LESLIE: Good afternoon,
ladies and gentlemen.
Today we're privileged to have
with us Dr. Carolyn Porco, who
is the leader of the Imaging
Science Team
on the Cassini Mission.
And she is also an imaging
scientist for the New Horizons
Mission, which is also a post
that she held as well for the
Voyager Mission.
She's received her doctorate
degree from the California
Institute of Technology in the
Division of Geological and
Planetary Sciences, and she's a
tenured faculty member with
the University of Arizona.
She's the editor and creator
of the Cassini Team CICLOPS
website, which is where you
can view images from the
Cassini Mission.
And she's also the CEO of
Diamond Sky Productions, a
small company dedicated the
artful and useful use of
planetary images.
Asteroid number 7,231 is named
in her honor, and she's
responsible for sending the
remains of renowned planetary
geologist, Eugene Schumacher,
to the moon.
Please join me in welcoming
Dr. Porco.
DR. CAROLYN PORCO: Thank
you very much.
Is there any way we can lower
the lights in this room
because the pictures will look
so much better if the lights
can be lowered.
Thank you, Leslie, for
that introduction.
I just want to say, ever since
the TED conference--
I don't know if you guys know
about the TED conference.
You must, because it sort of
happens in your backyard,
where I met Larry and Sergey,
and I got invited to come to
give a talk here.
I've been really looking forward
to coming here, and
this place is kind
of legendary.
The cafes are legendary, and
I've now sampled the cafes.
I know what that's all about.
And there's something I know is
going to be legendary soon,
and I just sampled it, but
I never knew about it.
And that is your heated
toilet seats.
You do realize the rest of the
world doesn't live like that.
OK, and I can tell you that's
one perk you're not going to
find at NASA.
So anyway, it's a thrill.
It's even more of a thrill than
I thought to be here.
I feel that I have lived a
charmed existence to have
grown up during a
time when I did.
I was a young girl when
our country became
a spacefaring nation.
And images from the moon, and
Venus, and Mars were being
sent back to Earth and being
published in the newspapers of
New York, which is
where I grew up.
I was a teenager when Neil
Armstrong first walked on the
moon in 1969.
I was a young graduate student
when the Viking Spacecraft
landed on Mars in 1976.
And I was a senior graduate
student when the Voyager
Spacecraft first flew by Saturn
in the early 1980s.
A newly minted PhD, I became
part of the Voyager Imaging
Team in 1984, '83 and
participated in our first
reconnaissance of the planets
Uranus and Neptune.
And now I'm extraordinarily
privileged to be part of one
of the most dazzling
interplanetary endeavors we
have ever undertaken.
And I've got, as far as I'm
concerned, the best job in the
whole inner solar system.
I am the leader of the Imaging
Team on Cassini.
We are responsible for taking
all those lovely images of
Saturn that you've seen over
the last several years.
And these missions of
exploration that humankind has
been undertaking for the last
50 years, I think you would
agree, are all part of a much
larger human quest, or human
voyage, to come to understand
something about our origins,
and how our planet, we living
on it, came to be.
And one of the most promising
places we could hope to
explore in our solar system, an
answer to those questions,
is the Saturn system.
Because Saturn with its complex
systems, subsystems,
if you will, of atmosphere,
magnetosphere, rings, and
moons all interacting provides
the ideal destination for
studying many of the same
physical processes that
planetary scientists today
believe were responsible for
the formation of the solar
system, and are responsible
and ongoing today for the
present day dynamics of our
solar system and solar systems
around other stars that are
being discovered
in our galaxy.
So aside from offering splendor
and beauty beyond
compare, Saturn is one planetary
system whose
exploration offers enormous
cosmic reach.
We, of course, had been to
Saturn with the Pioneer
Spacecraft in the voyages in
the early 1980s, but our
investigation of this planetary
system began in
exquisite detail when in the
summer of 2004, the Cassini
Spacecraft flawlessly glided
into orbit around Saturn and
became, at that point, the
farthest robotic outpost that
humanity had ever established
around the sun.
And for me, our return to this
particular planetary system is
not only part of, but also a
metaphor, for that grander
human voyage to come
to understand the
interconnectedness of everything
surrounding us.
So I'm thrilled to be able to
tell you this afternoon, to
show you how this particular leg
of this voyage, this grand
voyage, through the Saturn
system, as Cassini is
revealing it to us, is how
Saturn and everything around
it has been shown to us over
the last 1,000 days that
Cassini has been in orbit.
And to give you a sense, and a
decidedly visual one at that,
for how this very major
exploratory expedition that
Cassini, and we, are presently
conducting around Saturn is
unfolding
The first obvious example of
cosmic reach, of course, of
Saturn's rings, they're the
reason why Saturn is the icon.
It is among planets in
our solar system.
The rings are a tremendous
visual spectacle.
They are 280,000 kilometers
across.
That is about one
light second.
They would fit in nicely
between the
Earth and the moon.
And they consist of countless
orbiting bodies.
This is ice particles ranging
in size from the finest snow
you might ski on in Utah, all
the way to the sizes of small
apartment buildings, screaming
around Saturn at tens of
thousands of miles per hour yet
only very gently jostling
each other.
They only collide, if and when
they do, at a few millimeters
per second.
They are what physicists call
a very equillibrated system.
Any violent collisions
in the system died
out a long time ago.
And because of that, they
are tremendously thin.
They're only one, two,
three stories in
a modern day building.
They're paper thin.
They're very mathematically
precise.
They trace out the plane, have
gravitational equilibrium
around the planet.
And despite their visual
enormity, they contain, in
fact, comparatively speaking,
very little mass.
If you took all the mass in
Saturn's rings and recomposed
it back into a small moon of the
proper density, it would
be no bigger than this little
moon here, Enceladus, so a lot
of visual display for
very little mass.
Is there a laser pointer I can
get a hold of, somebody?
OK, the processes that are
ongoing in this disk--
OK, thank you.
There's 47 buttons on this.
I hope I hit the right one.
By the way, these are the
shadows of the rings cast on
the northern hemisphere
of the planet.
And the processes that are
ongoing in this disk of
material are believed to be
similar or identical to the
ones that went on in the nebula
from which the sun and
the planets form-- this is shown
here in this artist's
rendition--
and in disks that we are
presently seeing
around other stars.
This is a Hubble Space Telescope
picture of a
protostellar disk around a
very young M-dwarf star.
And then reaching a trillion
times larger, the same
processes we see going on in
Saturn's rings occur in the
disks of dust, and gas,
and stars that
are the spiral galaxies.
So there is a great deal to be
learned in studying Saturn's
rings about disk systems all
throughout the cosmos.
And in this sense, what we are
learning, and hope to learn
further with Cassini,
is truly universal.
The rings exhibit an enormous
variety of structure
discovered a long time
ago when the
Voyagers first flew by.
We didn't understand where
most of it came from, and
we're only now getting glimmers
of it with Cassini.
They break down, some of you may
already know, into three
main elements.
This is the A, the B,
and the C ring.
The B ring is the
most massive.
It's the densest. It casts the
deepest, darkest shadows on
the planet.
It's where a lot of this
structure is that we are
having a hard time
understanding.
The A ring is a little
bit more transparent.
It's punctuated by
gravity-driven features that
are driven by the gravity
of orbiting moons.
