Instant Genius - Space weather, with Sean Elvidge

Episode Date: September 4, 2022

Jason Goodyer talks with Sean Elvidge on everything you need to know about weather in space. Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Music just as the artist intended. Visit name audio.com. to learn more. Hello and welcome to Incident 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 Dr. Sean Elvich from the Space Environment Group at the University of Birmingham. He tells me everything we need to know about space weather, solar flares and coronal mass ejections.

By way of kicking things off then, so we're talking about coronal mass ejections and solar flares and things. So I thought perhaps the best way to start this is to talk very briefly about what processes are going on within the sun and on its surface. You know, what are we seeing when we look up at the sun? So I think a lot of people think of the sun probably as fairly boring, to be honest. I mean, it's, you know, it's pretty constant throughout human history. It's, okay, it's important for life and those kind of things. But in fact, it's, you know, it fairly constant comes and goes, rises.

but the sun's actually incredibly active and evolving and interesting star. So what we have is rather than this very static surface, perhaps we can only see, there's actually all manner of these nuclear reactions going on. We've got processes, we've got a sort of a period where it goes from increased activity to sort of lower activities over shortish, 11 sort of year times scales. and what's happening is that magnetic fields and things that are inside the sun sort of bubble and they're sort of not very stable.

There are a lot of instability. So if you imagine like a rubber band ball, now the rubber bands here on my magnetic field and essentially what the sun is doing is that these kind of instabilities means that the rubber bands pop out a bit and they go in a bit and they evolve and stretch. And then occasionally the rubber bands break. and it's actually when they break and they have these breakages that we have huge quantities of matter thrown out into space and these are what these coronal mass ejections are. So the sun is actually very active, really interesting and the source of an awful lot of study. So you mentioned there

that's what a CME or a coronal mass ejection is. But do we get different kinds of CMEs? Essentially not really. We sometimes classify them slightly differently because when we're observing them on the earth, sometimes the nice pictures or videos that the news might show you have them popping out of the side, which means we can get a really nice view of them. Now, in practice, the ones that we're most interested are is when they don't look like a nice bubble popping out the side, but they look a little bit more like just quite a thin circle or what we call a halo CME, and that's because those ones are actually pointing straight at us. So we don't have the nice side-on view, but they're the ones which are then most interesting because they are traveling towards the

earth. So they're all sort of the same things. What you do often get, perhaps in the media and other sources, is a mix-up between CME's coronal mass ejections and solar flares. They are not, you know, people use them sometimes interchangeably as terms, but they're very different. So the CME are these, as the word suggests, mass ejections from the sun's corona, coronal mass ejection, and they're, you know, huge amounts of matter, perhaps billion tons, that kind of, you know, incomprehensible amounts of size, moving at several million miles per hour. So huge. But solar flares are actually sometimes associated with a CME, but not always. It doesn't have to happen like that. And these are much quicker in general. I mean, the slowest ones,

maybe a few hours, but they can be tens of seconds for the really big impulsive events. and they're like a massive dump of x-rays that get sort of fired out. So they're not the same thing, but they sometimes get mixed up and added together. You mentioned there that the sun's a very unstable object. So how frequently are these events occurring? So that is a, well, one of the great open questions in our field is actually predicting when they're going to come. But in terms of sort of rough sort of timescale, so as I said, the sun goes through periods of high and low on roughly an 11-year cycle. The minimum of that cycle, the solar minimum, happened in about early 2020. We were probably at the minimum. And we'll probably get to the next solar maximum

in about 2025-ish. These things are all very ish. At solar minimum, perhaps the CME you'll get one every five days or so, not necessarily pointing at the earth, but what we observe, you know, about one every five days. At solar maximum, you're probably going to get a lot of get something like two or three CMEs a day. So that's the, and it sort of gradually ramps up between those kind of two numbers. So say when we do have one of these events then, what, what actually happens, you know, for us on earth, you know, what sort of impact can they have on us? Sure. So, so you have this CME, so you've had your rubber band snap and it's flung out a load of material into space incredibly quickly. And it's sort of just,

