Instant Genius - NASA’s DART asteroid deflection mission, with Tim Gregory

Episode Date: September 15, 2022

Geologist and chemist Tim Gregory tells us what to look out for when NASA’s DART spacecraft completes its year-long journey and crashes into an asteroid. Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

Now more people than ever can bring in their bill for a better deal at Verizon. Got AT&T or T-Mobile? We got you. Xfinity or Spectrum? You too. So tell your friends, your family, your quirky neighbor Jeff. Grab your megaphone and yell it from the rooftop. Get a better deal at Verizon.

Because chances are anyone in shouting distance is included. Bring in your AT&T, T-Mobile, Xfinity, or Spectrum bill, and we'll give you a better deal on the best network on the best-overdial network. Come by Verizon today. Best Network based on Route Metrics, Best Overall Mobile Network Performance, U.S. Second Half, 25, all rights reserved. Must provide recent consumer mobile bill in the name of the person redeeming the deal. Additional Terms Conditions and Restrictions applies.

You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost. Or you could book a stay with Hilton. Welcome to your ocean front room. Just steps from the water.

The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton for the stay. When you need to build up your team to handle the growing chaos at work, use Indeed sponsored jobs. It gives your job post the boost it needs to be seen and helps reach people

with the right skills, certifications, and more. Spend less time searching and more time actually interviewing candidates who check all your boxes. Listeners of this show will get a $75-sponsored job credit at Indeed.com slash podcast. That's Indeed.com slash podcast. Terms and conditions apply. Need a hiring hero? This is a job for Indeed sponsored jobs. This podcast is sponsored by name, audio and focal. Streaming has made music more accessible than ever, but true listening is about more than ease. It's about quality.

British audio experts name audio, alongside French acoustic specialist focal, combine handcrafted tradition with cutting-edge innovation and high-end materials, delivering digital precision with analogue warmth, so you can experience exceptional sound at home. Music just as the artist intended. Visit name audio.com to learn more.

And welcome to Instant Genius, a bite-sized masterclass in podcast form. I'm Jason Goodyear, commissioning editor at BBC Science Focus magazine. In this episode, I speak to chemist and geologist Tim Gregory about Dart, NASA's exciting mission to deflect the path of an asteroid by crashing a spacecraft into it. We're here to talk about the Dart mission, which is the mission to knock an asteroid off its path. So first off, can you sort of sum up what the mission's about, you know, what its acronym means and this sort of thing for me? So with it being a NASA mission, they love a good acronym. Dart is no exception.

It stands for the double asteroid redirection test. And it's essentially a big science experiment to see if crashing a spacecraft into an asteroid is a good way to change its orbit around the sun and potentially deflect an Earth-crossing asteroid away from being Earth-crossing in the future, should that happen, or rather when that happens. Yeah, so the asteroids, well, the clues in the title really, the double asteroid redirection test. So can you tell me a bit about the asteroid targets that are the object of this mission, please? Yeah, so double asteroid, it's kind of a cool little system because much like the Earth has a celestial companion with the moon, some asteroids have celestial companions too. We call them binary asteroids, and this particular asteroid really is asteroids because it's a binary system. It's made from two individual objects, Didimus A, which is about 780 meters across.

That's about seven football pitches. And it's smaller companion Dymorphus, which is 160 metres across. And the DART mission is going to target the smaller of the two Dymorphus. So why was this particular binary asteroid system chosen as the target for the mission? So it's important to stress that this particular asteroid system doesn't pose a threat to the Earth. it was merely just chosen as a target for this science experiment, and it was chosen from a few different candidates based on its orbit around the sun. It's got a very well-determined orbit,

and once Dart crashes into this asteroid, we'll be able to track the new orbit to see if it's changed. So whereabouts is this pair of asteroids at the moment then? How far away from Earth? So they're a long way from the Earth. Dart launched last year, actually, in November, aboard a SpaceX Falcon 9 rocket, and it's going to collide into this asteroid on the 26th of September if everything goes to plan.

And so, you know, although these objects are relatively close to the Earth, relative to outer solar system objects and Mars, it still takes the best part of a year to get to them. So what are we talking about when we're talking about these asteroids then? Like, do we know anything about their composition and that sort of thing? So one of the really sort of mind-blowing things about these asteroids is that we don't actually know a lot about them, other than their orbital parameters, we don't know what they look like, we don't know exactly

what they're made of. And that's actually true for basically every single asteroid in the solar system. The word asteroid means star-like, because the astronomers who first started spotting these objects in the sky, they noticed that they were just point sources of light in the sky through their telescopes like stars, but similar to planets, they seem to move from night to night against the fixed backdrop of stars, hence the name asteroid star-like. And even to modern telescopes, asteroids are so small that they still appear as point sources. There's only a small handful of asteroids that we've ever got up close and personal with space missions. And this particular asteroid system, we won't know exactly what it looks like or its exact sort of geological

