The sun is our closest laboratory for understanding how stars work. Decades of space missions have studied the sun, yet its outer atmosphere, the corona, remains a mystery. NASA's Parker Solar Probe was built to change that. Dean Regas talks with Dr. Joe Westlake, heliophysics division director at NASA Headquarters, about what we're learning from humanity's closest approach to a star.
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Learn more about SOHO, STEREO, Solar Dynamics Observatory, and, of course, the Parker Solar Probe.
Episode Transcript: Looking Up is transcribed using a combination of AI speech recognition and human editors. It may contain errors. Please check the corresponding audio before quoting in print.
Dean Regas: What do astronomers do during the daytime? Study the sun, of course! It's our closest star by far, at only 93 million miles away, or 150 million kilometers. Only, I say it's definitely easier to study than the next nearest star, Proxima Centauri, which is a whopping 25 trillion miles away, or 40 trillion kilometers, from Earth. Places like the National Solar Observatory in Sunspot, New Mexico, can document fluctuating activity and monitor changes over time at our superstar. But where can you watch the sun all day and all night? Let's go to space.
From the studios of Cincinnati Public Radio, I'm your host, Dean Regas, and this is Looking Up, the show that takes you deep into the cosmos or just to the telescope in your backyard to learn more about what makes this amazing universe of ours so, great. My guest today is Dr. Joe Westlake, Heliophysics Division director at NASA headquarters and a solar expert, to tell us about the Parker Solar Probe.
There are a lot of astronomers who dedicate their lives to just studying the sun. I mean, it does present a perfect laboratory to understand the workings of a star up close and personal. Satellites like the Solar and Heliospheric Observatory, known more easily as SOHO.
[OTD in Space - Dec. 2: NASA Launches SOHO Sun-Watching Satellite]: This sun-monitoring satellite is a collaborative project between NASA and the European Space Agency that has been operational for more than 20 years. Its main objective is to investigate the physics behind how the sun works.
Dean Regas: And the Solar Dynamics Observatory can observe the sun 24 hours a day. SOHO, for instance, sits almost 1 million miles from us and closer to the sun, too. Okay, it's still like 92 million miles from the sun, but SOHO has been watching the sun steadily since its launch in 1995, making it one of the longest-lasting missions ever.
Another mission called STEREO, short for the Solar Terrestrial Relations Observatory yeah, that's a little bit of an acronym stretch for me, but…
[STEREO Mission Turns 10]: STEREO is a mission to help us understand what we call space weather, how the activity on the sun can affect us here at Earth.
Dean Regas: This launched twin satellites in 2006 in opposite directions into space. One craft, STEREO-A, left Earth in a path around the sun, while the other, STEREO-B, headed off in the other direction, also, around the sun. That meant the two crafts working in tandem could monitor the entire sun, not just the side that always faces us.
This was the first time in human history that we could see the far side of the sun. Astronomers could watch how solar storms like sunspots, solar prominences, and flares evolved over months. There was nothing hidden from us on the sun.
Well, there still was a huge mystery: the corona of the sun. This is the outer atmosphere of the sun. It's the wispy, ethereal clouds you see during a total solar eclipse. For some reason, the corona, which is well off of the sun's surface, is hotter than the surface itself.
[NASA's Parker Solar Probe Touches The Sun For The First Time]: The corona is about 300 times hotter than the photosphere, the visible surface of the sun below.
Dean Regas: A lot hotter. Now, why is that? Maybe we can fly something through the corona to find out.
Joe Westlake: My name is Joe Westlake. I am the director of heliophysics at NASA headquarters.
Dean Regas: Well, Joe, thanks so much for joining me today.
Joe Westlake: Yeah, super jazzed to be here, super jazzed to talk to you about all the work we're doing in heliophysics and Parker Solar Probe.
Dean Regas: Yeah. I mean, the Parker Solar Probe mission is it has been on quite a journey. Give us the itinerary from launch to where it's gone.