tears through the solar system going past the planets through past satellites on its way. It doesn't really matter what's in its way and it'll just keep going. What you can see on Earth, and I'll try and quantify that in a minute, is the sort of pretty thing that everyone likes is the Aurora, the Northern Southern Lights. In terms of actual impacts, we have disruptions to communications, the power grid, navigation, radio, satellite operations. All of these things are impacted by. the impact of a CME, or sort of what we call space weather. And space weather has this,

you know, is banded about quite a lot. But that's really taking some of these more theoretical concepts that I would say is space science and the impacts that they then have on the Earth. Now, the thing is, not all CMEs are actually geo-effective. That means effective at Earth. And it depends on what the magnetic field is doing. So the CME, as it's been, released also is bringing a bit of magnetic field with it. We call it the interplanetary magnetic field. And we're interested whether that's pointing sort of north or primarily north or primarily south. Obviously it can do anything in between. But, you know, 3D is hard to think about. So let's just think of 2D, north and south. If it's north, that essentially lines up with the Earth's magnetic

field and then our magnetic field acts as sort of a shield which helps bounce off most of the effects. If it's primarily a southward into planetary magnetic field or a negative BZ is what they sort of call it, sometimes you see that leak into news releases as well, which isn't very meaningful. But if you've got a southward, predominantly southwards, then, in fact, that sort of interacts with the Earth's magnetic field and makes the events much more geo-effective. So we're interested in, or the impacts are relying to when we have these negative magnetic fields. And we have, as I said, all of these kind of impacts up the ground. And I think perhaps on one of those, something like maybe the most common one that people will know and think about is

GPS, global positioning system, and or more broadly, that should be called GNSS, because GPS is the Americans one, but there's, you know, Galileo in Europe and various others. They rely on passing signals through the Earth's atmosphere. And impacts to the Earth's atmosphere means you can get impact on those systems. So they're such a big part of our lives now, GPS or GNNS. We use them every day. They're on our phones. But even more serious things like navigating airplanes and that sort of thing. So that could have a serious impact, I presume, if we had a big one of these. Yeah, absolutely. So as you said, GPS, we'll say GPS, because to be honest, we all slip into saying that. It has become this technology which underpins so much. In general, the service is, you know,

it knows that space weather is a thing. and the service is hardened against it. It's protected pretty well in most cases. Perhaps 20 years ago or so, it was not so good, and Space Web would have a bigger impact on those kind of positional errors. But a severe storm certainly would have pretty big impacts on that network. But I think what's really important is also, and perhaps people don't realize as much,

is that GPS does a lot more than just for use for navigation to, say, the supermarkets. it has both a position and a timing element. And it's actually timing that we also take huge advantage of because it gives you sort of nanosecond precise timing. And it essentially underpins all business transactions because it's very important to know exactly when something's happening, whether it's a financial transaction, the timestamp that we get essentially for free,

people see it as I can just get my GPS signal for free and get nanosecond timing. And that now underpins loads of stuff, even down to, in Hollywood, where they're actually now using GPS to link up audio and video from multiple cameras on film shoots because it's so precise. Disruptions to all of these sort of hidden uses of GNSS is one of the sort of really the challenges for society. Because if there is a big storm that knocks out all of these sort of tertiary level things, then there's some large unknowns there that people will find out how bad it is.

has been. You mentioned there the impact could be very severe if we had one of these large events. I mean, do we, in our records, are there any large events that have been observed that could have this sort of catastrophic effect? So the generally considered the largest event that we have good knowledge about and sort of that we benchmark everything against is called the Carrington event and it happened in 1859. So this was just on the edge of us having some technology which could observe the impact. So things like telegraph poles and we can see, we can see some impacts on the systems. But that is the reference event, we say, that if that happened now, what would be the case? So how many days of outages of GNSS would we have? How much, you know, how many satellite comms

would we lose? What would be the impacts on the ground and in the, for satellites? So that's our reference event. Now, a lot of work, as you might imagine, has gone into estimating how often one of those events come along. So we had this really big one in 1859. We've had various quite big ones in the interim years, sort of 2003. There was a really big storm. In 2012, that's quite a big storm.