And then here is the C ring,
which is very diaphonous, and
is actually populated
by these very
sharp-edged plateaus of material.
Again, we don't know exactly
why, we don't know, in fact,
at all why those plateaus
exist. And so the subtle
colorations you see here are
due to the contamination of
basically what is water
ice by very small
amounts of other materials.
And we're in the process
of working out what the
composition of that
material is.
So Saturn is, as you know,
very far away.
It's ten times farther
away from the sun
than the Earth is.
And the Cassini Spacecraft at
launch was very massive.
It was six metric tons.
And even launching Cassini on
the largest launch vehicle
that we had at the time, which
was a Titan IV, adding solid
rocket motors to it, strapping
those on, and putting Cassini
on top of the Centaur upper
stage-- this was about as much
power as we could throw at the
thing-- that still wasn't
enough to get Cassini,
because it was so
massive, directly to Saturn.
So we had to loop it around the
inner solar system twice.
We had to send it
by Venus twice.
We had to send it by
the Earth once.
And then finally on the eve of
the year 2001, which I thought
was tremendously poetic, we sent
it by Jupiter for a final
push on to Saturn.
Now understand that the object
of this exercise is to get the
spacecraft to its target as
quickly as possible so that
those of us who are involved in
the mission are still alive
by the time the spacecraft
gets there.
But that means that by
the time it gets
there, it is hauling.
And we actually have to slow it
down in order to allow it
to get captured into
Saturn orbit.
And that was done in a 19-minute
maneuver, shown here
in an artist's depiction, where
we basically threw the
engines in reverse.
Actually we didn't do that.
We just turned the spacecraft
around.
Half of the mass at launch of
Cassini was fuel that was
burned in this maneuver
to slow it down.
We didn't slow the speed down.
We actually slowed the
acceleration down to allow it
to get captured into orbit.
And so this maneuver brought us
closer to the rings than we
had ever been before, will ever
get again, very likely
never be as close as we were
during this maneuver ever
again in the course
of the mission.
And so the scientists for years
were clamoring to be
allowed this opportunity to
take data when we were
cruising over the rings.
And that's, in fact,
what we did.
We collected a beautiful
collection of images of the
highest resolution we've
ever had on the rings.
And we saw many things.
I don't have the time to
show you all of them.
One thing we saw a
lot of was waves.
In this picture, the smallest
thing you could see, the
tiniest little pixel there, is
only a couple of several
hundred meters, so just several
football fields, OK.
These are waves.
These are the fingerprints of
orbiting moons that are
perturbing the ring particles.
You see here, something called
the density wave. This is
where the perturbed non-circular
orbits of the
ring particles are all phased in
such a way as to give rise
to these regions of higher than
average concentrations of
particles which, in fact,
spiral all the
way around the planet.
These are spiral
density waves.
We're looking, incidentally, on
the dark side of the rings.
So what you see here as dark is
actually bright, if you saw
it on the lit side.
So the highest concentration
here are the dark regions.
They spiral around the planet.
These are the kissing cousins
of the spiral
arms you see in galaxies.
Same mathematics was co-opted
from galactic structure, the
physics of galactic structure,
and applied to Saturn's rings
to, in fact, predict that when
Voyager got there in the early
1980s, it would find
these features.
And, in fact, it did.
With Cassini, we got just
a very much better look.
These are bending waves.
These are the vertical
equivalent of density waves.
This is where it's not the
eccentricities of the orbits
that are perturbed, it's
the inclinations.
And so this is a feature
where there are crests.
This is like corrugated
cardboard.
The whole ring plane is warped
like corrugated cardboard, and
the crests spiral around
the planet.
OK, again, these are due to the
perturbations of orbiting moons.
This was on the dark side.
When we crossed over the rings
and passed on to the lit side
and then turned around and
looked up at the rings as we
were receding, we saw these
kinds of things.
Lower resolution picture by
about a factor of three, but
still, you could see lots
of waves, lots of waves.
You even see this thing,
corduroy structure.
This is the perturbations of
a moon orbiting, actually,
within the rings.
So lots of phenomena we
got a very good look
at with these pictures.
And one thing, one remarkable
and very telling discovery we
made in this collection of
images, are these little
propeller features.
OK, these are the beginnings of
gaps that are being made in
the rings by bigger than
average particles.
They're about several kilometers
across, a few
hundred meters wide.
The pixel scale here is the
highest it ever got for us.
This is like a half a football
field per pixel.
And so from the dimensions of
these features, we can tell
the size of the bodies
that are making
these incipient gaps.
And they look to be something
like 20 to 60 meters in
radius, so that is a little
bit bigger, several times
bigger, than the largest
particle size.
OK, and this one observation has
given us insight into the
particle size distribution in
the rings and also will
eventually tell us something
about the
way the rings evolved.
But there are even bigger
bodies that are embedded
within the rings, of course,
and they're having dramatic
and more obvious effects
on the rings.
This is the A ring.
This is the famous F ring that
is shepherded by two
shepherding satellites called
Prometheus and Pandora.
This gap is called
the Encke gap.
Keep this gap in mind.
This is called the Keller gap.
I'll show you this later.
This gap is about 300
kilometers wide.
It is inhabited by a
moon called Pan.
These, by the way, are all those
density waves that are
created by other moons
orbiting Saturn.
The next picture is going to
show you a high resolution
view of this that we got
during the Saturn Orbit
Insertion Maneuver.
And there you see it.
It's so beautiful, it looks
simulated, but it's actually a
real image.
There are ringlets
in this gap.
Remember this is 300 hundred
kilometers wide.
These are waves in the edges of
the gap that are created by
the perturbations of Pan.
It excites eccentricities
in the orbits of the
particles in the rings.
And those eccentricities, again,
they're all properly
phased that they give rise
to this pattern.
You can see the streamers
spiraling away from this edge,
also again the perturbed and
phased motions of particles.
And here is a view we
got later on in
the mission of Pan.
This is the culprit.
This satellite is about
30 kilometers across.
The rings are only a few tens
of meters so you can see it
protruding up and down.
It's a beautiful picture.
It was very thrilling
to finally get a
closer view of Pan.
We also looked closely at the
Keeler gap, which is 42
kilometers across, and we
discovered Daphnis.
This is a little moon, only
eight kilometers across.
It's doing the same thing
on the edges of its gap.
It's raising waves.
And the study of these systems,
a moon in a gap in a
disk of material--
though I should say these
systems provide the best
analogs we have available to us
in our solar system for the
systems that are being
discovered
nowadays, every day.
That is growing planets or
protoplanets in disks around
of the stars.
And the study of the manner in
which these bodies, like Pan
or Daphnis, open up the gap
in their disk and keep the
material at bay through their
gravitational interactions is
going to prove very fruitful
for the study, or for
investigations, concerning
planet formation,
understanding how, for example,
Jupiter, a planet
like Jupiter, growing out of
the solar nebula, accreting
material little by little,
getting bigger and bigger,
finally comes to get so big, it
truncates its own growth by
opening up a gap.
Now one of our main objectives
was also to determine the
physical characteristics of
moons that were orbiting near
the rings and also the physical
characteristics of
any moons that we might
discover, because we were
suspecting that their physical
characteristics would tell us
something about their origins.
And that's, in fact, exactly
what we've done.
This work has gone on in my
group in Boulder, Colorado.
And let me first pause here
and tell you our general
notions about how rings come
about, in case you don't know.
