The Supermassive Podcast - 34: How to Deflect an Asteroid

Episode Date: October 27, 2022

Terrified that an asteroid could wipe out the planet? Don’t panic…the Supermassive team are here to help. Izzie and Dr Becky talk to Professor Alan Fitzsimmons about the results of the DART asteroid deflection mission and Samuel L Jackson (who knew he’s studying for a Phd at the Open University?) tells us how scientists plan to track and tackle threatening space rocks. Plus why the Deep Impact movie terrifies both Izzie and Dr Becky, but for very different reasons, and Dr Robert Massey takes us through the November night sky. The Year in Space from the Supermassive Podcast is out now: https://geni.us/jNcrw Send in your questions to [e-mail] The Supermassive Podcast is a Boffin Media Production by Izzie Clarke and Richard Hollingham for the Royal Astronomical Society. 

It's a type of natural disaster that we can predict to the second. I'm just going to remember them as lumpy potatoes to be quite honest. So it doesn't really matter. We're dealing with the fate of the planet. Incredible. Yeah, it's brilliant. Hello and welcome to the Supermassive podcast from the Royal Astronomical Society with me, science journalist Izzy Clark and astrophysicist Dr. Becky Smethurst.

This month, we're defending the planet. Kind of. I love that sound effect. We're looking at the latest mission called DART, which tested whether we could deflect an asteroid. Plus, we'll explore the process to actually protect the planet if space stuff is ever headed our way

and spoiler the plan is not just blind panicking who knew so relieved so coming up we speak to professor alan fitzsimmons from queen's university belfast about how dart nudged an asteroid out of the way as well as samuel l jackson no like this is amazing it's not that Samuel L Jackson but it's genuinely someone called Samuel L Jackson he's from the Open University and he's going to chat about the plan to defend the planet I love that I mean Samuel L Jackson probably could also come to us yeah I mean if he would also like to come on the podcast I'm sure he could yeah we would love to yeah if you're listening Samuel his people people, our people. Do we have people?

We don't have people. No, it's probably just me. Anyway, Dr Robert Massey, the Deputy Director of the Royal Astronomical Society, is obviously here too. Robert, how likely is it that an asteroid is on course to hit Earth? You know, a cheery start and all of that. It's a really cheery start to the day, isn't it? Yeah. I mean, look, the answer is it will certainly happen again, as it has very many times in the past, but it doesn't keep me awake at night. I mean, look, in 2013, there was a rock

about 20 metres in diameter that exploded above the Russian city of Chelyabinsk in the southern Ural Mountains. And that had a force of a 500 kiloton nuclear explosion and injured 1500 people so actually the probably the worst event in recorded history of that type you know in the past we've always sat there and thought oh nobody's actually been hurt by an incoming rock but this was a perfect example unfortunately of where it did happen so it does remind us of the risk and there was also one but most of them actually happen and people don't see them so there's also one in december 2018 which was a bit less powerful than Chelyabinsk, but still pretty big. And it exploded over the Bering Strait.

Nobody on the ground saw it, but it was detected by satellites. So these sort of events happen quite a lot. And, you know, obviously the trick is to detect them before they hit, detect the rocks before they hit. Definitely the bigger ones and then work out how to deflect them in exactly the way that data's done. I think it's also worth putting out there that we're constantly looking for asteroids as well, right? We're always monitoring as many different telescopes that sole purpose is to look for things that move in the sky. I mean, that's right. And there's also that, you know, all the monitoring telescopes have picked up, what is it, more than 90% of the rocks that would pose any kind of significant threat.

I mean, I say significant threat. Obviously, it wasn't great in jelly beans, but the kind of extinction level event things, the very big rocks, we're pretty confident we know about all of those. And even the smaller ones, there's very, very good survey data cataloguing and categorising them all, which is why we don't worry too much in the short term. But in the long term, it's obviously a risk,

and it's sensible to work out ways to deal with it. Exactly with exactly yeah we've got to be prepared if something dark and mysterious turns up from the edges of the solar system cheers robert we'll catch up with you later in the show to take on some listener questions dart also known as the double asteroid redirection test is a nasa space mission aimed at testing a method of planetary defense against near-Earth objects. Essentially, it was a spacecraft that aimed to bump into an asteroid and change its trajectory. It launched on the 24th of November 2021 and recently reached the target asteroid on the 26th of September this year. But did it work? Well, we'll find out. I spoke with Professor Alan Fitzsimmons from Queen's University Belfast, who first explained why we need missions like this.

