Pop!Tech Carolyn Porco

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Posted by: peder on Jun 22, 2007

As leader of the Imaging Science Team on the Cassini mission to Saturn, Carolyn Porco brings to the Pop!Tech stage breathtaking images and stories of exploration and discovery that, by her own admission, make grown men cry.

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POP! TECH
BRINGS TOGETHER
THE WORLD'S LEADING THINKERS
TO SHARE INSPIRATION AND IDEAS
IGNITING CHANGE
AND UNLOCKING
HUMAN POTENTIAL
THIS IS PART
OF THEIR ONGOING
CONVERSATION
POP! TECH
POP! CAST
Presented by Lexus Hybrid Drive
GIVES MORE TO THE DRIVER. TAKES LESS FROM THE WORLD.
CAROLYN PORCO POP!TECH 2005 I'm delighted to be here.
I've never been at such a conference before, and I'm delighted to be the one to tell you about
what's going on a billion miles away from here.
On the evening of June 30th of last year, 2004, in a maneuver that was so flawless
and so perfect it seemed dreamt,
the most ambitious interplanetary spacecraft ever built called Cassini
glided into orbit around the planet Saturn.
And at that point it became the farthest robotic outpost that humanity had ever
established around the sun.
And on January 14th of this year, an aerodynamically shaped flying saucer
drifted on a piece of fabric through the hazy atmosphere of Saturn's largest moon,
and landed firmly on its surface.
The humans had arrived in the outer solar system 10 times farther from the sun than the Earth,
and 7 times farther than we had ever landed anything before.
We might as well have traveled to a strange planet and orbit around
a star in another quadrant of our galaxy.
That's how alien the environment at Saturn is compared to the cozy conditions we have
here, nestled in close to the sun.
Out of all the planetary systems that we could study in our solar system
Saturn is in fact the richest, because it has an atmosphere,
magnetosphere, a whole system of satellites, moons, rings and so on;
and it is an ideal destination for the study of the same physical processes
that we believe occurred in the early days of our solar system
and in the present day dynamics of the solar system,
and in fact in systems that we are discovering, as I speak, around other stars.
So in studying Saturn and its rings and moons and so on,
we will have the opportunity to study a range of scientific objectives reaching well beyond
Saturn itself, and that is why this ambitious spacecraft has been sent to Saturn.
So I'm going to take you this afternoon through a tour, a very rapid-fire tour--
so hold on to your seats--of the Saturn system as it is being revealed to us
by Cassini.
And I'll just say, if you haven't been paying attention to our images up until now,
just prepare to be amazed.
So this is the Saturn--this is the Cassini spacecraft itself.
It's the size of a school bus.
It weighed 6 metric tons at launch.
It carries 12 scientific instruments designed to look in the untraviolet
and all the way into the near infrared.
The cameras, of which I am the principle investigator, sit on this remote sensing pallet.
We call them cameras; they're actually telescopes and now are on wide angle.
This is the antenna with which we communicate with the Earth.
It's also the radar instrument for showering the surface of Titan with radar--
and I'll say more about that later--
and has instruments for measuring magnetic fields and particles and so on.
And then it carries the European built Huygens probe because Titan is a major target
of the Cassini mission.
The mission design is unlike its predecessor, the Voyager spacecraft,
which flew by Saturn in the early 1980s.
It is an orbiter.
That's what we are doing. We are in orbit.
We're going to be there forever, actually,
but the nominal mission length is 4 years,
and during those 4 years we'll be looking down on the system at the planet.
We will be encountering some of the moons in the Saturn system.
In fact we will have something like 82 satellite flybys in the course of 4 years.
This is unprecedented in magnitude.
So I'm going to start with Saturn itself, telling you what we found.
Saturn is a gaseous planet.
It is banded--very delicately banded like Jupiter.
In fact it has all the same kinds of features we find on Jupiter--the clouds,
the eddies, the vortices, the waves and so on.
They're only deeper at Saturn in the atmosphere, because Saturn is colder,
and there's more haze above these cloud layers,
and so we have a difficult time seeing them in the visible,
but we know where to look.
