Asteroids, Comets & the Latest from the DART Mission: A Cosmic Update

Hello again, and thank you for joining us on Space Nuts, the astronomy and space science podcast and radio show on community radio across Australia. My name is Andrew Dunkley. Great to have your company in this the six hundred and seventh episode of our program Can You Believe It? And this one is one hundred percent dedicated to comets and asteroids in one way or another. We've got an update on the potential impact of asteroid. Why are four with the Moon? They've been keeping an eye on this and they've come up with an answer and it's it's really clever the way they've done it. More news out of the Dart mission. Something else has happened there. Yes, it's on a collision course with nothing. Had you worry there for a moment? And three I Atlas is chemically unstable. In fact, it's falling down drunk. We'll tell you why on this episode of Space Nuts fifteen sec Channel ten nine Ignition, Space Nuts SI two Space Nurse as Can I Report It? Nels? Good joining us again for another stint on this little podcast of ours is Professor Fred Watts, an astronomer at last. Hello, Fred, Allou Andrew and it's nice to talk to you. What a surprise to see you. Now we have got a real rock and program today. Oh I love it. It's all about rocks and ice and asteroids and something else which we'll get too later that's not rock and ice. But first, an update on the potential impact of asteroid Why Are four with the moon. They were a little bit worried that it's chances of hitting the moon were well, I think I heard in the early stages it's discovery, the people were quoting twenty or thirty percent chance of it hitting the moon. That kind of got wound back to a more reasonable number. But now they've got definitive evidence of what's going to happen. That's correct. I mean, it's not just the moon that worried us for a while with asteroid twenty twenty four YR four, because when it was discovered back in twenty twenty four, as you might guess, Why Are four, when its trajectory was analyzed and IVE got to remember that an object is only sixty meters across, which is flying through space. You make observations of its position, and if you've only observed it over a short period of period of time, the uncertainties in its weld. Both its past orbit and its future orbit are very large. So it's what we call the arc, the arc of observation. The wider the arc of observations that you can make, the more accurate is going to be your assessment of where it's come from and where it's going. And so those early assessments, actually they were in early twenty twenty five when these calculations were made, but it did suggest a small chance that it might hit the Earth, and that was very quickly. I mean, I think I'm sure you and I talked about this on space. Yeah, we did. It was very quickly ruled out. But as it sort of wandered on its way early in twenty twenty five, there was still a possibility that it might hit the Moon, and the time that it would happen would be twenty thirty five was basically the targeted time for Sorry, no, is that right? Twenty thirty two? Thirty two? Yeah, yeah, that's correct. Sorry, I'm mixing up my numbers. You deserve when you get to a certain age. Twenty thirty two, there was a non zero chance that it would hit the Moon, and the story what happened then was, of course this object is. It's what we call a near Earth asteroid because it approaches near the Earth, but it's not near the Earth all the time. Most of the time, it's a long way away as it goes around in its orbit around the Sun. And it sort of disappeared from view essentially, certainly from the purview of ground based telescopes. There was not going to be any way we thought of observing it again until twenty twenty eight, when it would make another close approach, not one that had any risk attached to it. But we didn't expect to be able to see its position in any detail until twenty twenty eight, which we would need in order to predict where it might be in twenty thirty two, whether it's going to hit the Moon or not. But there are some scientists at who use the James Webb Space Telescope who tend not to let faintness stand in their way, because that's why you couldn't observe this object. It was just too faint and sure enough, earlier this year a last month in fact, they've made two sets of observations where they've actually picked up. The image a tiny faint image of. Twenty twenty four yr four they've picked it up and allowed them the calculations to basically take those new positions, the twenty twenty six positions into the orbit calculation, and what they've done is they've ruled out any possibility of it hitting the Moon. So that's an unexpected story for us. I didn't think we'll be talking about this again until twenty twenty eight, but no, we've talked about it in twenty twenty six, and the web telescope has come to rescue. Some people are disappointed andrew an asteroid hitting the