The common wisdom says that
there was a body, very likely
a pre-existing moon in orbit
around Saturn that got bashed
up by an incoming projectile.
And that material eventually
spread out to form a ring.
It's just a simple, predictable,
physical process.
It spreads out the
former ring.
There are collisions.
The collisions are
very elastic.
They grind down the particles,
but they also flatten the
system into a ring, OK, a ring
that, as I said, inhabits the
equator plane of the planet.
OK, another idea is that the
pregenitor body that forms the
rings maybe came in from afar.
Maybe it was a body that came
in from the Kuiper Belt.
But anyway, the idea is, a
catastrophic destruction of a
pre-existing body, material gets
swept up in and circles
the planet.
Well over the last three years,
we've accumulated
enough information on the ring
moons, like Pan, like Daphnis,
and also like Atlas.
This is a body orbiting
outside the outer
edge of the A ring.
This is the Keeler gap.
This also is about the size of
Pan, 30 kilometers across,
looks like a flying saucer.
And also, Pandora, this is
bigger, 81 kilometers across.
This is one of the F
Ring shepherds, OK.
We have now information on the
sizes, the shapes, the orbits
of these bodies, even their
masses and their densities.
And putting all this together,
we have found that these
bodies are shaped like you would
expect for a body formed
by accretion.
So in and of themselves, they
are not the remnants of this
collision that form the rings,
but we think, instead, that
they have grown around
a denser core.
And that denser core may be
something that dates all the
way back to the original
creation of the rings.
So we're getting glimpses of
the chronology of events in
the Saturn ring-moon system
from Cassini so far.
And speaking of moons, Saturn is
accompanied by a very large
and diverse collection
of them now.
There's something
like 57 moons.
There may even be more,
because I only looked
about a month ago.
They are being discovered
all the time.
They range in size from a few
kilometers across to Titan,
which is Saturn's
largest moon.
It's as big across as the US.
And it's the inner collection of
moons, which go out to only
a few million kilometers
from Saturn.
That is the system that's being
investigated by Cassini.
And this system is of particular
interest because it
is believed because these moons
are all in orbit in the
same plane, they're all orbiting
in the same direction
around a big massive central
body, they are like a
miniature solar system.
And so our goals in studying the
Saturn satellite system,
this particular component of it,
were not only to come away
with accurate measures of their
compositions and their
physical characteristics,
not only to further our
understanding of their
geological histories and their
thermal histories and so on but
also to study the system
as a whole with an eye towards
testing our ideas about
planetary formation, both the
formation of our own planet,
and others we are discovering
today.
Now the Cassini tour through
the Saturn system is
unprecedented.
It's enormous in magnitude,
calls for 82 close satellite
flybys within four years.
All of them are closer than the
flybys that were conducted
by Voyager.
44 of those are of
Titan alone.
And the remainder of them were
flybys of this handful of
medium-size moons that are, as
I said, within a few million
kilometers of Saturn.
And some of these flybys
were exquisitely close.
They flew as close to these
moons as the Space Station
flies above the Earth.
And most of these exquisitely
close flybys were conducted in
the year 2005.
I call that the Year
of the Moon.
That's when we came up close and
personal to all of these
and have discovered some
remarkable things about their
geologies and physical
characteristics.
And we certainly, if you've been
paying attention, seen
that we return some
fantastic images.
This is Tethys, a moon that's
about 1,000 kilometers across.
That's about 600 hundred miles,
sports some amazing
basins on its surface.
Here it's shown with the rings
in the background, one of our
beautiful images.
This is Rhea, 50% bigger
than Tethys, so
1,500 kilometers across.
That's about 1,000 miles, OK.
So we're talking about something
maybe the size of
the Southwest US.
This is Rhea hiding
behind the rings.
This is one of our beautiful
pictures of Dione.
This is about the size of
Tethys, again about 1,000
kilometers across seen against
the glow of Saturn with the
rings in the foreground.
Here's another view of Dione,
OK, taken at very high phase
angle as the sun was either
rising or setting.
I don't remember.
And here's a close up of that.
OK, now I don't know
about you but this
calls out for an astronaut.
Doesn't it?
Don't you want to see an
astronaut walking across the
surface of that?
Actually you wouldn't be able
to resolve an astronaut
because the smallest pixel here
is about 100 meters, so
that's about a football
field across.
This is actually a very big,
very large crater.
And then here's our Death Star
moon, Mimas, OK, two and a
half times smaller than Dione.
And then smaller again, about
two times smaller than, or
half the size of Mimas, is
Hyperion, looking like a great
cosmic sponge.
And then finally, I'm going
to show you Iapetus.
Iapetus is a moon that's half
the size of our moon.
It's about the size
of Rhea, 1,500,
1,400 kilometers across.
And we have found some fantastic
geology on Iapetus,
as you can see.
This is the moon that's half
black on one side, half white
on the other, half
black and white.
And here you can see this
amazing landslide at the
bottom of a 15 kilometer
high cliff.
OK, so it's not out of the
question in my mind that some
day your descendants might be
taking extreme excursions into
the Saturn system and
ice climbing on
the cliffs of Iapetus.
And I envy them.
I should say that all of
these moons are made
out of water ice.
That's the most abundant
material in the Saturn system,
in the satellite system.
And water at these
temperatures is a
rock-forming mineral.
So they're mostly water ice.
All you have to do is look at
the cratered surface of these
bodies to know that there was
a time many, many years ago,
in the early history of the
solar system, when there were
a great many bodies careening
around the solar system and
smashing headlong into the
planets and forming satellites
at tremendous speeds.
And these collisions did a great
deal to actually build
our solar system and make it
look like it does today.
They were responsible for
allowing the planets, first
and foremost, to grow to
their present size.
It was cometesmal, small
comet-like bodies that made up
Uranus and Neptune,
for example.
It was a collision that was
responsible for tilting Uranus
on its side.
It was a collision with a
Mars-sized object that
actually created our moon.
Soon after the Earth formed,
a Mars-size object came and
collided with the earth and
pulverized the outer layer,
throwing it into space, from
whence that material
collected, and the
moon formed.
And as I showed you, collisions
are responsible for
smashing up satellites and
creating ring systems.
So collisions, in fact, are the
creators of worlds, and
they are the destroyers
of worlds.
And don't forget, it was a
collision that wiped out the
dinosaurs and cleared the way
for the eventual development
and evolution of the primates,
of which we like to think that
humans are the culmination.
Or put it another way, it would
been very hard to invent
Google with a Tyrannosaurus rex
breathing down your neck.
So collisions have actually
done a great deal for us.
And they have been a tremendous
process of force in
sculpting the solar system.
And the craters that they create
on the surfaces of
these bodies can actually
be studied and examined.
Their morphologies can be
examined to give us
information about the properties
of the material
into which they've
been placed.
And to understand something of
a chronology of events in the
Saturn system.
If you look at the distribution
of craters, and
you know something about the
projectiles population, you
can say something about the
order of events, that things
happened in the system.
I don't have the time to go
through all that we are
learning about that right now,
but I am going to concentrate
on two moons in particular which
have stood out over the
last 1,000 days.
And they are Titan, which is
Saturn's largest moon, about
50% larger than our moon.
And then Enceladus, which is
a tenth the size of Titan.
Now Titan has long intrigued
planetary scientists.
