Over the past 40 years, a handful of space probes has given us glimpses of Saturn. But NASA’s Cassini, which explored the gas giant’s realm for 13 years, delivered the most breathtaking new insights. NOVA takes you inside Cassini’s epic journey as it makes stunning discoveries: Saturn’s rings are younger than the dinosaurs and may be remnants of an ice moon. And geysers erupting ice and gas on the moon Enceladus show that it could have all the ingredients for life. But to protect it, the Cassini mission team makes a bittersweet decision. (Premiering August 7 at 9 pm on PBS)
The Planets: Saturn
PBS Airdate: August 7, 2019
NARRATOR: A billion miles from the sun, past Mars and Jupiter, a planet like no other…
MICHELE DOUGHERTY (Principal Investigator, Cassini Magnetometer): All you can see is this beautiful vision of the rings around it.
NARRATOR: …Saturn. Of all the distant worlds…
EDGARD RIVERA-VALENTÍN (Lunar and Planetary Institute): Saturn is very weird. Every time we think we have Saturn pegged, we get another piece of evidence that tells us, “No. Everything we thought was wrong.”
NARRATOR: …it’s the most mysterious and alluring.
JEFF CUZZI (Ring Scientist, Cassini): It’s a puzzle you want to solve.
NARRATOR: We’ve visited three times. Pioneer and Voyager offered a passing glimpse…
LINDA SPILKER (Project Scientist, Cassini): We started taking pictures several weeks out.
CAROLYN PORCO (Imaging Team Leader, Cassini): It’s a frenzied period of lots of activity and sleepless nights and discovery and conquest. And then it’s all over.
NARRATOR: but Cassini came to stay…
LINDA SPILKER: And what a wonderland we found.
NARRATOR: …and to astonish…
KEVIN BAINES (Scientist, Cassini): We found water ice, and that basically blew our minds.
CAROLYN PORCO: Just right out of the gate, we saw vertical structures. We just lacked the imagination that it would require to predict what it would look like.
JONATHAN LUNINE (Scientist, Cassini): I think that Enceladus may be the first place where we will discover a form of life that’s independent from life on the earth.
NARRATOR: …and in the end, a heartbreaking choice to save a world.
JULIE WEBSTER (Chief Engineer, Cassini): I was supposed to call “end of mission.” I couldn’t get the words out.
LINDA SPILKER: It’s still hard.
NARRATOR: The Planets: Saturn, right now, on NOVA.
Beyond the warm worlds of the inner solar system, beyond the gas giant Jupiter, in the freezing region far beyond the sun, lies Saturn, a planet made unique thanks to a nearly 45,000-mile-wide ring of frozen water.
Here, trillions of pieces of ice have been sculpted by gravitational forces into some of the solar systems most stunning vistas. Even from nearly a billion miles away, this planet inspires.
CAROLYN PORCO: We were about, 13 or 14 years old, you know, just tootling around trying to find, you know, this and that, and then we saw Saturn. And it’s just so alien and mysterious looking.
MICHELE DOUGHERTY: All you can see is this beautiful vision of the rings around it.
JEFF CUZZI: It’s a thin, flat disk, touching nowhere, you know? It’s, they’re just fascinating. And you just can’t help but wonder what causes that structure.
ED RIVERA: Saturn is very weird. Every time we think we have Saturn pegged, we get another piece of evidence that tells us, “No. Everything we thought was wrong.”
NARRATOR: Saturn is a planet of mysteries. Why did this world become so large? What drives its strange weather? And where did its beautiful, bright rings come from?
Today, our probes are beginning to shed light on these questions, making discoveries which hint that Saturn’s true beauty lies beyond its rings, hidden within its extraordinary moons.
CAROLYN PORCO: We now have what I consider to be the most promising place to go look for life. Will we find life if we go back? I don’t know. Nobody knows. But we want to try.