Well, it seems an obvious question because we are used to the idea of asteroids and comets hitting the Earth from Hollywood movies and TV shows now. In reality, they have hit the Earth in the past. For example, we have the dinosaurs 66 million years ago that were wiped out by a large asteroid hitting us then. And importantly, it's a natural process. It will happen again in the future. But it's a strange kind of natural disaster because it's a type of natural disaster that we can predict to the second if we detect the asteroid beforehand. that we can predict to the second if we detect the asteroid beforehand. And also, potentially, we have the ability to stop that natural disaster happening

by deflecting the asteroid onto a different course. And that was the purpose of the DART mission. I think this is a fascinating mission. Tell me about this target asteroid. You know, why this one in particular? And what was DART looking and aiming to do? Yeah well we now have over 30,000 near-earth asteroids that have been discovered that can come close to our planet so choosing the right target for this test of deflecting asteroids was pretty

important and of course we want to do it in a safe way. So we chose this asteroid system called Didymos, but not Didymos itself. We chose an asteroid moon orbiting it called Dimorphos for a number of reasons. First of all, we knew it was going to make a close approach to Earth in September this year. So that meant we could observe it very easily with telescopes on Earth and monitor what happened. Secondly, we can see that Demorphos, the asteroid moon, is about the same size of asteroid that we think might have a problem with over the next few centuries. It's the kind of asteroid that's small enough. We don't know how many of them there are yet exactly. We haven't found them all. But if it does hit us,

it would actually cause some local devastation. So it's the kind of asteroid we want to protect ourselves with. Finally, because it's going around another asteroid, when we do that deflection, it's going around another asteroid, when we do that deflection, we're mostly changing the orbit of Dimorphos about its parent asteroid Didymos. And we're not changing the orbit of Didymos and Dimorphos much around the sun itself. So we've got no chance of making a mistake and taking this asteroid that will miss us in the future and putting it on an impact trajectory. So safety first. And given that this is just a test of the technology, let's keep things straightforward, at least at this point.

And yeah, let's focus on this. We've got to make sure that people know that Didymos and Dimorphos are not on track to hit Earth. This is a proof of concept mission. How was it that DART managed to do this? You know, talk me through what it was like when this moment happened. Well, the one thing it sounds crazy to remember is that until 70 minutes before DART reached its target, we had never directly got a picture of its target demorphos. Because it orbits so close to its parent asteroid Didymos,

just 1.2 kilometres separates their centres, then even things like the Hubble Space Telescope and the James Webb Space Telescope can't see them as anything else than a point of light. They don't have the resolution. So it was using radar images of the system from when it last did a close approach in 2003 and using measurements or by optical telescopes on earth to measure what we call the light curve the brightness of the

asteroid system as a function of time that allowed us to predict exactly where Didymos would be and where Dimorphos would be and then as I as I said, 70 minutes before impact, we got the first clear image from DART of the target. And at that point, we're all just sitting back and being incredibly excited because it's hands off. From four hours before impact, DART was making its own decisions on where to go. And then a little while later, it achieved lock. Yeah. 30 minutes before impact, it had precision lock. And then we just sat back and watched Dimorphos grow larger, very slowly and then very quickly in the last few seconds of the mission before impact. of what starts off as something being quite far off in the distance and then just getting a bit closer and closer and then suddenly half of a black screen with a little bit of rubble at the top

where I'm assuming that is just like, you know that it's worked because it's stopped transmitting that signal back. That's right. That's when the cheer went out, where we didn't get a whole image back because it was taken one second before impact. Remember that Dart was travelling at six kilometres per second. And so when that last image was taken one second before impact. Remember that DART was travelling at six kilometres per second.

And so when that last image was taken one second before impact, it was still six kilometres from the asteroid, but it only got a chance to transmit a bit of that image before it hit Dimorphos and successfully completed that part of the mission. How do you know if this is actually work? And so to test that what we needed to do is go to the system after DART had hit it and measure precisely the new position of the asteroid moon Dimorphos and compare it to where it would have been without DART hitting it.

So basically measure how much the orbit of the moon had changed and that would tell us how much the orbit of the moon had changed. And that would tell us how much we deflected Dimorphos from its original path. How much did it change? What did you find? Did it work? Well, the great thing, of course, is that we did get that deflection. We changed the orbit of the moon from 11 hours, 55 minutes to 11 hours, 23 minutes. We actually changed the orbit of a moon in the solar system which is still so incredible yeah it's brilliant so the next thing we need to do though is use that data plus the data we get from the dart cameras plus the cameras on the italian cube set that was carried along leisha cube to actually understand what happened to the moon, according to the laws of physics, it should have

moved it at least by about five to ten minutes in terms of the orbital period. Now, we expected it to change more than that, and indeed it did. It changed the orbital period by 32 minutes, and that's because a huge amount of ejector material from Dimorphos was thrown out in the opposite direction into space. And that also helps move the asteroid. And that's where we get this much bigger orbital change. There are talks of the next missions that are similar to this, one of which you're very heavily involved in. So can you tell me about that? Well, that's right. So in October 2024, we're going to be launching a follow-up mission