And before Cassini arrived
there, it was the greatest
single expanse of unexplored
terrain that we have left in
our solar system and was
believed to be, in many
respects, more like
its environment.
Surface environment was believed
to be more like the
Earth's than any other that we
have in the solar system.
Like the Earth's, its atmosphere
is very thick, and
it consists largely of
molecular nitrogen.
Like the Earth, its thermal
structure consists of a
troposphere, where the
temperature decreases as you
go up, And then a stratosphere,
where you turn
around, and the temperature
increases as
you go further up.
Like Earth's, its atmosphere has
a mild greenhouse effect
near the surface.
So its surface is some twenty
degrees warmer than it would
be otherwise.
But its atmosphere lacks free
oxygen, and it is suffused
with small but significant
amounts of methane, and
ethane, and propane, and other
simple organic materials
containing hydrogen carbon,
which we called hydrocarbons.
And for all these reasons,
Titan's atmosphere was
believed to be an analog, or at
least the closest analog we
would ever find in our solar
system to the atmosphere that
scientists believe existed on
the surface of the Earth prior
to the emergence of life.
And that's not all.
The compounds, the organic
materials in the atmosphere
form a ubiquitous haze that is
formed, by the way, from the
break up of methane high in the
atmosphere, separating the
carbon and hydrogens.
The carbons join together.
They create these polymers,
which end
up being haze particles.
Those haze particles,
it was suspected,
would grow over time.
And they would fall
over the years.
Over billions of years, they
would fall, or at least as
long as Titan had an atmosphere,
would fall down to
the surface and possibly
coat the surface
with an organic sludge.
OK, and some of these compounds,
methane and ethane
in particular, could be liquid
at the surface of Titan
despite the unimaginable cold
of minus 300 degrees
Fahrenheit.
In fact, what water does on
Earth, methane does on Titan.
It can be in the form of a
solid, a liquid, or a vapor.
So all of this opened up a
world, literally, of bizarre
possibilities.
First of all, you have hundreds
of kilometers of
globe-enveloping haze, OK,
surrounding Titan,
making its days dark.
High noon on Titan is as dark as
deep Earth twilight is here
on the Earth.
We could have patchy
methane clouds
floating above the surface.
And in places, we might have
rain, gentle methane rains
falling slowly because the
gravity is less than it is
here on Earth.
And these rains over time
could cut gullies.
They could form deep canyons.
They could form rivers, and
cataracts, and cut canyons,
and wash the sludge, perhaps,
off the high mountains, and
into having the drain into
low-lying basins and craters.
So stop and imagine this
environment for a while.
You're standing on
Titan, a moon in
the outer solar system.
You're standing on an icy
surface, a water ice surface.
It's very dark.
It's broad daylight,
but it's dark.
It's cold, impossibly cold.
It's misty.
And before you lies
Lake Michigan
brimming with paint thinner.
That is what we thought existed
under the clouds,
under the haze of Titan before
Cassini got there.
So it was with tremendous
anticipation that we looked
forward to Cassini's exploration
of Titan.
And what we have, in fact,
found on Titan, though
different in detail, is every
bit as fascinating as the
story that I just described
to you.
And for those of us involved
in this mission, it's been
like a Jules Verne adventure
come true.
Titan's atmosphere is,
in fact, very thick.
You can clearly and beautifully
see that in this
image that is backlit
by the sun.
And you can see the rings in
another moon in the background
in just one of another of our
tremendously gorgeous images
that we're taking around
Saturn right now.
But despite the haze and the
impenetrable atmosphere, we do
have instruments on
Cassini that can
see down to the surface.
We outfitted our cameras with
filters that allow us to see
in the near infrared through
spectral channels that
actually allow light to
penetrate through the
atmosphere.
And also, there is a radar
instrument on Cassini, which
is virtually identical to the
instrument that mapped the
surface of Venus with the
Magellan Spacecraft in the
early 1990's.
And with all of these, we have
finally been able to
reconnoiter the surface of
Titan, if you will, and open
up this previously unexplored
terrain to view.
And here's what we first saw of
the surface of Titan from
the Cassini orbiter.
First, you can see bright,
and you can see dark, OK.
And that's what it looked
like to us, not
exactly easy to interpret.
For a planetary geologist to
look at an image like this,
the first thing they see
is something linear.
This looks linear.
This looks basically linear.
That says tectonics.
There is something there that's
cracking the surface in
a linear fashion, like the
San Andreas fault, OK.
We looked on the other side
of Titan, This is a higher
resolution view of the same
thing I just showed you.
So we see circular things.
We don't see too many
circular things, OK.
Circular thing are craters,
we think, maybe craters.
Maybe they're calderas,
Maybe they're
volcanoes, not really sure.
This looks like a caldera.
We see things that look
like they flowed.
We see what we called pull apart
features, things that
looked tectonically
ripped apart, but
very hard to interpret.
We do see black.
We do see white.
Then we look at the other
side of Titan.
We see again bright and dark.
Even though we weren't quite
sure what we were talking
about, we started to call these
things islands, because
they looked like islands.
But we didn't know.
Were they regions that were
higher than the surroundings?
Were they lower than
the surroundings?
We had no clue.
It's always a hazy
day on Titan, OK.
So there's no shadows.
Without shadows, it is very
difficult to tell what's up
and what's down.
And so that left us really
bereft of definitive
explanations.
And there was nothing that was
so unambiguous, so clearly a
feature or a pattern that we
had seen on Earth that we
could say ah we understand
this.
We were really at
a loss to know.
But we did see, again, on this
side, we saw some things that
look like craters.
And again, I said we called
these things islands.
We got to calling this
Great Britain.
This was Ireland.
This was France.
This was Iberia.
This was Peloponnese.
The geography is not
quite right, but it
didn't bother us.
We saw things that looked like
they were wind swept, OK, but
not much else we could see.
But then a remarkable
event happened.
And it was one that we knew
would be the Rosetta Stone and
help us interpret our
images that we
were taking from orbit.
And that was about six months
after getting into Saturn
orbit came what many regard as
the highlight of Cassini's
explorations of Titan.
A flying saucer-shaped device,
which had been carried by
Cassini for seven years, was
deployed to the Titan
atmosphere.
And successfully drifted on a
piece of fabric for two and a
half hours through the hazy
atmosphere and came to land on
its surface.
This was that the deployment and
a mission of the Huygens
probe, the European-built
Huygens probe.
And this I can tell you was
a positively extraordinary
achievement.
And for those of us in
Darmstadt, Germany at the
European Space Operations
Center, where this event was
monitored, it was a very
emotional event.
It was the day that humans had
landed a device of their own
making in the outer
solar system.
It was like living
science fiction.
And I've come to call this a
grown men crying kind of day,
because grown men were
disappearing into corners to
have their own little private
moments during this event, so
that they wouldn't get busted
by their colleagues, being
seen losing it because of the
overwhelming emotion of the
whole event.
And it was, to me, an event that
was so significant, it
should have been celebrated with
ticker tape parades in
every city across the US and
Europe, and unfortunately that
didn't happen.
But it was extraordinary
for another reason.
And that's because the
celebratory presentations
during this event were given
in just a host of accents.
English was used, but they were
given in English accents,
in American accents, in French
accents, and Dutch, and
Italian, and German accents.
It was, in fact, for me, a
moving demonstration of what
the words United Nations
is supposed to mean.