SATURN PRESENT DAY
NARRATOR: Picture a place with no surface on which to stand, only endless atmosphere. Compared to Earth, Saturn is so alien that it’s hard to imagine how it could have grown from the same ingredients. So how did this incredible, mysterious planet come to be?
4.6 BILLION YEARS AGO
NARRATOR: Saturn begins as a tiny ragged world, tumbling chaotically through space. Just like the inner rocky worlds, it clumps together with other objects to grow. But there is a crucial difference: Saturn is forming far from the sun.
SHAWN BROOKS (Investigation Scientist, Cassini): Among the planets in the solar system, Saturn and Jupiter were two of the first ones to form. They formed at a very unique place in the solar system, what is known as the “snowline.”
LEIGH FLETCHER (Co-investigator, Cassini): Now, the snowline is the location at which the temperature of the original solar nebula got cold enough for ice to form. And that ice then goes on to form the building blocks for the larger planets that are present further out.
JONATHAN LUNINE: Now, what that snowline does is it puts a large amount of additional solid material into this disk. And so, that would accelerate the growth of the giant planets. So, it allowed them to form their cores more quickly than if only rock were present.
NARRATOR: As the infant Saturn sweeps through its orbit, it’s able to scoop up huge amounts of extra frozen matter, unavailable to the worlds of the inner solar system. Under the force of gravity, this abundant ice and rock collides and combines, helping the young Saturn grow into a giant.
Just a few million years after its birth, Saturn has formed into a great ball of rock and ice. So, how did this world become the giant planet of gas we know today? The clues to what happened next would be revealed by one of the most ambitious deep space missions ever attempted.
NARRATOR: The Voyager probes are two almost-identical spacecraft, built to explore the solar system’s distant worlds.
CAROLYN PORCO: Voyager was unlike anything that had come before. It was a long-duration, tricky, uncertain journey across the solar system and beyond.
LINDA SPILKER: We started taking pictures several weeks out, and Saturn just grew larger and larger in those images, and more and more detail.
JEFF CUZZI: I remember getting down to J.P.L., and the whole place was full of all these big R.V.s from all the T.V. networks. And I was amazed that there was all this interest. So I got in, and people showed me these images, and they were just spectacular.
LINDA SPILKER: You could start to see evidence of the banded structure around Saturn. You could start to see detail in the rings, and it was just sort of like watching this zoom in to see Saturn.
JEFF CUZZI: There are all these ringlets and structure and bright and dark; beautiful, beautiful sight.
CARL SAGAN (Archival News Footage): It’s just an amazing harvest of pictures, you know? There’s tens of thousands of photographs of Saturn and its rings and its moons, taken by the Voyager 2 spacecraft.
CAROLYN PORCO: It’s a frenzied period of lots of activity and sleepless nights and discovery and conquest. And then it’s all over.
VOYAGER 1 DEPARTURE
NARRATOR: The Voyager probes completely transform our understanding of Saturn, showing, in great detail, the composition of the upper atmosphere, almost all of it made of helium and hydrogen, the very same gases abundant in the early solar system. It’s critical evidence in piecing together Saturn’s story and its evolution from a rocky world.
4.6 BILLION YEARS AGO
NARRATOR: Just a few million years after the formation of the sun, Saturn is beginning a radical transformation. Many times more massive than the worlds of the inner solar system, its gravity is powerful enough to draw in hydrogen and helium gas.
JONATHAN LUNINE: Saturn got a large core, perhaps 20 times the mass of the earth, that was large enough to cause all of that hydrogen and helium gas around it to collapse onto the core.
LINDA SPILKER: It had enough gravity then to pull in a lot of the other gases, and from that, to grow this huge what we call “gas giant” planet.
KEVIN BAINES: When you get to a certain size, then you start grabbing onto these clouds of water and hydrogen and helium that are still hanging around. It’s a runaway effect. Once you grow a little bit, now you’re going to expand really fast. So, that’s how you grow from a small, relatively small body to a huge body, in only a few million years.
