In this episode, we are joined by European Space Agency scientist Dr. Dave Williams who talks about the incredible Solar Orbiter mission. This will study the solar wind, the interior of the Sun, and will observe the polar region of our star for the very first time!
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Chris
Welcome to The Astroholic Explains
Alfredo
A podcast where we try to explain the Universe’s greatest mysteries with fictional stories, Q&A’s, and interviews.
Chris
Join Dr. Alfredo Carpineti, the self-styled Astroholic
Alfredo
and Chris, my partner in life and in science,
Chris
featuring experts and brilliant voice actors, join us in a light-hearted journey of discovery.
Chris
Today we are joined by another special guest.
Alfredo
Yes, so we have guests now!
Chris
Today’s special guest is Dave! Dave, please introduce yourself.
Dave Williams
So my name is Dave Williams. I’m a solar physicist working at the European Space Agency’s astronomy center in Spain. And I’m an instrument scientist on this year’s newly launched Solar Orbiter mission.
Dave Williams
We’re very excited about the Solar Orbiter.
Chris
Now, I don’t know much about the Solar Orbiter. But from what I gather, it is in line with one of the solar system’s big mysteries. Is it investigating why the atmosphere around the Sun is a massively different temperature to the temperature of the surface of the Sun…? You’re nodding…. This is not a visual production!
Alfredo
I’m just admiring and I’m glad that Dave can share with the general: “I’ve gotta ask a question, and there’s gonna be a lot of caveats while I explain that I’m not a scientist…” and I really appreciate that of you. But you don’t do that with me. With me, you’re just like, ‘I’m saying things. I don’t care…’ and now there is somebody here and then wonder, ‘I think I know what I’m talking about.’ But yes, that is a good question.
Dave Williams
I didn’t wanna interrupt you because we’re getting everything right!
Chris
Okay, so the Sun and mysteries and the Solar Orbiter, please tell us a little bit more.
Dave Williams
Right. So, Solar Orbiter is a mission that we’ve launched to try and understand the whole system that the Sun creates. So like school very, very often we learn about the stars. Which is our Sun and the planets that go around it. But we very often don’t think about the gas that fills all that space in between them, and it’s a really active place. So the Sun is constantly throwing off what we call a solar wind, which a lot of stars do. I mean, most of us have some sort of solar wind or stellar wind coming off them. And we know that eventually, by the time that solar wind gets only as far as the earth, which is one of the inner planets, it’s very churned up and it contains a lot of very high speed particles, dangerous radiation, magnetic fields that are very tangled and do strange things when they interact with our planets,
Chris
Like the Aurora?
Dave Williams
Exactly like the aurora. That’s a good example. That’s a very happy face!
Alfredo
I think it’s also important to mention the dangers to our technology…
Dave Williams
Yeah, this is a huge thing, which is, I guess, not appreciated even by everybody in the scientific community. In throwing off this sort of river of magnetically charged plasma at the earth, it disturbs our magnetic fields. And if you’ve done A-level physics, for example, or early University physics, you’ll know that when you have a magnetic field that changes, it induces a current. And if you’ve got a magnetic field that changes on a planetary scale, it can induce currents on a planetary scale as well.
Chris
That can make quite massive differences.
Dave Williams
Yeah. When it’s sort of relatively benign, you can notice the difference, but there are little blips all the time which can be quite bad. And we think very often of big events. There’s one that we just missed in 2012 because it was pointed away from the earth. But those things are going to hit… Oh and the Carrington Event, of course, which is where we discovered solar flares back in 1850s. Then, when those things hit the earth, they can actually do quite a lot damage to long conducting things like telegraph lines or power lines.
Alfredo
With the Carrington Event, (which happened if I remember correctly in 1859), the receivers of telegraph lines across the United States caught fire. There was so much electricity, and aurorae were seen potentially at very southern latitudes. It was incredible! I think Lloyds, the Insurance company, made an estimate that it would cost the US economy $1 trillion if the same event happened today. We are definitely not prepared.
Dave Williams
We’re somewhat distracted with other things..
