The Story of Space Imaging with Carolyn “Madam Saturn” Porco

How much has space imaging furthered our understanding of the Universe? Neil deGrasse Tyson and comedian Chuck Nice learn the story of cameras on space probes like Voyager and Cassini and the exciting science of Saturn with planetary scientist Carolyn Porco.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  Up next on StarTalk, I've got my friend and colleague Carolyn Porco, otherwise known as Madame Saturn, and she's going to tell us about the history of getting cameras onboard space probes. We'll also find out what gives Saturn its colors and what else is in store for us. Not only the pale blue dot taken by Voyager, but its reprise taken by Cassini, and we'll reflect on the meaning and significance of Moonrise, that iconic picture taken by Apollo 8.

• 0:35Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide.

• 0:44Neil deGrasse Tyson?

  StarTalk begins right now.

• 0:48Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson here, your personal astrophysicist. Got with me Chuck Knight. Chuck, how you doing, man?

• 0:55Chuck Nice?

  Oh, great, man. How's it going?

• 0:57Neil deGrasse Tyson?

  All right. You're my co-host extraordinaire.

• 1:01Chuck Nice?

  Oh, fantastic.

• 1:02Neil deGrasse Tyson?

  I don't tell you that as often as I want to.

• 1:04Chuck Nice?

  I'll take it anytime I can get it.

• 1:07Neil deGrasse Tyson?

  We've got a special guest today.

• 1:09Chuck Nice?

  Yeah.

• 1:09Neil deGrasse Tyson?

  A longtime friend and colleague, Madame Saturn.

• 1:13Chuck Nice?

  Yes.

• 1:14Neil deGrasse Tyson?

  Does she have a name beyond that? I don't know, and I don't think so, but until we verify, let's call her Carolyn Porco. Carolyn, welcome back to StarTalk.

• 1:24Carolyn Porco?

  Thank you. It's great to be here. Hello to both of you. You both look great. It's good to see you again.

• 1:29Neil deGrasse Tyson?

  Excellent.

• 1:29Chuck Nice?

  Good to see you.

• 1:30Neil deGrasse Tyson?

  Excellent. We got you on because we're going to talk about world-changing, civilization-moving space images. And you've been a part of this parade of cosmic perspectives that have come to us from photography in space. And I'm delighted to sort of get your take on this and what roles you played in the past, present, and maybe even the future. So Carolyn, I've got a three-line bio for you. This is, I think, encapsulates why we've got you on the show today. You were a member of the Voyager imaging team. Voyager was launched back in 1977, so you've been at this for a while. You're also a leader and head of

• 2:12Neil deGrasse Tyson?

  the imaging team of Cassini that was NASA's mission to Saturn.

• 2:18Neil deGrasse Tyson?

  And are currently your visiting scholar at UC Berkeley. And my favorite planet after Earth is Saturn. And so every day I was looking at my inbox to see if a new beautiful image was coming from your Saturn portfolio. So Carolyn, welcome back to StarTalk.

• 2:35Carolyn Porco?

  Thank you. Thanks for having me.

• 2:37Neil deGrasse Tyson?

  And let me add to that three-line resume, Carolyn, that on July 19th, 2013, you oversaw the, an image taken by the Cassini spacecraft while it orbited Saturn called "The Day the Earth Smiled." And many have called that the greatest selfie ever taken. Now, before we go there, before we go there, because there's some earlier tracking I want to get through. So Carolyn, as I've come to understand, the early planetary probes, as conceived by NASA, did not contain cameras. They contained all manner of sophisticated scientific equipment to measure like magnetic

• 3:18Neil deGrasse Tyson?

  fields and, and, and plasma densities and all this, but not photos. And so what do you know about the history of this?

• 3:27Carolyn Porco?

  Yeah, it has a very interesting history and not surprising. Carl Sagan is involved in this because he was one of, one of the original planetary, planetary scientists. In fact, the Voyager imaging team leader, Brad Smith, referred to Carl as the first planetary scientist. But anyway, it was the first maritime mission to Venus. This was going to be the first mission to a planet because we'd begin with, you know, Ranger, Surveyor, so on to the moon. It was the first mission to Venus and the...