And that is a group of nations
joined in a common cause.
And in this case, it was a
massive undertaking to explore
a planetary system that for all
of human history had been
unreachable.
And now humans had touched
it with something
of their own making.
It was a very remarkable and
historical day, and certainly
a day that I'm not
likely to forget.
I don't think anyone there
will forget it.
But anyway, I digress.
The probe took many measurements
of the atmosphere
on its two and a half hour
descent down to the surface,
including panoramic images.
And it's hard to describe what
it was like to see those first
images that were released for
public consumption, because it
was a shock.
And this is what we saw, OK.
This is a mosaic, in fact, of
images that were taken as the
probe descended.
And we saw this region
here, OK.
And it was shockingly
easy to interpret.
It was, as you can see, drainage
pattern that could
only be produced by
a flowing liquid.
In fact, you can follow the
channels in this drainage
pattern, and they actually move
away from this boundary,
and go down here, and
join this tributary.
And they all drain into this
region right here.
OK, we know from stereo images
taken during this descent,
you're looking at something
here that's high.
This is about a hundred meters
higher than this area.
The next picture is just-- this
by the way is taken at
1600 kilometers up.
This picture is taken it eight
kilometers up, OK.
You're looking at a shoreline,
OK, we weren't sure, at this
point, was this liquid, OK.
But you're looking at something
that looks like a
shoreline, OK, and islands,
offshore islands.
OK, bear in mind, 16 kilometers,
8 kilometers,
that's roughly airliner
altitude.
If you were going to take to
get in an airplane and fly
from San Francisco to New York,
you would be flying at
something like 12, 11 or
12 kilometers altitude.
OK, so this is the view you
would have out the window of
Titanian Airlines as you flew
across the surface of Titan.
And maybe, someday, someone will
actually get the chance
to do that.
And then here, finally, is the
picture that we collected on
the surface, the Huygens probe
took once it landed.
OK, you can see the horizon
in the background.
You could see boulders
in the front.
But they look big.
But they're actually no
bigger than about
6, 12 inches across.
So they're like stones,
almost certainly made
out of water ice.
These are, again, stones
or pebbles.
They look very well sorted.
The idea is that probably some
liquid flowed across this
surface at one time and sorted
all these stones and pebbles.
But the probe landed
not in liquid.
It landed in what is the
equivalent of a Titan mudflat,
an unconsolidated ground that
is suffused with liquid
methane and very likely made
of the accumulation of the
organic matter that I told you
falls out of the sky and
probably accumulated in low
lying depressions on the
surface, very much like what
had been expected.
So all told, the Huygens Mission
was a glorious success
and a triumph and gave us the
kind of ground truth that
helped us, and is helping us
still, interpret our images
from orbit.
But still at this point, this
was early 2005, there were no
open bodies of liquid.
We thought we'd find lots of
liquid on the surface.
No open bodies of liquid to
be seen anywhere, not from
Huygens and not from
the orbiter.
And still, of course, the
exploration of Titan continued
from orbit.
We continued to take pictures.
And the radar instrument
continued to take its data.
And it discovered another
unambiguous pattern in the
equatorial region of Titan.
It discovered that
vast regions were
covered with dunes.
These dunes are 100
meters high.
They're several kilometers
across.
They go on for hundreds
and hundreds of miles.
There's a region that fifteen
hundred kilometers worth of
surface areas extent around the
equator is covered with
these dunes.
OK, this is an enormous
geological feature on the
surface of Titan.
And it indicates steady
bi-directional flow of wind,
or else you wouldn't get
dunes like this.
And obviously conditions
that are dry
enough to loft particles.
That's how you create dunes,
so not only no bodies of
liquid, very dry conditions.
So a great puzzle, we didn't
see any liquid.
We're still looking for it.
Finally, Cassini got to
investigate the polar regions.
This picture was taken of
the south polar region.
That's what this
cross is here.
And this was the closest we got
at this point to something
that looked like a lake, OK.
It has a shoreline that looks
like it could be a lake, a
very dark material inside.
OK, if you fly over Minnesota
and look down at the lakes,
they look black, OK.
So we thought this was probably
the closest we'd come
to a lake feature.
We thought this region here was
dotted, maybe, with lakes.
This was like a lake district.
Actually this is, in
absolute size, the
size of Lake Victoria.
But if you scale it, relative to
the surface area of Titan,
which is much smaller, it's
more like the size of the
Black Sea on the Earth.
OK, so this is what we saw in
the south polar region, but we
didn't have any definitive
evidence that this was liquid.
It could easily have been argued
this is just a residue.
Maybe there was liquid
there at one point.
It evaporated.
This is the residue that's
left behind.
We didn't have any definitive
evidence.
And then we looked in the north
polar region just this
past February.
And this is what we saw.
This is our imaging data.
And you could see
these regions.
This is a cloud feature.
You could see these
dark areas here.
OK, they look, again, like
features we saw in the south.
One of them is very large.
In fact, if you scale
it as large as the
Mediterranean Sea--
and then the radar got images
that overlap, and they are
interpreting these dark areas
to be liquid because they're
the darkest things that they
see with the radar data.
So you are looking here at where
it appears the liquids
have gone on Titan.
These are hydrocarbons,
we think.
You could see some of these
shorelines look like
the coast of Maine.
And not only do we see big
areas, lots of big bodies, but
we see also a region that has
smaller features in it that
look like the lake district
that we saw in the south.
And here we're cruising over
the radar data here.
And this is the pole.
So it appears that the liquid on
Titan, at least during the
present season, which is
southern summer, northern
winter, have migrated
to the poles.
And why that should be the case,
we don't know, probably
says something significant
though about the
meteorology of Titan.
But all told, we have found on
Titan, I think you would
agree, a very remarkable and
even mystical place, one that
is exotic and alien, but also
strangely Earth-like in its
geological formations and
processes, and just a
fascinating place whose geologic
diversity, and
complexity, and richness is
rivaled by no other body in
the solar system except
the Earth itself.
And we will see more of Titan in
the next 1,000 days of the
Cassini mission.
But now in this tale of two
moons that I'm telling you, we
move on to Enceladus.
And Enceladus is very much
smaller, a tenth the size of
Titan, very bright very white,
in fact the brightest, whitest
object we have in our
solar system.
It's no bigger than England,
or Great Britain.
And I don't mean this to be
a threat, just for size
comparison.
But despite its size, what we
have found on Enceladus with
Cassini has completely
thrown us for a loop.
First, from a close examination
of its surface,
and I'm going to show you
a picture now where the
resolution is ten times better
than it is here.
We can see a surface that
doesn't look at all like the
heavily cratered surfaces
of the other moons.
This is a body that has
obviously been geologically
active in the past. It is
crisscrossed by tectonic
fractures at wild angles.
Many generations of cracks, and
troughs, and ridges, and
so on, very deep chasms,
mountain folds, and so on, a
few craters here and there but
otherwise a very young, very
geologically active place.
And the mother lode of all the
discoveries that we have made
on Enceladus, far and away, were
found at the south pole.
And you're looking
here, this is the
south pole of Enceladus.
It is circumscribed by these
mountain folds and
characterized or crossed by
these very deep fractures.
They're about a 135 kilometers
across, just a
few kilometers wide.
This whole region is youthful.
There's no craters, obviously
does have tectonic features
and folds in it.