NARRATOR: Just a few hundred-million years after its birth, Saturn is now vast, so big, it could contain 5,000 Earth-sized worlds. Over time, this gas will compress and condense, eventually becoming the second largest planet in the solar system.
The Voyager probes reveal some of the mysteries of Saturn, but they raise more questions than they answer: What is happening beneath Saturn’s strange hazy exterior? Does the planet still have a rocky core? And what is powering the massive storms swirling across its surface?
CAROLYN PORCO: After Voyager was over, all of us were just really eager to go back, because everything we saw we just, you know, we just skimmed the top. We didn’t have time to delve into it.
CASSINI PROBE BUILD
NARRATOR: Just a few years after Voyager’s flyby, planning begins on a new probe, loaded with instruments to uncover Saturn’s secrets.
Building a craft like this is a huge challenge.
MICHELE DOUGHERTY: It’s difficult to put a number on how many people were involved in Cassini; tens of thousands I would say.
JULIE WEBSTER: There’s over 10 miles of wiring in the main harness alone. And you have to check out every wire. It’s a very, very complex effort. So, it took us two and a half years to put the thing together.
CAROLYN PORCO: All of us spent a lot of effort to get to that moment, so there’s a lot of emotion attached to it. And then you see it launch, and you know that it’s on a journey to a very, very distant place, and so, you feel like you’re going, too.
NARRATOR: Cassini is one of the heaviest interplanetary probes ever launched, weighing in at over six tons, but its huge size complicates its route to Saturn.
MICHELE DOUGHERTY: To be able to launch a spacecraft as large as Cassini, with enough fuel to be able to do exciting science out at Saturn, you can’t use all that fuel up in getting out to Saturn. And so what is done is we use flybys past other planets.
It’s almost like two, sort of, billiard balls. If the moving one bumps into the stationary one, it gives the stationary one a bit of energy. So, it’s an exchange of energy. The spacecraft is flown really close to a planet, gets a bit of a kick and gets kicked out onto the next one.
NARRATOR: The journey to Saturn will require two trips past Venus, one past Earth and, finally, a speed boost from Jupiter. These maneuvers help Cassini reach speeds of over 60,000 miles per hour.
But the probe’s most difficult moment is yet to come.
JEFF CUZZI: The one critical sequence: going into orbit around Saturn. You can get there, you throw a rock and the rock flies, but when we get there we have to stop. So, we had to fire the rocket at exactly the right time, in exactly the right direction, for exactly the right amount of time, or after all that planning, we just go right by.
JULIE WEBSTER: The time to get data from Saturn to the Earth is 90 minutes. So, if you send a command to the spacecraft, it takes 90 minutes to get out there, lets the command work it, and then it takes 90 minutes to get back.
Until you get there, there’s always this chance in your mind that something’s not right.
CASSINI MISSION CONTROL: The Doppler has flattened out.
JULIE WEBSTER: So, there was a great deal of relief.
NARRATOR: When Cassini arrives, the images it sends back to Earth are breathtaking.
JEFF CUZZI: I was sitting in what they call the blue room, being interviewed, while they were beaming for the first time. And then one of these pictures came on, and I just went, “Wow, look at that.” That was really the jumping-out-of-the-chair moment for me, and it was just the first day.
CARL MURRAY (Scientist, Cassini): What we were seeing was the highest resolution that had ever been seen. I saw phenomena that I’d only seen in, kind of, computer simulations before. And now I was seeing it for the first time, and, and realizing all this, all this was real.
CAROLYN PORCO: And we were seeing details in the rings that were shocking, shocking. We just lacked the imagination that it would require to predict what it would look like.
NARRATOR: Thanks to Cassini’s powerful instruments, Saturn’s billion-year-old mysteries start to become clearer. Peering into Saturn’s tumultuous atmosphere produces new insights about the planet’s distant past. One of the biggest questions is, “what lies within the clouds?”