Alfredo
Yes. Everything is happening. But yes, there are a lot of things that can kill us. Something that people ask me a lot is about black holes and how dangerous they are and I’m just like, you know that everything else in space is trying to kill us..?
Chris
If there was like a solar flare big enough that it actually disrupted so much electrical equipment and stuff on Earth that things blew up.. that could actually happen?!
Alfredo
Yeah!
Dave Williams
Yeah. And it would take a very long time to recover from it as well, because there isn’t a factory knocking out a generator a day. These things are enormous machines, and they take months to build as well. So it’d be a real dip in recovery time. Wow, we have to wait to get things like generators for hospitals backup. And so it’s quite a big deal if it happens. But there’s sort of another kind of silence. I don’t say killer, exactly, but a silent damage that’s going on all the time, which is the small blips which are quite dramatic, but we don’t necessarily notice because they’re so short. They’re damaging transformers and power lines and that kind of stuff all the time and the economic damage caused by just what’s going on all the time, is equivalent to the economic damage that would be produced by these sort of mega events as well. And we don’t hear about it because it’s not a single event. And that’s not how we sort of perceive history, right? Something’s going on all the time. There’s no ‘single event’ for us to kind of go ‘Oh, yeah, remember that thing was really bad’. But what’s actually happening is that the solar wind interacting with our planet is inducing overcurrent in electrical systems worldwide. Electrical systems get old. Their resistance changes. There’s constant damage happening all the time, like a war of attrition.
Alfredo
Well, that is fascinating and I had no idea about it!
Dave Williams
So that’s one of the things that has inspired us to launch a mission to dive deeper towards the Sun and find out “how does the solar wind behave when we get close to it?” And where’s it really coming from? Because we were pretty sure that there are open magnetic field regions, which is to say you have like a North Pole element, let’s say on the Sun. And magnetic field doesn’t really connect to anything else on the Sun. And we have closed systems as well as these. But in these open places the solar wind can really rush out quite fast. And in fact, as a consequence of the fact that the atmosphere of the Sun is so hot, it just expands. And actually the earth is embedded within the atmosphere of the Sun, which just extends out to beyond the orbit of Pluto. The Sun is the whole system and we’re just kind of like swimming in its stream, I gues.s
Alfredo
That is very cool. So, my question for you is, what is the most exciting thing about the Solar Orbiter that you’re looking forward to?
Dave Williams
Yeah, that’s a really nice one. I used to work on other solar missions, like the Japanese Hinode mission and I’ve worked with the ESA/NASA Soho mission as well. And one of the challenges you always have is trying to make sure that everybody is focusing. If you want to connect up the different bits of information that we need, it’s like making a picture of a whole animal. One instrument sees his foot, another one sees its head, the other one looks at the color of its hair. It’s difficult to get all these instruments looking in the right place at the right times. And what we’re going to do with the Solar Orbiter, which is really, really cool, is we’re going to measure the solar wind as it flows past the spacecraft. We’re going to measure the electrons, the protons, the heavy ions, the magnetic field, the radio waves that are induced by turbulence and other processes. And we’re going to measure all those things and then look with our telescopes at where we think it’s coming from and see if we can make that connection. Because if we can make that connection, that’s great. And we understand something important about not just our star, but all stellar planetary systems. I think of all the planets we’re looking for out there in the universe, we need to know “how do they interact with their parent stars?”. So on one level if we can make that connection, that’s fantastic. If we cannot make that connection, then well, we have some really deep thinking to do about what it is that causes the conditions in interplanetary space. By the way I’m completely obsessed with The Expanse at the moment.
Alfredo
Us too
Dave Williams
I was thinking about, you know, how would the conditions of space affect these kind of, you know, future ventures, which are not so hard to conceptualize right? Mining in space and exploring new worlds and things like that. So everything we’re doing is really trying to understand how a star affects the planets around it and the space around those planets as well. And so if we can understand our star, that’s great, and we’re on a solid footing for understanding the variation that other stars create. And if we can’t understand it, well, then we need to go back to something fundamental. And try to investigate the physics of whatever it is, that’s causing that lack of knowledge, you know. So we’re sourcing it holistically, I guess.