It is characterized by elevated
temperatures.
This whole region is warmer than
the rest of Enceladus.
That would be as bizarre as
finding that the whole of the
Antarctic is warmer
than the Tropics.
I don't mean the atmosphere.
I'm talking about the surface.
The fractures here are different
in color, because
they're different
in composition.
They are coated with simple
organic materials.
And then more surprising than
all of that is what we saw
when we found ourselves in a
geometry to look back in the
direction of the sun.
It's what we call a high
phase geometry.
It's a geometry that highlights
the presence of
very, very fine particles.
OK, and this is what we saw.
We saw that the surface from the
south pole of Enceladus,
and the south pole is right
here, is emerging these jets
of very fine particles extending
tens of kilometers
into space and feeding--
if you take a picture like this
and you process the faint
light levels with color to bring
out the contours, the
faint light levels, this
is what you see.
These jets are feeding a huge
plume that extends--
in fact, we see in other
pictures-- extends tens of
thousands of kilometers
away from Enceladus.
So this, in fact, was
quite a surprise.
It turns out we know now that
these jets of particles are
accompanied by water vapor, and
water vapor that is laced
with simple organic materials.
OK, the analysis of all this
information, other pictures
we've taken of the jets of
Enceladus, including the
information gathered by other
instruments about the water
composition and the composition
of the organics,
all of this, was put together by
my team and I. And we have
reached, I wouldn't call it
necessarily a conclusion, but
we think it is possible that
these jets are erupting from
sub-surface reservoirs
of liquid water.
OK, and if we are correct
about this, then we have
stumbled upon what I call the
Holy Grail of modern day
planetary exploration.
That is we found an environment
that contains
liquid water, organic materials,
and excess warmth.
Or, in other words, an
environment that is conducive,
possibly conducive, to the
presence of living organisms.
And I don't think I need to tell
you what the discovery of
living organisms or life in our
solar system, should that
ever happened, the kind of
implications that would have.
Because if we could demonstrate
that life had
arisen not once, but twice,
independently in our solar
system, then we can infer that
it has occurred a staggering
number of times throughout the
13.7 billion year history of
the universe.
Cassini, of course, continues
to orbit Saturn.
It obeys our every command.
It's returning magnificent image
after beautiful image of
a planetary system that I think,
you would agree now, is
rich in beauty and otherworldly
phenomena.
And I don't think I have to
convince the inventors of
Google Earth of the value of
images of planetary bodies,
and of the culture-shifting
power of images.
Our space program has led the
world in taking such images,
and images that have become
cultural icons.
And I'm going to remind you
of a couple of them.
Those of you who were alert and
coherent during the 1960s,
I don't know if any of you were
even alive during the
1960s, I was.
You'll remember this famous
picture taken by the Apollo 8
astronauts on December
29, 1968.
And this was a picture that
had an enormous impact on
earthlings and on our
perspective of our cosmic
place and our responsibility
for
stewardship of our own planet.
I think it's even credited with
adding impetus to the
environmental movement
during the '60s.
Well, eight months ago, we on
Cassini, I'm very proud to
say, caught sight of something
again that no human had ever
seen before.
It was a total eclipse of
the sun seen from the
other side of Saturn.
OK, and you can see in this
gorgeous image, the main rings
highlighted backlit
by the sun.
You can see the refracted
image of the sun.
This is the light being bent
around Saturn by the
atmosphere.
You can see the whole system is
encircled in this beautiful
blue ring, which is coincident
with the orbit of Enceladus.
This is a ring that
is the result of
exhalations of Enceladus.
And if you look closely enough,
and as if this weren't
brilliant enough, within this
impossibly lovely scene, you
can spot from a billion miles
across interplanetary space,
our own planet Earth cradled in
the arms of Saturn's rings.
And I think it will be a long
time before we see anything so
moving again.
I believe that nothing has
greater power to alter and
correct our own impression of
ourselves, and where we fit
into the scheme of things, than
seeing ourselves from
afar and capturing a glimpse of
our own little blue ocean
planet in the skies
of other worlds.
And that changing mindset, that
changing worldview, may
in the end be the greatest
legacy of all our
interplanetary travels and the
finest reward that we'll ever
receive for this, hopefully,
never-ending journey of
discovery that was begun
50 years ago.
Thank you.
Leslie, what do we do now?
Do I take questions?
OK, questions, are there
any questions?
Can we put the lights
up, please?
Yes?
AUDIENCE: Where is the methane
on Titan coming from?
DR. CAROLYN PORCO: Well,
that's a good question.
That's a 64 million
dollar question.
People are working hard to
try to figure that out.
It could be outgassing.
That's the explanation du jour
is that it's being outcast
from the interior in volcanic
eruptions perhaps, or somehow.
And then, of course, there are
those who like to think that
it's bacteria on the surface of
Titan that can live there
and produce methane.
That's another maybe not so
popular view, but there are
holdouts for that
point of view.
Any other questions?
Yes?
AUDIENCE: Is there any way we
can find these pictures?
DR. CAROLYN PORCO: Yes,
Ciclops.org, it stands for
Cassini Imaging Central
Laboratory for Operations,
O-P-S, C-I-C-L-O-P-S.org.
That's where we post all
the images that we
take with our cameras.
Yes?
AUDIENCE: On this picture, can
you explain the image?
Why doesn't the ring connect?
Why is there discontinuity
there?
DR. CAROLYN PORCO:
Do you mean this?
AUDIENCE:
[UNINTELLIGIBLE PHRASE]
DR. CAROLYN PORCO: OK, first,
you have to know that this
picture was taken--
I forget now myself--
it's either taken over nine
hours or taken over six or
three hours.
So the spacecraft was in
slightly different positions
when it was taking--
and it's a mosaic.
It's not one picture.
Lots of pictures have
gone into this.
So when it was taking this
picture here, it was in a
different position than
when it was taking
that picture there.
So that's why it kind of
looks funny there.
But you're looking at light.
You're above the rings.
The sun is below.
So you're actually looking at
the dark side of the rings but
the sunlight is filtering
through the rings.
And you can see, in fact,
where the rings are--
well before I get into that.
This, from here down, is the
southern hemisphere of the
dark side of Saturn.
And that looks bright because
the light is hitting the rings
and shining back on to the
southern part of the planet.
OK, and then against that bright
southern hemisphere,
even though it's on the night
side of Saturn, you are seeing
the silhouettes of
the rings here.
So really the rings here
are not lit at all.
There's no sunlight
here at all.
But this is a silhouette.
So you wouldn't see anything
ring-like at all were it not
for the fact that you're
seeing a silhouette.
OK, and then because the rings
orbit in exactly one plane,
that plane intersects the
planet right there.
So no light is getting there.
AUDIENCE: So is this
[UNINTELLIGIBLE] right on the
edge of the planet?
DR. CAROLYN PORCO: Here?
AUDIENCE: Yeah, all along the
edge of the planet, the rings
don't connect up,
that's because--
DR. CAROLYN PORCO: That's
the shadow.
AUDIENCE: That's the shadow
versus the actual rings?
DR. CAROLYN PORCO: That's the
shadow, the shadow of Saturn
cast on the rings.
AUDIENCE: OK.
DR. CAROLYN PORCO: Yes?
AUDIENCE: Why are the rings of
Saturn [UNINTELLIGIBLE] any
other gaseous planets?
