Unexplainable - Finding asteroids before they find us

Episode Date: January 26, 2022

Scientists are constantly searching for asteroids that could crash into Earth. But if they find one, will they be able to do anything about it? NASA has launched a spaceship that will slam into an asteroid to find out. For more, go to http://vox.com/unexplainable It’s a great place to view show transcripts and read more about the topics on our show. Also, email us! [e-mail] We read every email. Support Unexplainable by making a financial contribution to Vox! bit.ly/givepodcasts Learn more about your ad choices. Visit podcastchoices.com/adchoices

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For less, give AncestryDNA. Visit Ancestry.ca.C.T.A. today. Offer ends May 10th. Terms apply. Hollywood's got a long tradition of making movies about huge stuff crashing into Earth. There's Armageddon. You want to send these boys into space, fine. Sure they'll make good astronauts.

They don't know Jack about drilling. There's deep impact. We get hit all the time by rocks and meteors. But the comet we discovered is the size of New York City. And there's the most recent entry to the cannon, don't look up. You cannot go around saying to people that there's a hundred percent chance that they're going to die. You know, it's just nuts. But this kind of thing isn't just relegated to science fiction.

Our science editor, Brian Resnick, says this is a problem that scientists, and even government officials, have been taking seriously for decades. Congress actually got this huge wake-up call when it comes to celestial objects smashing into planets. This was in 1994, and this was the year scientists actually witnessed a comet heading straight for Jupiter. Amateur astronomers all over the world are craning their necks up to the heavens to see a collision of a disintegrating comet with the planet Jupiter. For the first time, astronomers could actually look and see what happens when one of these giant comets hits a planet directly. You know, nobody knew for sure what might happen. And so everybody was waiting to see, will these pieces just disappear into Jupiter's atmosphere or will there be something cool to see?

This is Kelly Fast. She was a reason. research astronomer at the time, and she was there. She was watching this really epic moment in 1994. We know when and where these pieces are going to hit Jupiter. Let's get the telescopes of the world ready to watch this to see what kind of science we can do. Yeah, this is the latitude that we're looking for something right there. There was a number of different groups at this observatory, and so a real kind of, almost like a conference party-type atmosphere going on. everybody just excited about the science.

And then they saw it. Oh, my God. Look at that. Oh, boy. It was amazing. It's a dynamic planet. Things were changing all the time, but not in that way. This comet had broken up before impact, so it was just multiple pieces slamming right into Jupiter.

Material kind of shot back up and up into the atmosphere into this big, like, umbrella, plume. that would then drop back down onto the atmosphere from Jupiter's gravity. And then that heated up the upper atmosphere. This comet, it was about two kilometers wide to like a mile, which is less than a quarter of the size of the object that wiped out the dinosaurs. But if this comet had hit Earth instead of Jupiter, we're talking about an extinction level event. This would have been a global catastrophe.

But it also was sort of that wake-up call that, you know what, impacts are still happening in the solar system. And it wasn't just scientists watching this huge collision on Jupiter. Congress actually perked its ears up too and decided to do something. The threat posed by Earth orbit-crossing asteroids and comets has long been a concern of mine and of the committee. The Science Committee has proposed augmenting funding for this important effort. Congress tasked NASA to really just find any objects that could pose a threat to the Earth. This eventually led to what's called the Planetary Defense Coordination Office, and this is where Kelly works today.

It's finding asteroids before they find us, and then maybe getting them before they get us. I'm Noah, I'm Hassanfeld, and this week on Unexplainable, can we find out where all the asteroids and comets are, and whether they're heading towards us? And if we do find one, can we actually do anything about it? Okay, so Brian, what did Congress actually do once they got worried about a comet, maybe coming out, kill all of us?

Yeah, so after this huge collision on Jupiter, Congress actually asked NASA to look for comets, asteroids, anything larger than a kilometer that could collide and hit with the Earth. Not just looking for anything in the solar system, but things called near-earth objects, which, you know, would be in our, like, solar neighborhood. Yeah, so how do they actually map these asteroids? Are they basically, like, I don't know, just taking a telescope and randomly pointing it at spots in space and seeing if they find stuff?

