( intro music )
( radio signal )
( ethereal music )
( audience applause )
Linda: Ten years ago today,
the Cassini spacecraft
flawlessly executed a
nail-biting 96 minute burn
to become the first
man-made object
to go into orbit around Saturn.
And Cassini carried with
it ESA's Huygens Probe,
which we later sent down
to the surface of Titan.
And so we celebrate today
Cassini's ten-year anniversary,
and I'll share
with you just a few
of the amazing findings
that we've made with Cassini.
What we have here is one of my
favorite pictures of
Saturn and the rings.
It's a view that you
won't see from the Earth.
Cassini is high above Saturn's
north pole looking down
and the rings form a giant
bulls-eye around the planet.
And you can actually
see Saturn's shadow
going out across the rings.
Up on the north pole, you see
a greenish six-sided area.
We call this the hexagon.
Very interesting and
intriguing kind of storm.
Saturn is the
second-largest planet
in our solar system.
It only has pretty much
a hydrogen atmosphere,
no solid surface underneath it.
And if you could build a bathtub
big enough to hold Saturn,
Saturn would float.
So how big is Saturn really?
Well if we put the Earth
and the moon to scale,
next to Saturn, along with
the distance between them,
we can see that
Saturn is indeed huge.
In fact, it would take
764 Earths to fill up
the volume of Saturn,
a giant planet, indeed.
Well let's look a
little bit more closely
at that north polar hexagon.
If you look at the
image on your left,
you can see this greenish
area surrounded by
a six-sided jet stream.
Voyager, 30 years ago,
saw this jet stream
with these six sides,
and it's still there today.
It's a very interesting puzzle.
Greenish in color,
that's its winter hemisphere.
As the sun continues
to shine in the north,
we'll see that greenish
color become more of
the golden color we're used
to for Saturn's atmosphere.
Tiny white clouds circle
inside the hexagon.
And Cassini
discovered at the very
center of the hexagon
a giant hurricane.
That hurricane
would span half
the continental United States.
It would go from
Washington, D.C.
to Tulsa, Oklahoma:
a giant storm.
The sun is shining
from the right,
and you can actually
see shadows from
the eyewall of that
giant hurricane.
We study the hexagon and
the hurricane at Saturn
to get a better understanding
of the weather
here on the Earth.
Let's move on to Saturn's rings.
I actually started
working on rings
in the Voyager days.
And so they hold a
special place in my heart.
There's a lot of intricate
detailed structure
inside of the rings.
The rings are made up of
billions upon billions
of icy particles orbiting Saturn
in an intricate cosmic dance.
And every once in a
while these particles
jostle and run into one another.
The rings have
very simple names.
As you go outward, you
can have, you can see
you have the A ring
on your far right.
Then there's a gap,
the very bright B ring,
most of the particles are there.
The particles range in
size from tiny marbles
to giant mountain-sized
particles.
That grayish ring is the C ring,
and then finally the
innermost ring, the D ring.
And at the end of the mission,
Cassini is gonna dive in
between Saturn's D ring
and the top of the atmosphere
for some remarkable
brand new science.
You'll notice that
there's a black gap
in between the A ring
and the B ring.
That's the Cassini division,
named after the
astronomer Cassini,
who first discovered
it, and our mission
is named in honor
of that astronomer.
Well, Cassini had a rare
opportunity in 2009.
We were actually able
to observe the rings
when the Sun was
edge on to them.
And anything that
would cast a shadow
would be visible and seen.
So let's look at the
outer edge of the B ring
and see what
Cassini saw in 2009.
Here's the outer
edge of the B ring,
that bright ring with
all of those structures,
the Cassini division on top.
The Sun is shining
from the top down,
and you can see all
sorts of shadows.
Here are particles that are
one or two miles in size
casting these long shadows
at the edge of the ring.
And the ring itself is
only about 30 feet thick.
A good analogy for how
we see these shadows.
Imagine yourself riding
along on the space station.
You look down on Egypt,
and you want to
find the pyramids.
But if you look at noon,
you won't see any shadows,
and it'll be very
hard to pick them out.
Now imagine that
you look for these
same pyramids at sunset.
And they'll be casting
these long shadows.
