This image made available by NASA shows an artist's rendering of the Parker Solar Probe approaching the sun.

'Once in a lifetime': NASA makes historic trip through the sun's corona, solar physicist explains

NASA has announced that its Parker Solar Probe has flown through the sun's corona. Kelly Korreck, a solar physicist at NASA's headquarters, joined The World's host Marco Werman to discuss this remarkable feat that took 60 years to accomplish.

The World

This image made available by NASA shows an artist's rendering of the Parker Solar Probe approaching the sun. On Tuesday, Dec. 14, 2021, NASA announced that the spacecraft has plunged through the unexplored solar atmosphere known as the corona in April, and will keep drawing ever closer to the sun and diving deeper into the corona.

Steve Gribben/Johns Hopkins APL/NASA/AP

Imagine: 94 million miles. That's the distance from the Earth to the sun's outer atmosphere, known as the corona.

NASA has announced that its Parker Solar Probe has flown through the sun's corona.

The spacecraft dipped in and out at least three times, and just to be super clear — this is a huge deal.

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Kelly Korreck, a solar physicist at NASA's headquarters, joined The World's host Marco Werman to discuss this remarkable feat.

"This is a once-in-a-lifetime type of thing," Korreck said. "It has taken us, first of all, at least 60 years to get there. And there's so much technology and science that has to go into that. ... It's like going to the Moon for the first time," Korreck said.  

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The original plan to reach the sun was hatched in 1958, under the same plan that formed NASA. But the technology just wasn't there, Korreck said, until the early 2000s.

Marco Werman: So, paint a picture for us. What and where exactly is the sun's corona?
Kelly Korreck: So, the sun's corona is the sun's crown or outer atmosphere. During an eclipse, you can see this solar corona, this outer atmosphere. It's very wispy, and it is the interaction of the sun within the rest of the solar system. 
Why is NASA's doing this? What is the Parker Solar Probe recording while it's flying through the corona?
So, NASA is doing this because the sun is key to understanding space weather, which is all the effects of the sun on the Earth and that near Earth's environment, as well as throughout the solar system. So, these are huge explosions that happen on the sun. Coronal mass ejections — billions of tons of material equivalent to 80 million school busses — racing at us at around a millions of miles an hour. All of these things can interact with our satellites, with our power grids on Earth. And so NASA really needs to get in there and study what's going on to understand both the sun, the solar corona, where a lot of these things originate, as well as the solar wind that then blows by our planet and other planets in the solar system. 
So, these bursts of magnetic energy from the sun in these corona flares, I mean, there's been news. Recently, I was reading that if those bursts are really large, they can have an impact here on Earth, internet undersea cables, I mean — what could happen? 
Definitely. There's a lot that because of our technology the sun interacts with during space weather. So there are things such as it will cause drag on satellites and so satellites will have less of a lifetime. It could disable GPS. So if you're going along and trying to land a plane, I guess that's pretty difficult, and it could take down a power grid. Think of all the things we use electricity for —  our computers, our phones, all those things wouldn't be available. So those are the reasons why we study this and it's actually a government-wide effort. NASA is the science arm of that, to really understand what's going on so that we can protect against those types of events. 
And a big event like this  — I was also reading that there's a 1.5%  to 2% chance that could happen in the next 10 years. 
So, the sun goes through cycles every 11 years. It goes through a cycle of being maximum activity. A lot of these activities [occur] three to five times a day, the possibility of some of these explosions, to very low ... three to five [times] a week. So there's a huge variation in how active the sun is. So there's a probability that as we go toward solar max in 2025, that some of these large events might actually occur.
From your point of view as a solar physicist, what are you hoping to learn about the corona from the Parker Solar Probe? 
What I'm hoping to understand is, first of all, how it is heated. How do you get the solar corona to go to a million degrees? How is that energy generated? And then how is the solar wind formed and that wind that carries that hot plasma along? How did that start? Those are two of the main things that we are looking for as scientists. 
To that point, how is the Parker Solar Probe able to withstand those massively high temperatures?
Lots of really ingenious engineering. First of all, the heat that we experience there is much more like a sauna than, say, a hot plate. So, you know, if you put your hand on a hot plate at 100 degrees, you're going to get a burn. Whereas if you were to sit in a sauna, you know you can get up to 120. There's no burning involved. And so the corona is much more diffuse. So we don't get the quick heating and so we race in and race out — being the fastest human-made object helps a lot in this — as well as the beautifully designed carbon heat shield that's in front of the probe, as well as in the metals that were used — special metals that can survive this. 
Yeah, but even diffuse sauna like heat and the corona. I mean, how hot is it? What is the number?
The corona is around a million degrees, and the spacecraft got up to around 800 degrees Celsius during the encounter with the atmosphere. 
How long does one sweep through the corona take? 
We have what are considered encounters, and those encounters are around 11 days from when we go relatively close to the sun until we come back out. ... No, we don't spend the entire time in the corona. We pass through at around five hours — the corona itself — around five hours this time and survived, right?
How big is this vehicle, the Parker Solar Probe? 
Parker Solar Probe is, I like to say, I'm around 5 foot 4. It's about two of me stacked on top of each other, but a little bit wider. So it's not a very big spacecraft. And that partially is because to propel something that far and that fast, it has to be lightweight. We had to overcome the Earth's gravity and get us speeding along at 145 kilometers per second, or that's 380,000 miles per hour as we were going into the corona.
Yeah, that is fast. How excited are you with all this news, Kelly?
It is surreal. Yeah, this was always the goal. But when you finally reach the goal, especially a little bit earlier than I had predicted, I was thinking it was still going to be about a year away ... So it's amazing, you know, really, I'm trying to take time with my team and really thank them for all the amazing hard work ... We've been working on this since 2009, 2010. So, you know, it's also been a decade for us in terms of working on the instrumentation and really just taking it all in, being really grateful and being really curious, seeing more data as more comes in ... 

This interview was lightly edited and condensed for clarity.