This summer, NASA will be sending the Parker Solar Probe on a mission to the
Sun, and we're gonna find out more about it starting now. The Sun is the closest
star to Earth and we know more about it than any star in the universe. But for
all that we know about the Sun, there are things about it we still don't
understand. For example, the Sun is surrounded by an extensive atmosphere
called the corona. It extends out to millions of kilometers into space, and we
can only glimpse the corona during a total solar eclipse. [background crowd cheering]
[crowd cheering] [man screaming like an idiot] OH MY GOD! WOWWWW! HOLY CRAP, THIS IS AMAZING!!!
[Narrator:] Anyway...while the Sun is about 9,930 degrees at its surface,
temperatures in the corona skyrocket north of millions of degrees. And that's
weird - that's like backing up from a campfire and suddenly combusting. The
corona is also the source of highly energetic solar flares and massive
eruptions - called coronal mass ejections - which can unleash billions of tons of
matter at millions of miles per hour. Fortunately, Earth's magnetic field
protects us from these dangerous particles, and we can see them slamming
into the upper atmosphere as Aurora. Changes in the solar wind and Earth's
response to it are called "space weather". And while space weather can make for
spectacular a rural displays, it can also disrupt satellites, shorten their
lifetimes, and even change their orbits. These are the same satellites that we
rely on for essential operations like communication, navigation, hurricane
monitoring, and HBO. A massive enough solar storm directed at Earth would
knock out our electric, grid shut down the internet, and force us to actually
have constructive and meaningful conversations with each other, face to
face, like animals. However, if we could predict space weather, we could better
protect our spacecraft and our astronauts, or
at the very least know how much time we have to finish binge watching Game of
Thrones before the end of modern-day civilization. Anyway, in order to forecast
space weather, we need to understand just what is going on inside the Sun's corona,
and the only way to do that is to go there. That's why NASA is launching the
Parker Solar Probe to the Sun this August.
It's named after Eugene Parker, a solar physicist who developed ideas about the
solar wind and other phenomena. NASA's science missions are usually named after
dead scientists like Hubble Kepler, Chandra, Spitzer, and so on. But this time
it's different because Parker is still alive! In fact, he just celebrated his
91st birthday on June 10th, and he's about to get the best set of birthday
candles when his probe launches to the Sun. But the Sun is the hardest place in
the solar system to get to. Why is that? Because Earth is traveling at about 30
km/s. That means that in order to drop into the Sun, you'd have to accelerate to
30 km/s in the opposite direction. By comparison, Earth's escape velocity is
only 11 kilometers per second. That means it's easier to get to Pluto than it is
to get to the Sun! So NASA will launch Parker on a Delta 4 heavy lift rocket in
August 2018. After separating from its upper stage, Parker will descend toward a
gravity assist from Venus. Normally, we use gravity assists to accelerate
spacecraft to the outer solar system. But it turns out you can also use gravity
assists to slow down and descend into the inner solar system.
Parker will make seven flybys of Venus
over the next seven years to gradually shrink
its orbit around the Sun, coming as close as 3.9 million miles to the Sun at
perihelion. This is well within the orbit of Mercury, and it's about eight times
closer than any spacecraft has ever gotten to the Sun before.
Let's put it this way: if the distance from the earth to the Sun were shrunk to
the size of a football field, Parker would be just inside the four yard line.
Parker will make one orbit every 88 days, reaching a maximum speed at perihelion
of about four hundred and thirty thousand miles per hour. That's fast
enough to go from Philly to Washington DC in one second! The Sun's corona is
anywhere from one to two million degrees, so Parker needs to use a specially
designed carbon composite heat shield to protect itself. Temperatures on the Sun-facing
side of the shield will reach up to 2500 degrees Fahrenheit, while the
instruments behind the shield will operate at room temperature. So how come
the shield only gets to 2500 degrees? Isn't the corona two million degrees?
Well yes it is, but the corona is about 10 billion times less dense than air, so
only a fraction of its particles will actually hit the shield. Still, Parker
will be subjected to more than 500 times the sun's radiation here on Earth.
That's more than enough to overload at solar panels, so Parker will
automatically retract its panels as it approaches the Sun! However, the tips of
the panels are bent outward ever so slightly, allowing it to catch just
enough sunlight to power the spacecraft. As Parker departs the Sun, the panels
will swing back out to keep things running. The solar panels are also going
to use a gallon of pressurized water to keep them cool, a first for any
spacecraft. For all of this to work, Parker will be a fully autonomous
spacecraft handling its own navigation, aiming its heat shield toward the Sun,
keeping the solar panels at the correct angle, and oh yeah, doing science.
Speaking of which, let's talk about what Parker will do as it buzzes the Sun.
The biggest question about the Sun is why is its corona so much hotter than its surface?
Temperatures suddenly jump from 10,000 degrees at the surface to millions of
degrees in the corona, but why is this? Well, it could be a couple of reasons. It
could be that there are shock waves of plasma rising from the surface and
slamming into the atmosphere releasing their energy as heat. Or it could be a
bunch of tiny solar flares all over the Sun,
and are constantly heating the corona. Or maybe it's some combination of the two,
or perhaps it's neither of these. The second question is what causes the solar
wind? The solar wind is a steady stream of charged particles blowing outward
from the Sun. The solar wind can blow faster or slower depending on where it's
coming from. There's a 1 million kilometer per hour wind coming from the
Sun's equatorial regions. Believe it or not, that's the slow wind! A much faster
wind blows through magnetic poles in the corona's polar regions, and these can
reach speeds of up to 3 million kilometers per hour. And if that wasn't
strange enough, even the compositions of these two winds are different! So why is
the corona so much hotter than the surface, and what's going on with that
solar wind? To answer those questions, Parker is equipped with four science
payloads. The FIELDS experiment will measure the electric and magnetic fields
of the corona. Everything from sunspots to flares to
coronal mass ejections are driven by magnetic activity and it's interaction
with plasma. Getting direct measurements of the magnetic and electric fields will
go a long way toward helping us understand the complex origins of these
phenomena. The integrated science investigation of the Sun or "ISoIS"
will observe energetic electrons protons and heavy ions that are accelerated to
high energies in the corona. These are the same particles that form the solar
wind and can blast Earth's magnetic field during solar storms. The Wide Field
Imager for Solar PRobe, or WISPR, is a set of telescopes and cameras that will
take images of the solar corona and inner heliosphere. WISPR will make
movies of the solar wind shock fronts and other structures as they approach
and pass the spacecraft. In other words, we're going to see the solar wind as it
flies by! How cool is that? Finally, the Solar Wind Electrons Alphas
and Protons, or SWEAP, will count the electrons, protons, and helium ions in the
solar wind, and measure their properties such as velocity, density, and temperature.
Parker is due to launch this August and it's going to be another seven years
before it reaches the Sun and starts getting science data. But it's going to
be worth the wait, and I'm pretty excited about what we're going to learn. So what
are you looking forward to about this mission? What is it about the Sun or
anything else that you would like to know about? Leave a comment below and
I'll be sure to check it out. And if you enjoyed this video please be sure to
give it a thumbs up, subscribe, hit that notification bell, and share this video
with a friend because you'll be making somebody's day (mine!) and helping me to grow
this channel. So thanks for watching, and we'll see you soon!