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Narrator: NASA's Parker Solar Probe is a mission to explore the Sun. How can it do that?
Why won’t the spacecraft melt? Excellent questions. 
You can’t face off with the sun without packing the right gear. 
This is why Solar Probe is equipped with a white shield that reflects heat off the front and keeps things cool in the back.
Betsy Congdon: The heat shield is made of a couple of different materials. 
One is of carbon carbon which is a lot like the graphite epoxy 
you might see in your golf clubs or tennis rackets, but it’s been super heated. 
The inside is a carbon foam which is another form of carbon which
is about 97% air. It's a very light weight way of making
a very strong structure.
Narrator: Nobody likes a needy explorer. Solar Probe can take care of itself, thank you very much, 
and that’s because it has autonomy software that will keep its instruments safe and cool behind the heat shield.
We are too far away to joystick it into place,
so it basically has to always be sensing whether
or not the heat shield is in the right position and correct itself 
if it isn’t. There are these things called solar limb sensors, 
just poking out at the very edge of the shadow. If those get illuminated, 
the spacecraft knows, “Oh, I’m going the wrong direction,” and can actually right itself. 
Narrator: It’s important to stay hydrated in the Sun, even for a spacecraft! 
Solar Probe circulates water to keep the solar cells 
from overheating. It stays cool and keeps power.
Betsy: Basically water flows behind the solar arrays and into the radiators, 
so the water warms up behind the solar cells and then cools 
down at the radiator that heat transfer is happening a lot like 
the veins in your body 
Narrator: Yes, you read right: Heat is not the same as temperature. Temperature is a measurement, but heat is an energy transfer.
This matters because Solar Probe will be 
visiting the sun’s outer layer, the corona. Like all stars, 
the Sun is made of plasma. How tightly packed that plasma is 
depends on the layer. While the Sun’s corona has a very high temperature
the plasma particles are fairly spread out, so even though the temperature 
in the corona is 1,000,000 Fahrenheit,
the heat around the spacecraft is manageable. 
Betsy: The corona and where we are going is actually not that dense at all, there’s only a couple particles. 
Those are very hot, but we aren’t touching a lot of them. 
So, it’s kind of like when you put your hand into an oven. The oven might be at 400 degrees Fahrenheit, 
but your hand isn’t going to be at 400 degrees Fahrenheit. 
Narrator: Thanks to its design and destination, this cool, confident spacecraft is all set to explore. 
We can just sit back and chill, as Parker Solar Probe takes the heat.
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