with the European Space Agency called HERA. And that is going back to Didymos and Dimorphos. Because even with all these fantastic images and data from both DART and NatureCube and our ground-based telescopes here on Earth and the orbiting telescopes, we still don't know some important things like exactly how massive is DeMorphis. We'll actually rendezvous with the asteroids and we'll spend up to a year not only

with Hera, but Hera itself carries two extra CubeSats called Juventus and Milani. And altogether, the three spacecraft will give us a tremendous picture that's not only useful, actually, for planetary defence, but it will be our first real in-depth exploration of a binary near-Earth asteroid. And so we're going to get huge amounts of science out of it as well as hopefully protecting the planet in the future. What else is next for planetary defence? Well, alongside HERA, while HERA is flying,

we're going to have the next stages in searching for potentially threatening asteroids. So in two years' time, the Vera Rubin Observatory will start observations. It's basically the world's largest digital camera. Hopefully a couple of years after that, a space surveillance mission will be launched called the Near-Earth Object Surveyor Mission by NASA. As an infrared space telescope, it will not only allow us to discover and track these near-Earth asteroids, it will immediately tell us the size of them. It's important to remember that while we've got future missions and future telescopes coming up, the day-to-day surveillance of near Earth space continues. So right now we have many telescopes surveying the night sky every clear

night to look for, identify and track near Earth asteroids. The big three being Pan-STARRS, the Catalina Sky Survey, and the ATLAS survey, which I'm involved with. They're really responsible for the bulk of these five or six new near-Earth asteroids discovered on average every 24 hours. Basically, watch this space for the next 10 to 15 years, because not only we will really continue advancing our knowledge of how to deflect asteroids, we're really also going to be building up this catalogue of what's coming towards us, or potentially coming towards us, in the next couple of centuries. That was Alan Fitzsimmons from Queen's University Belfast. Right, so Becky, how is it that an asteroid can then have a little orbiting asteroid pile like Didymos and Dimorphos?

Like where would that come from? Yeah, it's what's called a binary asteroid, right? Just like a binary star, if you've heard of these. And there's a few ideas for how they might form depending really on their composition, like what they're made of and where they're found in the solar system, whether they're from the inner solar system or the outer solar system. So, for example, those that are essentially glorified rubble piles, they're just almost like pebbles held together.

If you have an impact, maybe in the early days of the solar system, with another sort of small little asteroid, what you can do is essentially disrupt that rubble pile and send a few bits of it just flying off in the impact and one of those can become your little asteroid moon so that's one way we think it might happen but then also you know if you have something larger like a much larger asteroid you could literally just capture a smaller asteroid with gravity and make that your moon in the same way that we think mars's moons were captured

asteroids as well these lumpy potatoes of phobos and deimos i remember that right i just gotta remember them as lumpy potatoes to be quite honest so it doesn't really um and those asteroids that allow you to be like slightly closer into the sun they actually get bombarded by really high levels of solar radiation so do you remember we talked about radiation pressure a few episodes ago as well yeah yeah yeah almost like this pressure that objects feel literally from photons of light hitting them well that can actually spin up smaller objects like asteroids that are close to the sun if you think about spinning faster and faster and faster like when you're on a roundabout or something you feel that force pushing you outwards right and it's that same force that makes like earth and saturn especially bulge at the equator a little bit right we call them oblate spheroids and if you've got an

asteroid that's a little bit smaller and not able to hold itself together with gravity as as easily you know bulging at the equator because this solar radiation, you know, you can imagine a blob of it eventually flies off and becomes your asteroid moon as well. So there's lots of different ways we think it could happen for these different sort of types of asteroids and places that we find them in the solar system. Right. Okay. And, you know, we see a lot of asteroids orbiting our planet, but not necessarily heading straight for it thank goodness so how does that happen what's going on there i mean i feel like as humans we can't help but have this earth-centric view right that we think we're incredibly important yeah we're obsessed with

ourselves not everything is about us okay what yeah i mean you gotta remember asteroids are orbiting the sun as are we as well so everything is on the move and i think that's what people forget we almost picture earth is like stationary as this sitting duck like a stationary target that stuff is just flinging towards but it's not we're moving the earth moves its entire diameter every seven minutes in its orbit wow so it's moving at a fair clop as well yeah the asteroids are then moving too and then space is just mind-bogglingly big right so if you think of it in terms of cross-sectional areas right in terms of how much area does the earth cover in the vastness of space and how much area does this little asteroid cover in the vastness

