NASA Redirects an Asteroid

Season 2 • Episode 8

65 million years ago, an asteroid struck the earth; in the ensuing planetary darkness, the dinosaurs went extinct. But the dinosaurs didn’t have a space program.

We do, and we can now spot incoming asteroids with steadily improving confidence. 

If we see one on a collision course with the Earth, we know from the movies that the solution is to nuke it. Right? 

Actually, NASA has a better, cleverer idea. If you can just nudge an asteroid slightly off its current path, maybe 25 or 50 years before it hits us, it won’t hit the earth. It will sail harmlessly past us.

In 2022, NASA put that idea to the test. It sent a tiny spacecraft 7 million miles into space, for the express purpose of crashing into a known asteroid—to see if we could bump it into a different path. 

We quickly found out. This is the story of the DART mission.

Guests: Dr. Richard Binzel, MIT professor. Dr. Elena Adams, lead engineer for NASA’s DART mission. Dr. Lori Glaze, director of NASA’s planetary science division. 

Episode transcript


Theme begins.

What would we do if we detected a deadly asteroid on a collision course with the Earth? Sorry, Hollywood—the best idea would not be blowing it up with nukes.

ADAMS: 09:42:28  / if you blow up an asteroid, you create a large number of chunks. And those chunks will still have the same velocity. They’ll still be going the same direction. 

No, NASA’s got a better plan. And in September 2022, they tried it.

ADAMS: 11:11:12  Oh, yeah. Little kamikaze spacecraft, yeah, for the good of humanity.

I’m David Pogue, and this is “Unsung Science.”

First Ad

Season 2, Episode ___: NASA Redirects an Asteroid.

There are so many movies about asteroids hitting the earth. “Armageddon.” “Deep Impact.” “Don’t Look Up.” “When Worlds Collide.” “Ice Age: Collision Course.” And a whoooollllle lot of even worse movies. 

NARR: It cannot think. It cannot reason. It cannot change its course. And it’s going to strike the earth…in six days. (chord!)

I mean, we can forgive Hollywood screenwriters, right? An asteroid plot supplies instant drama and high stakes for the characters. Here’s Billy Bob Thornton sinking his teeth into the “Armageddon” dialogue:

From 11:13 in “Armageddon:”

BILLY BOB: lt’s what we call a global killer. The end of mankind.

And here’s President Morgan Freeman in “Deep Impact:”

MORGAN: 1:31:00  Within a week, the skies will be dark with dust from the impact, and they will stay dark for years. All plant life will be dead within… four weeks.

I mean, that’s pretty high stakes!

An asteroid strike also offers a brilliant audio-visual spectacle—not a bad feature in a movie.

NARR: Tremendous tidal waves smashing New York City. The molten fires from bowels of the earth, gushing out to consume our world. (chord!)

In all of the recent asteroid movies, our solution to the threat is always something like this:

“Armageddon” 19:30

GUY: Are you suggesting we blow this thing up from the inside?

SCIENCE: That’s exactly what I’m saying.

BINZEL: 14:21:29  I’ve never been able to sit still watching any of the asteroid movies (LAUGH) and not just want to get up and walk away. / 14:21:38  / the asteroid movies are all about entertainment and not about science.

Dr. Richard Binzel is a professor of planetary science at MIT. He is the asteroid guy. 

BINZEL: 13:50:14  I have been studying asteroids since I was 15 years old. And– I still find them fascinating to this day.

As it turns out, asteroids are crumbs left over from the formation of our solar system. 

BINZEL: 14:12:26  Most of the asteroids in our solar system are between the orbits of Mars and Jupiter. It’s called the asteroid belt. / And occasionally, they’ll find themselves kicked into an orbit that crosses that of the earth. 

Binzel has discovered plenty of asteroids himself—and even named them.