Moon, especially if you know when it's going to happen, and you would know where it was going to happen as well, could have produced some quite interesting pyrotechnics. It would allow spectroscopy, which would tell you a little bit about the asteroid's makeup as well as the makeup of the lunar regulars and lunar terrain that it's smashed into. But that's not going to happen. And so for anybody like astronauts who might happen to be hanging about on the Moon in twenty thirty two, and they may well be both Chinese teycher notes and Western astronauts on. The moon by then that will be a great relief. I'm sure, yes, yes, you don't really want a mission interrupted by a piece of look and ice. What would could you if it did hit the moon? Let's just play that hard at the moment and you were looking at it at the time, would you actually say it with the naked eye or with the telescope? I don't think you would with the naked eye, but you certainly would with telescopes, and even maybe a relatively small telescope. We've known, I mean, certainly since the nineteen fifties that rocks do hit the moon, and often these are ones that are much smaller than the sixty meters of Yr four. It's for a long time. I remember, you know, when I was first getting into astronomy in the nineteen fifties that people talked, and in particular Patrick Moore talked about these what were called TLS transient lunar events, and there were flashes basically that amateur astronomers kept reporting said every so often there'll be something, you know, they'd be looking at the Moon through a telescope and suddenly there'd be a flash. And for a long time it was not shut not known really whether this was due to some sort of residual volcanic activity on the Moon or whether it was impact of asteroids and large meteor meteorites. And it was really once we'd seen the Apollo results and got to know the Moon a lot better because of the Apollo missions, that it was deemed to be impacts that caused these transient lunar events. And so it would certainly be a sixty meter object hitting the Moon is quite significant, and that I don't think it will be naked eye visibility, but you probably wouldn't need that big a telescope to be able to see it. So yeah, so interesting, especially you know, sorry, especially if you could predict when and where it was going to happen. You'd have all the amateur astronomers in the world on that side of the Earth a seems a moon with their eyes glued to the telescope. Yeah, now just need you probably do explain how this works. But the scientists using the James Web took images eight days apart. Is that that's obviously significant because then they get a straight line observation. Is that how it works? No, what happens is in fact what even just one of those observations would have been invaluable. Two is devastatingly invaluable. It makes it, you know, it increases your accuracy even more because what they do they combine those new observations with what we knew from its orbit the last when we observed it in twenty twenty four twenty five. So what you've suddenly got is you've you know, the arc of observation might just have been a few months at the end of twenty twenty four early twenty twenty five. Now what you've done is you've extended that arc by a year effectively, and that gives you a much much more accurate value of what we call its orbital elements. The asteroid is its orbit is actually delineated by six numbers, and those are the orbital elements, as they're called. Those numbers get more accurate the more the longer you can observe it for. So and it's not just that how long you can observe it for, it's the interval between, you know, what's the interval of time between the observations, which is what we've got here. We've suddenly got observations made a year later. It's it's absolutely narrowed down the uncertainties in the in the orbital elements, and so what we can then do is another great word. From those orbital elements, we can generate what's called an ephemeris, and the femurist tells you where the asteroid is going to be. It's a future predictions. That was what my MSc was on, making orbital elements and fMRI ds with of asteroids with a really new invention called computers. Yes, it's I think there'll be a big hit. Well that'd be hopefully not depending where you're standing. It was certainly I told you it was a big hit with the with the External Examiner, a gentleman in Glasgow University by the name of Archie Roy. He said, this work should be pop people should belt I read about this. It never was. But the one copy is actually behind me. It's one of the two thick volumes at the end. The others my PhD thesis. I keep thinking of questions while we talk about this, But what I find extraordinary is that the James Webspace Telescope was trying to find something sixty meters in size from a distance of forty eight million kilometers thirty million miles YEP and it founded twice. It's pretty fantastic, isn't