makeup until we get up close and personal in 12 days' time. So what does, what does Dart look like? What sort of instruments does it have on board, you know? And what's it going to do when it reaches these asteroids? So DART is quite a hefty spacecraft. It weighs more than half a ton. It's 610 kilograms. And so when it slams into the asteroid, it's going to impart quite a lot of inertia, which is, well, the hope is that it's going to change the asteroids course by a predictable way that we'll be able to measure going forward into the future. And one of my favorite things about this mission is that stood on board. There's a cube sat. And CubeSats are tiny little miniature satellites. They're sort of the size of a champagne bottle, that sort of size. And this particular cube

is Italian in origin, and it's got a camera on board, and it is going to be the only witness to the collision with this asteroid. And so, you know, we'll be waiting with baited breath of this cube sat to beam back images of the collision when it finally does happen. So at the time of impact, I think the dart and the asteroid system are going to be more than 10 million kilometres from Earth. Is that right? Yes, that's right. They're an awful long way from Earth, and our only eyes sort of on the event are going to be this CubeSat. And over the, you know, the intervening weeks, months and years, it's going to be ground-based telescopes that track the

new orbit of the asteroid around the sun to see exactly how much it's been deflected. So how do the scientists sort of navigate towards the asteroids then over this incredibly long distance? How does Dart actually get there? Because you said it's only 800 metres across. Yeah, that's right. So it's got on-onboard camera that's sort of fixed onto the asteroid. We can track them pretty well from the surface of the Earth using ground-based telescopes. And, you know, over the last couple of weeks, there have been a couple of rocket boosts to steer dart towards its target. And the final rocket boost, interestingly, will be entirely done by the spacecraft computer. It's going to be hands off in the sort of the final countdown to impact.

It's going to be completely automated. I guess in the same sort of baited breath moment as the Mars rover's landing on the surface of Mars, when the computer takes over and we all see here on Earth thinking, oh, goodness, as it worked. So it's going to be quite an exciting day when the collision happens. So I've read some things about people describing the collision as kinetic impact. So that sounds a bit like a pair of trendy trainers to me. So what exactly does that mean? Maybe NASA should release a pair of trendy trainers called kinetic impacts.

I'd definitely buy a pair of them. So one of the things that we don't know how to do yet as a species, and particularly as a space-faring species, is deflect asteroids and change their course around the sun. there are many weird and wonderful ways that we might achieve that aim. And kinetic impact is essentially what it says on the tin. It's slamming a spacecraft into an asteroid to ever so slightly nudge its orbit around the sun away from the earth. And it sounds impossible that something as lightweight as a spacecraft, even a spacecraft like Dart, which weighs more than half a ton, could possibly nudge something like an asteroid, which wear millions of tons. But you don't

need to nudge an asteroid by very much for it to miss the Earth entirely, because these things, it's important to kind of get your head around there, not travelling in straight lines towards the Earth, or at least if we found an asteroid hanging towards the Earth, it wouldn't be travelling in a straight line. These things are in orbit around the Sun, along with the planets, including the Earth, and so you don't have to nudge their trajectory around the Sun by very much, you know, fractions of a degree, and you'll miss the Earth by millions of miles. And so kinetic impact is slamming a spacecraft into an asteroid to try and deflect it. But there are other ways that you could possibly do it as well. There's a particularly inventive method that I like,

but it's never been tried, and that's painting the surface of an asteroid. And that will change its reflective properties, which kind of, it almost turns it into like a natural engine as the asteroid reflects sunlight of the painted side of the asteroid. That reflected sunlight might be enough just to push the asteroid out of its orbit away from the Earth. So this is brand-new, uncharted territory for our species. So you mentioned the little Italian CubeSat. Presumably that takes a bit of a time

to beam back data, but is there any chance that we, as members of the public, we're going to be able to watch this this whole thing take place? I'm sure NASA will be doing lots of press on the day. This is gaining traction in the media slowly, actually. I've noticed over the last couple of days a few new stories about it.

And with this mission being the first of its kind, I'm hoping that NASA will do a live stream similar to the one that he did for this the James Webb Space Telescope Image Press release a couple of months ago. So once this, you know, let's presume this mission's been a success, that it's successfully collided with the asteroid. How then do we go about figuring out how successful the mission is? Well, I guess that's the thing. We're not exactly sure what's going to happen. There are computer models that have been run that will predict exactly how much this asteroid

will be deflected, and there will be predictions about the new orbit of the asteroid after impact, and I guess exactly how close observational data will match with those models, will tell us exactly how much of a success it's been. But even if this mission doesn't match the models and the predictions, it still will be a success. You know, the nature of doing any sort of science is sometimes you just don't know what's going to happen. And with this mission being the first of its kind, I think the margin for success is very wide, I guess, to paraphrase the Apollo astronauts, hopefully it will be a success, but it might be a very successful failure. So a lot of people, when it comes to things like these DART spacecraft, these spacecraft like

Dart, a lot of people tend to sort of anthropomorphize them. And a lot of people will be thinking, well, what's going to happen to poor old DART after the impact, you know? Is it just going to drift off quietly into space? That's a good question. It depends on the nature of the asteroid. You see, some asteroids are very sort of compact on their surface if you were to jump on them. ignoring the low gravity, they'd feel very firm underfoot. But some asteroids are incredibly loose. They're more like loose aggregates of rubble, and we call them rubble pile asteroids.