And they'll be very easy to see
on the desert in Egypt.
And in the same way,
Cassini for the first time
could see that there were
big particles in the rings
at the outer edge of the B ring.
These objects are
probably made of
agglomerations
of ring particles.
And the way these come
together and coalesce,
give us information
about how the planets
in our solar system
actually came together
and formed as well.
This is a view of
the largest moon
in the Saturn system.
This is giant Titan.
It's 3,000 miles across,
about the size of
the planet Mercury.
A Titan has a liquid water ocean
underneath its icy
crust, and this is one
possible place that
might harbor life.
Titan has a thick
nitrogen atmosphere.
It's about four times as dense
as the atmosphere in this room.
And the surface is a chilly
minus 290 degrees Fahrenheit.
There's also methane in
the atmosphere of Titan,
and that methane at
the top is broken apart
by sunlight, forms these
long smoggy hydrocarbons
and gives Titan that sort
of golden-colored haze.
And we can't really
see through the haze.
And it took ESA's
Huygens Probe
to parachute down through
to the surface of Titan
to give us our first
view of an amazing world.
It turns out that methane
plays the same role
on Titan that water
plays here on the Earth,
with the same kind of weather.
Only now you have
methane clouds.
Methane rain.
Methane flowing through
the river channels,
and methane filling
the lakes and seas.
In fact, if you look at
this image behind me,
that topmost black smudge,
that's Ligeia Mare,
the second-largest sea on Titan.
And if we look up close
at that particular sea,
here's the radar view
with the long wavelengths.
You can penetrate
down through the haze.
You can see the river
channels of methane
flowing into this
particular lake,
and even tiny islands
in this particular sea.
This, this sea Ligeia
Mare is about 50 percent
bigger than Lake Superior
here on the Earth.
And it's about 500 feet deep.
That's something we
found out with Cassini.
And if you take the
seas and you add up
all the hydrocarbons that
are present in the seas,
it turns out there's
about a hundred times
more hydrocarbons
on Titan
than all of the reservoirs
here on the Earth.
It's just too bad
Titan's so far away,
or our hydrocarbon
problems would be solved.
( laughter )
And the seas themselves
are very interesting,
because you wonder,
with liquid methane,
could a form of life
exist that would use
liquid methane,
rather than water,
to form and move about.
So very intriguing to
think about that for Titan.
Now we move on to another world,
another moon around Saturn.
This is Enceladus.
Enceladus is only
about 300 miles across.
So 1/10th the size of Titan.
And what you see here
is an icy white surface
with very few craters.
And the brightness and
the absence of craters
tell us that this is a
very, very young surface.
And Cassini was
the first to see,
at the south pole
you can see these
bluish fractures down
here at the bottom.
We nicknamed them tiger stripes.
They kind of reminded
us of tiger stripes,
and we were really
amazed to see what was
coming out of these tiger
stripes on this tiny moon.
I was amazed as everyone
else when we first
took a look and saw, and
this is in a backlit view,
coming out of those
tiger stripes were jets.
Jets of water
vapor and water ice
with some other
compounds mixed in.
We saw dozens and
dozens of these jets
actively going off.
Some of the tiniest
particles escape
and actually go
on to form a ring
within Enceladus'
orbit, the E ring.
So just so intriguing to see.
In fact, Cassini
actually flew through
those jets and sampled
their composition.
And we found carbon
dioxide, we found ammonia,
we found salts.
We found the kinds
of ingredients
that you'd need to
find to have life.
And it turns out there's
a liquid water ocean
underneath Enceladus' south pole
supplying these jets and vents.
And in a sense we
have free samples.
We just don't know if
there might be life
inside of these free samples.
So we have two worlds:
Titan and Enceladus,
that might possibly have life.
And finally, another
iconic backlit image.
This image was
taken when Cassini
was in Saturn's shadow.
This doesn't happen very
often in the mission.
When we took this
mosaic, that bluish ring
around the outside,
that's the E ring
created by tiny particles
coming from Enceladus.
And if you look
at that white ring
completely around Saturn,
sunlight is refracted
through the atmosphere.
And that's every sunrise
and sunset on Saturn
seen all at the same time.
And there's actually
three other planets
in this image.