BINZEL: 14:34:40  / the first one, I named for my grandfather, who was very inspirational to me in becoming a scientist. / the second one, I named for my wife. (LAUGH)

POGUE: 14:34:53  That’s very nice. Does the size, makeup, and trajectory of the one you named for your wife live up to her awesomeness? (LAUGHTER)

BINZEL: 14:35:50  / My wife’s asteroid is safely orbiting between Mars and Jupiter, where the sun is always shining. (LAUGH)

POGUE: 14:36:01  You’ve rehearsed that.

BINZEL: 14:36:02  I did. (LAUGHTER)

Binzel also invented the Torino scale, which does for asteroids what the Richter scale does for earthquakes. It rates every asteroid from 0 to 10, based on its likelihood to hit us, and how damaging it would be.

POGUE: 13:59:14  So what’s a ten on your scale?

BINZEL: 13:59:16  So on the Torino Scale, ten is effectively / dinosaur killer impact.

POGUE: 13:59:22  Okay. And then what are zeroes?

BINZEL: 13:59:24  / all the objects we know of today reside at zero or one on the Torino Scale, which simply means they’re so small that / they don’t matter, or that we know for sure there’s no impact possibility. /

And there are a lot of objects at zero or one on the Torino scale. Millions.

BINZEL: 14:40:39  /the earth is, a matter of fact, is being struck all the time. / the earth sweeps up about 15 tons of dust, meteor dust every day. 14:40:58  / And occasionally, several times a year, something is large enough that it can survive passage through the atmosphere and deliver rocks to the surface of the earth that you can pick up as samples. And those are what we call meteorites.

And most of those are very tiny. Let’s put it this way: Most asteroids entering our atmosphere couldn’t take out a sand castle, let alone humanity.

But on a much broader time horizon—hundreds, thousands, millions of years—big asteroids do hit us. 

BINZEL: 13:53:01  / Most famously, the– dinosaurs met their demise, we believe, 65 million years ago./

POGUE: 13:55:34  /Have there been any asteroids that did damage in more recent times?

BINZEL: 13:56:15  Well, probably most people are familiar with the impact over Tunguska, Siberia in 1908. That object was about 50 meters across, or a little over 100, 150 feet across– that broke up in the atmosphere. / But the shock wave / did hit the ground and– do– do great damage on the ground.  

13:56:53  And then more recently, in 2013 was an air blast over Chelyabinsk.

That would be Chelyabinsk, Russia We’ve got some truly spectacular videos of that one, thanks to Russian dashcams. See footnote 1.

Footnote 1: See, Russian citizens have a hit-and-run problem. You’re driving along, and some idiot crashes into your car. But they don’t want to deal with things like responsibility or consequences! So they just speed away. 

So you try to get reimbursed by your insurance company, and guess what? They say, “Oh, SURE it was hit and run. You just crashed own car, and don’t want to take blame. No money for you!”

Oh Suuuurrre it vas Chheet and rron. You just Crreshed OWN car. And ton’t vunt to tek bllllame (whole tongue). No mahhhney for you!

Slower, heaver.

Russians have their fair share of run-ins with corrupt highway cops, too.

And THAT is why millions of Russians now have dashboard cameras running all the time. So they can prove what happened if they get scammed. 

And THAT is why YouTube is full of amazing videos of the Chelyabinsk fireball making landfall in Russia. 

The sound of impact and alarmts:

End of footnote 1.

Anyway. In 2013, in Chelyabinsk, 1500 people were injured, and thousands of buildings were damaged. So, as Richard Binzel sums it up:

BINZEL: 14:02:19  The chances of your day being ruined by an asteroid impact are really very small. But if you think of our civilization over time scale of a century or more, then the chance of an impact is a few percent that something like another Chelyabinsk or Tunguska could be happening– again over the next century.

So. In 2016, Congress authorized the creation of NASA’s Planetary Defense Coordination Office. Yes, that’s a real place. As Jennifer Lawrence and Leo DiCaprio put it in the movie “Don’t Look Up”—

About 6:00 in “Don’t Look Up”

JLAW: /the Planetary Defense Coordination Office? Is that a real place?

LEO: I have no idea.

YES it’s a real place! It’s a department of NASA’s Planetary Science Division, whose director is Dr. Lori Glaze.