We've carried lots of spectral filters to allow us to probe to different levels of the atmosphere.
And so we can examine Saturn at particular wavelengths,
and this is a near infrafred wavelength that allows us to see structures,
and you can see -- this is a movie we've made of our images --
and you can see lots of activity.
The imaging scientists have their eye right now--well, they have their eye on lots of things,
but one intriguing feature is, this band in the southern hemisphere
has lots of these dark oval storms about 1000 kilometers across.
It's kind of like Florida--lots of storms going in and out.
And what we're finding--just one example of the kinds of things we're finding;
we knew these storms died. Unlike storms on Earth, which peter out,
these die by merging, but we had never seen--until Cassini we'd never seen a storm
actually get created, so now we have found storms that get created.
They get created created, in fact, in association with big eruptive events,
like this one here, which we have reproduced in garrish false color,
which everbody loves. [audience laughs]
So over the course of the mission we're going to be producing a lot of movies
of the Saturn atmosphere, because that is the best way to examine the meteorology,
is to look at things is motion; and we should be able to develop
a three-dimensional picture of what's going on in the Saturn atmosphere.
We're interested in this, because we don't know presently
what energizes the winds in Saturn's atmosphere or Jupiter's atmosphere
or even our own for that matter; so we have a lot to gain by studying another planet like Saturn.
The rings, of course, are the reason why Saturn is the icon in our solar system,
and they are a tremendously beautiful visual spectacle.
They're 1 light-second across.
They're about 280,000 kilometers across.
They would fit in nicely between the Earth and the moon,
and wouldn't that be a fantastic site to come out one night
and see Saturn's rings hovering above your head,
but they--although very solid looking, they consist of lots of particles,
billions and billions of particles and all in independent orbit around the planet.
This is an artist depiction circa 1983, but actually it still reproduces what we think
the ring particles look like today.
The range in sizes from the size of houses all the way down to the finest powder
you might ski on in the state of Utah,
and they all are in a plane.
They are in what physicists call a very equilibrated system.
Any violent collisions in this system died out long ago.
Because of that, they are paper thin, and they trace out the plane of gravitational equilibrium
around the planet, and despite their enormity--
if you put them all back together again to make a moon of the proper density,
they would be no bigger than this little moon here, Enceladus,
which can be seen here in this picture that I predict is going to put
the space artists out of business.
Bear in mind in these pictures--because it's confusing, I think, for those who haven't seen it--
These are not bands in the atmosphere; these are the shadows cast by the rings
onto the northern hemisphere of the planet.
So the processes ongoing in this disc of material, as I said,
are believed to have occurred in the disc of dust and gas from which the planet
formed, and reaching even a trillion times larger in size
in the discs, these pinwheels of dust, of gas and matter that form the spiral galaxies.
In fact, the mathematics and the psysics underlying the structure in a spiral galaxy
was co-opted with very little change and applied to the study of Saturn's rings
to predict the presence of waves in the rings that, in fact, were found by Voyager
when Voyager visited in the 1980s.
So there is a great deal to be learned in studying Saturn's rings,
about the very early stages of our solar system, and also about processes that are going on
in disc systems throughout the cosmos.
So in this sense what we hope to learn from Cassini is truly universal.
The rings exhibit a bewildering variety of structures; most of it unexplained.
The features that we do think we understand quite well, are those that are produced by orbiting moons.
I'll say a lot about that later, but this is a view that we had of Saturn's rings
as Cassini approached before we got into orbit, and I'm just going to orient you here.
This is the A ring.
This is the Cassini division discovered by Cassini.
This is the B ring. It's the densest portion of Saturn's rings,
and then this is the C ring.
They look different; the structures in them are different, and we don't know what that means just yet.
Perhaps these are different ring elements that had different origins,
but these are the kind of questions that we will be hoping to answer as the years unfold.
Now, Saturn is very, very far away, and Cassini was very massive.