KEVIN BAINES: You see clouds of different things floating around, but what are those clouds made of? We didn’t really know until we got there with Cassini. Some of the clouds actually are made of water ice! We found water ice, and that basically blew our minds. It showed there is water down there.
NARRATOR: The discovery of icy clouds, along with the measurements of the gravitational field of the giant planet, hint at what may have happened to the young, rocky, ice planet. Data collected by Cassini suggests that Saturn no longer consists of a rocky core surrounded by a vast atmosphere, but rather it is a single object with no distinct boundaries.
JEFF CUZZI: Saturn doesn’t really have a solid surface anywhere.
LEIGH FLETCHER: That core that presumably was there in the first place, would’ve effectively disintegrated or been mixed in with all of the other material that was present. So, it may be today that the material is still there, but it’s completely distributed within the envelope of Saturn itself.
NARRATOR: What began as a rocky, icy world is now a fully-fledged gas giant. And within its gaseous atmosphere, incredible mechanisms are at play. Saturn’s atmosphere is characterized by many unusual, even bizarre features: huge weather systems that take on strange forms, persisting for hundreds of years, perhaps none more striking than the formation nicknamed the “giant hexagon.” It’s over 16,000 miles across, big enough to swallow almost four Earth-sized objects.
But what could be driving this huge planetary weather system? What powers weather is very different, depending on where you find yourself in the solar system.
KEVIN BAINES: The earth’s atmosphere and the weather on Earth is, is driven, largely by one thing, and that’s the sun. And the sun pours its energy down through the atmosphere and it hits the surface, and the surface of the earth then warms up.
LEIGH FLETCHER: With Earth, you’ve got all the energy coming in from the sun, heating up the surface, creating thermals that then, then drive the atmospheric flows that we see. Somewhere like Saturn doesn’t have a surface to be heated up, so when you compare the weather systems on these giant planets to those that we have on Earth, you have to sort of tear up the rulebook a little bit.
NARRATOR: The sun is the great controller of Earth’s atmosphere, but in the outer reaches of the solar system, where Saturn lives, sunlight is one hundred times weaker. It means some other heat source must be driving Saturn’s weather, something deep within, creating huge complex forms that arise in its atmosphere.
As Cassini studies the cloud tops of Saturn, it’s able to infer a huge amount about the truly strange world that must lie beneath and the energy source that helps power this planet.
CAROLYN PORCO: We had a whole variety of scientific goals at Saturn, and one of the main ones was to understand the meteorology of the Saturn atmosphere and what energizes the winds that we see on it, and so on. And we have affirmed, now, the belief that atmospheric systems on Saturn are actually powered by energy from below, from an internal heat source on Saturn. They’re not powered by sunlight, like we have on the earth.
NARRATOR: Looking deep inside the planet reveals a heat source shaped by extreme pressure. Within huge clouds of water, Cassini records lightning 10,000 times more powerful than any on Earth. This lightning transforms methane gas into enormous clouds of soot.
At 5,000 miles deep, the pressure of the atmosphere is 80 times greater than that at the bottom of our deepest oceans, enough to transform this sooty, graphite rain into diamonds. But even these diamonds are likely destroyed by the pressures of Saturn, eventually dissolving.
Eighteen-thousand miles down, Saturn’s heat source is revealed. Here, pressures are so intense that the atmosphere behaves like a liquid metal, able to conduct electricity. In this state, molten helium falls like rain. As this strange rain merges with the surrounding material, kinetic energy is released as incredible amounts of heat. And it’s this extraordinary heat source that helps drive Saturn’s weather.
Within just a few hundred-million years of its birth, Saturn has witnessed great drama. Now it will remain largely unchanged for billions of years, vast, but still very different from the planet we know today.
And in time, its great size will lead to its ultimate, iconic transformation.
JEFF CUZZI: The rings have always made Saturn kind of special. If you ask a kid to draw a picture of a planet, they will draw a picture of Saturn.
