Science Friday - Parker Solar Probe Will Make Closest-Ever Approach To Sun

Episode Date: December 24, 2024

On December 24, NASA’s Parker Solar Probe will make the closest-ever approach to the sun by a spacecraft. Parker has made more than 20 close approaches to the sun before, but this one will swoop in even closer than 3.8 million miles away from the sun’s surface.Since the probe was launched back in 2018, it’s helped scientists better understand our star and unravel mysteries about solar wind, high-energy solar particles, the sun’s corona and more. Scientists hope that this upcoming approach will reveal even more about the star at the center of our solar system.Ira Flatow talks with Dr. Nour Rawafi, project scientist for NASA’s Parker Solar Probe mission and astrophysicist at the Johns Hopkins Applied Physics Laboratory in Maryland. They discuss the goal of this close approach, how the spacecraft will stand the heat, and what else there is to learn about our sun.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Early on the morning of Christmas Eve, we got closer to the sun than ever before. We have been waiting for this moment since 1958. On Christmas Eve of this year, we will be embracing a star. I'm dreaming of that moment. It's Tuesday, December 24th, and you're listening to Science Friday. I'm sci-fri producer Rasha Uridi. This morning, at around 6.40 a.m., NASA's Parker Solar Probe made its 22nd close approach to the sun, and its nearest one yet.

It swooped into just under four million miles away from the sun's surface. We spoke with the program's Project Scientists last week to learn more. Here's Irafledo. Since the probe was launched back in 2018, it has helped scientists to better understand our closest star. Solve some of its mysteries about solar wind, high energy solar particles, the corona, and lots more. And now scientists hope that this up-close and personal view will reveal even more about the energy source we all depend on for our existence. Here to discuss is Dr. Nurowaffe, the project scientist for NASA's Parker Solar Probe Mission and astrophysicist at the Johns Hopkins Applied Physics Laboratory in Maryland. Dr. Ruwafi, welcome to Science Friday.

Thank you for having me. It's a pleasure of talking to you. Oh, it's our pleasure. Let's talk about the part. Parker Solar Probe. I know that on December 24th, it's going to set a record for the closest approach to the sun ever. And we're talking just 3.8 million miles. And given that the Earth is 93 million miles away, this is pretty darn close, is it not? It's extremely close. If you think of it, I mean, it's only 4% of the Sun Earth distance, which is very, very close. And the fascinating thing, for people who saw the eclipse on April 8th of this year, park a solar probe will be flying through the structures we saw during that eclipse. So it's so

fascinating to be so close to a star because our sun, the star, is the biggest object in the whole solar system. By itself, it weighs more than 99.8% of the total mass of the solar system. And it drives almost everything. The other thing, Two, that environment that Parkasuripos is flying through is extremely harsh. And it's done it 21 times already, but the 22nd is going to hit the closest approach ever to the sun, and we cannot wait for it. Wow. And how fast will it be moving? Parkasurup will be flying at 191 kilometer per second. And there again, it's a big number.

Here on Earth, if you are flying from Philadelphia to D.C., you will do it in about one second. But let me say this. I was born after 1969 when we landed Neil Armstrong and Company on the Moon. I'm dreaming to see women and men back to the Moon again, that I can see it live. And it will take them about three to four days to get there. But if you pick a ride on Parkosolar Probe at that speed, 191 kilometers per second, you will get from the Earth to the Moon in about half an hour. Wow.

Now you talked about the harsh environments being so close. to the sun, why does the Parker solar probe not burn up? I mean, it has a special heat shield. Describe how that all works. It took us 60 years to get this point. Scientists and engineers have been thinking about this mission since 1958. But obviously, we did not have the technology to fly the spacecraft safely around the sun. And to do it, you need a heat shield to protect it from the excessive heat that is coming from the sun. When Parker's solar probe is, Its closest approach, the heat shield side that is facing the sun will be glowing at about 2,000 degrees Fahrenheit. Wow.

About a yard behind, it's almost room temperature. One yard away. Yeah, and that's where the body of the spacecraft and most of the instruments resides. They reside in the shadow cone of the heat shield. So this heat shield is basically carbon foam. And it's so efficient in heat dissipation. And it's like magic, but it's actually not magic. It's engineering.

Okay, you mentioned that it's shielding the probes. What are the probes picking up? What kind of sampling is going on here? We are at the solar maximum now, and the sun is extremely active now. And every now and then we see this big explosion on the sun, like flare and coroner mass ejections. And these explosions accelerate particles to almost speed of light. And these particles represent a hazard to space equipment like telecommunications satellites like GPS or to humans in space now, particularly that we are thinking to send women and men to the moon

and hopefully soon to Mars as well. We need to protect them from this radiation. But add to that, that the solar corona that we saw during the total solar eclipse has a lot of other mysteries as well. And one of them is that outermost layer of the atmosphere. that is the corona, is over 300 times hotter than the solar surface. Wow. Why is it hotter? Doesn't it seem weird that it's hotter?