As I said, it was 6 metric tons at launch,
and even launching Cassini on the largest launch vehicle that we had at the time in the American arsenal,
and that was a Titan IV missile along with solid rocket motors strapped onto it,
and then putting Cassini on top of a Centaur upper stage wasn't enough to get it directly to Saturn;
so we looped it around the inner solar system twice.
It encountered Venus twice.
It encountered the Earth, and then it encountered Jupiter for the final push on to Saturn.
These were all gravity-assist maneuvers where the spacecraft steals momentum
from the planet in order to increase its speed.
Now, bear in mind that the object of this exercise is to get the spacecraft
to Saturn 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. [audience laughs]
But all this meant is that by the time we got there, the spacecraft was screaming by,
and we actually had to slow it down in order to allow it to be captured into orbit.
So more than half of the mass of the spacecraft at launch, was fuel that was expended in this maneuver
which took about 90 minutes for us to slow the spacecraft down.
As I said, it went just eerily perfect,
and after that the scientists clamored for years with the engineers at the Jet Propulsion Laboratory
to be allowed to maneuver the spacecraft so that we could take pictures of the rings,
because this brought us closer to the rings than we had ever been before
and will ever be again, certainly in this mission; maybe even in our lifetimes.
We collected a fantastic array of pictures during this--again, something like a 90-minute or hour long period of time.
And this is a lot of what we saw; we saw wave features.
These are the waves, as I said, that are the kissing cousins of the spiral arms in galaxies,
and they are the handiwork of orbiting moons.
There are places where the moons are perturbing the ring particles.
Here in a density wave is where the non-circular orbits of the particles--
again perturbed by the moons--are phased.
They're oriented in such a way as to give you narrow regions of
larger than average concentrations of particles that spiral around the planet,
and this is, in fact, a bending wave--what we call a bending wave.
It's a corrugation in the ring plane, again, brought about by the perturbation
of a moon exciting the inclination of the particles so that they all behave in a very coherent way
to create these beautiful structures.
By studying these structures, we come to understand what the nature of the particles is
in the rings and how they behave, how they colide with each other.
These are all fundamental things we want to learn about the rings
and also what this information will tell us about the way planetary formation started.
Other places where we're seeing perturbations by moons is local.
That is moons embedded within the rings are also capable of sculpting the rings
through their gravitational perturbations.
This was a picture taken after we had crossed over the dark side of the rings
and went below the ring plane onto the illuminated side,
and looked back at the rings, and this is the F ring discovered
or first imaged by Voyager.
Here is Prometheus, one of the shepherding satellites.
This is the outer edge of the A ring, so this is basically empty.
Here you see these structures we had never seen before,
and they are structures created by Prometheus as it orbits interior to the F ring.
They're beautiful structures.
Here's another view of them.
This is giving us insight into what happens when you have a moon close to a ring
creating perturbations in it.
Here is a picture taken later on; not during the Saturn orbit insertion maneuver,
where we caught Prometheus actually stealing material out of the F ring.
Then for completion, this is Pandora, the outer shepherd; both of these moons acting together keep the ring narrow.
pThere are other notable places in the rings where embedded moons are leaving their mark
in rather intriguing ways.
Again, this is a Saturn orbit insertion maneuver picture outer edge of the A ring.
This is a gap called the Encke Gap, and we had seen with Voyager
that there were ringlets in this gap, and we knew then that there had to be a moon in it.
We found it later with Voyager, and here we imaged it for the first time with Cassini.
There's Pan, the dominator of this gap, and the manner in which a moon like Pan
in a gap, opening a gap and maintaining a gap in a disc of material like Saturn's rings,
is going to prove very fruitful to those who study the formation of planets
and in trying to understand, for example, how a planet like Jupiter
growing out of the solar nebula by ecreting material and growing larger and larger
finally comes to truncate its own growth by opening up a gap in the ring.
So there's, as I said, a lot of dynamical relationships that we will come to understand
from studying Saturn's rings that will be applicable to greater systems of greater size.
This is the Keeler gap and one of our--oh, here's the Encke Gap again, and this is Pan.