CAROLYN PORCO: Saturn’s rings are what you would call a debris disk. It’s a collection of icy particles, ranging in size from the largest being the size of small apartment buildings, all the way down to just the tiniest little piece of dust.
NARRATOR: But the sparkling brilliance of Saturn’s rings are a mystery.
JEFF CUZZI: They’re so white and purely ice. But we know that Saturn’s rings are being bombarded all the time by meteorites from the outer solar system, which are not white, they’re dark; they’re sooty, like charcoal.
SHAWN BROOKS: We know that the rings are exposed to in-falling material and that they appear to be contaminated by this material. I like to give the analogy of fresh snow in the city: eventually, over time, the snow just kind of gets dirty.
NARRATOR: So, why are the rings so bright? Thanks to a series of flybys, Cassini is able to make a startling discovery.
JEFF CUZZI: They cannot stay as bright and clean as they are today, if they’re much older than one-hundred-million years.
CARL MURRAY: At the end of the day, you have to accept the evidence, and the evidence says that the rings are actually much younger than we thought.
CAROLYN PORCO: So, it means that during the time of the dinosaurs, Saturn didn’t have rings. Some Velociraptor with a telescope, looking at Saturn, would not have seen rings.
NARRATOR: So, if the rings are young, then where did they come from? Cassini would give us hints that the answer lies not with planet itself, but with the worlds trapped in orbit around it, Saturn’s moons.
ROBERT PAPPALARDO (Former Project Scientist, Cassini): The surfaces of these moons are like storybooks, telling us about the history of how the Saturn system, how these moons evolved. Our job is to unravel the story that that moon is telling us.
LINDA SPILKER: Saturn has 62 moons. Some of them look like flying saucers or pancakes or potatoes. They are very irregularly shaped. Once a moon gets bigger, its gravity tends to round it out, and you get more of a rounded, nicely shaped moon.
JONATHAN LUNINE: The moons are the archaeological debris from planet formation. And the, their size, their orbits, even their composition, tell us about the details of the environment within which they formed. So, it’s possible, in the case of Saturn, that we can use the different moons to understand different eras, different epochs of the evolution of Saturn.
NARRATOR: As Cassini continues its journey, it reveals many moons made almost entirely of ice. And some of them take on extraordinary forms in and around the rings.
17 MILES ACROSS
255 MILES ACROSS
950 MILES ACROSS
NARRATOR: Cassini analyzes the ice moons in ever-greater detail. And it becomes apparent many of them are made of the same icy material as the rings themselves, which suggests that Saturn’s rings may once have been a moon.
CAROLYN PORCO: The satellite system that we’re seeing around Saturn now is probably not the original satellite system that it had, because if the rings were created by the destruction of one or two pre-existing moons, it means that there were moons before that don’t exist any longer.
10-100 MILLION YEARS AGO
NARRATOR: Millions of years ago, Saturn has an extra moon, perhaps 250 miles across and formed almost entirely of ice. But this moon is doomed. It’s orbiting just too close to resist the immense forces of Saturn’s gravity.
LINDA SPILKER: The rings probably formed from an object that got too close to Saturn. There’s this invisible boundary around Saturn, called the “Roche limit,” and that’s the limit, depending on what you’re made of, where Saturn’s gravity is strong enough it will actually pull you apart, that the gravity on the side closer to Saturn is strong enough that compared to the gravity on the other side, it will literally rip you apart. You don’t have enough gravity of your own to stay together.
NARRATOR: A leading theory suggests that just beyond Saturn’s atmosphere, an ice moon approaches close to or even just inside its Roche limit. As Saturn’s immense gravitational force pulls it apart, the moon begins to rupture catastrophically, a world ripped apart by its proximity to a giant.
Up to seventeen-thousand-trillion tons of ice breaks apart in orbit around Saturn. And thanks to the speeds this material is travelling, it’s likely that in just a few days it spreads out to encircle the great giant. Saturn’s iconic ring is now in place.