It's weird. If you think of it from everyday experience, if you have a heat source, the further you move away from it, it should cool down. But obviously, that does not work for the solar corona. And get this. The rise of the temperature is not gradual. It's sudden. So we have the photosphere that is the surface of the sun that we see with the naked eye.

It's at about 10,000 degrees Fahrenheit. You move about 3,000 kilometers above, and all of a sudden, the temperature of the gas will jump to 2 million, 3 million degrees Fahrenheit. No kidding. Which is fascinating. And obviously, you have this boiling gas that is multimillion degrees high. You cannot keep it static. So there is a flow that rises from it to feel the whole heliosphere that we call the solar wind.

And the mystery about the solar wind that the particles get accelerated to handle of kilometers per second of a very short distance. And we don't understand where they got the energy from. That had to do possibly with the corona? Yeah, it's the corona, yeah. It's actually that same gas that is multimillion degree hot also generates the solar wind. So when we built Parker SolarPoop, we have these three big phenomena in mind. But Parker SolarPub is way, way more than that.

We are flying through a region of space that we never visited before. and every observation is a potential discovery. And that is exactly what we are learning from the data, the abundance of data that Park and Solar Probe returned to us. We are discovering other phenomena about the Sun, about Venus, about dust, about comets, that Park and Solar Pro basically is rewriting the books about the Sun. Tell us some of those things it's rewriting. So one of the discoveries that we made from orbit 1,

and actually when we launched Park of Solar Pro, we thought, yeah, probably toward the end of the mission, we will get some insights into this. And it's also a historical discovery as well. Back in 1929, a scientist, a physicist called Henry Russell, was studying dust around stars. And he came to a conclusion that there should be original around the star that should be totally devoid of dust. And the reason for it is that when dust particles that are micron size get very close to the star, they got so hard, they sublimate, and they are pushed out by the radiation pressure. The obvious place to look for this dust-free zone is the sun.

And since that time, people looked for it over and over and over again, but they couldn't find the firm evidence for it. Parker's allotrome from orbit one gave us the evidence that the dust-free zone exists around the sun. That's actually not only a discovery about the sun. It's a discovery for billions and billions of stars out there in the universe. So Parker helped confirm this old theory about a dust-free zone around the sun. What about the magnetic field? Has Parker taught you anything about that?

Again, from orbit one and the following orbits, we observed these kinks in the magnetic field that we call switchbacks. So basically, the magnetic field will roll of itself forming an as shape. And they are like gazillions of them when you get close to the sun. So many of them. and obviously they are, they carry a lot of energy with them. And trying to explain what heats and accelerate the plasma, we are basically looking at energy sources.

And these switchbacks could be one of them. When we saw them, we said, yeah, this could be one of them. So now trying to understand where do they come from, how do they form and how do the evolve, we are actually getting closer and closer to understand the heating and the acceleration of the solar wind, which is fascinating. Is there anything about how the sun works that we don't understand in great detail?

And could the Parker help us understand that? Yeah, absolutely. When we talk about the solar activity, the flares and coroner mass ejections, that's actually one of the big phenomena out there. By the way, it's not only our son. Other stars in the universe do it as well. So if we can explain that, if we can understand that and try to predict it, that will help us tremendously here on Earth and up there in space as well. Because, you know, we depend so

much in space now. I mean, our internets, we get it from space. Our economy in the future will be driven from space. And this activity affects us so much. So coming to an understanding when the sun is about to produce one of these big explosions will help us tremendously here. Because we can mitigate their effects. Yeah, because it could knock out satellites, right? Absolutely, it does. And one of the prime examples is the 40 satellites of space, space axe that were knocked out about two years ago. After the break, looking ahead with the Parker Solar Probe. Hi, Ira here, reminding you that Science Friday has a dollar-for-dollar donation match, which means that any donation made through December 31st will be doubled. So now is the time to head

over to ScienceFriday.com slash support and make a gift. Our 2025 programming depends on the generosity of our fans and listeners. Again, that's ScienceFriday.com slash support and thanks. Let's talk about something I found very interesting that you said, and that is that the sun is in a really active period called the solar maximum. How does that happen, and what's exciting about that to you. The solar cycle is another big mystery about the sun. I mean, we know about it for hundreds of years now, but we don't really understand how the sun produces this cyclic activity that we see on the surface in the corona as well. Parka solar probe will address some aspects of that, we'll address the activity of it. But to understand the solar cycle itself, we need other

missions that hopefully NASA will be it in the future and help us understand them. And by the way, the Ducatal survey that came out just two weeks ago, recommended one of these missions that will fly above the poles of the sun to help us understand how the magnetic fields and the plasma behaves there, and that will give us insights at the, how the magnetic fields are created in the interior of the sun. How do they rise to create this cyclic activity that is a solar cycle? When the sun is at a solar minimum, when it's not very active, does that affect the weather here on Earth also? The sun is active all the time, except when at solar, minimum, the activity is at a lower levels.