Alfredo
I think it is a fantastic approach. I think it’s not only important for the sake of science in itself, but also for further exploration of the solar system.
Dave Williams
Absolutely. It’s exploring the solar system by looking at the most influential body, at the centre of it all.
Chris
Tell me more about the kind of durability of the Solar Orbiter because we are literally throwing something human-made as close to the Sun as we ever have. How are we doing that? What is this made out of? How big is it?
Dave Williams
So to give you sort of a sense of the scale of it, it’s about two and a half by two and a half by three meters, kind of a cuboid, like a decent sized living room. And then if you add on the solar panels on the sides that it will need to generate energy for itself. That adds an extra distance, which brings up to 18 meters across. So it’s quite surprising when you see these things unfold because you realize how much area of solar panels you need to power something like this. And it weighs about 1.8 tons. That’ll drop as it uses bits of fuel, but not by a half or anything. So that gives us some sort of scale of it. And at the front, we have a heat shield. The covering is made by an Irish company called MBO. It came up with a really nice material which can protect the internal workings of the satellite from the fierce temperatures of the Sun. We know that on the front of it, we’re expecting it to get up to about 500 degrees Celsius. Much hotter than any oven that we cook in! But behind that, the electronics that we have in the sides, basically have to operate at room temperature, or just below because like all the electronics that we build on Earth, we build it for room temperature or maybe a little bit on either side. So we have to control that really high heat input from the Sun, in such a way that we can actually operate electronics that drive the telescopes and the sensors. One of the frustrating things for me as a sort of a more-telescope-based scientist is that you have to make the entrance holes for those telescopes quite small, if you make them quite large and loads of heat floods in and you’ve got to get rid of it. So the entrance apertures that we have are sort of on the order of 10 centimeters or less, which is quite small compared to stuff that we’ve flown in the past. Two years ago, NASA launched the Parker Solar Probe. Solar Orbiter we’ll get down to 0.28 of the distance between the Sun and the Earth, so about a quarter of the distance between the Sun and the Earth. Parker Solar Probe gets in much, much, much closer, but so close that they can’t afford to cut holes in the heat shield to let light i, because we’re letting too much heat and just cook everything inside. It’s one of those kinda interesting example of like innovation through competition. NASA’s approach has been to get much closer to the Sun and everything’s in, as we say, ‘in situ’ there. So we measure how the plasma feels at that point. But the only camera they have is able to look off to the side and catch bits of the outer atmosphere of the Sun. Whereas our approach has been to stand back a little bit and so that we can let telescopes work and see what it is that’s generating the plasma that flows over us. Of course the upside to all that is that we get to work together after a while. So we’ll be able to compare the measurements we have in different places.
Chris
That’s really cool. How long is the Solar Orbiter Mission expected to last for and how long can the probe actually survive in those temperatures?
Dave Williams
Solar Orbiter has a pretty tough life actually, we started off at the earth, of course where it launched. Sort of like we have to fire past Venus a couple times and past Earth again and past Venus and having launched it in February this year, we’re coming up on the commissioning phase being finished. So hopefully everything is going to be tickety boo. And then we can really take it over as a science mission. We’ll have a cruise phase where it gets closer into the Sun, we get it down to that sort of 0.2 / 0.3 AU distance to the Sun, and then we’ll go into the nominal mission phase which lasts from the end of 2021 till the end of 2025. And then we’re hoping all things going well that we can carry on with the mission for another five years. And the reason we do that is that will keep sending it past Venus. Because with Venus, you can play a nice trick where you exchange some angular momentum, you can exchange some tilt of the orbit between Venus and Solar Orbiter. Venus won’t feel a thing but Solar Orbiter certainly will because it is much smaller. We’re doing what they call a gravity assist maneuver.
Chris
It’s like a slingshot!