• 4:04Neil deGrasse Tyson?

  And Venus is, of course, the closest planet to Earth. So why wouldn't it be Venus? You go to the closest place.

• 4:10Carolyn Porco?

  Yeah. Good idea. So anyway, the scientists, the scientists involved in that mission did not want to carry a camera. And they said, and this was told to me by Carl, they said that they thought essentially that cameras were for kids. You know, there was no really, you know, important science that could be done with a camera. And it was Carl, Carl tried to convince them that that wouldn't be a, you know, a sensible thing to leave off the camera. They didn't believe him and he lost the battle, but he won the war because all future missions thankfully carried cameras. And it's just, it just shows you how silly

• 4:55Carolyn Porco?

  people can be because what is an imaging device, especially a space imaging device that takes, you know, a scene and turns it into an array of numbers which get relayed back to Mother Earth? What is that except a bunch of detectors? In fact, in the case of Cassini, a million, a thousand on the side, a millionth individual detectors arrayed in two dimensions. They're okay, the scientists were okay with carrying one detector that could just look in one spot, take whatever information it needed. For some reason, they did not like the idea of a two dimensional array of a million of these things. But anyway,

• 5:40Carolyn Porco?

  that's, it's true. It was, there was really strong pushback against carrying a camera. And we know of-

• 5:45Neil deGrasse Tyson?

  But isn't it, it's not, well, it's not because they were just ignorant. It's that if you're going to carry a camera, that means you can't carry something else. Right? Every ounce matters on these space-

• 5:58Carolyn Porco?

  I know, but what-

• 5:58Neil deGrasse Tyson?

  For the-

• 5:59Carolyn Porco?

  Okay, but what they couldn't see was the utility in imaging data. That's really what it came down to. But, you know, with cameras, I don't, they didn't do this on the early missions, but with cameras, of course, you can take movies, you could see phenomena as they're developing, and you could put filters in front of cameras and you can, you know, put, you make spectral measurements and so on. But, but anyway, I just, as an interesting footnote to the history of planetary exploration, that it was actually pushback against cameras when cameras, I mean, just look at the handles of, of-

• 6:38Carolyn Porco?

  You know, the discoveries that have been made and the planetary program and how much of it is there because of imaging devices.

• 6:48Neil deGrasse Tyson?

  So you're saying these original planetary scientists were boneheaded? That's what you're saying?

• 6:52Carolyn Porco?

  No, you said it. You said it.

• 6:54Neil deGrasse Tyson?

  I said it. I'll say it.

• 6:56Carolyn Porco?

  Okay.

• 6:57Neil deGrasse Tyson?

  I'll say it.

• 6:57Carolyn Porco?

  But you know what? We still have boneheaded scientists. I'm just not going to mention any names.

• 7:05Neil deGrasse Tyson?

  So tell me about the pale blue dot and Voyager.

• 7:07Carolyn Porco?

  Okay, so I love talking about.

• 7:09Neil deGrasse Tyson?

  Because we're speaking, you lived it. So this is oral history as well as scientific history.

• 7:15Carolyn Porco?

  Yeah, so I'm going to tell it to you from my point of view. I was made an imaging team member officially after I graduated Caltech in May. And then I finally moved to Arizona to be a postdoc under Brad Smith, the Voyager imaging team leader. And that's when I became an official member of the Voyager imaging team. And soon after that, I began hawking around this idea to take a picture of the Earth from the outer solar system. And I had in mind, you know, the perspective that it would give us of our place.

• 7:54Carolyn Porco?

  I also had in mind that it would show what aliens coming to the Earth would see. You know, to take a picture of the Earth and all the other planets.

• 8:05Neil deGrasse Tyson?

  Aliens coming to the solar system would then see Earth in the distance.

• 8:08Carolyn Porco?

  Yes, that's right. So I just thought this would be a cool thing to do. And I began hawking it around. I spoke to Brad Smith about this. I spoke to Ed Stone about this, who was the project scientist Voyager. Okay?