But as Cassini turns its instruments towards it, it sees a single ring, transformed.
CAROLYN PORCO: The images we returned, they were phenomenal. They were resolution a factor of maybe 20 times better than anything we had had before.
NARRATOR: Today, Cassini reveals how Saturn’s giant rings have evolved. This debris now forms a disk wider than Jupiter, yet, on average, just 30 feet thick. Within, moon-sized chunks of ice orbit the structure, clearing great voids, turning one ring into many.
But it’s as Cassini captures images with the sun directly above the equator that the most surprising feature of the rings emerges.
CAROLYN PORCO: We knew this was going to be a time for us to investigate the third dimension, something that you don’t get to see when you just look at a picture of Saturn’s rings. And what we found was staggering. Just right out of the gate, we saw vertical structures. I just can’t tell you how surprised we were to see this. It’s just the spectacle of it was just unanticipated.
I have just imagined flying along in a shuttlecraft across the ring, right close to the ring, so, to my perspective, it would be almost like it was an infinite sheet of gleaming debris, and I’m flying along and flying along and flying along and suddenly I come upon a wall of rubble that’s two miles high. I mean, is that cool or what? Really, I’ve said over and over again, they should put that in a movie.
NARRATOR: This once tiny world of rock and ice that has seen the most dramatic transformations is today the solar system’s greatest jewel.
After more than a decade in orbit, Cassini has forever deepened our understanding of Saturn. But its mission is far from over, because just beyond the rings lies another treasure, a tiny world that may hold answers to some of our deepest questions about the possibility of life in the solar system: the ice moon Enceladus.
MICHELE DOUGHERTY: Enceladus is one of the moons in a regular orbit around Saturn. It’s quite small, its diameter is 500 kilometers.
ROBERT PAPPALARDO: From far away, it looks smooth. When we look at it close up, we see that those smooth areas are really places where there’s been fracture upon fracture, fault upon fault, destroying, disrupting the surface.
CAROLYN PORCO: Got to see these five prominent fractures, deep, long fractures crossing this region. And eventually, over time, we were able to find that there were geysers coming from those fractures.
NARRATOR: Cassini discovers this tiny moon is alive with activity. Its giant plumes eject over 500 pounds of ice and water vapor into space every second.
MICHELE DOUGHERTY: I think for me, and for a lot of scientists on Cassini, the biggest surprise was that Enceladus was active. There’s this little moon out there, which is supposed to be dead, and it’s spewing out this vast amount of water vapor.
CAROLYN PORCO: It became clear, once we had found the plume, that we needed to get as deep into it as possible. Cassini, over 13 years, did 23 flybys. We flew through the plume in about a dozen of those.
NARRATOR: Piloted from nearly a billion miles away. Cassini, on its closest flyby, passes within just 30 miles of the surface of Enceladus. And what its instruments detect is breathtaking.
LINDA SPILKER: We were able to sample directly the material coming out of Enceladus’ plume, and what a wonderland we found.
JONATHAN LUNINE: We are sampling a subterranean or subsurface ocean. And indeed Cassini, as it flew through the plume, found, not only water vapor and water ice, but salts.
ROBERT PAPPALARDO: Some of these particles, the fact that they’re salty tells us, almost certainly, that they came from an underground ocean. Under that ice, there is an ocean, and then beneath that ocean is rock.
NARRATOR: And it is there because of Saturn. As Enceladus moves around the planet, its vast gravitational force pulls at the moon, holding it in orbit. But every couple of orbits, another larger moon, called Dione, draws Enceladus back. This process repeatedly stretches and squeezes its core, warming and melting the icy interior.
But it’s what Cassini finds next that changes everything. As the plumes are analyzed in ever-greater detail, scientists discover complex organic compounds.
MICHELE DOUGHERTY: Once we got over our shock, we then started focusing on the fact that there was organic material leaking out from this little moon as well, and then everyone got excited.