Joe Westlake: Parker Solar Probe is our mission to touch the sun, to get into the atmosphere of the sun, to do that. I mean, you would think that you could just launch from Earth, point in that direction, and just end up in that location.
The trouble is, is that you actually need to figure out how to get there and how to safely take your spacecraft there a multitude of times. So, what we really had to do is, instead of accelerating straight in towards the star and going as fast as you could, we had to figure out a way to slow down. So, we were constantly using Venus in order to lower our closest approach to the sun, the perihelion of that orbit.
And so, over a couple of years, you know, we launched in 2018. Every couple of months, we have one of these visits to the sun. And each one of them, we're getting closer and closer and closer. And at this point, we are as close as we're going to get to the sun. And so, we just keep bringing home amazing science from this mission.
Dean Regas: Well, and of course, this sounds incredibly dangerous. You know, flying a spacecraft close to the sun. So, besides the obvious thoughts and troubles like melting, that comes to my mind. What are the dangers of flying that close to the sun?
Joe Westlake: Yeah. So, no big deal, being the fastest human-made object and having to autonomously figure out how to point your shield, their sun shield, towards the sun all the time. Also, making sure that, you know, the backside of you, which is looking into the cold, dark space, doesn't cool down too much. And, you know, you can still get power out of the solar panels and all that kind of stuff. It's a really complicated mission in that regard with a ton of autonomy on board.
You mentioned the heat this carbon-carbon shield, it's like 4 1/2 inches thick, this shield that protects our spacecraft. It is like 2,500 degrees Fahrenheit on the front end, and then on the back end, that protects our instruments and everything, that's like a balmy 75, 80 degrees. So, you're keeping things at room temperature while you're in the atmosphere of the sun, which is pretty cool.
And then we've got a whole multitude of instruments, and they're made from these like exotic materials, like rocket nozzle materials and other things that keep them protected from, you know, the heat of the sun. That engineering took us quite some time, quite a bit of effort to make it happen, but gee, the payout has been amazing.
Dean Regas: Well, I suppose the key is to not spend too much time that close. So, how close did it get, and how fast did the spacecraft go?
Joe Westlake: Okay, so, when I think about how close that it gets, if you think about a football field, the football field is the distance from the sun to the Earth, right? Just imagine that distance in your head. Parker Solar Probe, in its closest approach, got to the 4-yard line. So, we're within, you know, some number of millions of miles going faster than anything has ever gone, human-made, at this point as we zip across the sun, all while being out of contact with the Earth.
Dean Regas: So, what were some of the surprising results you got from analyzing the, you know, the atmosphere of the sun?
Joe Westlake: Oh my gosh, there's an incredible amount of things that we learned about the sun as we went in. You know, this is one of those grand missions that's been on the docket for the longest time. But the science that we've obtained the surprises were related to some of those early mysteries.
For instance, if you look at the photosphere, that's like a balmy 4,000, 5,000 degrees Celsius kind of thing. If you look into the sun's atmosphere, it's like tens of thousands of degrees. It is significantly hotter than it is in the photosphere. It's like standing next to a fire and walking away from it and getting hotter. It just makes no sense. There's no real reason why that would happen, that's in our physical experience that we have here on Earth.
So, we said, hey, the only way we're really going to solve this is if we get in close. So, as we flew into the solar atmosphere, you know, we saw a bunch of things that were happening in the particles and the fields that surprised us. Like, for instance, there are these things called switchbacks, in which the field is going out from the sun you know, we always see particles and things, the solar wind emanating from the sun, but there's these weird features when all of a sudden, it turns around and heads back. Some of those switchbacks are associated with how that heat is created, and some of the like turbulent motions and wave motions that are going on within the sun's upper atmosphere.
The funny thing about Parker Solar Probe has been it has found evidence of basically all forms of solar heating, and that there is a long form of potentially hybridization, right? So, like all of the different forms different forms are happening, could be wave heating, you know, it could be turbulent motions, it could be, you know, tying of field lines and other things. There's all kinds of different things happening. And just like any physical process that we research, it turns out it's more complicated than we ever expected.