it. It would just pop above the background noise. You know, when you're doing these observations, you've got various sources of what we call noise, which is basically uncertainty, and these are probably very close to that noise level. But it's just shown up enough that gives them what they call what we call a three sigma certainty. It's you know, that's a level of certainty that you need. It's just a technical term for the statistical analysis that's being used. Maybe they got help from AI as well. Maybe, Yeah, it's possible. I have a doomsday question though. Great, and we're going to talk about the Dark Mission next because there's new information about that deflection test. But when do you intervene? Like if we left it a couple of years because James Webb couldn't find it and then we realized it was going to hit Earth or something to that effect, when is it too late to we divene? It's with an asteroid like that, it's almost too late already because you've only got so if we'd observed this in twenty twenty eight and the probability of an impact with Earth had gone up. I mean that disappeared long ago, so it's not a problem. But if that happened, you've only got four years, and we're not ready quite yet to mount an emergency mission. I think down the track we will be, having seen what's come out the story, we're going to do next tent. I think down the track we will have probably planetary defense rockets and spacecraft almost ready to go, so that you could think about deflecting an object if it looked as though it was going to impact the Earth. But I suspect with four years, that's not very long for a modified orbit to evolve into one that will miss the planet altogether. I think what would happen would be you'd mobilize civil defense resources because you'd probably quite quickly get an idea where the collision was going to be. You'd have a circle of uncertainty, but you would know roughly where it was, which side of the planet was going to be facing it. And a sixty meter object, I mean, it's probably twice the size of what exploded over Chellyabinsk in twenty thirteen, and we know that that caused structural damage when the shockwave hit the ground from thirty kilometers high, and it was the broken glass that caused all the injuries. Nobody died, but people. Did get injured. And if you knew something like that was going to happen, then you'd get the people out or get them in bunkers or whatever, because that would be the most likely scenario. And air burst it may be what happened at Tunguska. Actually, yes, there's been. Yeah. I think the latest theory is it was actually a atmospheric graze rather than an impact in the course explosion downwards. Yeah, radiating out. The images from that are incredible. It can look them up all the trees. Yeah, just flattened. Unbelievable. Yeah. If you would like to read about the latest observations regarding asteroid twenty twenty four yr two, you can go to the science blog dot com website, or you can go to the ESET website where that publish the findings. There's a space Nuts with Andrew Dunkley and Professor Fred Watson. Let's take a break from the show to tell you about our sponsor, nord VPN. Now, if you've ever felt like your online privacy is slipping through the cracks, then you're not alone, hackers, scammers, harvesters. They're all out there trying to get your private info, whether that's your passwords or your personal details to sell on the dark web, or to use themselves to access your bank account's, credit card details, and who knows what else. 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Were chieving the goal before this decade is out of landing a man on the Moon and returning him safely to the Europeece Nuts, Well, we said we talk about it, and we're going to talk about it the Dart mission. I think we should start by kind of just revisiting what that mission was all about and why, well, we know why, to see if we could move something that may hit Earth one day off a bit so that it missed us. I probably just explained it. But yeah, this was four years ago, wasn't it, Fred. Indeed it was, that's right, twenty twenty two, it was. I think it was its September. I can't remember the question, but I think it's about then. So a really really clever experiment conducted by NASA and a team of project scientists. What do you do to test whether you can move an asteroid? What you don't do is slap something into an asteroid and see whether you can change its orbit around the Sun. And that's because the orbits of planets, asteroids and comets actually as well, are very very stable. It's quite hard to change them because you're talking about, you know, lots of rather large forces, gravitational forces and things like that. So what they did was they said Okay, we won't do that. What we'll do is we'll find an asteroid with a moon, and we now know there are a lot of those, and they chose an asteroid called Didimos, if I remember rightly, about half a kilometer