JEFF CUZZI: So, here you have a hot, liquid, salty, organic-rich, sub-surface ocean, and a lot of people feel that this is one of the better places where life may even exist today in the solar system.
CAROLYN PORCO: I don’t know what to think. I just know that, you know, Enceladus is a place that we know more about. It’s a, it’s an alien environment that meets all our formal requirements for a place that could support life.
NARRATOR: Deep beneath Enceladus’s icy shell, hot rock is in contact with water, almost certainly creating hydrothermal vents. On Earth, these types of vents support a multitude of life, and leading theories suggest that these might have been the setting for the emergence of life on Earth, which makes some wonder if the same thing is happening on Enceladus.
JONATHAN LUNINE: I think that Enceladus may be the first place where we will discover a form of life that’s independent from life on the earth, which would be one of the most spectacular discoveries that science has ever made.
LINDA SPILKER: If it doesn’t have life, that would be equally amazing, too, because here you have the conditions right for life and yet it didn’t form, so maybe you need something else to get life started.
NARRATOR: But for Cassini’s scientists, the exotic world under the ice of Enceladus is a bittersweet discovery.
SEPTEMBER 15, 2017
MICHELE DOUGHERTY: As we were approaching the end-of-mission phase, we were essentially running out of fuel. We knew we had to end the mission somehow.
LINDA SPILKER: And to protect, in particular to protect Enceladus, because it would be pretty bad to go back to Enceladus and discover life and it turned out to be Earth microbes on Enceladus. So…we didn’t sterilize Cassini; we didn’t know we had to.
CAROLYN PORCO: You don’t want to go to a place like Enceladus and find something that the previous spacecraft delivered there.
CASSINI MISSION CONTROL: This is BCS1. We just have transmission high rate mode.
JPL MISSION CONTROL
NARRATOR: Cassini ends its mission in spectacular fashion, making a series of ever-closer orbits to study the planet’s rings, before a final dive into Saturn’s atmosphere, a journey from which it will never return.
MICHELE DOUGHERTY: Some of us were concerned the spacecraft wouldn’t even survive the first orbit, because we were going through the gap between the rings and the atmosphere of Saturn. We didn’t know what was there. We thought it was empty, but we weren’t sure.
NARRATOR: Cassini survives its approach to Saturn intact and continues on towards its demise.
MICHELE DOUGHERTY: We were out at J.P.L., watching the signal come in from the spacecraft, and there was a spike.
LINDA SPILKER: And it went away, but it seemed to come back.
MICHELE DOUGHERTY: Because the spacecraft hadn’t been told its life was ending, and so it had been programmed to keep in touch with the Earth, so it moved itself.
CASSINI MISSION CONTROL: Can we call loss of signal at 115546?
LEIGH FLETCHER: The last command that my colleagues uploaded to the spacecraft was a list of the 200 or some scientists and engineers that had been involved in the development of one of the instruments, which means that as Cassini was literally disintegrating, in its computer memory was a final thought of home. And I think that’s just a tremendous, tremendous thing.
CASSINI MISSION CONTROL: We’ve just heard the signal from the spacecraft is gone and within the next 45 seconds, so will be the spacecraft.
MICHELE DOUGHERTY: And then it lost control, it began to tumble.
NARRATOR: The world that had has borne witness to some of the greatest dramas in the solar system’s history consumes the craft that has given us its remarkable story.
CASSINI MISSION CONTROL: Congratulations to you all.
JULIE WEBSTER: I was supposed to call, “End of mission. Thanks and Godspeed, Cassini.” I couldn’t get the words out.
LINDA SPILKER: There was some applause, but mostly people just...
CARL MURRAY: People were just looking at each other. It was, it was so sad; really, really sad.
LINDA SPILKER: It’s still hard.
NARRATOR: We journeyed out to Saturn to see this great beauty up close, to understand its deep history and explore its rings. But in the end, we were rewarded with something far more profound, early hints of a second home for life.