I just described what Pan does to you, and here is what it does to the inner edge
of the gap in which it sits.
This is a picture that I think kills at a thousand paces.
It was just a beautiful surprise during the Saturn orbit insertion maneuver.
Then here in the Keeler Gap we found a little moon doing the same thing, keeping a gap open
and also creating waves.
Speaking of moons, Saturn has a whole collection of them.
There's now 47 in total, and Cassini is meant to investigate
the moons that are in the inner satellite system.
They extend only to about a few million kilometers away from the planet.
Insofar as they are all orbiting in a plane around Saturn,
the conditions in the nebula around Saturn out of which they form,
they are like a miniature solar system.
So we're not only going to be interested in the geological histories of these bodies
and in their physical characteristics, like their densities and masses and so on,
but we are hoping to study the system as a whole to gain greater insight into the planetary formation process.
Cassini will, as I said, enjoy something like 82 satellite flybys.
Forty-five of those are of Titan, because Titan, the largest moon, is the gravity-assist body
by which we maneuver the orientation of the spacecraft and flying close to it.
But there will be--out of those 82 flybys, there also has already been
a handful of exquisitely close flybys, where we fly over the surface of the moon
even closer than the space station flies above the Earth, and those flybys have given
us really some intimate details on the surfaces of the--and the conditions of the sarturnian moons.
One thing, the saturnian moons, most of them have in common is craters
okay, impact scars, and you only have to look at a moon like Rhea,
which is about half the size of our moon; or the death star moon Mimas
which is about 3-1/2 times smaller than Rhea to see that there was a time long ago,
when there were lots of bodies careening around the solar system with enormous amounts of energy,
and smashing headlong into the planets and into the satellites as they were forming.
And these collisions did a great deal to sculpt the solar system and make it look like it does today.
They were responsible, first of all, for allowing the planets to grow to their present size.
They were responsible--a collision with a Mars-sized object was responsible
for tilting Uranus on it's side.
A collision with a Mars-sized object was probably responsible for creating our moon
by carving out the outer part of the earth, throwing it into orbit from which later on the moon
coalesced and became a body.
The smashed up small satellites.
The impactor that created this crater on Mimas came very close to smashing it to bits,
so it doesn't take a rocket scientist to figure out there must have been some collisions
which did in fact break up small moons, and in fact that's one of our thoughts
for how planetary rings come about.
Then, of course, don't forget that--and some of these collisions probably
created the irregular bodies we see in the Saturn system.
There's Epimetheus, about a hundred kilometers across.
There's Pandora; I showed you Pandora before, again about a hundred kilometers across
looking a lot smoother than Epimetheus, but nonetheless cratered.
And then here is Hyperion, about 200 kilometers across,
looking like something Marsha pulled out of the ocean. [audience laughs]
Okay, so lots of cratered objects everywhere.
And also don't forget we think it was a collision with a comet that wiped out the dinosaurs,
which cleared the way for the eventual development and successful evolution of primates
of which we like to think we're the culmination. [audience laughs]
So collisions are a planetary--an important planetary process,
and we can learn a lot by studying the effects that they have on bodies.
One of the things we do with the craters is look at the density of craters
across the surface of a body, because that's they way we work out the chronology
of what's happened to this moon.
If the moon is cratered in places but not in others,
we say that the place where it's not cratered is a young surface.
It has been reworked.
It's the reason why the moon is cratered and the Earth is not.
The Earth's surface has been reworked,
in our case through play tectonics. So that's the way we come to understand
the geological history, and we're doing that quite a lot in studying
the saturnian moons.
This is the moon Iapetus, known ever since it was discovered in the 17th century
to be very, very bright on one side and very dark on the other.
It's one of the most intriguing bodies, and it's where, by the way, Arthur C. Clark
put the monolith in the book version 2001, so I just got--I got to know
he had to--I believe he had to know there must have been something strange
about Iapetus, and it turns out, there is indeed.
This is the first time we were looking at the dark face of Iapetus.