of space like the probability that across all the space in the solar system that they intersect is very very low i mean it's not zero right which is which is why we're here with the dark mission yeah i was trying to be prepared but it's still very very low okay so even though we have these you know have you ever seen those animations of like here's all the known positions of asteroids around the earth and it just looks like this sort of mess of things everywhere yeah and i look at that and i'm just assuming that that is from those are plotted by all of the telescopes that we have and you know the different projects that we have for this very reason to know where things are at what point yeah but thankfully But thankfully, all of those ones that we do track, we know they're not ever going to be an issue to us,

at least in the next hundred years, which is how long we sort of run all the models for, you know, and then that, you know, because beyond that, we think, okay, well, our uncertainties in their positions and stuff make it too uncertain to say anything. But at least in the next hundred years, all the ones we know of are not going to be any issue to us. And also in the next hundred years, not my problem.

Sorry. Sorry, grandkids. But, you know, astronomers do know all of these large objects in our system. But how often do we see objects from outside of our system coming in? Is that something that people like Alan need to add to their list of, you know, natural disasters? I mean, yeah, it is something we need to add to their list of you know natural disasters i mean yeah it is something we need to consider although if we think about it in terms of cross-sectional areas again the probabilities drop because it's not just the solar system like area of space it's this you know entire section

of our galaxy that you consider so i mean in terms of interstellar sort of visitors we've spotted two of these so far it's probably been a lot more of those but obviously in terms of recent years we've managed to spot them so we had a mua mua in 2017 yeah the bane of all newsreaders um and borisov in 2019 more recently and when we spotted those in the sky moving we could tell that they had orbits that essentially showed that they weren't tied to the sun in any way like the speed and the angle and the eccentricity that they were coming in at it was like yeah that's nothing to do with the solar system and they just essentially flew by at huge distances which is why we didn't spot them until quite late actually and we saw it sort of on its way back out we do actually think we've been

hit by some interstellar meteors before as well though yeah so this happened back in 2014 one in 2014 and one in 2017 now the time like no one thought okay that's what it was but it was sort of after the fact i think it was a paper that came out in 2019 actually analyzed sort of the angle and the trajectory that it came in at to recreate its orbit and realized again like it was moving so fast and it's such a steep angle that it couldn't be anything to do with the sun and it was very likely that it was like an interstellar meteor that hits very small rocks but it still means that that's possible and it is something we need to consider as well but we would spot those in the same way that we would spot an asteroid or a comet coming from the far reaches of the solar system

as well coming in that could be a danger you, looking for stuff that's moving on the sky, seeing when we could spot it as well. So as Alan said, we know about all of the large objects in our solar system, but that doesn't mean we can't be prepared for the worst case scenario, just in case. And so back at the national astronomy meeting in july i spoke with phd student samuel l jackson i'm literally i'm never gonna tell you and he studies the brightness variation of asteroids and he told me about a really interesting conference that he attended that simulated the emergency response of an asteroid heading our way.

Yeah, so this was a conference organised within the context of the United Nations Office for Outer Space Affairs in conjunction with NASA, ESA and various scientists around the world. And there was a point during the conference where we went from simulating the detection of a potentially hazardous asteroid so just picking it up in in a telescope image and going wonder where that's going yeah yeah and over the week as we simulated it more and more the impact probability kind of went up and we're going oh no this is this is coming our way so it then started pivoting from is this going to hit us to what happens if it does there was so much to cover here so let's start at that first point of detection so you see an asteroid and that's probably where someone like you comes in as an astronomer and you say okay let's look at this asteroid what are you looking for to test you know a trajectory of an asteroid yeah so what you need is you need multiple detections really so you see that first dot on your image and you compare it to

the database of of known asteroids and it's quite exciting when you realise oh I don't know that one and so you try and estimate just on the images that you got that night where it might be in subsequent nights and from there you need to get it in about three different nights over a decent enough time span and then you can start to fit orbits to it and try and work out exactly where it's going to go next and then did you cover at this conference that stage of you know as an astronomer you've detected something that you think is on track to collide with earth what is that next step you can't like call up the police and be like excuse me i have something to report you know how do you go about reporting something like that so all of the data goes through a organization called the minor planet center and they collate all of the orbital information for asteroids and we report can

report these positions to them they submit those and if something like that happens it goes through to either national space agencies and then they take it up with the united nations through the united nations office for outer space affairs and then there are various subdivisions there that start to make decisions so it very quickly goes beyond the astronomers and out of our our hands yeah yeah and then it would be good to know what is that i don't know how much you can say but like damage control you know what are the things that if you don't have time to either change the trajectory of the asteroid what measures are then put in place to try and protect as many lives as possible if that were to collide with Earth. Yeah, so there was a lot of debate about that, actually.