POGUE: 14:19:27  / I have to say, when I hear that NASA has a planetary defense wing, I think it’s more aliens. (LAUGH) I mean, it sounds like warfare, not bumping away rocks.

LORI: 14:19:39  Yeah. 14:20:31  But Planetary Defense Coordination Office has the job of identifying any potential asteroids that are out there. 14:20:16  /we wanna be prepared if there were one that were gonna be potentially dangerous./

14:22:27  / NASA actually funds several telescopes that are dedicated to searching for potentially hazardous asteroids or new– objects that are out there. / There are also other people around the world that are looking for these– potentially hazardous asteroids all the time./

POGUE: 14:23:16  So somebody somewhere has a big Excel spreadsheet with a list of everything we’ve seen? (LAUGH)

LORI: 14:23:21  Yes, we have what’s called the Minor Planet Center– that keeps track of all of the objects that we know of./

POGUE: 14:24:56  All right, so since I’ve heard I was going to meet you, this is what I’ve been wondering: Getting hit by an asteroid is a common layperson, deep-seated worry, along with all the other ways the world (LAUGH) could end. /

LORI: 14:25:16  It’s probably not at the top of the list to worry about, getting hit by an asteroid. /Right now, we don’t know of any that are of significant size that are– potentially gonna hit the Earth anytime over the next hundred years or so.

Well, that’s good. But if it’s nothing to worry about, why did NASA spend 325 million dollars on a special spacecraft, solely to discover if we can deflect an asteroid that’s on a trajectory to hit us?

LORI: 14:26:04  Well, here’s the– here’s the problem that we have. Even though it’s a low probability, it’s a pretty serious consequence. So right now we don’t feel like we have– an imminent threat from an asteroid. But we darn well wanna be ready if we find one that could be potentially dangerous.

POGUE: 14:32:19  Okay, great. So it seems like– / the best way not to get our planet demolished is not to blow up the asteroid, but to knock it to any other path, right? Like– like, speed it up a little, slow it down a little, change its angle a little. /

LORI: 14:32:41  All of those are good. / the most effective, we believe, will be to actually– try and slow it down a little bit. /

14:33:15  / if we could slow it down enough several years in advance– ten, 20, 30, 50 years in advance– just slow it down a tiny, tiny bit, then Earth will have already gone by when the asteroid crosses Earth’s path. So that’s what we’re doing with DART. 

NASA loves acronyms. DART stands for Double Asteroid Redirection Test. Because its target is, in fact, a double asteroid. It’s a huge rock called Didymos, which is Greek for “twin.” It’s a big mama—about half a mile across, weighing 11 billion pounds. 

But Didymos has a little moon of its own—a moonlet—called Dimorphos, which is Greek for “having two forms.” That moonlet is the target for the DART mission.

Now, am I the only person who’s gonna have trouble remembering which is which? Dimorphos. Didymos. I mean, come on, guys—they’re way too similar.

But I did get this tip: 

ADAMS: 09:38:42  / We’re going to hit Dimorphos, which is the moon of the larger asteroid. /

POGUE: 09:39:00  / which I understand NASA people sometimes call Didymoon.

ADAMS: 09:39:08  Yes. Didymoon is much, much cuter. (LAUGHTER) And bi– big fan of Didymoon.

That’s Dr. Elena Adams. She’s NASA’s lead engineer on the DART mission, and I’m going to interpret that exchange as her permission to refer to Dimorphos—that’s the moonlet—as Didymoon for the rest of this episode.

Anyway, the DART mission is a joint venture of NASA and the Johns Hopkins Applied Physics Laboratory. DART is basically a six-foot cube, wrapped in gold foil, with a camera on the bottom and two 19-foot solar panels. It lifted off in November 2021 atop a SpaceX booster…

the liftoff:

NASA: 3..2..1…And …liftoff, of the Falcon 9 and DART, on NASA’s first planetary defense test to intentionally crash into an asteroid!

…and took ten months to travel 107 million/over 400 million miles, to rendezvous with the asteroid.