Yeah, this is fairly simple. Scientists use telescopes on the ground. They use telescopes in space. And basically, when you look at the sky, the stars are fixed points. But then you keep taking images, and you find there's that one star that keeps appearing in a different, place with every image. That's how they're found. You're looking for a moving point of light against the stars. This is a difficult problem for a few reasons. Your telescopes, your telescopes only

go so faint. And so there might be some fainter or more darkly colored asteroids out there that aren't reflecting as much sunlight. But also, like, we need to catch them at the right place at the right time. So there could be things that are just like hidden from our view because they're on the other side of the sun. They could be very far out in the solar. system and on their way in, and we just can't see them yet. The Earth is going around the sun, like going around the racetrack, and all the asteroids are going around the sun, going around the racetrack. And there are times where, you know, you can see the asteroids, certain asteroids from Earth

if they're close enough and bright enough and you have the right capability. But then there are times when asteroids are over on the other side of the sun from where you are on Earth. I guess I would think of asteroids as just sort of like space rocks, zooming across space, like in a straight line and maybe like some. Some will pass Earth and go by us, and some will hit us. But you're saying they're all on their own orbits around the sun? Yeah, yeah.

So you don't have like, you're like most of the way there. Like, yes. Okay. asteroids will zoom across the solar system, but then they're still reigned in by the sun. and pass closer. You kind of still have to wait for the solar system to refresh itself and to bring them around. Just like make a bunch of loops.

And if we look, what, four or five loops in the future, maybe we could see it's going to crash into us. Yeah, I mean, there's a limit to how far in the future we can, like, reasonably guess. But, yeah, for the most part, like, this is what they try to do. They try to see where these objects are. They try to predict the path of their orbits, what they'll look like on their next path around the sun

and just ask, like, And on any of these loops around the sun are they coming very close to Earth? And do we know if any huge asteroids are going to hit us anytime soon? So some good news here. These huge kilometer, kind of like planet doomsday asteroids, NASA says they found more than 95% of them. And like more good news is that like, you know, tracking their orbits into the future, none of these are going to be.

a threat at least within the next hundred years. How do they know, like, how many total asteroids there are? You said they found 95%. What about the other five? How do they know those are out there? The short answer is that they keep finding them. Okay. If you keep seeing new ones every single year, that can give you an idea of how much

there are left to find. It's kind of like, so imagine you're fishing in a pond, and you're catching fish, and you're tagging them, and then you're putting them back in the pond. So if you keep catching the same fish, you can reasonably conclude you've probably seen all the fish in the pond or most of them. But if you keep catching new fish that you haven't seen before, you can then model from there, like, how many must still be in the pond, just like on the rate of discovery. If your catalog keeps growing, you know you're not there yet when it starts really leveling off, then you can kind of feel a little better. Okay, so are we good then? Like, if we found all the big asteroids out there, can I just stop worrying about asteroids?

No, no, not really. Why? I think this is, like, the real story about asteroids that, like, really gets us away from the Hollywood version into, like, the real problem that scientists and the world has to deal with. You say find all the asteroids. As you get smaller and smaller in size, there's more and more of them. So at first, they were just asked to look for all the asteroids that are a kilometer or larger. And then in 2005, Congress asked NASA to look for anything 140 meters in larger.

And 140 meters is like the size of a skyscraper. I guess you can call them medium-sized asteroids, but I would not want to be up close near one. And I would, you know. What would that do if it hit Earth? Would that be an extinction event or less than that? It wouldn't end life on Earth, but it would be like, it would be a huge catastrophe. Like these are sometimes dubbed city killers. So if one hit a populated area could have fallen in the city, create a huge airburst explosion,

eject material from the Earth that would then like rain down. Like really an event that I think would be remembered throughout history as one of the great catastrophes on Earth. Okay, so how many of these sort of medium-sized asteroids has NASA found? There's a concerning amount of them. So of the 140 meter and larger, we've found about 40%. Oh, that's a lot less good. We still need to find the rest of them. How are we going to find the other 60%?