• 8:24Neil deGrasse Tyson?

  Gotcha. And would he later become head of the Jeff Polis?

• 8:27Carolyn Porco?

  Yes, he did for a time. He was the head, yeah, after Voyager. But anyways, so I was told by Ed Stone, you know, no, we're not going to take an image like this unless you can find some science to it. Ed was a professor at Caltech and one of the, just a gem of a guy. And he was trying to encourage me. He said, "Go find some science you can do with this, and maybe we'll do it." And I couldn't think of any, and I ended up going off and doing something else. But meanwhile... Few years go by, it's 1988, and I find out that Carl Sagan had proposed the same thing. He had done it a year or two before I did,

• 9:09Carolyn Porco?

  but he was also having trouble getting anyone to, you know, want to get interested in this. Certainly not the project leadership, not at STON, but the other, the managers at JPL, because they would have been a dangerous thing to do in those days. Take a picture like that because the Huygens antenna on Voyager was always, 100% of the time, pointed towards the Earth, and they feared if you had to take the Huygens antenna off the Earth, in order to move the camera into place to take the picture, we might lose the spacecraft. So it turned out, not until 1989 was it clear that we were going to be able to do this. So, and I should say, that I told Carl, after I found out that he was trying to do it,

• 9:54Carolyn Porco?

  I met him at a DPS meeting, Division of Planetary Scientists meeting, and said, you know, I was trying to do this too, and I didn't get anywhere. He said, why don't you join me and help us? So I was tasked with computing the exposure times for, for the pictures we were going to take. We ended up taking six, six of the eight planets, and, and the picture finally was, happened, and it really happened, this is why Carl really gets the credit here. He had to go to NASA headquarters, speak to NASA headquarters people to get permission and get the funding to take this picture. And I think the funding amounted to, in present day dollars, would have amounted to something

• 10:39Carolyn Porco?

  like asking for $4 million. You know, it was, was asking a lot, I guess, to do this. So, anyway, it finally got done, and lots of people poo-pooed this idea, and people thought, you know, it's only going to be less than a pixel. How could this possibly be an interesting, an interesting picture? But as we all know, it's what Carl had to say about it. And the way he romanced it, and he turned it into an allegory on the human condition that has turned it, the picture and the phrase "pale blue dot", into a meme, if you will. You know, it really, and, and a, well, like I said, it's an allegory of, of where we stand. So that, that established...

• 11:22Carolyn Porco?

  Almost a protocol in planetary exploration because it seems like every mission since then has taken a picture of the Earth. So there's pictures of the Earth taken from the surface of Mars, pictures of the Earth's from the Galileo spacecraft on its way to Jupiter and so on. And of course...

• 11:42Neil deGrasse Tyson?

  So Carolyn, I'm stuck on something. Why would pointing a camera cost $4 million?

• 11:49Carolyn Porco?

  Because you had...

• 11:50Chuck Nice?

  It was a Kodak. It was a Kodak.

• 11:56Neil deGrasse Tyson?

  What's the film made of? Gold? I mean, what? Is it the procedures? It was just the effort? The overhead?

• 12:04Carolyn Porco?

  It was keeping the marching army at JPL that managed and ran the whole project and took care of the spacecraft, keeping them all on board for some extra time. That was basically part of it. For most of it.

• 12:25Neil deGrasse Tyson?

  Okay, so it's during the time you were taking that picture, they're not doing anything else that they should have been doing. And so then you can cost that up and you get to $4 million. That's what you're saying?

• 12:37Carolyn Porco?

  No, we didn't do that picture until the mission, the Voyager planetary portion of the mission was over. So no stop...

• 12:46Neil deGrasse Tyson?

  So you had to keep it... You had to keep the marching army marching. That's what it is.

• 12:50Carolyn Porco?

  Yes, yes.

• 12:51Neil deGrasse Tyson?

  That makes sense.

• 12:52Chuck Nice?

  It was basically overtime. Is that it? It's like, we can't do this. We have to pay overtime.

• 13:00Neil deGrasse Tyson?

  Everybody gets time and a half.