But every now and then, the sun can produce a big explosion whenever it wants. As I say it, the sun will do what the sun wants to do at any time. So, yeah, by the way, we actually launched Parkosolar Probe in August 2018 when the sun was very, very quiet. And now we are actually at solar maximum. We covered with Parkosolar probe a half of solar cycle. So was that by accident?

You got there at a good time? No, no, not really, no. I mean, for a mission like Parker Solar Pro, you tell any scientist out there or an engineer out there, as long as we can get the mission, you launch it anytime. Right. So, but we were so lucky to launch it at solar minimum. The reason for that, and by the way,

I personally was asked this question. You build this big mission. You invested so much into it. Why do you launch it when the sun is quiet? And my answer, that's probably the perfect time to launch this mission. Because? Because the sun by nature is a very complex object. And the complexity is even higher when we are at solar maximum.

So ideally, to understand this complex medium, we want to start with the simplest state possible. Right. That is the solar minimum. And then you build the knowledge as the activity rises toward the maximum. And that's exactly what we did with Parka Solar Probe, back of the mission. So historically, when people were thinking about a solar probe, they were always thinking about Jupiter. We fly the spacecraft out to Jupiter, get a gravity assist, and then have a deep dive into the solar atmosphere.

But those type of missions will basically result in one or two flybys, and they are very limited in time. Basically, you get maybe a day worth of data when you are close to the sun, very close to the sun. But that mission is so complex and so challenging. It's costly as well. And NASA tried, I think, four of times to do it that way. And all of them didn't really come to fruition. But back in 2006, seven, engineers at the Applied Physics Lab of Johns Hopkins came up with a new idea. Instead of using Jupiter, they said, okay, if we can use Venus multiple times, we can actually get ground.

gradually closer and closer to the sun. Every time we fly by Venus, we slow the spacecraft a tiny bit down, and then it will dive closer to the sun. And the nice thing about this aspect, first of all, the mission is feasible, it's more cost-effective, and instead of one or two flybys

that are basically, each one of them will provide about one day worth of date. We will have seven years for the prime mission alone. And Parkasol or Probe, now we are flying it around the sun for, we completed 21 orbit, by the way, and we are very close to the sun for the 22nd orbit. Parkosurotrop has been flying through this extremely harsh environment, but it's doing so well, and that is really surprising to us.

That's surprising to you. It's amazing. When you look at all the subsystems, they are doing then better than we thought. Well, then you must be sad when what's its eventual fate going to be? So, okay, personally, you know what, this mission has the potential to go way, way longer than the prime mission. Really? Yeah. All the subsystem are doing way better than we thought.

So it's basically like we launched it yesterday, which is fascinating. So after the prime mission, it is really a massive decision to extend the mission. But the hope for us that the mission will continue to cover this whole, this whole. solar cycle going from the maximum to the minimum and hopefully beyond after that as well. Well, hey, look at the Voyagers. They've been going on for decades, right? Absolutely. And Voyager was built only for four years. Now it's almost, it's 47 years or so. December 24th, the day of the flyby is coming up. I hear the excitement in your voice. It sounds incredible. As everybody at NASA and Johns Hopkins is excited as you,

you are? I think everybody is excited about this. We have been waiting for this moment since 1958. And let me put it a little bit in historical context as well. And in 1969, when we landed Neil Armstrong and other folks on the moon, and Armstrong was hooping on the moon saying his famous quote, this is a small step for men, a huge leap for mankind. I was not born back them. But still, when I see it, it's actually, I feel like I'm seeing it live. Back then, we landed humans in the moon.

On Christmas Eve of this year, we will be embracing a star. Which is, I mean, I'm dreaming of that moment. Well, I'm wishing all the best for your project, for the Parker probe and everybody else who's been working on it for so long.

And good luck. And I'm going to thank you very much for taking time to be with us today. Thank you so much. really pleasure to talk to you, Ira. Dr. Nirowaffe is the project scientist for NASA's Parker Solar Prob Mission and astrophysicist at the Johns Hopkins Applied Physics Laboratory in Maryland. On tomorrow's episode, Dinosaurs with a side of eggnog. Lots of folks help make this show happen, including...

Sandy Roberts. George Harper. Annie Niro. Jason Rosenberg. I'm Rasha Uriety. Catch you tomorrow.