Do we just need to keep looking at new places or waiting for asteroids with even bigger orbits to pass near us? Some of it is just time. We just need to be patient and wait. And, you know, like there are ideas like, so NASA, wants to put a space-based telescope that is just focused on finding asteroids, and it's called the Near Earth Object Surveyor, and they plan to launch that in 2026. But for right now, Kelly tells us that at the rate we're going,

we'll probably find all of these within 30 years. Okay, so then in 30 years, once we find all the city killers, are we in the clear then? Yeah, but then, like, we would probably need to set the bar a little, a little higher too. So right now we're looking for asteroids that are 140 meters and larger, but there are smaller ones too. And those smaller ones, like a couple meters in size, our atmosphere does a really good job taking care of those, disintegrating those. We just see pretty fireballs and call it a day. But the ones that don't disintegrate, those could still

have really big consequences. Yeah, how bad could could, I don't know, like a 20, 30, 40 meter asteroid? How bad could that be? We've seen these in our lifetimes, and they can cause a lot of damage. So in 2013, there was a meteor that exploded over a city in Russia, and that was, like, it exploded with the force of more than a nuclear weapon. They were like dash cam recordings of this, right? I feel like I remember seeing them. It was widely documented.

It's the biggest meteor in more than a century to hit the planet. A thousand people were injured from shards of flying glass and debris. You saw the explosion from dash cams. You saw a windows break. And this asteroid, you know, when it's in the atmosphere, you start to call it a meteor. But same thing. You know, it was less than 20 meters. And it exploded far enough away from people that, like, it wasn't, you know, this mass death event.

But it did, like, hurt a lot of people. It did cause a lot of damage. And that was, like, a little bitty asteroid. Did scientists know this was coming? No, no. they did not know who's coming. If you knew it was coming, you'd get people out of the city, I had hope. Yeah, that feels not great.

Yeah, even medium-sized asteroids can definitely sneak up on us. So in 2019, there was this asteroid that was really quite a bit bigger than the one that exploded over Russia. It was something more like 100 meters. The Washington Post reports NASA has confirmed a so-called city killer asteroid narrowly missed hitting Earth. It passed, but it was pretty. be close. It came in between the distance between the Earth and the Moon. So, you know, that's kind of like disconcertingly close and we just were surprised. What's more alarming, scientists say they had no idea it was coming. That is alarming. They're supposed to know.

Whoops. And these medium-sized, you know, city killer asteroids, every century, maybe there would be like one in a hundred chance these things would hit somewhere. But, you know, there's still a chance and we need to have a plan for it. are so slim, maybe not in our lifetime, our children's lifetimes, they're children's, but wouldn't you like to know just to be sure? If scientists are looking off into space and they find one of these asteroids coming towards us, say it's like a medium-sized 140-meter asteroid, is there anything they can do about it? Can they, you know, pull up Bruce Willis and go up there and get it out of the way?

Well, maybe. And there are a few different options here, but we're not sure what would happen if we tried to push an asteroid out of the way? And NASA's actually trying to figure that out right now. Coming up after the break, if we found out an asteroid was heading toward Earth, could we actually do anything about it? And what would happen if we try? No one actually knows the answers to any of these questions,

so that's why they're going to whack this asteroid and see what happens. That's next. It's all about you. And when you fly with Virgin Atlantic in their upper-class cabin, They take the VIP treatment to the next level. With a private wing to check in and your own security channel at London Heathrow, you can glide from your car to their clubhouse, a destination in its own right in 10 minutes or less.

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It's unexplainable. We're back here with Brian. Hi. We've been talking about asteroids, the big Hollywood-style planet killers, but also the smaller ones that are way more likely to actually hit Earth at some point. So we've got a basic idea of how to find and track them. But what happens if we actually do find one that's heading right towards Earth? Oh, personally, I'm going to, like, find a table to, like, hide under and just cowards.

Yeah, just hide from the asteroid. Yeah, I'm going to hide. But on a societal level, yes, there are some ideas out there of how to, like, get rid of an asteroid. Yeah, what kind of ideas? You know, there's some wild ones of, like, you know, you could just try to bomb it, like with nuclear weapons. Or, like, send oil drillers like Armageddon style to drill into it and bomb it from the inside. We're not astronauts. We're oil drillers.