With such short timescales, there would obviously be mass panic. Yeah. So you've also got to contend with things like breakdown of law and order. Right, OK. So you have to be concerned that you're not going to panic everyone entirely, but you need to do these systematic evacuations if you can say if you've only got a few days then it's too risky to send in your evacuation teams to do it there are those worrying circumstances where you go what if we can do nothing but there are those decisions to make of who can we save and it is I'm glad I don't have to make those decisions

I mean that's fascinating what was the what was the feel of the conference like because I imagine those are some big questions that you have to ask and you know ask your colleagues around you and how do you make a decision for such a large group of people? Yeah so the conference started with with the exercise everyone was very excited to get going you know we we like doing what we do on the astronomy side, so it felt like a nice challenge. And then as it became simulated as being more and more out of our control, as the disaster management team started to get involved,

I certainly myself felt a lot more sombre and started really more critically looking at it to try and put myself in the mindset of what if this was actually real because it's very easy in a simulation to go oh it's not real it doesn't matter yeah but we were there simulating this because we need to know what to do if this happens in the future this isn't some arbitrary thing this we're dealing with the fate of the planet so it was that sort of there was a pivotal moment where my brain just switched to actually this isn't that fun yeah yeah yeah and this is actually very serious and so you know looking at this journey of an asteroid do you think that that puts pressure on you as an astronomer to make sure

that you're you know looking for the right things or and you know how do you feel about it finding possible solutions i mean i would be very glad to see the dart mission completed because we will we will know at least whether it fails or it works, we will at least know. And that enables us to think about these scenarios in the future with much more certainty. And if it doesn't work, we've got other ways of deflecting asteroids. There's weird ways, like you can paint one side of them and let solar pressure push it off orbit

or fly a spacecraft in tandem alongside it to try and pull it over many years so we would know to focus more on those at least but my my strong hope is that it will work as we hope and will provide us a very critical means of protecting ourselves going into the future but yeah it there is a bit of pressure but it's it's good pressure because we know we're doing something for the benefit of everyone honestly like what a job and I think this is probably the moment to say that I was deeply scarred by the film Deep Impact as a child like it's not even funny it is it is quite funny so was I though Izzy like it did scar me I mean Deep Impact and ET apparently was the

ones that scarred me as a child but Deep Impact it was mostly that uh Frodo and Sarah right had to raise that kid at the end as teenagers like that's more terrifying than the asteroid and you could quote me on that parenthood more terrifying so here is the thing here is the thing I saw it when I was too young. Didn't really understand. I was probably about six. And I didn't watch the end. I was so scared.

So I don't know how it ends. Still haven't seen it, actually, to be quite honest. Well, spoiler alert, they have to raise baby at the end. They're teenagers. Well, I wonder if that was mentioned at the conference that Sam attended. But anyway, thank you so much to Samuel L. Jackson from the Open University. This is the Supermassive podcast from the Royal Astronomical Society with me, astrophysicist Dr. Becky Smethurst, and with science journalist, terrified of deep impact, Izzy Clark. This month is all about planetary defence.

But before we get to everyone's questions, can I just say that I got Andy Saunders' Apollo remastered book. And it is amazing. I know what you mean, like Becky, when anyone comes over and I just get out the book and I'm like, guys, you need to look at this. I'll make some teas and I'll just leave you to it. Like, it's amazing. And I just keep dipping in and out of it just occasionally like i'll leave it for a

week and i'll come back to it and i'll dip in again i'll find something new i'm just i'm just not getting tired of it like i just keep wanting to like stroke the page it's so pretty yeah yeah it's incredible so i actually went to um the european space agency open day because i was working there just hosting a stage and got to chat with him and and and a national matthias mora just about going back to the moon and just hearing about his process on how he actually approached this is incredible so yeah just another plug for that book because it's just incredible and you know talking about amazing images webb has finally released its version of the pillars of creation this is what we thought was going to be that first iconic image that was what my money was on i was

like it's going to be the pillars of creation it's such an iconic hubble image and i think it was originally on the sort of big list that they put together of possibilities for the first images but it possibly didn't quite work out for sort of the timings that they had but oh my i mean they released it the day have you downloaded the full resolution version that's like 19 000 pixels by 10 000 no but i will you should oh you can zoom for days and like pan around it's so funny because my computer's almost too slow to keep up with it like i'll zoom and it'll be blurry and then all of a sudden it'll go oh no no there it's yeah blurry blurry wonder it's so amazing yeah and