Dean Regas: So, if I'm hearing you right, for all the theoretical heliophysicists out there, why is the corona so hot? The answer is yes.
Joe Westlake: Yes. Absolutely.
Dean Regas: Good. All right. Boy, I summed that up nicely. That's my theory, at least.
Joe Westlake: It's sort of naive to think, though, that like the answer is going to be summed up in one word. Right. A star is such a complex object. And you think about the complexity of like, if I pick up a handful of dirt, the complexity that's within that handful of dirt is amazing, at whatever scale you look at.
To think that the sun isn't going to show that kind of complexity as we go from like the large scale I'm looking at the disk of the sun from the Earth to I'm looking at a singular flare, to I'm looking at the convection patterns, to I'm inspecting the atmosphere of the sun, it's kind of, again, a little naive.
Dean Regas: Well, and you mentioned other stars. How does our sun rank compared to, you know, like the distant stars we see at night?
Joe Westlake: Yeah. I mean, I think our star is sort of No. 1. It's personally my favorite given all the things that it does for me on a daily basis. I think people are a little bit rude, frankly, to our star. You know, it's sort of an average main you know, main set of stars, and it's middle of its lifetime, Goldilocks, so, on and so, forth. But as we get in closer and as we understand what is actually going on in our star, the uniqueness of the physics of what's going on in that star helps us to understand so many different things that would go on in other systems and other stars.
You know, let's say one day we're going to image some other stellar system. Wouldn't it be great to have a physical understanding of our own star that is so, good that from the minimal pixels that we're going to get, we can interpret what we think is going on with that star and whether that's going to impact the habitability of those planets.
Dean Regas: So, the spacecraft has been under all the stress flying through the atmosphere of the sun several times. I'm sure there's tons of design challenges. You mentioned like exotic materials used for the heat shields. Where do we find those, like on Earth? Or are there any practical uses for them on Earth?
Joe Westlake: Yeah, this is one of those things that came out of the developments that went into a lot of our reentry technologies, right? I mean, the heat of reentry you probably just saw thinking about Artemis II and the challenges that you go through in re-entering the Earth's atmosphere with such a speed leads you to these materials that are these carbon-carbon composites, like we've used on the shuttle tiles and other things.
This one's a little bit special. It's got sort of a surface layering of an additional composite that's on top. So, that's one of the materials. But you know, things like niobium and other things that have real like intense heat resistance that we use throughout our spacecraft.
But one of the cool things so, there's a bunch of videos out from these flybys. If you look at some of those videos, they come from our WISPR instrument, in which you're actually looking at the white light that's coming off of the side of the sun. And you can see I think of it like those Star Wars scenes where they're on one of the planets and they're flying through on these speeders and all the trees are zooming by. Right. You can see flares and coronal mass ejections and other things sort of zooming by as you're going through.
But there's this like constant shower of stuff that's coming around. And a lot of that is like ablation of this heat shield that's coming into view as you're going through. And, you know, we've got many, many years left on this heat shield, but you're watching it actually physically interact with the sun, which is pretty cool.
Dean Regas: Yeah. I somehow got one of the old, retired panels off one of the shuttles or something like that. And I remember I remember them demonstrating it back when I went to Space Camp as an adult, by the way.
Joe Westlake: That's awesome.
Dean Regas: They're demonstrating the, you know, the heat shield technology. They had this like giant torch and somebody holding it, and they're like, put your hand on the other side, Dean. I'm like, oh, is this safe? And did it. But yeah, you couldn't feel it. Like you burned it for like forever, and then you touch it. It's not even hot at all. It was incredible material.
Joe Westlake: Yeah. That was one of the favorite demos from the Parker team when they were developing it would be to go in the clean room with a sample of the shield and be able to say, okay, you know, who's going to break out the blowtorch, and who's going to risk their hand on the other side? Again, it's just amazing. You can be sat 3.8 million miles from the sun, have the front side of that be 2,800, 3,000 degrees Fahrenheit, and the backside of it be basically room temperature is wild.