Even with Voyager we couldn't do this.
and you see that it's heavily cratered, which tell us right away
it's an ancient surface, and that wiped out--as soon as we saw this picture,
it wiped out a whole class of explanations for why one side of this moon was dark,
and we have seen the boundary between the dark and the bright,
now looking quite feathered, and we think probably the best hypothesis
for how this moon got this way is that dark material was in place
on this leading hemisphere from the outside.
That's about all right now that we know.
We've collected some gorgeous images.
Here is a fantastic land slide in a crater with a cliff about 15 kilometers high,
so maybe 50 years from now when we are taking extreme excursions into the Saturn system,
perhaps on spacecraft that Peter has funded, if you or your children
or your grandchildren are interested in ice climbing, this is going to be the ticket. [audience laughs]
Okay, so of all the icy moons of Saturn, most of them are heavily cratered,
but one of them has stuck out for years now.
We knew from the ground that Enceladus, which is only about 500 kilometers across, was very bazarre.
It was as white--almost completely white all over, which is very peculiar.
No other object in the solar system was this white, and it was bright.
It reflects nearly all the light that falls on it; again, very unusual for a solar system body,
and so we had suspicions that Enceladus was going to be very intriguiging
when Cassini got there, and we certainly have not been disappointed
We find first that when you examine it in false color, when you really, really stretch the color
as much as you can--as I said, it's pretty colorless
we find something peculiar about the cracks on the surface.
Okay, it's different than the rest of the body, and when we've looked at even closer up to Enceladus,
It was just incredibly bizarre.
This is what the surface of Enceladus looks like.
I think you would agree, it looks nothing like the cratered moons that I showed you before.
It is obviously a young surface.
It shows generations of fractures and tectonics--not plate tectonics
but nonetheless fractures.
We have folds of mountains.
Here we have--and looking at it even finer scale, we see more and more fractures.
We see fractures that bifurcate craters.
This is a crater here that has been somewhat eroded, and you can see fractures across it.
It was so intriguing to us that this last July, we tweaked the orbit of Cassini
enough to bring us only 175 kilometers over the south pole of the body.
This is not what it looks like. [audience laughs]
This is not another one of George Bush's bright ideas. [audience laughs]
This is just to show you how small Enceladus is and yet is just a fascinating object.
I'm not sure if I--no I didn't include the movie.
Okay. So anyway, as I said, this past July we flew close over its south pole,
and we found amazing things.
First of all, we found the south polar region is delineated by a series of basically fractures
that seem to be telling us Enceladus might have had a change in spin rate.
This is the signature, we think, of a past event or slow evolution of the spin rate of Enceladus.
We found--and when I say we now I mean Cassini in general--found that the south polar region
is anomalously warm.
This would be like finding the south pole of the Earth was warmer than the tropics.
That's how bizarre this is.
The instruments that can measure composition have found that these fractures,
these blue fractures and false color are actually the sites of organic materials.
We also found the instruments that flew over and can measure material around the spacecraft,
found water vapor up at about 400 kilometers above the south pole,
and fine iced particles, a spray of fine iced particles.
Enceladus is venting.
It's like Old Faithful around Saturn.
It is venting material to space; it means it's geologically active,
and I can't tell you how exciting this is.
There's warmth, there's geologic activity and there is organic matter.
So the implications of all these findings are thrilling and are probably telling us that
this is another place in the solar system where, just perhaps, we might have the conditions
that could support living organisms.
That's not saying we have found life there.
are just very intriguing to us.
What is making Enceladus presently warm, we don't quite yet understand,
but I can assure you this topic is receiving a lot of attention as I write.
In fact, we are busy--the imaging team is busy writing up its paper to be submitted to
the journal Science on our Enceladus results.
As exciting as Enceladus is, I've probably saved the most exciting for last,
and that's Titan.
Titan is Saturn's largest moon, and would alone have made the journey back to Saturn worthwhile.
We've known for 50 years now, it had organic matter in its atmosphere.
The simplest organic material was found 50 years ago.
That's methane, a carbon and 4 hydrogens.
In the 1970s, more simple organic compounds were found.