it's just amazing like the amount of stars you can see in that image because obviously with the hubble image with an optical telescope you have all the dust that's in this gas where these stars are forming that's blocking yeah the visible light because we know that stars form in dusty places because dust acts as like a catalyst for stars to form it can help speed up the process so it blocks a lot of the view so while the Hubble image is I mean it's almost artistic the Hubble image right with these big dusty clouds blocking everything all these beautiful colors the JWST image the thing that gets me is just the number of stars that you can see like you couldn't count them all like they're just everywhere in that image that have been revealed by the fact that the infrared light

of the telescope can sort of pierce through that dust as well and this was just the near-cam image i think we're going to be getting the Miri image, which is the longer infrared wavelengths that show you where the dust itself actually is and glowing. They're almost spooky-looking, aren't they? And all that dust is. So I'm really excited if that's coming soon as well. Robert, what was your first reaction when you saw it? Well, I actually remember when Deep Impact was a film

I saw as a grown-up, as does our producer who's sitting here today. We were just smiling at your childhood trauma, but I do take it seriously. But yeah, it's a fantastic sort of redux of that classic image which comes back from 1995, and it tells you something about how fantastic Hubble has been in doing that for so long. Probably came out about the same time as Deep Impact.

Yeah, I think you might be right. When I was a PhD student, I was looking at stuff. Oh, 1998. Yes. No, no, even earlier, back in the early 90s. No, no, Deep Impact came out in 1998. Pillars of Creation predates Deep Impact. To answer your question, yeah, it's very akin to the stuff I was working on at the time.

So I remember looking at those first images of the Orion Air Balloon, the first images of the Pillars of Creation. And for the first time, we were seeing these close-ups, I mean, genuine close-ups of star-forming regions, you know, seeing places where planets were forming around them and seeing stars in the Pillars of Creation that are only a few hundred thousand years old. So, you know, a few hundred thousand years, that's not a short period of time. But it is in astronomy, the idea that, you know, you see these thousand years, that's not a short period of time. But it is in astronomy. And the idea that, you know, you see these stars that have almost effectively just switched on. And they're, you know, clearing the gas around them and knowing that, you know, if you look at it again in a few million years' time, they'll be drifting off into interstellar space. Just absolutely fantastic.

And, Becky, I imagine the people analyzing the data will be doing exactly what you do. They're zooming into this vast image, trying to sit there and unpick every single feature they can see. I mean, fantastic. I hope there's some PhD students who are getting to work on this. What a fantastic project. Oh, 100%. Yeah, absolutely. Okay, well, shall we get on to some listener questions then?

Becky, can you take this one from Ayesha Siddiqui Chowdhury on Twitter, who asks, can this DART technology be used to deflect asteroids in the future? And if required, after some modification, can this technique prove to be a sustainable solution for planetary defence? That's the idea. That's the hope, Ayesha. It all comes down though to the amount of energy or momentum that DART was actually able to transfer to Dimorphos. So we know that the orbit of the asteroid has now changed, the orbit of this little moon asteroid around its bigger asteroid, by about 33 minutes, something like that. And some of that change in the orbit comes from the

DART spacecraft itself and that impact, you know know kind of like a cue ball in the game of pool or snooker right but some of it actually comes from the ejector that was thrown out in the impact did you see the images from like the hubble space telescope is he afterwards it's great i'm not sure if it was from hubble but it was just where you see the asteroid tracking and then it's like a a puff a puff of dust yeah yeah i think that was hubble or jd riski i think it was one of the two of them as well like recorded that so that little puff is the ejector so you can imagine any sort of explosion that you've seen in a film or a collision of an asteroid right there's always that big mushroom cloud that goes up afterwards

and so that's essentially what that was but what that did was actually also contributed to the change in energy so it was kind of like um you know if you blow up a balloon and then you let it go around the room and it fires obviously the air out one end and it goes in the opposite direction doesn't it yeah so because that ejector came out in sort of the opposite direction it's actually slowed down the asteroid even more so some of that orbit change is from dart and some of it's from the ejector now the ejector is obviously unique to that asteroid so we need to piece out which bit which bit of the orbit change is from the energy caused by the ejector being thrown out and which bit of the orbit change is caused by the energy transferred by the dart spacecraft once we've done that and that's going to be another

number of years because it's going to be you know really careful observations of where the ejector went how much mass was in that that's going to come from you know more observations of telescopes but also the ESA mission uh HERA that's going to go back to the system in about three or four years as well to see what sort of like the the masses of the asteroids are so it's going to take a number of years to get at that but once we have it we'll have okay this is how much energy that smashing in a spacecraft into an asteroid can transfer that's the minimum amount we know that maybe depending on what the asteroid's made of it's you know we're going to get an ejector and that's going to cause some more but once we know that minimum amount you can then run the maths basically for any asteroid and say okay this asteroid of roughly