across, which had a little moon called Dimorphos, which is about I think one hundred and seventy meters. Is a figure that comes to mind, this little moon that goes around Didimos once in I've got a feeling remembering it is about eleven hours it's orbital period. So you smash something into the little asteroid moon, and what you then look for is how the orbit of the moon around its parent body, in other words, the orbit of Dimorphos around Didimos, how that changes, Because something on that scale is much easier to change than the orbit of an asteroid around the Sun. And as we all know, it was incredibly successful. The orbit of the orbital period of Dimorphous I think it was reduced by was it thirty three minutes? I think was the figure if I remember rightly, the Dart spacecraft and remembering these numbers from the last time we talked about it, Andrew, I think it was three tons. I think thereabouts. Hit dimorphous at six kilometers per second caused a huge plume of data, sorry, a huge plume of debris. Not data, lots of data as well, but debris two. And that was all in fact visible from Earth as well as from things like the Hubble space telescope. So it was an experiment that was well devised, well set up, and had excellent results. It did exactly it Actually it did better than what the mission scientist hoped. And the reason why it did better was because there was a much bigger effect. When you hit something at six kilometers per second. Everything's vapor the surface that you hit, which is actually a rubble pile, but the surface he hits vaporized, as is the spacecraft itself, and that vapor acts like a rocket exhaust. So it's not just the nudge that you get from knocking something weighing three tons into an asteroid. It's also the sort of exhaust effect that comes from that as well. So it and that was what was very hard to quantify. We didn't really know what that would be, but it was enough to make a significant difference. So that's the backstory. Andrew, Yes, then you were right. It was the twenty sixth of September twenty twenty two. Okay, great, yeah. Yeah, if you want to just check the of the dark impact while you're looking there, so correct if I've said it wrong. I said three tons, but I might be wrong. I can't someone I'll do that, But I guess we could move on to what's actually happened now they've done a more analysis and something spectacular has happened as a contract that event three and a half years. Ago, and the way it's happened is neat as well, because what you're looking for, if you're looking at the way an asteroid change an asteroid orbit changes, you're looking for incredible precision in space. And there are limits as to how. Precise we can get those measurements using telescopes. It's all about the position in space of the object. Telescopes are great at that, of course, but there is a better way for asteroids, and that is to use ocultations. And an ocultation is when an object like an asteroid passes in front of a star and you can predict this is going to happen. So what you do is for an object that's only one hundred and seventy meters across, which is the size of Dimorphous you've got. What you do is your space astronomers along a line who are observing and because you're not quite sure where the shadow of the asteroid cast in the light of the star is going to fall. But with telescopes, what you can do is you can see the dip in a star's light as the asteroid passes in front of it. It's what we call an ocultation. And if you've got enough observers on the ground, it gives you a much higher level of precision as to where in the sky that asteroid is. And so that process was carried out I think last year, and so that means that you've suddenly got very very accurate measurements of the position not just of Dimorphis itself, but also the parent asteroid Didimos. In fact, I think you might be Didimos that was used for the occultation. And so the bottom line is that low and behold, it didn't just the impact didn't just change the orbit of Dimorphous around Dilimos. It changed the orbit of the whole system, the pair of them around the Sun. And that is the first time one of the nice quotes in one of these articles. It's the first time a human made object has measurably altered the path of a celestial body around the Sun. That's in a NASA statement. That is incredible. And of course the obvious question is now, will we be able to track where it will go versus where it would have gone? Yes, And indeed that's already sort of already happening, because there'll be further observations. And it's the same as we were just talking about in regard to Yr four. The longer the arc of observations you've got, the more accurate your knowledge of its orbit. Now the changing orbit is not much. I can't remember how many days I've got the paper in front of me. Actually, the main paper, it doesn't actually give us the orbit little period of the pair around the Sun, but they've changed that orbital