The Voyager investigation of Titan proved interesting.
The cameras got no better than this.
We couldn't see down to the surface of Titan because the ubiquitous haze
in the atmosphere that is created by the breakup of methane high in the atmosphere--
the carbons form polymers and aerosols like photochemical smog
that build up in the atmosphere but also over time, over eons were believed to fall through the atmosphere
and coat the surface in some kind of organic sludge.
At least that's the mental picture we had.
The Voyager's spectrometers, these are other instruments on the spacecraft,
confirm the existence of simple organic compounds and found some other very intriguing things.
Titan's atmosphere is largely molecular nitrogen like the atmosphere here in this room.
The surface pressure is 50% greater than the surface pressure in this room,
so it has a substantial atmosphere.
The thermal structure of the atmosphere is similar to that on the Earth.
Different processes, but nonetheless the same kind of thermal structure,
and also other physical characteristics in common with the Earth.
There is a condensable material in the atmosphere of Titan, and that is methane.
Methane is to Titan what water is to the Earth.
Methane can be there as a gas; it can be there as a solid; it can be there as a liquid;
And so this opened up the possibility that we would find on Titan some very familiar
geological processes and atmospheric processes except working on
and by very unfamiliar substances.
And so on the basis of these discoveries--but from Voyager, Titan's surface environment
was believed to be more similar to the Earth's than any other that we had in the solar system.
Of course, it is 300 degrees below zero Fahrenheit,
and also there's no free oxygen, but nonetheless the presence of organics
and the lack of free oxygen led scientists to believe also that the present day atmosphere of Titan
would be similar, in some important respects, to the atmosphere that we had
here on the early Earth prior to the emergence of life.
So it was with great anticipation that over the last 25 years, in fact,
leading up to Cassini's arrival at Saturn, that scientists looked to the exploration of Titan
that Cassini would allow.
And, of course, it's the surfact that we--because we didn't see it with Voyager--
we were most eager to see.
We outfitted our cameras with special filters that allow us to see in the near infrared
where Voyager cameras couldn't see, and we have been very successful at that.
We saw surface features.
This is the hemisphere that faces Saturn.
We could see a cloud complex in the southern hemisphere.
Okay, so there are clouds on Titan. There are probably methane clouds.
It is the place on--there aren't a lot of clouds on Titan, but where we see clouds
is predominantly in the southern hemisphere. And bear in mind that for the orbiter instruments,
like my own,
investigation of Titan is like an exercise in pattern recognition,
It is always a hazy day on Titan.
There are no shadows, and so we couldn't use the tools that we had come to learn to use
over 50 years of exploring planets, looking at the shadows cast by the sun
to deduce what's up and what's down and what kind of topography is on the surface.
We can't do that with Titan, and so we knew that it was going to be a compilation of the results
from all the instruments that would be needed in order to figure out what was going on
on Titan and also, of course, what we came to find with the Huygens probe.
So far, this is some of the best data we have of the part of the surface of Titan
that's leading in its orbit.
You can see basically dark and bright patterns, and I'll tell you now that we're fairly confident
we're looking here at a low-lying dark area and an upper--or highlands here.
We came to call these things islands.
We didn't know at first if they were like islands, but that's what they looked like to us,
so this became Great Britain.
This became Ireland. [audience laughs]
Here's France.
Here's Iberia.
This is Peloponnesia; the geography is not really precise, [audience laughs]
but that's okay.
Very interesting features if you look at them up close.
I'll just point out some things we were able to deduce.
This looks very aeolian; looks very much like features we saw on Mars.
So either wind or perhaps even something flowing on the surface created features
like this flowing from left to right.
We see very few circular features. As I said before,
it's the paucity of craters, or the presence of craters, that allows us to work out a chronology.
And here, we see there is a circular feature there and maybe one there.
This tells us the surface is young and has been re-worked.
Here are sinuous channels across Great Britain, pull-apart features,
some tectonics, tensional features.
Here is the other side of Titan. Again, this has been confirmed to be an impact crater
with an ejector blanket, but the same sort of features, just difficult to make any sense out of.