Dave Williams
Essentially like a slingshot from Star Trek, so you can sort of crank up – but no go back in time (laughs). You can crank up the orbit. So that tilts more and more compared to the orbit of the other planets. And that lets us do something extremely cool for a whole bunch of reasons. Which is to see the north and south poles of the Sun, which we’ve never seen before.
Chris
Oh, wow. So you’re using Venus to actually tilt the orbiter? That’s incredible.
Alfredo
That is incredible. The thing that’s completely shocking to me is that we’ve never seen the north and south pole of the Sun.
Dave Williams
No, it hasn’t been a priority until, I guess maybe 20 years ago when we started talking about this mission as a concept. And there are two major things you can do when you do that. One is you just get to see the poles of the Sun. I mean look what happened when we went to Jupiter and Saturn! The hexagonal waves on Saturn, the marble colours we saw on Jupiter that let us see different depths of the atmosphere, and I guess different compositions of the material there. That is just beautiful on an appreciation of nature level. But looking at it, there are a lot of questions we have about how the gas on the inside of the star flows. We know that it doesn’t sort of rotate as a single solid body, so it doesn’t rotate like a football. The equator spins much quicker than the poles do. Which means the equator starts racing ahead of the poles. It would be like some place in Central Africa moving east of us by 10 degrees every couple of days, as the equator moves faster than Europe does. And that has all sorts of weird potential effects that some of which we think we understand that drive things like Sunspots, for example, and solar flares and ejections of mass from the atmosphere of the Sun. But there are crucial questions we can’t answer by only looking from above the equator of the Sun. If you can look higher up you can try and match sound waves at the equator with sound waves that you see at the poles. Doing that matching you can actually do a seismology of the Sun. So in the same way when you go looking for oil deposits or for coal. You can put like, you know, explosion over here and put microphones everywhere else, and work out where the cavities are.
Alfredo
I absolutely adore asteroseismology!
Dave Williams
It’s almost too cool to be a science, right?
Alfredo
You’re pretty much using some waves to work out what’s the interior of not only the Sun, but also other stars, for example. And it’s fantastic.
Dave Williams
You can even do something, which sounds almost ridiculous. But once you studied how it works, it makes sense. You can actually try and work out what the relative balance of the different chemical elements is. You can basically work out what’s the flavor of the Sun inside. From looking at the relative balances of carbon, nitrogen, oxygen, hydrogen, helium.
Alfredo
Do I remember correctly that Solar Orbiter will measure up to a depth of over 200,000km from the surface?
Dave Williams
Yeah. Which brings you down into the realm of where we think it changes from a solid body rotator to the fluid body rotator and where we think the magnetic field is actually generated. So like a dynamo effect that you have.
Alfredo
That is phenomenal.
Dave Williams
Yeah. And that’s because we were constantly cranking that level of view as you get further and further away from the equator you get to look deeper and deeper down. What’s really cool about that is that much the same way the gravitational waves lets us sort of sense what’s happening way way out in the universe, we can use sound waves to penetrate where light cannot penetrate on the Sun. So we can use the sort of ‘the bouncing around of sound waves’ on the interior of the Sun, we’re in space, you know, famously you can’t hear anything but the effect of those sound waves how on the surface, we can then see with the telescopes and through a complex process of inversion, which is way beyond me, but really excellent stuff, you can work out where the speed of rotation of the Sun changes. And if you plug that into your models you can tweak how much nitrogen there is or how much carbon there is to work out where the crossover point should be and whether you were right or wrong. And weird as it is to say, we actually don’t definitively know how much helium there is in the Sun. Because helium is really, really hard to measure!
Alfredo
For all of you that love a good dead language pun, Helium is called that because it was discovered in the Sun (Helios in Greek)
Dave Williams
Exactly right. They noticed that there was this element that they didn’t know what it was, and it’s only the second element in the whole period table. The second most important element in the universe. And the Sun is making more and more of it which of course complicates the picture because there should be more deeper down than higher up.
Chris
Am I wrong in saying that helium is finite on earth, that it’s something that is running out?
Dave Williams
Whatever helium we have, we typically get from mine deposits, right? We get it from pockets of gas deep down within the planet. And until we come up with this nuclear fusion from hydrogen, we won’t be making any more helium. So we are currently running out of helium.
