so they can be harvested for materials. I won’t tell you exactly how it turns out in the film, but John wants to know: could this plan work? Would the impact of those smaller chunks really be less harmful than the original comet?

A trail of smoke from the 2013 Chelyabinsk meteor
By Nikita Plekhanov - http://gallery.ru/watch?ph=z6Q-ewl8g
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https://commons.wikimedia.org/w/index.php?curid=24661798
A trail of smoke from the 2013 Chelyabinsk meteor

Don’t Try This At Home, Folks

To find out, I called up Dr. Amy Mainzer. As the principal investigator for NASA’s Near Earth Object Wide-Field Infrared Survey Mission (or NEOWISE) and the scientific advisor for Don’t Look Up, she’s doubly an expert for this particular question.

“It is sort of THE question, can you really do something like that? And as it turns out… I wouldn’t recommend it,” said Dr. Mainzer.

Dr. Mainzer explained that when calculating how destructive a comet or asteroid might be if it hit Earth, scientists look at four factors. First, how dense is the object? Some asteroids are composed of practically solid iron (extremely dense) whereas comets are frothier, a mixture of ice, dust, and rock.

Second, at what angle will this object hit the planet? Asteroids tend to be orbiting the sun, not unlike the Earth, and are therefore more likely to enter the atmosphere at a narrow angle— almost like a stone being skipped off a pond. Comets, on the other hand, can have wild elliptical orbits that line them up to smack into a planet at a 90-degree angle—with much more severe consequences.

“But the two parameters that are the most important,” Dr. Mainzer told me, “are the mass of the object as well as its speed.”

Have you ever looked up and seen a shooting star streak across the sky? If so, how big would you guess the meteor making that bright flash of light is? Since meteors typically burn up in the mesosphere (about 30 to 50 miles up in the sky) you’d be forgiven for thinking they’d be pretty big — at least the size of a washing machine or watermelon. That’s what I would have guessed anyway.

But I was very wrong.

“When you see a shooting star in the night sky,” Dr. Mainzer says, “you’re typically looking at something that’s maybe the size of a sand grain or maybe a grain of rice, if it’s really bright.”

Comets and asteroids are moving at incredible speeds. Halley’s Comet clocks in at over 120,000 miles per hour. That means it could traverse the space between the Earth and the moon in less time than it takes to watch Don’t Look Up. At speeds like that, even small objects produce tremendous amounts of kinetic energy when they hit our atmosphere.

Do The Math

Impact Earth screenshot
A screenshot of what might happen if just one 2km comet chunk hit the planet - from Impact Earth (https://impact.ese.ic.ac.uk/)

Dr. Mainzer told me an object has to be smaller than 20 meters in diameter in order to avoid serious damage on the ground. Even then, there can still be serious consequences. The meteor that blew up over Russia in 2013 was about that size, and the ensuing shockwave shattered so many windows that about 1,600 people wound up in the hospital with broken glass injuries.

By comparison, the planet killer from Don’t Look Up is nine kilometers wide.

“Do the math on that and each one of those chunks is still very large… and maybe capable on its own of having global impact effects,” Dr. Mainzer said.

After I got off the zoom with Dr. Mainzer, I used a sphere calculator to work out exactly how big those chunks would be… and each one would still be over 2 kilometers across!

Purdue University actually put together a web program called Impact Earth (I highly recommend it) where you can plug in details for a potential asteroid or comet to see how it might… well, impact Earth.

So, I plugged in the info for a two-kilometer comet with low density, coming in at high speed at a 90-degree angle… and if just one of them hit New York City it would leave a crater the width of Manhattan, ignite clothing from Virginia Beach to the Canadian border, and shatter glass in buildings as far away as Cuba.

So… thirty pieces that size hitting the planet at the same time? I can’t say if it would have exactly the same amount of damage as the original meteor, but from the perspective of life on Earth there might not be much of a distinction. We’d all likely be dead!

“Let’s put it this way,” Dr. Mainzer told me. “Doing what the guy advocates doing is a really bad idea.”

To submit a question to the Outside/In team, record it as a voice memo on your smartphone and send it to outsidein@nhpr.org, or call the hotline, 1-844-GO-OTTER.

Outside/In is a podcast! Subscribe wherever you get yours.

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