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>> Hi, I'm Nicky Fox.

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And I'm in charge of all

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sun science here at NASA.

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Oh.

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This is "Ask NASA,"

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and I'm here to answer

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your questions.

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"Is the sun a ball of fire?"

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No, it's not.

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We know that the sun

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can't be a ball of fire,

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because we need oxygen

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to be able to have combustion

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and there's no oxygen in space.

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The sun, however,

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is a giant nuclear furnace.

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The core in the very center

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is very, very similar

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to a nuclear reactor.

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And all of the--

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these particles get

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squashed together and there's

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a huge amount of pressure.

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And they go--

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undergo chemical reactions.

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And so there are very different

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layers as you move out

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towards the edge of the sun.

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"Why does NASA send

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missions to the sun?"

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Because the sun

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is the most important thing

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in our solar system.

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The sun generates light

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but also a tremendous

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amount of energy.

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And it sends all of this

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material to us here on Earth,

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and so we live in the extended

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atmosphere of the sun.

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We've looked at the sun

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in every different wavelength.

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But recently, NASA launched

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the Parker Solar Probe

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which is a daring mission

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to go into the very atmosphere,

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the very heart

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of the atmosphere of the sun.

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So I have a model

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of the Parker Solar Probe

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spacecraft here.

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Can I get some sun

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in here, please?

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So the important thing

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is as the spacecraft

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moves around the sun,

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the heat shield has

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to remain pointed towards

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the sun at all times.

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So the heat shield--

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the front of the heat shield

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will get to about

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2,500 degrees Fahrenheit.

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But the main body

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of the spacecraft is nice

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and cool at about

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80 degrees Fahrenheit.

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Which is a bit like a balmy,

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Florida evening in August

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I guess!

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And that's Parker Solar Probe.

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Thank you!

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Good!

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[ laughter ]

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>> I love how polite you are!

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[ laughter ]

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>> So one of the things

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that we discovered

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with Parker Solar Probe

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on the very first orbit

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was switchbacks.

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Switchbacks...

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If only I had a model

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of The Corona.

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Oh, thank you!

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So, switchbacks are really

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reversals in the material

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coming from the sun.

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So the sun has a magnetic field

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and that is continually

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moving away--

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or so we thought, continually

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moving away from the sun.

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But what we found

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with Parker Solar Probe

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is this magnetic field

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actually kind of

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reverses on itself

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and makes an "S" shape.

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We call that a switchback.

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It's hard to twist

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a magnetic field,

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it's like trying to twist

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a rubber hose-- it's hard!

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And so, somehow there's

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this energy going into th--

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the magnetic field

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that's causing this "S" shape.

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And when it releases,

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it's letting all of this excess

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energy out into the solar wind.

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Thank you.

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Studying the sun is really

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important as we get ready

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to support the Artemis mission.

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We're really protected here

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on the planet by our

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magnetic field and all

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of that atmosphere around us.

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Our astronauts, when they--

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they will be on the moon.

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And of course, as we journey

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further to Mars and beyond,

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we'll be traveling through

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the solar wind and living

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really more in the atmosphere

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of the sun.

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And so it's key as we

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go forward to the moon,

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to Mars and beyond

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with our Artemis mission

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that we really understand

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the source of energy

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in the heart

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of our solar system.

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Parker Solar Probe

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on her final closest approach

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after she's done all

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of those Venus flybys,

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she will be about 3.9 million

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miles above the sun's surface.

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We have many materials

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on Parker Solar Probe

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that don't melt despite

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how close they are to the sun.

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In fact, that was one

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of the big technology

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challenges for us

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to find materials not only

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that don't melt,

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but can actually withstand

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the incredible change

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in temperature because

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Parker goes very close

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to the sun and then comes out

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around the orbit of Venus.

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Which means that all

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these materials go really

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hot and then really cold

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at least 24 times.

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So the critical thing

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for Parker Solar Probe,

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of course, is to keep

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that heat shield pointing

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at the sun.

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At some point,

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she will run out of fuel.

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At that point, unfortunately,

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she will start to turn.

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And the full illumination

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of the sun will hit parts

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of the spacecraft that are not

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designed to see the sun.

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And so she'll break up

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into large pieces,

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and then they will get

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gradually smaller and smaller

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until they become really tiny.

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And so I like to think

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that she will become part

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of the Corona, and she will

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orbit the sun forever.

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So honestly, we don't know

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what new science

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we're going to expect.

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We've already seen

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unbelievable stuff on

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our first couple of orbits.

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Science is a voyage

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of discovery.

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And that is what

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Parker Solar Probe is doing,

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she is going into a region

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where we've never been before.

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And so honestly?

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We expect the unexpected.

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My favorite aspect about

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the sun is it's a star.

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And it's a star that

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we can go and visit.

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And so you think, you know,

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you look up in the night sky,

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you see all of those stars

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and yet we're actually

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sending a spacecraft

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right into the atmosphere

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of a star right now.

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And that means we're going

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to understand more about

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other stars in our universe.

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And that's amazing.

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>> Do you have a question

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for NASA?

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Send your questions