Clip from the 9/26 NASA TV broadcast

I hope you appreciate the difficulty of the DART mission. I mean, Didymos and Didymoon are hurtling through space at about 51,000 miles an hour. They orbit the sun, just as we do—and the closest they ever come to us is about 7 million miles away. 

And that little moon that we’re gonna try to hit? We’ve never even seen it! True! You can’t see it with any telescope ever built. It’s too small and too far away. There was no way to know its shape, color, mass, or what it’s made of—it could be solid rock, or metallic, or it could be a lumpy blob of gravel. 

ADAMS: 09:47:20  And that’s what makes this so challenging. Because / we also don’t know what it’s made out of. We don’t know its shape. And how do you hit something that– where you don’t even know its shape?

09:47:37  / as an engineer, I hope it’s a perfect sphere, because then you can hit directly in the center perfectly, like.

POGUE: 09:47:59  Yeah. Good luck with that.

ADAMS: 09:48:00  Yeah. (LAUGHTER) One can dream. (LAUGHTER)

Even Didymos, the bigger rock, is so far away that it shows up on our telescopes as just a couple of white pixels.

The only reason we even know that it has a moon is that when we point our telescopes at it, we see a brief dimming once every 12 hours or so. Which could only mean that something is passing in front of it.

ADAMS: 10:19:31  / as the / little moon is coming in front of the bigger asteroid, the brightness actually dips. Because– this creates a shadow on top of the asteroid.

POGUE: 10:19:50  I see. So I could– even though I can’t really see the moon…

ADAMS: 10:19:53  Yeah. You know that something happened, because all of a sudden it just got dimmer.

POGUE: 10:19:57  Okay./

ADAMS: 09:40:52  / And that dimming is at 11 hours and 55 minutes. Right? So after we impact, we plan to change the orbit. / it will be something 11 hours and 45 minutes.

That’s right. The goal of the DART mission was supposed to be bumping the moonlet into a closer orbit to Didymos, so that it completes an orbit 10 minutes faster.

When I visited NASA in September, they showed me models and animations of the six-foot DART spacecraft and the 560-foot moon it was designed to hit. I mean, the size differential was ridiculous. 

POGUE: 10:03:34  It– it doesn’t sound like your spacecraft could do very much to this gigantic thing.

ADAMS: 10:03:39  That’s right. /10:03:51  it’s basically like throwing a tennis ball at a 747. If it goes fast enough, you’re gonna move it. But it’s gonna be a very slight change. /10:04:13  It’s going to be just a few inches. / It’s– it’s really a super safe test. //

POGUE: 10:15:00  Okay. So we’re not talking about exploding or flying off. We’re just nudging it a little–

ADAMS: 10:15:05  No. Just a little nudge. Just a little nudge. A tap.

POGUE: 10:15:08  Okay.

ADAMS: 10:04:13  / It’s a first test of can we actually do it? And what do we learn from this?

10:05:07  /  How will the asteroid, you know, what kind of plume will you create? How much will that actually move an asteroid? 

10:04:50  And we measure all of that. / Because/ only recently has– have we been able to hit these really small things far away.

But wait—we haven’t even finished listing all the ways that make this mission HARD.

We’ll get to that…after a break for ads. Hey—someone’s gotta pay the bills.


Welcome back!

I was about to help you go slack-jawed in amazement at the difficulty of the DART mission to hit an asteroid.

For example, at the moment of impact, DART’s speed is 14,000 miles an hour. And it takes 38 seconds for a signal from earth to travel that far. So NASA can’t possibly pilot the DART spacecraft from the ground in real time. Instead—DART will have to be self-driving.

ADAMS: 09:55:49  / the last four hours of this mission are completely autonomous. / the spacecraft has to make its own decisions. /

09:56:11  / SMART Nav, which is our autonavigation system on the spacecraft, does everything by itself.

09:56:32  / It points– our camera to the asteroid.

