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You're going into environment that's
completely unforgiving. The temperatures

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that we're seeing on the spacecraft or
have not been seen by any other

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spacecraft ever before. The scariest
thing about the Sun is the unknown. We

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see it every day
but we see it from 93 million miles away.

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This first perihelion were going into we
have very minimal contact - all we can

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get is a tone. I'm going to be waiting on
the edge of my seat for those beacon

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tones. The Sun facing side will be exposed to in excess of 2,500 degrees Fahrenheit

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We're gonna go closer to the Sun than
any other spacecraft has gone before. We're

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not going to do that once we're not
gonna do it twice - we're gonna do that 24

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times - and that is terrifying. We really don't know what we're gonna find until we get

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there. 
In 1958 Gene Parker had an idea that the

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area around the Sun would behave in a
certain way. There are two really

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overarching mysteries that we have
always wanted to study: why is the corona

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hotter than the surface of the Sun? Why
is the solar wind continuously

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accelerated? We are now in what we call
our encounter attitude the TPS is pointed

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at the Sun and we will not leave that
attitude until we get back around the

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backside of the Sun. So we keep the
thermal shield between the spacecraft

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body and the Sun. We have designed the
spacecraft to be able to do the right

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thing no matter what it sees. You can't
do Parker Solar Probe unless you're

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willing to build a spacecraft that could take care of

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itself; you can't build Parker Solar Probe

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unless you can build a shield that could
withstand the thermal environment; you

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can't do Parker Solar Probe unless you
can keep the power generation cool - and

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all these things contain some level of
risk.

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The Sun is a wideband radio source so
any spacecraft is either in front of the

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Sun behind the Sun or near the Sun you
can't talk to it. Parker Solar Probe is

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designed to transmit four different kinds of beacon tones A is a good beacon,

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the fault management system is reporting
that all systems are nominal.

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The other three tones mean that some
type of fault has occurred on board. We

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will be mostly out of contact with the
spacecraft through encounter so the only

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thing we will have is those beacon tones.
We will be all waiting for the call: "APL,

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APL - I am Parker Solar Probe. I'm doing well, and I have surprises for you. The fear

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and tension and stress is all going to
be focused on those last few minutes.

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This truly is a mission of discovery.