Alfredo
But I will point out that every single element on earth is finite. Just to be pedantic! There might be a lot of uranium in the core but it doesn’t mean that it’s infinite!
Chris
Okay. Yeah. Okay, fair point.
Dave Williams
Moral of the story: enjoy your balloons while you can.
Chris
There is one thing that I do want to know now and I dread to kind of ask because you’ve already made it sound so awesome. And I just get the feeling this is going to be another rover. Is SolO going to come home?
Dave Williams
Well certainly not. The orbit that we put it into, that whizzing past Venus that it does, I think in the end we go around the Sun three times for every two Venus orbits. After a while Venus can’t help anymore to change the inclination, so at the end of the 10 year sort of program that we have in our plans, we get to about 34 degrees inclination. And I think Venus can help get it maybe a little tiny fraction above that. But eventually it will just run out of fuel. And fuel is important because there is not only sort of the Earth and Venus and the Sun and Jupiter, way out there that controls what happens to the spacecraft, there’s micro-meteorites, also radiation pressure from the Sun, there’s all sorts of different forces acting on these things. Which LISA Pathfinder had to fight really hard against to stay in the same place all the time. But eventually, if you run out of fuel for your thrusters, you start getting nudged about the solar system by different factors. And you can end up in a stable orbit or an unstable orbit. We’ll probably have track of this satellite for years after it stops working. But I mean, as with all these things, it takes so much work to get them operating, that we try and run them for as long as we possibly can. While they’re in any way cost effective.
Chris
So will it be locked into just a constant orbit or will it fall into the Sun?
Dave Williams
It almost certainly will not fall into the Sun. It will be too far out for that. So it would take quite a big perturbation to get that to happen but we think it will just keep wandering the solar system and doing fly pasts of Venus.
Alfredo
So if climate change or antibiotic resistance hasn’t killed us and you’re listening to this from the year 2060 and you’re trying to create an archaeological museum of space: the Solar Orbiter is out there about 50 million kilometres, more or less, from the Sun reaching about 34 degrees from on the plane of the solar system. So get out there!
Dave Williams
Get out there every three orbits of Venus, to see Solar Orbiter pass the planet!
Chris
Bring it home!
Alfredo
Yes, bring it home! And also even in 2060 please leave a positive review about this episode
Dave Williams
For posterity.
Alfredo
For posterity!
Dave Williams
And I think that the lending thing reminds me something else, which is that we’re lucky that we’re going past Venus because should something happen and it ended up sort of, you know, not flying past Venus but flowing into Venus, (trying not to make an Expanse reference, of course) but but if it ends up crashing into Venus, we don’t have to worry about planetary protection in the same way that we will do if it was going past Mars. So we don’t have to have the same cleanliness requirements for biological contamination. There is the requirement to stop it from going blind to ultraviolet radiation, for example, and to not measure the wrong kind of particles in space. But we don’t have to go the extra mile you’d have to go for anything that goes to Mars.
Alfredo
Because nothing survives on Venus because it is a hellish place with acid rain. Seriously, for me it is one of the exciting places that we should think about building a base, but the base needs to be floating. Like Cloud City in Star Wars. Just don’t go for a stroll at night. Ooooh that could be another interesting thing for a fictional episode for the Astroholic Explain, so bear that in mind!
Chris
Will bear it in mind!
Alfredo
Okay, I think this is that we have time for today. Thank you very much.
Chris
This has been an absolute pleasure. Thank you so much.
Dave Williams
Likewise, it’s lovely talking to you guys about this stuff. I’m psyched!
Alfredo
We are very excited for the first results from Solar Orbiter so we can bring you back here and then you can tell us all about it.
Dave Williams
We should have at least some sample images this year!
Chris
I guess there may even be a chance of another episode in season two, and which will have a sequel episode to this episode!
Alfredo
We’ll just have to wait and see. Fingers crossed.
Dave Williams
Fingers crossed is right!
Main Image: ESA/ATG medialab