09:56:48  / And then it tells the spacecraft go there, or, you know, move to the left. Move to the right. 09:57: / And– we on the ground will be sweating a lot. (LAUGH) /

POGUE: 09:58:55  / So in theory, if e– everything goes well on your / video, you’ll be seeing, you know, this rock getting bigger, bigger, bigger. And then the feed goes dead?

ADAMS: 09:59:08  Yes. Yes. / 09:59:43  / You will hear people cheering, because it– you can’t stop people cheering at that point, because that means that, okay, we’ve lost the signal. 

Oh, and there’s one more problem. We don’t know exactly where the moonlet will be in its orbit at the time of impact.

POGUE: 10:01:19  So / it won’t happen that Didymoon is on the– behind the big rock?

ADAMS: 10:01:26  You just described my nightmare. (LAUGHTER) Behind or in front. Because the asteroid itself is actually– really bright. The bigger asteroid is gonna be brighter than the smaller asteroid. So the– as the small asteroid passes in front of– in front of it, we won’t be able to see it.

10:01:45  Or if it passes in the back, we won’t be able to hit it. Because there’s another rock in the way. So, yes. / people have been observing this asteroid/ since 1996. / So they think they understand the phase, which is where that asteroid is. / And they know it within about 10%, we think. /

Now, the DART spacecraft has a big ol’ camera on the bottom. That’s how it sees its way to Didymoon. But everyone was well aware that that camera would never broadcast the impact itself or the aftermath, because—well, you know—if we’re lucky, it’ll have smashed itself to smithereens.

But on this particular mission, there was going to be a witness: a separate camera off to the side. 

ADAMS: 09:52:41  / So we have– a little friend. It’s called a LICIACube cubesat. And– it was provided to us by the Italian Space Agency. 

POGUE: 09:54:36  What’s the internal NASA nickname?

ADAMS: 09:54:39  Oh, SelfieSat.

POGUE: 09:54:40  SelfieSat?

ADAMS: 09:54:40  Yeah. (LAUGH)

/09:54:07  / So we’re very hopeful that they’ll be able to capture the moment of– us impact– impacting the asteroid, but also creating the giant plume of stuff that’s gonna come out after we impact.

The SelfieSat rode into space on board the DART craft. And then, two weeks before the asteroid impact, it popped out of a slot on DART like a piece of toast, and parked itself in position to take some pix.

Actually, that selfie sat is only the beginning of DART’s surprises. Its primary mission, of course, was supposed to be deflecting an asteroid for the first time in human history. But it would also carry a veritable science fair of technology demos that could be useful in future space missions. 

ADAMS: 10:08:06  / One might say we’re a bit of a Christmas tree of technology demonstrations. We are demonstrating– the large– NEXT-C, next generation ion thruster. 

Yes, she said ion thruster. That’s actually a thing. It uses electricity to accelerate ions for propulsion. Ion drives don’t supply a ton of power, but they’re super fuel-efficient—so for long space journeys, they can fire continuously for a long time. 

POGUE: 10:08:53  And is that the thruster we’re using to get to the asteroid?

ADAMS: 10:08:56  Oh, no. Not at all.

POGUE: 10:08:57  No? (LAUGH) It’s just an experiment?

ADAMS: 10:08:59  It– it is just an experiment. / it could be used for future missions.

The technology demos also include a super-powered dish antenna, a new improved core computer, and those two solar panels.

ADAMS: 10:10:30  / so usually solar arrays are very rigid. / But– these arrays are actually blankets that are rolled on tubes.

/10:49:08  / When they’re first installed in the spacecraft, it looks like a tube– two tubes on the sides of the spacecraft. And after the spacecraft separation from the launch vehicle, from the rocket– we roll them out and– one at a time. (LAUGH)

10:10:49  And you deploy them like snap bracelets. They– they roll out and then they snap. / They’re super lightweight. So for future missions to– the outer solar system, you know, NASA is very interested in going to the Uranus system next.

10:11:07  / For those missions, these solar arrays are really enablers, because they’re so lightweight. 