If you look at the
upper left there,
Mars and Venus, a little
bit difficult to see.
And if you just look
here, right here,
that tiny pale blue dot
is actually the Earth,
actually the Earth and the moon.
And when, in the 20
minutes we were taking
those pictures of the
Earth and the moon,
we actually asked
people, "Go outside.
Wave at Saturn."
( laughter )
So your photons can
be captured by Cassini
in these pictures of
the Earth and the moon.
And while you're at
it, out there waving,
in fact, how many people
here waved at Saturn
on that particular day?
Well that's great.
Yeah, my husband Tom
and I were out there
waving as well.
And we asked people to take
pictures of themselves,
selfies, and send
us those selfies.
And we took all of those
selfies and we recreated
this Saturn backlit mosaic.
Here it is.
( laughter )
Made up of thousands of selfies.
So we were really happy
to see all of the interest
that the public had,
and we're very grateful
to NASA for continuing to
fund extended missions.
It's been 10 years.
We hope to have
another three years
to our mission as well.
And very recently we
had a naming contest.
We asked people, you
know, we've got this
exciting 22 orbits at
the end of our mission,
help us name those orbits.
And then we got 2,000
different entries,
sorted through those,
and we came up with
the winning entry.
And I'm pleased to present
for the very first time tonight,
the winner of that
naming contest.
Cassini Grand Finale.
( laughter )
So thank you so much
for your contributions.
And that's the name of
the end of our mission.
And I'm gonna be showing
you a short movie
that'll show you
something about
the science we'll be collecting
in the last three years,
including a chance to
see what one of those
orbits look like in
the Grand Finale.
And with Cassini, we
had a rare opportunity
and we seized it.
Now sit back and
enjoy the movie.
( drum music )
Voiceover: Cassini is there
 in the Saturn system now.
 It has been making
 discoveries
 for the last several years,
 and there's more to come.
( drums )
Voiceover: By
 studying the satellites
 in this Saturnian system,
 we begin to understand
 something also about the
 origin of the solar system.
( drums )
Voiceover: There
 is strong evidence now
 that most of the
 surface of Titan
 is in fact covered with
 organic material of some kind.
( drums )
Voiceover: We're
 gonna be looking at
 lakes on the surface
 of this moon in detail.
 We're gonna be looking
 at the atmosphere
 to see how the climate
 changes over time.
Voiceover: We have some
 global circulation models
 that tell us if
 the winds pick up.
 We think there could be waves
on the lakes of liquid methane.
( drums )
Voiceover: Can you
 imagine anybody thinking
 that we would discover
 active cryovolcanism
 on one of these moons?
 Geysers?
Voiceover: One of the
 things that we'll do
 in the next couple of years
 is make the first ever
 flyby through the plume
 when the plume output
 is at its maximum.
Voiceover: And then of course
 there's the planet
 Saturn itself.
 As we go through
 our series of orbits
 and as the seasons change,
 it's like having
 a brand new mission.
Voiceover: One Saturn year
 is nearly 30 Earth years.
 To be there for nearly
 half of a Saturn year,
 is a once-in-a-lifetime
 opportunity.
Voiceover: The
 sun now is coming up
 on the north pole.
 So we're getting
 to see territory
 that was darkness when
 we first arrived in 2004.
 Pretty soon we'll
 have the whole hexagon
 and the hurricane inside of
 it illuminated by the sun.
 And then of course the
 mission's end itself
 is completely unique.
Voiceover: Starting
 in 2016, ending in 2017,
 these orbits will
 take us up and over
 the north and south
 poles of the planet.
Voiceover: We're
 actually going
 to dive in between the
 innermost edge of the D ring
 and the upper atmosphere
 of the planet itself.
Voiceover: From
 that we're gonna learn
 how is Saturn constructed
 from inside out.
Voiceover: We'll also
 get the magnetic field
 of the planet, the
 mass of the rings
 for the very first time,
 and get to sample a
 place that no spacecraft
 has ever flown before.
Voiceover: This is a mission
 that cannot be duplicated.
 So we really want to
 take advantage of this
 opportunity to observe
 seasonal variation
 in the system.
( bold orchestra music )
( applause )
( outro music )