We're not even supposed to be here. I honestly don't know about drilling into an asteroid. but I do know, like, this is the idea of kind of detonating a nuclear explosion near one is an idea that's discussed seriously. But, like, that's not exactly the place you want to start with, with, you know, dealing with an asteroid. Like, nuclear weapons are obviously dangerous. And also, like, if you do detonate one of these weapons and it does, like, blow up an asteroid, like, the pieces of that asteroid could, like, potentially, like, come back together because of gravity.

they could do unpredictable things. Like the pieces might be able to hit us too, right? Yeah, it's kind of like a big, messy, like it's like the sledgehammer approach to this problem. And there actually might be like a simpler and, dare I say, more elegant way of dealing with it. What's like a simpler option? Well, the simplest option is to try to nudge an asteroid.

Nudge it. Just like give a little boop, you know, like boop. How do you boop an asteroid? NASA is actually, in the process of, it's launched an experiment to see if they can boop an asteroid. It's called the double asteroid redirection test or dart. What's Dart going to do exactly? It's going to do something kind of beautifully simple.

Like, it's just going to try to slam into an asteroid, and then on Earth, scientists are going to look at it and to see what happens, to see if we can actually change an asteroid's orbit. So the idea is, like, the spaceship would slam into the asteroid and just the force of that slamming. It doesn't really sound like a boop. It sounds like a huge slamming into an asteroid. Well, what's a boop on like the cosmic scale?

You know, like... What are we, but cosmic boops? It's like a boop compared to, like, what happened to Jupiter. Like, that was a boom. This is a boop. I don't know. So what asteroid are they aiming for? What asteroid are they trying to boop out of the way?

So they chose an asteroid that... It's like actually it's close enough to Earth where we can get to it and like observe what happens when this spacecraft hits into it. But they did choose one weird thing. So the asteroid that we're going to hit is actually a little asteroid that orbits a bigger asteroid, like the moon orbits the Earth. What? Yeah. Okay. So this mini asteroid is called a moonlit.

A moonlit? Yeah, yeah. So it's cute. But basically, like, they're targeting this little moonlit asteroid because, like, you know, you don't want to, like, boop something in space and then have it hit into something important like us. So basically, they chose this moonlit because they can, like, change the orbit of the moonlit around the bigger asteroid. And it's, like, unlikely to do anything bad. But it also serves as a proof of concept because an orbit is an orbit. So if you can change the orbit of this moonlit,

then you can change the orbit of an asteroid. And when's this going to happen? So this is underway. NASA launched a spacecraft last year, and it's targeting an impact later this year, later in the fall. I spoke to science writer, Robin George Andrews, who did a lot of reporting on this,

and he told me all about how this could play out. Yeah, so it's one of these things. It's kind of remarkably simple. essentially NASA has released a spacecraft and it's going to hunt down an asteroid orbiting another asteroid and it's going to smash into that asteroid and see if it can change its orbit really. They're essentially playing space billiards and seeing if it works. Yeah, so this is, just to be clear, this has never been tried before. No, this has never been tried before now. This is the first time humanity has tried to flick an asteroid in a different direction. And this spacecraft that's going to try to do this, Dart, what does it look like?

Yeah, so Dart is essentially a box with solar panel wings. So it's kind of like a car-sized robot with an eye, with a single eye, with two fairly long wings coming out of either side sort of thing. And the target of this mission is a moonlit called Diamorphos, which is 160 meters across. So Dart will crash into this moonlit at 24,000 kilometers an hour, which is certainly breakneck speed. It's faster than any collision that happens in our everyday experience on us, so it will be quite the wallop.

Considering that this is a car-sized spacecraft, it's really going to hit this moonlit with quite a lot of momentum. It's not a little poke. So this spacecraft is going to slam into this asteroid that's orbiting another asteroid like what would they hope to see when that happens? So the moonlit is going around once every 12 hours-ish and they're hoping to change its orbit by at least 73 seconds.

I'm not quite sure why 73, but it's just by a matter of like over a minute kind of thing. And obviously they don't want to still hear communications from DART if DART is still chattering away after it's supposed to have hit this moonlit, then something has gone wrong sort of thing. So they really want to see an explosion, actually, rather than a calm, happy spacecraft. What are the reasons why maybe this won't work?

So the first one is the shape of the asteroid. So one of the scientists I was speaking to about this mission was jokingly handed a donut-shaped fridge magnet, because there was a chance that the small asteroid could be shaped so weirdly. it might have a hole in the middle, so I might just go right through the middle. Can you imagine that? Like thread in the needle. I mean, that would be hilarious.