Dean Regas: Well, the primary mission seems to have wound down. But how is the spacecraft doing? Like, is it ready for more? Is there a possible continuation of the mission?
Joe Westlake: Yeah, we've got a very healthy spacecraft on our hands. I mean, one of the really cool things that I think our NASA engineers do an amazing job of is that they carefully thought through the lifetime of this mission. They carefully thought through the contingencies, and they carefully thought that through and said, you know, remember, guys, we're only going to get one shot at this. Let's make it count. That spacecraft is incredibly healthy. It continues to orbit the sun. It continues to make these flybys on an about every quarter, every half a year kind of arrangement, and we are as close to the sun as we're going to get.
And so, with those continued flybys, you know, now it's just what multitude and different activities can we see from the sun in those flybys? How lucky can we get to see some really cool stuff? We've already seen some really unique activity. But then, you know, we're on the downside of the solar cycle, in which we're coming down from solar max. And some of that unwinding of the sun's magnetic fields creates really, you know, really active events in that declining side of the solar max that creates things like the aurora that we see here on the Earth, creates space weather that affects us, you know, in our day-to-day lives, our GPS, our actually even affects our agriculture these days, which is pretty wild to think about, that global positioning systems have gotten so, good that the agriculture community is now using these GPS systems at millimeter precision to really like plant and other things, which is impacted by the sun.
But as we continue to go forward with Parker Solar Probe, you know, we're going to visit the sun over and over and over again, frankly, until we run out of propulsion. And when we run out of propulsion, then we'll do our best. But then at that point, it's endgame, but that's quite a ways off. So, I think we're going to have many, many, many years of additional information coming down from this mission. And frankly, it will be amazing to be able to see the differences in the solar corona in its disorganized solar maximum state to its rather organized for a star solar minimum state, in which it's much calmer and less turbulent waters. I think we're going to see a lot of change in that time as well.
Dean Regas: Well, Joe, this has been so, great talking about the sun and the amazing Parker Solar Probe. Thanks so much.
Joe Westlake: Yeah. Thank you, Dean, really appreciate it. And thanks for having me on. This is great chat.
Dean Regas: So, how can you watch the sun safely at home? First off, I still hear my mom's warning in my head now: Dean, don't stare at the sun. You'll go blind. So, yeah, don't stare at the sun. Instead, check out all the cool solar observatories' websites. Browse SOHO, STEREO, Solar Dynamics Observatory, and, of course, the Parker Solar Probe. We'll link to them in the show notes, too.
Trust me, once you start, you could end up spending hours looking at the photos of sunspots, videos of eruptions larger than the Earth, and coronal mass ejections. Yeah, that's a thing. These send solar material rocketing through space at over 1 million miles an hour, and all these images and videos are free to use, open source, and are constantly updated with the latest news and info.
Speaking of coronal mass ejections, those are the solar eruptions when directed at the Earth that can cause northern lights to appear farther south on the globe. The sun goes through cycles of greater activity called solar maximum and less activity, solar minimum, about every 11 years. Yeah, we're not exactly sure why it is every 11 years, but it's been noted since the 1600s, and we're just ending our time in solar maximum. But for the next year, there's still chances for increased coronal mass ejections. And maybe, just maybe, you can see the northern lights one more time. That is, if you keep looking up.
Let me know what you find. In fact, give me a call. You can leave a message in the Looking Up voicemail box by calling 513-352-9188, and you might even hear your message and my response in a future episode.
Looking up with Dean Regas is a production of Cincinnati Public Radio. Kevin Reynolds and I created the podcast in 2017. Ella Rowen and Carlos Lopez Cornu produce and edit our show and are creating Looking Up-branded safe solar viewing glasses, especially for mothers.
Jenell Walton is our Vice President of Content, and Ronny Salerno is our digital platforms manager. Our theme song is, “Possible Light” by Ziv Moran. Our social media coordinator is Hannah McFarland, and our cover art is by Nicole Tiffany. I'm Dean Regas, keep looking up!