JEFF CUZZI: It’s sad that Cassini is no longer up there doing its thing, but it has left us a tremendous legacy of data that is going to keep us all busy for decades.
KEVIN BAINES: It’s revealed so much, and there’s still secrets in that data that, that become unlocked…I’m convinced graduate students 20 years from now will be finding new things in that data that we didn’t, didn’t know were there.
LINDA SPILKER: Now, when I go out in the night sky and look at Saturn, I know Cassini is there, that the bits of Cassini will always be part of Saturn. Saturn will never be quite the same.
CAROLYN PORCO: We landed a device of our own making on a world in in the outer solar system. We spent 13 years, you know, in the…just methodically, quietly, just monitoring, observing. And it’s, it, to me, it represents the best that humanity has to give. It’s really, it’s us at our finest.
PRODUCED AND DIRECTED BY
EXECUTIVE PRODUCER FOR BBC STUDIOS
ASSISTANT PRODUCER & ADDITIONAL DIRECTING
DIRECTOR OF PHOTOGRAPHY
Lola Post Production
Anže Rozman for Bleeding Fingers Music
Christopher J. King
POST PRODUCTION COORDINATOR
JUNIOR PRODUCTION MANAGER
Miguel Arnott Muzaly
BBC Motion Gallery
NASA/JPL/ASI/University of Arizona
NASA/JPL-Caltech/Space Science Institute
NASA/JPL-Caltech/Space Science Institute/Kevin M. Gill
NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill
Ocean Exploration Trust, Inc
Woods Hole Oceanographic Institute
ACADEMIC CONSULTANTS FOR THE OPEN UNIVERSITY
Stephen R. Lewis
David A. Rothery
For BBC Studios
BBC COMMISSIONING EDITOR
NOVA SERIES GRAPHICS
yU + co.
NOVA THEME MUSIC
ADDITIONAL NOVA THEME MUSIC
The Caption Center
POST PRODUCTION ONLINE EDITOR
Lindsey Rundell Denault
DIGITAL ASSOCIATE PRODUCERS
DIGITAL MANAGING PRODUCER
SENIOR DIGITAL PRODUCER
PROGRAM MANAGER, NOVA SCIENCE STUDIO
DIRECTOR OF EDUCATION AND OUTREACH
DIRECTOR OF NATIONAL AUDIENCE RESEARCH
AUDIENCE ENGAGEMENT EDITOR
DIRECTOR OF AUDIENCE DEVELOPMENT
DIRECTOR OF PUBLIC RELATIONS
LEGAL AND BUSINESS AFFAIRS
POST PRODUCTION ASSISTANT
SENIOR PROMOTIONS PRODUCER AND EDITOR
Michael H. Amundson
SENIOR EXECUTIVE PRODUCER, EMERITA
Paula S. Apsell
SENIOR SCIENCE EDITOR
SENIOR SERIES PRODUCER
DIRECTOR, BUSINESS OPERATIONS & FINANCE
Julia Cort Chris Schmidt
A BBC Studios Production with NOVA and WGBH Boston for PBS [logo] and BBC Earth [logo]co-produced by Tencent Penguin Pictures and The Open University.
© 2019 BBC
The Planets Additional Material © 2019 PBS
All rights reserved
Additional Material © 2019 WGBH Educational Foundation
All rights reserved
This program was produced by WGBH, which is solely responsible for its content. Some funders of NOVA also fund basic science research. Experts featured in this film may have received support from funders of this program.
Original funding for this program was provided by Draper, the David H. Koch Fund for Science and the Corporation for Public Broadcasting
Image: (CG illustration of Saturn)
Created by Lola Post Production/© BBC Studios
- Kevin Baines, Shawn Brooks, Jeffrey Cuzzi, Michele Dougherty, Leigh Fletcher, Johnathan Lunine, Carl Murray, Robert Pappalardo, Carolyn Porco, Edgard Rivera-Valentín, Linda Spilker, Julie Webster