period by wait for its point one five of a second. So it's very I mean, it's a matter of you know, it's it's these two orbit between the between the orbits of Mars and Jupiter, the part of the main asteroid belt. So their orbital periods are probably measured in sort of thousands of days or at least high numbers of hundreds of days, and to change that by zero point one five of a second is not very much. It speaks wonders for the volumes, for the accuracy with which the orbit has been determined. But it's look, it's it's it happened. It has actually happened that we've changed the orbit of an asteroid by hitting it, or hitting its little moon, in fact, by with a with a massive object. Did you manage to find out how much it weighed? Six hundred and ten kilograms, Okay, so that's weigh one hundred and forty pounds. Yeah, so it's less than a ton half a ton. Yeah, I apologize for three tons. That was the number from something else. I reckon if they if they could have got three tons up there, they would have used it, they would have done. Yeah, but that makes it even more spectacular. You know, something weighing less than a car clouting the moon of an asteroid can change the orbit of that asteroid and its parent body, just too very quickly. Since we're talking to an educated, an arandie audience here, the mechanism by which that changed is so you think, well, you've hit the you've hit the moon, asteroid. How does that change the orbit of the parent asteroid and what it does? Hitting the moon asteroid gives you a slight change in the position of the Barry center, and that's the center of mass of the two objects, their center of gravity combined, and it's that that has changed its orbit. It's the Barry center, which of course includes both of the objects. The Barry center is representative of both didimos and dimorphous because it's the center of mass between them. So changing the position of the Barry center or the orbit of the Barry Center essentially changes the orbit of the asteroid, which means that would something like that threatening the Earth, and you had enough enough years down the track for its orbit to evolve so that it would miss the Earth. That might be a way to do it. Yeah. I know a few people named Barry and they always wanting to be the center of attencing. It's had to cup, didn't it. Yeah, it did. It's a great story, it's great read. You can pick it up on the NASA website or you can go to fizz dot org. Phys I got to do that from now on because somebody came to us one day and said, I can't find this fi double z dot org because it's not it's fizz pH y s. Yes, but it's great news out of that experiment. Three and a half. Years post event, This is space nuts. Andrew Dugley with Professor Fred Watson withpen anguality they plant space nuts. Now to another piece of rock that has been getting a lot of attention in recent times. Three I Atlas, the XO comet or exo asteroid. Is it a comet or an asteroid thread comet? Comet? Yeah, yeah, it appears that it's it's very different from anything we've seen before, to the point where it's raging through our solar systems stone drunk off its face, not quite, but its chemical makeup is just way out of kilter with what we would have expected. That's right, So you know, this is three Eye Atlas is definitely the gift that keeps from giving because what we've got is a free sample from another solar system that is careering through our own solar system and enough for our telescopes to get details of it. It's now actually receding from Earth and from the Sun, but it's still producing gases from its icy surface. It behaves exactly like a comet. Wood from our own solar system gets near the Sun, the ice is basically turn into gas directly. This subly matate, and what then happens is we can sense what gases are there, what chemical compounds are there by looking at the spectrum of what we call the coma of the comet. That's the fuzzy area around it that's caused by all this out gasing material. And so Comet three I Atlas has recently been the subject of probably the world's most powerful, well certainly the world's most powerful millimeter wave radio telescope, the array in the high country of the Atta Karma, the Alma telescope, the Atta Karma La milimeter submilimeter array at about five thousand meters high, not very far from San Pedro de Atacama. And when I went to try and get in their back door one time, I nearly died because the air was so thin, and we didn't get in the back door either. So never mind, Alma is fabulous telescope. So what's the story Alma, which is run by various different organizations. But the scientists who have been observing three Eye Atlas with it have looked at the fingerprints the spectral fingerprints of two molecules. One is methanol, which is a type of alcohol, and the other is hydrogen cyanide HCN. It's an organic molecule very common in comets. So both of those are found in comets in the Solar System. But what is the surprise the amount