this mass on this orbit if you smash in a dart like spacecraft thing into it with this amount of energy what's that going to do to the orbit like how much is it going to change it how much is it going to deflect it by and so that would be great for a smaller asteroid you probably have a really big impact for a larger asteroid that change is probably not going to be as much but the change is cumulative over time right if you nudge it slightly then it goes more and more and more of course yeah what it was what its original course was over time so this is why when we say okay the bigger asteroids they are easier to spot because they're brighter but they could come from further away but so hopefully we'd have a bit more sort of warning time if there was an issue which more time is essentially what you need because you've got this limits the amount of energy you can

transfer but it's cumulative so the earlier you do it the better and those are the numbers we're trying to get out is like how soon do you need to do an impact to knock it off course? Yeah, OK, that makes a lot of sense. And Robert, Paul Sidhu wants to know, do you think that the success of DART's kinetic approach makes it less likely that a thermonuclear type device would be considered should the need arise to deflect an asteroid found to be on a collision trajectory for Earth? Yeah, Paul, great question.

If you want my view, I'd certainly rather see nuclear weapons used to protect us from space rocks and, you know, ever against people. I don't know what you're going to say. I'm like, okay. I was like, you'd prefer nuclear weapons over kinetic. No, no, no, no, no. I do, yeah. Controversially, yeah.

Don't do that. No, but for a very late attempt, it might be the kind of thing you might have to deploy if we didn't have enough notice. So there was a team at the Lawrence Livermore National Laboratory, U.S. team, and they looked at the way that you could do this. And they considered, first of all, total destruction of the incoming rock. Now, that's really hard because even very powerful nuclear weapons, if you have something that's, say, a kilometer across, it isn't going to destroy it completely. You could end up with some quite big pieces left over that still head towards the earth so it's not a great solution despite what you see in the films

however they also looked at what you could do to deflect it so if you put the uh nuclear weapon you know if you explode it alongside the object you know you obviously create local destruction on the surface there you get the ejector again hopefully that would nudge it out of the way and if you use enough energy then that might be the thing that would save you. So the conclusion of that paper was it is a reasonably efficient way to do it if you design it properly. But I absolutely also agree that it's much better to do this many years in advance and do it through gentle nudges rather than that much more desperate, you know, very spectacular approach. And also just not leaving nuclear waste in space. Yeah.

That could become a problem in the future. It's definitely the last ditch. Yeah, exactly. But it is interesting they'd looked at it and concluded it was something that would work if we had to do it. Okay, well, something to think about then. Thanks, everyone. And, you know, if you have a question

and you want us to answer it in a future episode, then email podcast at ras.ac.uk or tweet at Royal Astro Sock. So Robert, what can we see in the night sky this month? Well, we're getting deep into the autumn now, aren't we? Though it's still reasonably warm, you know, and the nights are drawing in and all of those things, you know, you could look at it as being cosy in bed, or you can be an astronomer and go outside and look at the lengthening night sky and take advantage of that. So the end of the month,

the clocks at the end of October, the clocks will go back and the sun sets even earlier. So by mid-December, you know, it's the sun setting just after four in London and half past three in Shetland, you know, that's really drawing in. So if the weather's good, obviously, then that's a great chance to look at the constellations, the autumn ones, like the groups like the square of Pegasus, Perseus and Taurus are really obvious now.

And if you're up really late or up really early, as I was this morning to do this recording, you can see Orion in the sky as well, which is a nice reminder of winter too. But in terms of other stuff, the month is really good for planets right now. We've still got Saturn there in the evening sky, very obvious after sunset, quite low down, but you know, get a small telescope if you've got one. If you've never seen the rings, you've still got plenty of time this year to look at those. Jupiter is really, really obvious a bit later on in the night. And unmistakable, beautiful moons and weather systems. And Mars is getting better too now.

Everybody, I think, loves Mars, right? It may be, you know, I know Saturn is the favorite amongst some of the people on this podcast. Mars looks boring through a telescope. I'm just going to put that out there. No, but you have to see it. If you see it in the night sky and you see an orange dot, you have to say hello to Mars.

It's a ritual in our house and I really recommend everyone else does it. Okay? I think that's great. I'm going to introduce that. See, I say hi to Jupiter. That's so funny.

I'm like, oh, hi Jupiter. In fact, I don't say Jupiter. I say Jupiter blue like I'm a child. But still, I'm like, hi Jupiter blue. So, if, but yeah, I mean, Becky's right.