Here we see things that look like flow has occurred, channels of some sort,
This is a radar image that was taken. Here is a big impact basin,
double rim--inner rim and outer rim.
Here are, again, channels braided--stream-like channels, like the type that we see in our images.
And so it's piecing all these things together that is going to give us a global view
of Titan over the course of four years.
But I can tell you that the most remarkable highlight of Cassini's exploration of Titan so far
has--and an event, as I said, that we had been anticipating would be the Rosetta Stone
in helping us understand our own remote observations, was the deployment
of the Huygens probe and its descent to the surface of Titan on January 14th.
Many of us were in Darmstadt, Germany, at the European Space Operations Center
for this event, and I can tell you, it's what I call a grown-men-crying kind of day.
It felt like the humans had arrived. It felt like living science fiction.
People were disappearing in corners to have their own little private moments,
It was an accomplishment, and even at the time, it felt like an accomplishment
that should have been celebrated with ticker tape parades in every major city
So this is, to me, a sad commentary on the state of our culture,
and I think it's something that needs to be fixed.
And I'm going to talk to Peter later about fixing-- [audience laughter and applause]
Anyway, I fear I'm probably running out of time here, but let me continue.
So the probe descended for 2-1/2 hours through the atmosphere.
It measured pressure; it measured temperature; it measured transparency of the atmosphere.
It took panoramic images on the way down. It had a camera, and it spun as it descended,
so it took panoramic images. And it contained a penetrometer, a device
that's not unlike this pointer here, that stuck out of the bottom of the probe like this
and when it landed, it measured the characteristics, the mechanical properties
of the material that it landed in.
So it acquired an immense amount of data on the way down.
Scientists are still busy trying to understand it all. But I'm an imaging scientist.
I am prejudiced, but I would say the pictures always have the greatest impact,
and it is difficult to describe what it is like to see the pictures returned by
the Huygens probe for the first time.
This gives you a sense of the panorama that the probe saw as it descended.
Hard to make it out here, but this was a series of pictures, especially this
region here, which was the most mind-blowing of all.
And again, it's difficult for me to describe what it felt like to see this.
I personally felt like somebody had hit me over the head with a frying pan,
and I was incoherent and stunned for hours later, because we had seen
This was something that just told us immediately, something had flowed
scientists had developed about what the surface of Titan would look like,
in fact, were probably correct. And I am going to jump to the punch here
and just tell you what we've come to learn, because I don't have much time.
But here is what we think is a shoreline. Okay? And it is not liquid
that we have here because the probe, when it landed, measured
something that had the mechanical properties of wet sand. Okay?
It didn't land in an open fluid, and in fact, we haven't seen anywhere on
the surface of Titan yet, bodies of open fluid, even though some predictions
atmosphere and ethane--all these light hydrocarbons would rain out of the atmosphere
and carve channels and fill in low-lying depressions and basins, and so
we thought we might see flowing rivers and lakes and seas and so on.
We haven't seen any unambiguous open bodies of fluid yet, but nonetheless,
we've come to see now that probably the liquid methane that has surely
flowed at some time on the surface of Titan, at least in this region,
drained off these highlands, which are about 100 meters elevation,
and into this low-lying region. And the Huygens probe landed somewhere around in here.
And so this liquid methane is suffusing this unconsolidated ground.
The probe was warm, and when it landed, its heat caused the evaporation
of this methane, and so that's how we know that. So the idea is that methane
comes out of the sky. Perhaps it's even springs that cause sapping,
and it drains into low-lying regions here. These dark regions are probably
the hydrocarbons, the organic matter that was predicted to fall out of the
atmosphere with time, and they probably cover everything, and then it
gets washed into the low-lying regions.
This picture was taken at about 16 km elevation. This is what they saw
at about 8 km elevation. It's having the stereo view that allowed the
Huygens imaging team to piece together the story I've just told you.