of methanol. It's as ther NRAO National Radio Astronomy Observatory press release says three I Atlas is heavily enriched in methanol compared to hydrogen cyanide, far beyond what is typically seen in comets born in our own solar system. You know what it is for it wait for it. You're gonna love this one. It's inroxinated. Well, oh, yes, I'll go with that. I know. I just invented a new word what he did. Yes, And you probably need to be reasonably androxinated in order to invent it. And it's so early, yes, so earlier in the day. That's right. Anyway, the observing team just coming back to a state of reality, perfect sobriety. It's methanolter to hydrogen cyanide ration of between seventy and one hundred and twenty, which means it's among the most methanol rich comets ever discovered. There's been a few in the Solar system that have got high levels of methanol, but this is, you know, it's up there on the extreme end of this distribution and familiar. I'll just read from the very nice National Radiostronomy Observatory press release on this, which says, these measurements imply that the ic material from three I Atlas was formed by or experienced very different conditions from those that shape most comets in our own solar system. Previous work with the James Web Space telescope has shown that three Eye Atlas had a coma dominated by carbon dioxide when it was far from the Sun, and these new Alma results add methanol as another unusual detail in its chemical inventory in nice paragraph, so it is unusual. It's an object that shows all the characteristics of a comet, but we're seeing all the extremes and maybe that shouldn't surprise us because we do know it has come from somewhere else. Which tromps the question, does that mean where it's come from might be quite different to our. Yeah, it's yes, that's right. It could you know, it would certainly lead credibility to any idea that chemical ratios within other solar systems are not necessarily what we find here in our own solar system. In other words, you know, there could be quite different chemistry going on, particularly in the early history of those solar systems. We think a lot of these compounds like methanol and hydrogen cyanide, we think a lot of these are formed very early in the history of a solar system in the cold of space, molecules, atoms combined together to form molecules, and we know that there is a very, very rich chemistry out there, which was kind of unexpected really. I mean, when I was a young astronomer, we thought always in terms of just elements, the elements that we can see in the atmospheres of stars, hydrogen, carbon, calcium, iron, all of those. But now such a lot of what we do with the you know, with the arsenal of wonderful astronomical instruments that we have today, we can look at the chemistry of these things, the actual chemical reactions that go on in the laboratory of deep space. Yeah. Something you don't know about Fred is he's been in astronomy so long that he got in trouble at school once for throwing an apple at Isaac Newton. So true story. Yeah, yeah, yeah, yeah, yeah I got the cane for that. Yeah. I got the cain a lot at school too, but not for throwing apples. I did throw out a sandwich at a teacher once, but yeah, I was egg gone to do that, and I felt for it was exactly and I can't remember was on Probably something hideous that I ate when I was a kid. If you're egged on, it must have been in it. Yeah, it was a very silly move and I'll always regret it. Okay, So if you want to read about that what constitutes a rather drunk rock in space, you can go to the National Radio Observatory website where they've published their findings. And Fred, that brings us to the end. Thank you so very much. It's a great pleasure. Andrew. Always good to chat, and we'll see you again next time. We will on a Q and A edition. Fred Watson, Professor Fred Watson, Astronomer at Large, joining us every week twice a week in fact, for space nuts. And if you would like to visit our website, please do one thing we could use for our Q and A episodes audio questions. We are desperately short of them. There's some weird quirk at the beginning of every year they dry up, and we don't know why that is an anomaly, but it is a thing. But if you go to our webs site space Nuts podcast dot com and click on the ask Me Anything tab at the top, it's just labeled AMA, you can send us your questions or comments. We welcome them. Don't forget to tell us who you are and where you're from. And thanks to Hu in the studio who couldn't be with us today because he went out on a bender last night and got inoxicated. Bomb boom and from me, from me Andrew Dunkley, thanks for your company. See on the next episode of Space Nuts. Bye byepauts. You'll be listening to the Space Nuts podcast. Available at Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player. You can also stream on demand at bides dot com. This has been another quality podcast production from nights dot com.