DR. CAROLYN PORCO: It could be
just a matter of statistics.
Right now, we see the solar
system when Saturn happens to
be the planet that has
big rings around it.
If estimates of the age of the
rings, and this is also being
debated among Cassini scientists
right now, but
going in to Cassini, our
estimates were that rings
didn't live longer and weren't
older than about a few hundred
million years old.
So to just calibrate that.
Back in the days of
the dinosaurs,
Saturn had no rings.
OK, we just happen to be
seeing it now when a
catastrophic disruption of a
pre-existing body, or maybe a
capture of a body happened,
it got broken apart
and it formed rings.
There are moons around Neptune
that exist, within what we
call the Roche limit.
That is they're close enough
to Neptune that if they get
broken up tomorrow, if all of
the moons within that region
got broken up tomorrow, they
would make a ring that was
comparable to, at least,
the A ring of Saturn.
So it just might be
timing, when we
happen to be here observing.
If it's true that rings are
just continually created,
eroded, created, and eroded.
Yes?
AUDIENCE: What's the expected
lifetime of the Cassini
[UNINTELLIGIBLE]--
DR. CAROLYN PORCO:
The Cassini what?
AUDIENCE: Imaging, how long
is it going to last?
Will it run out of power, or
fuel or navigation, or--
DR. CAROLYN PORCO:
OK, so the real
limit, you know is politics.
It's how much money the American
Congress wants to
give us to continue
going, literally.
The spacecraft is
in good health.
It's stabilized on gyros, and
there were four of them.
One of them was redundant.
And I think one of the remaining
three has arthritis,
a little bit of arthritis.
But even if the gyros went,
there's still thrusters.
We could turn the spacecraft
with thrusters.
In that case, we're
using fuel.
But that could still be done.
So we could still turn hither
and thither and take pictures.
Fuel is a precious commodity.
We're planning the extended
mission now, so we'll almost
certainly go through 2010.
And then after that, we'll
plan through 2012.
Almost certainly by then, our
budgets will be way down.
There's nothing on the horizon
that looks like it's going to
limit us mechanically,
electrically, functionally.
It's just how long they'll
provide funding for it to go.
You know, these missions have
a nasty habit of not dying.
They can't even kill
the Mars Rovers.
I think they've tried to
drive them off cliffs.
They won't die.
Yes?
AUDIENCE: Two questions, do you
have to pan the camera for
most of the images because
the light levels are low?
Or [UNINTELLIGIBLE] exposure
times can be short enough not
to turn the spacecraft?
DR. CAROLYN PORCO: Oh, I
see what you're saying.
OK, let's do one question at a
time, because by the time you
ask me the next one, I'll forget
the first. We do pan
but not really because
light levels are low.
Generally, we do that when we're
flying so close to a
body that the relative motion
would give us smear if we
didn't do that.
So Cassini is an amazing
spacecraft.
It's been programmed so that we
could say to it, point to
this latitude and longitude
on this satellite.
And keep the bore side
pointed there.
And it knows that as the thing
is turning, it does this.
OK, but for light levels, all
we have to do, it's like a
camera on Earth.
All we do is keep the
shutter open longer.
And because the spacecraft
is so massive,
it's enormously stable.
So we point it, and it
just stays there.
And we can keep the shutters
opened for minutes and get
beautiful images.
We could never do
that on Voyager.
On Voyager, we couldn't expose
longer than a few seconds
without getting smear.
So it's a tremendous
improvement.
That's one of the reasons why
our pictures look a lot better
than Voyager pictures.
The other is that were using
a CCD instead of a
selenium-sulfur vidicon tube,
which is what the Voyager
cameras were.
What's your second question?
AUDIENCE: The second question
is what's the data rate back
to Earth, and do you have to
buffer the images on the
spacecraft?
DR. CAROLYN PORCO: Oh yeah,
we have to buffer.
And I don't remember
the data rate.
Isn't that ridiculous?
But I don't remember.
I don't even want to say because
I'll guess, and I'll
get it wrong.
And this is being filmed.
And it'll go out there, and
I'll forever be wrong.
So I won't say it.
Yes?
AUDIENCE: Are there
any return trips
planned to Titan's surface?
DR. CAROLYN PORCO: Oh there's
lots of discussion right now
about what the next missions
are going to be.
And there's even a debate,
because missions are very hard
to get, especially missions
of the type that we are
conducting now.
All the simple things
have been done.
So missions now are
much more complex.
They have to carry many
more instruments.
OK, we want more data rate.
We want everything, more, more,
more, because we want to
just do a better job the
next time we go out.
And it takes a long
time to get out to
the outer solar system.
So you don't want to
do it piecemeal.
You want to send a nice,
healthy, well-equipped vehicle
out there to do what
you want it to do.
So the big missions are
few and far between.
And there's always debates about
what we should do next.
So there's a debate going
on right now.
Should the next big mission be
to the Jovian moon, Europa,
OK, which is believed to have
a subsurface ocean, but an
ocean that has something like
ten kilometers worth
of ice around it.
Or, with the results of Cassini
now have brought the
whole Saturn system to the fore
as an exciting place, and
an important scientific place
to go, I should say, in a
place that's scientifically
important to return
to because of Titan.
And also because of Enceladus.
If we're correct, and I have
to say that's a big if, we
still need to investigate
this, and it needs to be
looked at with a lot
more detail.
If we're correct that the jets
are erupting from liquid
water, then Enceladus has just
jumped to the front of the
line in my opinion.
There's a body of
astrobiological interest in
our solar system.
I'm fond of saying this.
All you have to do is land on
the surface, look up, and
stick your tongue out.
And you've got what
you came for.
And you know wouldn't it be
amazing if there were microbes
in those ice particles,
OK, flash frozen.
So that would be an exciting
place to go to too.
But there's the people who
want to go to Europa.
Then there's those of us who
think we should be going back
to Enceladus.
And then there's the people who
think well let's go back
to the Saturn system,
but we really should
concentrate on Titan.
So there's just a lot of debate
going on right now.
Yes?
AUDIENCE: Is there anybody who
wants a manned mission?
There's so much good science
being done by unmanned stuff.
Why is there this push to
send someone to Mars?
DR. CAROLYN PORCO: Well, OK, so
I'm a person who obviously
is deeply involved in the
robotic side of things.
And I'm in favor of sending
humans back into space.
I don't know if you read my
editorial that I wrote in the
New York Times, where I
basically pointed out
something we've all known.
People have been afraid
to say it.
But I think it's being said
more and more that the
previous 25 years of the human
flight program has been a
waste, because we've done
nothing but go around and
round in circles.
OK, we abandoned the
Apollo program.
We abandoned the Saturn V, which
was the biggest, most
powerful vehicle the
US had ever built.
We could have used it.
We could have been way ahead
of where we are now in the
human exploration of the solar
system had we not done that.
And it did not cost less
to go with the shuttle.
It cost more in the end.
But there has been always this
friction between the human
side and the robotics side.
And I'm hoping that maybe soon,
the twain shall meet.
And even the fans of the robotic
exploration will see
the benefit of having, at the
very least, developing
vehicles that would be powerful
enough to send humans
to the moon and Mars.
We could also use those same
launch vehicles to go out to
visit a planetary system
like Saturn.
We could do very much more
if we had those vehicles.