I want to remind you that 8 km or 10 km or 12 km is the altitude that
a jet airliner would fly from the U.S. to Europe. So this is the view you would have
out your window of Titanian Airlines as you fly across the surface of Titan. Quite exciting.
And then finally, arrival on the surface, and this is what the surface of Titan looks like.
The first time human eyes had ever seen a moon in the outer solar system.
[audience applause]
And I'm going to lose it right here if I'm not careful. [audience laughter]
This is a very foreshortened picture. These are ice boulders or pebbles.
They just look big in the foreground because the camera took a picture
down there and then to the horizon.
This is the horizon. Scientists have looked at the arrangement of the boulders
on this surface, and it's very size sorted. We don't see anything smaller
than about 3 cm; they don't see anything bigger than about 15 cm,
indicating that at one time, perhaps, there was a river or methane flowing across
So I think you will agree that we have found, on Titan, a remarkable place,
a remarkable surface environment that is strangely Earth-like.
It's a young surface. There have been tectonics. There have been some impacts
It's been altered by deposition, by precipitation, and we are now looking at a
remarkable three years in the nominal mission, perhaps even a decade of
exploring Titan and the rest of the Saturn system, with much to teach us
about the origin of planets, the origin of other solar systems, and perhaps
even about the origin of life itself.
If I've done nothing this afternoon, I hope I've convinced you and left you with
a strong impression of the magnitude and the breadth of what it is we're
accomplishing at Saturn and a sense of the good fortune we all have
to be alive right now at this time when we actually have the means
to explore and investigate our cosmic neighborhood.
Cassini is surely not the end of the road. Next January, we will finally see the
launch of a mission to Pluto, which will mark the beginning of the conclusion
of this first era of reconnaisance exploration in our solar system.
And so it is a transitional time, and we are standing, if you will, at the
threshhold of what will be a new era of planetary exploration, an era you
might call the Age of Contemplation, when we will be assimilating and
synthesizing all that we have learned in the previous 50 years of
reconnaisance and robotic exploration, all with an eye toward understanding what has made
Earth unique and tremendously successful abode of life that it has become in our solar system.
And there is much left to do over the next 50 years. I hope we will see continued
in-depth exploration of the planets, the moons, the asteroids, and so on,
with samples brought back from these bodies, brought into Earth-based
laboratories for detailed analysis. We will continue our robotics surface exploration
of Mars. We'll surely have additional exploration of Titan, hopefully Saturn's moon
Enceladus. Hopefully we'll see orbiters around every planet.
My fondest wish is that ultimately we will see streaming video from every planet
with associated commentary and explanatory computer graphics and dramatic
vignettes piped into vast banks of television screens in shopping malls
and supermarkets and concert halls!
[audience laughter]
So that these mythic accomplishments of extending our senses and
visiting other worlds will become as much of the fabric of our society as
"The Oprah Winfrey Show" is. And I think that this kind of media blitz
would be a much-needed antidote to the constant reminders of bad news
and human failure that we see all the time on television, and could be
an equally constant counterveiling reminder of the good and the glorious that we can achieve
if we set our minds to it.
I told Andrew I would speak something about spirituality.
I don't know if I have a moment--
--a moment to say something about it. I'll just say that, being a part of the exploration
of our solar system, and being a scientist has, I think, given me a privileged life,
and in fact, a very spiritual one. It has allowed me to feel connected to the workings of
the natural world,
and something very, very much bigger than myself and something whose results
will extend in space and time far beyond my own temporal existence.
And I think it's this inchoate desire to feel connected to something far greater
and immortal that motivates the religious to believe in a higher power.
I, for one, find at least the same gratification, the same spiritual fulfillment and joy
in the revelations of science. I think a greater, more humanistic exposition of these
revelations and connections and a greater exposition of the role that science
has played and continues to play as an integral and transforming feature
of human culture, would go a long way in assisting in the callamatous
confrontation that we see today between science and formal religion.
I think the exploration of our solar system is one of the signature enterprises
of our time. We should be reveling in it. It belongs to us. Thank you.
[from audience:] Yeah! [audience applause]
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Pop!Tech Carolyn Porco

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