That would be hilarious. It would be hilarious. Okay, so that's one thing that could go wrong. That's one thing that could go wrong. Also, if it's, like, the assumption that all its mass is distributed evenly may not be true. In zero or low gravity environments, anyway, rocks just behave slightly differently to the ones on Earth, where gravity is squashing everything together, you know. So it's, they could be quite honeycomb shaped in the inside or foamy, like cappuccino foam kind of thing.

And if you hit that at 24,000 kilometers an hour, will it just split it into millions of pieces or will it go straight through it? Or will it still be cohesive enough to take that impact, transfer the momentum and deflect it? No one actually knows the answers to any of these questions. So that's why they decide to, you know, they're going to whack this asteroid and see what happens. So are those the two big ones that might go wrong, like it goes through the center hole? Or if it turns out this asteroid isn't all that dense, or at least a part of it isn't that dense, it can kind of like cushion the impact or could do weird things to the impact that are kind of hard to predict. Yeah. The thing is, even if you hit it and it kind of smashes into loads of pieces, that's not necessarily a bad result.

It just kind of suggests that maybe if you need to deflect an asteroid for real, you just deflect it, you don't hit it as hard. you hit it a lot softer, and maybe you hit it a few little times to deflect it out the way sort of thing. So it's like, basically this test is answering how big a wallet do we need to give these city killer asteroids to save the planet if we need to? If DART does work,

and it turns out that it's possible to deflect an asteroid, what do we do in the future if we find an asteroid that's coming at us? So ideally, what you want to do is spot these asteroids way ahead a decade or more in advance, and then you can send a precursor mission to either observe it beforehand, so you get a better idea of what it's like, like an orbiter or something,

or you get a little small impactor to just poke it, just to see how it responds to that initial prod. You could then send a dart-like mission to kind of deflect these asteroids. It sounds like in the next few decades, potentially, we can solve this problem for the rest of humanity,

which hopefully will go on for a while, Hopefully, yeah, fingers crossed. Yeah. So in that sense, like, it's funny balancing those things because, like, hearing about asteroids and, like, I know I have bigger things to worry about in the world. You know, like, you know, infection risk being a huge salient one these days. But, you know, just thinking about, yeah, we need to prepare for future pandemics and future natural disasters.

But also, like, that doesn't mean we can't also have. have this intergenerational approach, that we can save lives in the year 2200. It's something we should want to do. Yeah. And in an ideal world, if that is possible, and that is the first piece of this, then it's extraordinary. It's the one natural disaster, essentially, that you could cancel out. Essentially, you can't stop volcano erupting or an earthquake happening or hurricanes in that way. You can mitigate the damage, but, you know, but an asteroid is, if you just flick it out the way of the earth, the threat is gone.

Yeah, and that you're saying that is kind of making me feel like Dart is something to feel really good about. Like, I don't know, maybe in the year 2200, DART will be a historic hailed thing because it helped avert a disaster. And, you know, that's something collectively as humanity, even though we might not avert this disaster in our lifetimes, we could potentially feel good about that, you know, on the long list of, problems to solve and disasters to mitigate, maybe we can actually solve one. Yeah. I mean, I think it's just really a testament to scientific know-how and, you know, international cooperation that you can get a mission like this kind of going, which has so many sciences working around the world to do it. And I do think that what, just imagine one day, you know, there is a city-killer asteroid heading towards Earth,

than in 10 years' time, and a descendant of Dart manages to deflect it out the way, saving millions, or maybe billions of lives spending on how big this thing actually is. You know, Dart will be the first step in that, and it will be one of the greatest human achievements, really. You know, the planet is protected. It's defended, and that's kind of an amazing thing to think about. This episode was reported by Brian Resnick and produced by me, Manning Wyn. There was editing from Catherine Wells, Meredith Hodnott, to Anne Noam Hassenfeld, who also did the scoring

for this episode. Richard Seema checks the facts, and Christian Ayala was on the mixing and sound design. The Unexplainedable team also includes Bert Pinkerton, and Liz Kelly Nelson is a VP of Vox Audio. Email us at Unexplanable at Vox.com if you have any thoughts on the show. And if you feel like leaving us a nice review

or a rating wherever you listen, we'd all really appreciate it. Unexplanable is part of the Vox Media Podcast Network, and we'll see you next Wednesday.