And here’s the weird part. When you see a picture of the DART spacecraft, those two big snap-bracelet solar panels look like its wings, like a dragonfly’s wings. But it turns out that 90% of their area is completely unnecessary for the mission of crashing into an asteroid. All that power is used exclusively for the ion drive experiment! If we weren’t testing the ion thrusters on this trip, DART would need only tiny stubby solar panels for its own use.

OK—and now… the moment I’ve all been waiting for—

Brass fanfare, please

…a flash back to September 26, 2022, when DART was supposed to crash into Didymoon. You’re about to find out whether the Double Asteroid Redirection Test hit the spot—or missed, and sailed off stupidly into space. See footnote 2.

Footnote 2: yes, NASA did have a plan if that happened. It would wait a couple years until Didymos came back around the sun again—and give it another shot. End Footnote 2.

So let’s recap. The goal was to send a 1200-pound, six-foot cube, 7 million miles from earth, traveling at 4 miles per second, to crash into a rock that’s 560 feet in diameter, flying at 14 miles a second. A spacecraft whose body and software were made during the pandemic lockdown. And a rock, by the way, that we’ve never seen. Shape unknown, material unknown. 

OK…so now let me take you to the Mission Operations Center at Johns Hopkins Applied Physics Laboratory in Baltimore, on that night. Elena Adams is standing beside her workstation, overseeing the engineers in their blue NASA shirts.

EMCEE: Now if you’re just joining us, we’re under an hour away from the DART spacecraft’s head-on collision with the asteroid Dimorphos. / And you’re watching a live stream of its approach to Dimorphos. 

At this point, the NASA livestream is showing the live video from DART’s camera. Maybe the word “video” is generous—the frame rate is 1 image per second, and all you’re seeing so far is a single white pixel in the middle of the black screen. But I mean, come on. It’s an asteroid 7 million miles away. Don’t be a snob. 

EMCEE: DART’s mission is a test of a planetary defense technique that could one day save humanity. Rest assured, the test poses no threat to Earth.

30 minutes to impact. That one white dot is now a white pea on a black background. You still can’t see Didymoon—only the main asteroid. 

SAMSON: We have 30 minutes to go until impact, and /so far, so good. /

25 minutes to impact. NASA cuts to Elena Adams in the operations center.

ELENA: / We’ve locked on Dimorphos, we are maneuvering towards it, and yeah, everything’s looking really good. / We’ve executed two burns, and everything’s looking on track.

18 minutes to impact. Now you can see, for the first time, a second dot—one faint gray pixel—above and to the right of the asteroid. SmartNAV sees it and locks on.

Agent: Go ahead, MS5.

MS5: We have precision lock, and still tracking Dimorphos. (Applause, cheering)

Eight minutes to impact. Our friend Lori Glaze, NASA’s director of planetary science, describes what the engineers are doing.

LORI: / And they’re also thinking about reassessing continuously what’s the probabilitly of miss? Right? As you get closer and closer, that probability should look smaller and smaller, and it is. /It looks really, really good right now.

Five minutes to impact. Here’s Elena Adams again.

ELENA: 5 min to impact, 5 min to impact. We are at 1100 miles away! (applause) Also our window for sending any commands to the spacecraft is done! Contingencies are done!

Some music from here to the end would not be amiss…

At this point, there’s no mistaking what we see from DART’s camera: Didymos has a moon. The big asteroid looked like a gray avocado—but up and to the right is a mini-avocado, about one-twentieth the size. That’s Didymoon. 

LORI: But you’ve been watching it over the last 30-45 minutes go from just a collection of individual pixels, and now you can actually see the shape and the shading and texture/.

Two minutes to impact. SmartNAV takes its little software hands off the wheel and folds them in its little software lap. The time for aiming is over. There’s nothing more it, or anyone, can do, but wait for impact. 

LORI: This’ll be / humanity’s first ever, ever attempt at trying to move another celestial body.

One minute to impact. Oh man. We are now so close, the main asteroid isn’t even in the picture anymore. It’s all Didymoon, filling the screen. And the detail—incredible. The thing is clearly egg-shaped, titled 45 degrees, bright at the top right, shaded at lower left. But it’s not smooth like an egg—this thing is studded with craggy boulders. 