It is tough through a telescope, but satisfying to say you've done it. So you do see brilliant astro images that show lots of detail. It's really hard to see that unless you have quite a large telescope in very good conditions. But if you have a modest one, you can still fairly easily see things like the polar ice cap and some of the dusky markings and you can imagine as you're looking at it just how frustrating it was to sketch and draw so those early observers imagine seeing canals and so on i don't entirely blame them because it's really difficult to see stuff and it is the best we'll see it until 2031 as well as soon as small though it remains so later on this year we'll talk about that more i think um this month

as well uranus much further away than than twice as far away as saturn really difficult thing to see but it's at its best this year on 9th of november so with a good telescope you might see this tiny blue green disc but you will need some kind of finder chart to see it's not all obvious to the eye and it's something that you know you probably need a bit of experience in looking for it but with a finder chart and a bit of knowledge of the stars, you should at least be able to find out where it is. And more pertinent to this particular episode, it's worth looking out for meteors in the first 10 days of November. Now, there are not any particularly very active showers, but I was looking at the International Meteor Organization website, which I do recommend as well. which I do recommend as well and they described the prospects

for what's called a torrid swarm which is meteors associated with a torrid meteor shower which are pebble sized objects Not usually a good one but one of the things associated with it is you may see an unusually large number of fireballs

so I don't think you'd be seeing don't expect to go out and see some massive display but if you do see some massive display. But if you do see some bright meteors, particularly bright meteors, it might be associated with this. We're talking about things that are not asteroid size, but the sizes of pebbles coming into the atmosphere. And that will generate a very bright meteor. So it's absolutely a matter of luck. But if you see one, you know, you've done well and enjoy the view. And the final thing, because it's the autumn, because it's getting dark, and because the sun is getting active as well, it's now getting to be a really good time to see displays of the northern or southern lights if you're down in the southern hemisphere.

So do look out for those too. We have seen some fantastic photos in the last few weeks, actually, particularly from further north in the UK. But of course, they can be seen further south as well. You just have to have to get lucky and have to look out for the alerts. So yeah, a lot going on. Did you see my pictures? I was literally just about to say, I'll be like, Becky's going to have something to say about this. Oh, when did you see those?

I saw them as a complete surprise, having never seen this before, on a transatlantic flight somewhere over canada life is hard that's the best view like literally you know i'd like finish my meal finish the film i was just putting my eye mask on to go down to sleep looked left and was like was that green brighter much than on nights it was so fantastic right like i feel bad because my my parents have gone on a Norwegian cruise to go see them and they've seen like just sort of fuzz. And we saw this incredibly defined ribbon that was moving. It had so much structure.

It was so bright that you were like, I can't believe that's real. It's like someone's spilt neon green paint on the sky. Whereas, you know, they were just sort of saying, well, the green comes out on a long exposure on your phone but it's difficult to pick out your eye this was just like hiya yeah it's me i didn't get any sleep i was just like staring out of the window because you were looking north so i mean biggest recommendation i can give you is if you're flying over canada or if you're flying over Canada or if you're flying over Norway or whatever it might be make sure that you're on the right side of the plane so that you're going to be looking north

so for me I was flying from Seattle to London so I was on the port side That was brilliant definitely seat booking considerations there for the next, that's brilliant That's why you always get a window seat I don't care if you have to move people to the toilet you can see the Northern Lights Just for for that shot did you post photos Becky I missed those oh I've

got to look I did I got like a photo and I got like a time lapse the time lapse was a little bit because I think iPhones struggle with night mode time lapses but the photos I I remember trying to get one there was reflections everywhere so I was like putting my phone behind the window blind like i was propping it up and then closing the window blind and like just leaving it behind there being like of course we couldn't have a better plug for the northern lights than this i think it's fantastic i saw it many years ago you know back in again 1991 something like that a little tiny bit of color this was in gloucestershire it was on the ground you know but i've never seen it from playing. I'm just going to say again, I am jealous.

But, you know, good luck to you. Yeah. Well, I think we should add this to the list of I want a location recording. Yes. Let's go to Lapland. How big is the budget for the podcast? Yeah, you better talk to the Royal Astronomy Society about that.

Yeah, OK, well. Well, I think that's it for this month. We'll be back next month with a look at returning to the moon. And Becky, ring that astronaut alarm. Whee! That was a good effort, yeah. Because we're going to be joined by Matthias

Maurer from the European Space Agency. Yes, I'm so excited for that. Also also we should probably say welcome back home to our best friend samantha christopher who's just come back from the international space station as well after being commander um welcome home samantha anyway we love you you can also uh before the next episode you can tweet us your favorite parts of our book the year in space which is out now yes it is it will have been out for one day amazing by the time this goes out um so yeah let us know uh what do you like the most in the book you can tweet us at royal astrosoc on twitter or you can email your thoughts musings

questions to podcast at ras.ac.uk and we'll try and cover them in a future episode. But until then, everybody, enjoy the book and happy stargazing.