Not quite on that level. And a lot of work, as I said, has gone into it. And we estimate that these very large Carrington-level events happen probably once in a hundred years. That's the sort of timescales we're looking. at. Now, that means that we absolutely need to prepare about it. And on the UK, as many other countries do, has a thing called the National Risk Register, where we classify risks facing the country. Now, if we were talking, say, three years ago, a good quiz question that I've often asked

students is, what is the number one risk facing the UK, according to the risk register? That's now a less interesting question because the answer was a global pandemic. And so we now will have a lot more than sort of intimate experience of that. But I think that is helpful in explaining space weather, because in terms of probability of occurrence, an extreme space weather event is the same level as a global pandemic. The impact is slightly less. I think at the moment it's registered as like the fifth largest risk facing the UK. But in terms of probability of occurrence, one in a hundred years is about the same as these global pandemics. So, And okay, we haven't had one since 1859. You can't be overdue them. It's not like, well, that was 150 years ago and you've just said it's one in 100 years. That's like saying, I haven't rolled a six in the last six rolls. So I'm definitely going to get one next. So you don't want to fall into that fallacy. But it is something that the country and the world sort of has to prepare for happening in the coming decades.

So having said that, what are we doing to prepare for this? So, I mean, a lot, perhaps in the background more than anything. And it's things like understanding the risks. So understanding, you know, I hinted that GNSS is used across all these different domains. But if you don't know that there's a chance of GNSS going out, well, then we need to understand, well, what does happen if it goes out, what happens, you know, to communications to airlines. Our primary way of communicating with most planes is via high frequency, HF communications,

which is not via satellites. You can do it via satellites, but most of it isn't. If you have these large outages, I'm going to lose communications with planes. And we should just have strategies in place to what do we do in that case? What is the immediate sort of golden hour response? Something's happened. How do we talk to the planes? What do we tell them to do?

What happens to the power grid? And so at the moment, a lot of the work is going into mitigating against the impacts. And the worst cases of big power outages, you know, how do we try and make the network resilient and robust? That's what we can do right now. The coming years and, well, work is already ongoing. There's a lot of work going on this is about also forecasting space weather accurately. So obviously a lot of people know about weather forecasting. And nowadays, whilst people don't always believe it, weather forecasting is pretty good over, you know,

certainly over the three to five day period. I mean, one of the problems people have is that we give 10-day forecasts and that's where the skill drops off. But in space weather, we are nowhere near that good at forecasting. So whilst we need to bring up technology and capability to mitigate it, we also need to put a lot of effort into how do I actually forecast what's happening. and that's one of the key ways that we become resilient. And the other thing is by adding it to the National Risk Register

because that puts it on government sort of warning levels, it's something they have to think about, and the UK has been world-leading in developing techniques and forecasting and really thinking about it. So there's two different approaches we have to do from the engineering side and from the fundamental science and physics side.

So just as a sort of tangent off from that then, So how long does it take one of these events to reach the Earth from the sun once it occurs? So the solar flare happens, and if it's a solar flare part, that essentially is arrived here within eight minutes, because they travel pretty much close to the speed of light. So as we observe it, we're seeing some of those effects. So there's some almost immediate radiation impacts that we have to deal with. the CME itself, which is likely the much bigger event that would be coming, the fastest I think we've ever observed would take around 18 to 19 hours. That's the kind of time scale, perhaps on average closer to 24 to 36 hours. So once you've observed it, there is a little bit of lead time in knowing it's on its way. However, if I leap all the way back to when I said knowing whether it's geo-effective means knowing what, is the direction of the magnetic field? We can't measure that until it passes through one of our satellites,

which is much closer to the Earth, which then is, you know, an hour's notice. So we can see something's coming and then we try to improve our models and our predictions of its impacts once it gets here, but we don't have an awful lot of notice. And certainly, I know there's certain industries and parts of the UK that would say they'd like to know five days in advance that these things are coming. And we're just, frankly, nowhere near that capability yet. So that's us on Earth. How about, say, if we've got some astronauts working in the ISS

or something like that, and one of these events happens, I mean, could that be potentially harmful to them? So the International Space Station is actually, whilst it seems like it's far away in space, is actually so very close to us, that it's well within the Earth's magnetic field. So that kind of protection that we get from the magnetic field generally applies to astronauts on the space station.