And so exactly what will happen to poor old dart after collision will entirely depend on the surface of the asteroid and its geological nature, which we just don't know right now. So just sort of looking forwards a little bit. So how do we go about tracking asteroids from the Earth? Is that technology improving? Yeah, so thankfully, space agencies around the world put a little bit of money aside for asteroid tracking. And there's a huge database of all of the asteroids, well, not all of them, but all the big asteroids that are orbiting the sun down to a certain size limit.

But once you get below a certain size, asteroids become quite tricky. And there's sort of this horrible, gray, blurry boundary between an asteroid being big enough to do a bit of damage if it hit the Earth, but so small that it's quite difficult to track. Luckily, space agencies are working on it, and we have a pretty good idea of exactly where all of the potentially hazardous asteroids are and their probability of hitting the Earth going forward into the future. So you mentioned there about the size of the asteroid and the kind of seriousness of its impact. So do we know exactly, or roughly even, how big an asteroid has to be to cause serious damage? Well, put it this way, an asteroid the size of the Eiffel Tower, which is about 300 meters in

diameter strikes the Earth approximately every 80,000 years. And that releases the same amount of energy as 50 hydrogen bombs being detonated simultaneously. And there are potentially 900 hazardous asteroids that are more than one kilometer across. And if one of those hit the earth, it would be the same as almost 2,000 hydrogen bombs worth of energy, which is, you know, on a local scale devastating, but it would certainly put a lot of the sort of crises that we've gone through in the last couple of decades into pale comparison if something like that happened. It's worth noting as well that the dinosaurs went extinct when an asteroid hit the Earth 64 million years ago, but that was a pretty big asteroid. That was about 20 kilometers across,

and it of course caused a mass extinction that led to the extinction of the dinosaurs, but the ultimate rise of the mammals. Yeah, so you mentioned there's 900 of these, like significantly large asteroids that we've observed. So how big is the threat of one of the these actually hitting the Earth? I mean, and can we even say that? Well, a particularly interesting asteroid is actually the target of a current NASA mission, Osiris Rex, and that's asteroid Benu. Benu is about 500 meters across, which is something like five football pitches, something like that. And there's actually a chance that it will hit the Earth in the latter half of the next century. In about 150 years or so, there's about a one in three thousand chance that it would hit

the Earth. And if it did hit the Earth, it would certainly cause a catastrophe, which is one of the reasons why NASA selected it for their Osiris Rex mission. So you mentioned there that, you know, in the, there's a one in, what did you say, one in 3,000 chance at this? Approximately, something like that, something like that. It's a little bit worrying, you know, are there any other missions planned to defend the Earth from asteroid impact? I'm sure that one's asteroid Benu has been, you know, more thoroughly studied by

Osiris Rex and its orbital parameters are nailed down a bit more. If that chance did increase, I would seriously hope that space agencies around the world would start scrambling more missions together to learn how to deflect asteroids. It's just worth reflecting as well on the price of this mission, how much it costed monetary cents. It costs 280 million quid, all said and done, the dark mission. And that sounds like a lot of money, but for something that might potentially, you know, save humankind from extinction in the future, it's actually not a lot. We spent two and a half times that amount of money on bananas last year in the supermarkets in the UK. And so it really is pittance

compared to how much we spend on other things. And for something is, as important as the long-term future of humanity. I think it's money pretty well spent. Thank you for listening to this episode of Instant Genius. That was chemist and geologist Tim Gregory. If you want to know more about space rocks, check out his book, Meteorite, the Stones from Out of Space that made our world.

The current issue of BBC's Science Focus magazine is out now. To read more about all things science, pick up a copy wherever you buy your favourite magazines, or visit ScienceFocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analog warmth. Alongside French acoustic specialist focal,

Name creates high-end audio systems, combining innovation with craftsmanship, so you can listen to music, just as the artist intended. Discover more at Name Audio.com. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank. There's a moment when you start to wonder, what's the right next step? Not about changing who they are, just finding the right kind of support.

At Kingsley Manor, life stays expressive, connected, and full of character, shaped by people who have lived interesting lives and aren't finished yet. doesn't feel like a change. It feels like a continuation. Explore your options at canesley manor.org, a nonprofit month-to-month senior community within the Front Porch family.