I just told you that the
tortured path we had to take
to get Cassini, six
metric tons, to
get Cassini to Saturn.
OK, if we were going to take a
path like that but had a much
larger launch vehicle, we could
have carried much more
than Cassini.
We could have carried
a Cassini orbiter.
We could have carried up a
vehicle was on the orbiter, a
vehicle that could have landed
on the surface of Enceladus,
and a balloon that we could
have deployed to Titan to
basically get blown around
by the winds on Titan and
investigate the surface
that way.
We could have done
so much more.
So I would rather not there be
this tension, this conflict
between the two.
I think that I could go on and
on about this topic, OK.
The NASA budget is 16,
17 billion dollars.
That's 0.6%, 0.5% percent of the
amount of money that the
federal government spends.
OK, that's a minute amount
of money for the
whole entire agency.
OK, you could double the NASA
budget, and it would go
unnoticed, OK, except for those
agencies that happen to
be in direct conflict when
it comes down to budget
committees.
But put all that aside.
You could double the
NASA budget.
It's a tiny agency.
It's a tiny budget.
We are a wealthy country.
We could do both.
Yes?
AUDIENCE: How hard would it be
to send a spaceship out there
to bring [UNINTELLIGIBLE]
back?
DR. CAROLYN PORCO: It would
be difficult because--
you're talking Titan
or Enceladus?
It matters because Enceladus
is closer to Saturn.
It's deeper in the gravitational
well.
Once you get into the
gravitational well, and that
takes energy.
I described to you what
we had to do.
We had to slow the
spacecraft down.
You actually have to expend
energy to slow down.
Once you get into the
gravitational well, then you
got to get out.
OK, so it's difficult
to do that.
That would not be the very
next thing we do.
The very next thing we would
do is send capable enough
instrumentation there to make
the kinds of measurements we
think we need to make.
If you're talking about
Enceladus, we'd want to
investigate the properties of
the organic materials, what's
called the handedness of it to
see if it's organics that has
had any biological processing
done to it,
that kind of thing.
Yes?
AUDIENCE: I was very depressed
to see that the New Horizons
spacecraft was just a flyby.
DR. CAROLYN PORCO: Oh yes.
AUDIENCE: And those of us who
were alive with the first Mars
flybys where we looked and said
uh, nothing there, looks
like the moon.
Realize flybys are very
misleading and frustrating,
especially with
[UNINTELLIGIBLE].
So what were the arguments
pro and con for that?
DR. CAROLYN PORCO: Do it now or
we're going to be dead by
the time it ever happens.
That's the somewhat of a joke.
But there's something to be said
for flybys because you do
have to reconnoiter the place
you're going to even know what
kind of instrumentation you
want to send there next.
So it wasn't a foolish
thing to do.
It would have been nice but
it wasn't a foolish
thing to do to flyby.
It would be a foolish thing to
do now to send flybys to
Uranus and Neptune, for
example, because we've
already done that.
The next missions to Uranus and
Neptune, in my opinion,
need to be orbiters.
Yet there are some people who
are saying well, we're never
going to get enough money
for orbiters.
Let's do more flybys.
You see, this is the bane of
living with limited resources.
AUDIENCE: Is it even
technologically possible to
[UNINTELLIGIBLE PHRASE]?
DR. CAROLYN PORCO: It's
difficult, actually.
When you say, it's difficult
just to get out there and--
AUDIENCE: Is it possible?
DR. CAROLYN PORCO: It would be
possible if you had enough
resources, yeah.
Why do you say that?
AUDIENCE: How big of a rocket
would you need to send it?
DR. CAROLYN PORCO: Well, yeah,
you need a big rocket to carry
a lot of fuel and so on.
We don't have the capability
now to do it.
I didn't know if that's
what you were saying.
You don't really mean
is it possible.
You mean is it practical.
Is it presently practical?
No.
Yes?
AUDIENCE: So there's something I
never understood about NASA,
and I continue to not
really understand.
DR. CAROLYN PORCO: I probably
don't either.
They don't have heated
toilet seats.
AUDIENCE: Oh, yeah,
that's a problem.
So I noticed that most of these
missions are extremely,
for obvious reasons, frontloaded
in time, and
resources, and research.
And then basically, at the
end of the day, we
bet it all on one.
And if we're really lucky,
two spacecraft--
whereas the actual assembly
cost and part cost of the
spacecraft is probably a small
part, or in this case, probe,
is a small part of the entire
research budget.
So why not launch ten probes
and if five of them break,
then whatever.
At least we don't have these
incidents like we're trying to
approach Mars after a ten-year
project and all of a sudden,
English and metric units get
messed up, and oh well, there
goes 10 years and 58
billion dollars.
DR. CAROLYN PORCO: OK, I think
you're under the wrong
impression that the costs of
the vehicles, the cost of
building the vehicles, the
instrumentation, the cost of
building all the software and so
on, that is used to operate
the spacecraft, and the
instruments is way more than
we have for research.
That is the vast bulk.
For the scientists involved,
this is always a tremendous
frustration.
We have budgets that allow us
to take pictures, archive
them, put them in the planetary
data system archive,
and very little money to
actually do research.
So that's where all
the money goes.
AUDIENCE: Sorry, by research,
I meant the whole R&D and
engineering effort of actually
designing a spacecraft in the
first place, so that the idea
would be-- and maybe I'm
totally wrong here-- but it just
seems that the cost of
the physical craft, once
you've done all the
engineering work and all the
software design is essentially
very small compared the
entire project.
So why not launch ten probes
instead of one?
DR. CAROLYN PORCO: Well
I think you may
be wrong about that.
But that's a philosophy that had
been followed in the early
days of NASA.
There was always redundant
spacecraft because they always
expected one to go belly up.
But we don't do that anymore
because the spacecraft are
getting more and more complex.
And there is some recurring cost
for building a second, a
third, a fourth, and besides you
gotta operate those too.
It's expensive in people time
and that's really where all
the funding is, so.
Yes?
AUDIENCE: Just to follow
up on that question,
[UNINTELLIGIBLE PHRASE]
what could be the additional
cost [UNINTELLIGIBLE]
first craft to launch another
craft of exactly the same
thing with say, just one
line of code changed?
DR. CAROLYN PORCO: I'm sorry.
I don't know the answer.
I don't know the exact number.
AUDIENCE:
[UNINTELLIGIBLE PHRASE]
AUDIENCE: That's right but--
DR. CAROLYN PORCO: I didn't hear
what you-- you said it's
really a what job?
AUDIENCE: It's a custom job?
DR. CAROLYN PORCO: Custom
job, yeah, that's right.
AUDIENCE: [UNINTELLIGIBLE]
target to target.
DR. CAROLYN PORCO: Well, OK, so
there were good intentions.
The Cassini spacecraft
was supposed to be--
there was a mission called
CRAF, comet rendezvous
asteroid flyby.
The CRAF Mission the Cassini
Mission was supposed to be
identical spacecraft.
It was called the Mariner
Mark II spacecraft line.
They were going to build
lots of these vehicles.
Design them and then just send
one to Saturn, one to a comet,
one here, and one there.
And then as always happens,
budgets get cut, and so you're
back just building one.
In fact, a CRAF Mission
got canceled.
So it's a good concept, but I
think it's just because things
are getting more and more
complex, it ends up being
custom because you only have
the budget for one.
Any other questions?
OK, well thank you for
staying so long.