Now, we have a second level of protection, which is also we have a nice thick atmosphere as well. So sort of radiation, if we think of as radiation, down on the ground, is fairly minimal from these events. In the space station, there's a bigger radiation environment, and astronauts are classified as radiation workers for exactly this reason. They carried decimiters. When Tim Peake was up there, there was a whole experiment. measuring radiation doses, but also you can get radiation impacts from just being on a plane,

because already you're high enough up in the atmosphere, you've got slightly less dense. So the ISS is sort of not too bad because it's protected. What is interesting is perhaps the next generation of, well, maybe it's also the previous generation of space travel, which is the moon and Mars and beyond. Because now that is a different story entirely. Mars doesn't have a big global magnetic field like we do. It perhaps has some coming and goes pockets of magnetic field, but on the whole, it's exposed to the space weather impacts

much more than anything we see here. And how we deal with that is a serious challenge which most people don't talk about, not just once we're on Mars, because perhaps you can dig underground, that the rock can protect you. But in a nine-month transit from Earth to Mars means, especially at Solar Max, when I said we get these things, you know, a couple of times a day,

then we are going to have to deal with it somehow. And it's the same with the moon. I mean, I think one of the things is if we went and looked at the American flags that are planted on the moon right now, they would no longer look like American flags. They'd probably just be white flags because they've been exposed to radiation for the last 50 years. And so there's no longer an American flag waving out there. There's probably just a white flag waving out there. So if we're going to be serious about this next generation of space travel and go to Mars, and it's easy to say the words, there are these systems that are going to have to be, because they would be completely, yes, life-altering to life-ending events. So how do we go about studying space weather,

then, what sort of things do we use, earth-based telescopes? How do we actually study these effects? Space science, which is trying to understand things like how the CMEs work and the processes on the sun. They have a lot of theoretical modelling and physics-based research and then space telescopes, ground-based instruments. We can look at the radio waves, we can look at optical, all manner of things, to try and understand the processes going on in the sun and what causes flares and CMEs. That's sort of on the space science side. weather side, until recently, we haven't had a lot of dedicated instrumentation, and we can piggyback essentially off other things. So we can use telescopes and ground-based telescopes,

but we can actually use, for example, the GPS network itself to infer information about the upper atmosphere. So if you're looking at the ionosphere, which is a charged part of the upper atmosphere, knowing how that impacts GPS means that we can go back the other way and see, oh, that's what must have been happening in the upper atmosphere. So we take advantage of any bit of instrumentation that's lying around. And also there are then dedicated space weather missions that can get launched and to study various different processes. And one of the things going on now is that what I haven't talked about is that there's a whole raft of effects that also affect the density of the upper atmosphere. Now, what that means is that the density changes slightly, as we have space wherever events,

which means a satellite passing in orbit sometimes doesn't go where we're expecting it to go. And if it's not going where you're expected to go, that's when you can have collisions. Now, we have had collisions in the past, and they've come from sometimes cases where we could have, we said they're going to miss, but they didn't miss, and that's, you know, we got it wrong. This is obviously a bigger topic than it ever has been with the mega constellations that are being launched. And in February of this year, there was a minor space weather, you know, this was a minor storm that caused the loss of 30 to 40 of the Starlink satellites as they were being deployed. And these are, you know, minor space weather event. It really wasn't a big event. So now, more than that, you know,

than ever, I think there's also this really big interest in, can we use those constellations themselves to also help us understand the space environment? So we have to bring together new instrumentation, but also take advantage of perhaps commercial mega constellations as well. Thank you for listening to this episode of Instant Genius. That was Dr. Sean Elvich. The current issue of BBC Science Focus magazine is out now. Head to your local shops to pick up a copy or visit sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music

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