ADAMS: It’s amazing, guys! Oh my goodness, look at that. Unbelievable. Yeah. 

LORI: Looks to me like we’re headed straight in. / Oh, wow.

And now the little moon is enormous, filling the screen. Absolutely coated in rocks and crags—it looks maybe like a dough ball rolled in coconut.  

ADAMS: 5, 4, 3, 2…1!… 

And yet we’re still getting closer! Now we’re seeing individual pebbles! Actual dusty pavement-looking stuff. And closer, and closer, and sharper and sharper!

ADAMS: Oh my gosh! WOOOO!!! (cheers) 

The final frame of video starts to appear—but all we get is a strip of it at the top of the frame—the rest of the screen goes solid red. 

Amid the cheering, you can hear Elena Adams, arms up in the air, yelling…


TEAM: Congratulations! Congratulations! Congratulations!

Fade out, end the music.

The next day, the first pictures from the Italian selfie bot arrived, taken a couple of minutes after impact. They were a little blurry, but they unmistakably showed a big bright Didymos—with a very splatty-looking ashy plume from the point of impact on Diddymoon. Those shots will keep NASA scientists busy for months or years.

It took NASA a few more weeks of collecting data measurements before we knew just how much that dead-on, head-on collision shifted the moonlet’s orbit. It turns out—ten minutes, exactly as they’d hoped. Didymoon now takes 11 hours and 45 minutes to go around Didymos, instead of 11:55. We puny humans changed the orbit of a celestial body!

Now, there are other ways to shift an asteroid’s trajectory besides crashing into it. NASA is also studying something called the gravity tractor technique, where you fly a heavy spacecraft alongside, and let your slight gravitational pull drag the asteroid slightly off course over a long period.

Or maybe we could attach an ion thruster to the asteroid, just like the one that DART itself tested. Or we could paint the asteroid white, and let the infinitesimal pressure of the sun’s rays shift its course over many years. And, yes, there are even certain situations where we could consider… the Hollywood technique.

“Armageddon” at 19:30 

ACTOR: Why don’t we just send up 150 nuclear warheads and blast that rock apart? 

In the meantime, it’s kind of a relief to know that we have a planetary defense organization. And you know what? According to NASA’s Lori Glaze, so do other countries.

LORI: 14:46:43  There are– there is– a whole organization of– / countries from all over that have joined the International Asteroid Warning Network. And they all work together. /

POGUE: 14:47:03  Really? Does that include our enemies?

LORI: 14:47:06  It includes the whole world.

I should also reiterate that at this point, we’ve already spotted the big asteroids that could kill us all; now the work is finding the smaller ones that could take out a city. 

LORI: 14:37:17  /the ones that really are kind of civilization-ending size asteroids, we know– we’ve already found 99% of those. // The smaller ones that could have regional damage, re– regional– you know, impacts, / there are some out there that we don’t know about. 

14:35:17  / So we’re actually right now already building the next telescope, a space telescope / called the Near Earth Object Surveyor. 14:35:39  / to search the sky 24 hours a day. 

14:35:39  / We should be able to get– to find up to 90% of those objects within a period of about ten years, once we get flying.

And, speaking of next steps—in 2024, the European Space Agency plans to return to the Didymos asteroid with a robotic spacecraft called Hera, which will fly along for a closer look at the damage the DART did. It’ll check out the crater we made, and see if we can figure out Didymoon’s exact mass.

But for mission director Elena Adams, it’s time for a new phase: studying the data, putting science to work, and maybe getting some sleep.

ADAMS: 10:55:03  But I do have to say, I do love my job for smashing such– you know, you build up this spacecraft and it’s– it’s like a Ferrari, right? It’s– (LAUGH) it’s just a beautiful piece of equipment. And then the– the whole point of it is to go smash into a rock. (LAUGH)

POGUE: 10:55:17  That’s sad. (LAUGHTER)

ADAMS: 10:55:19  But also kinda glorious. (LAUGHTER)