• 13:02Chuck Nice?

  How much we can't do?

• 13:03Carolyn Porco?

  You're laughing. You're laughing, but it really was sort of like that. So...

• 13:09Chuck Nice?

  Okay.

• 13:10Carolyn Porco?

  Anyway, so it was only a...

• 13:13Neil deGrasse Tyson?

  So just, I have to interlude. I have to quick interlude. I have an excerpt here from Carl Sagan's Pale Blue Dot, the book, which is probably among the most quoted sentences of the entire book, if you allow me.

• 13:26Carolyn Porco?

  I will allow you.

• 13:28Neil deGrasse Tyson?

  Okay, okay, thank you. By the way, you're supposed to be listening to this while you're looking at this pale blue dot. Okay, here it is. "Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe are challenged by this point of pale light."

• 13:49Neil deGrasse Tyson?

  Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

• 14:05Neil deGrasse Tyson?

  And it goes on and on and on, but that, and that's just representatively beautiful of a very long passage, and it's a take on that pale blue dot.

• 14:22Speaker 03

  Hey, I'm Roy Hill Percival, and I support StarTalk on Patreon, bringing the universe down to earth. This is StarTalk with Neil deGrasse Tyson.

• 14:38Neil deGrasse Tyson?

  Not many people know who, who have seen these beautiful passages from Carl about the pale blue dot, that a big part of this recitation is Carl explaining what a pixel is. This was early before that became common knowledge, right? What a pixel, how to think about it, how much resolution is there? So he goes through a whole disclaimer, or a primer, on how to look at a digital image, and what a pixel is, and that Earth barely fills a pixel. And, but one thing that he did not make clear is that Earth barely fills a pixel because of the resolution of the camera.

• 15:20Neil deGrasse Tyson?

  A higher resolution camera would have had many more pixels to represent Earth, but he never really went there. And you're left thinking, oh my gosh, from space, Earth is only one pixel. So we now fast forward, how many years, we go to the, Carolyn is ready to just knock, knock one out of the park. So Carolyn, pick us up at Saturday. Now we're up, now we're up to two pixels.

• 15:43Carolyn Porco?

  Well, okay, but let me, let me just say, let me just say, I have to be, I'm gonna nerd out on you, is that okay?

• 15:50Neil deGrasse Tyson?

  Yes.

• 15:51Carolyn Porco?

  I'm just gonna say that it's not only the size of the pixel, it is the diffraction limit of the camera that counts too. So there are, you know, you could have, you could have a CCD with a billion pixels on a side in, you know, at the focal plane of your telescope. But if your telescope has a certain diffraction limit, you can't see anything better than that. So, so it's a little bit more tricky. But anyway, fast forward where, where I get to be the imaging team leader on Cassini, less than a year from the time the Voyager pale blue dot was taken, and I had at the top of my bucket list, certain items that I wanted to do.

• 16:35Carolyn Porco?

  One was, I was gonna make sure that we did what the Voyager people really never got a good chance to do, and that was, as much as we could, put out true color images, because I wanted people to see what the solar system with Saturn and everything in it really looked like. And then another was, where we could use the cameras as movie cameras and just take repeated imagery, so that we could see phenomena as they were happening, and we did that in spades. And then finally, it was to redo the pale blue dot. And it didn't happen, it didn't really happen, I didn't have the time, we didn't have the,

• 17:16Carolyn Porco?

  the, things just weren't, you know, all set up the way they should need it.

• 17:21Neil deGrasse Tyson?

  Wait, just again, to put this in time context, the Voyager was launched 1977, it was passing Neptune in 1980, so it's done with the planets.

• 17:31Carolyn Porco?

  No, 1980, no, no, no, 1989.

• 17:33Neil deGrasse Tyson?

  No, 1990.

• 17:34Carolyn Porco?

  Eighty-nine.

• 17:35Neil deGrasse Tyson?

  Okay, no, but the pale blue dot was 1990, correct?

• 17:38Carolyn Porco?

  Valentine's Day 1990.

• 17:40Neil deGrasse Tyson?

  Gotcha. So it took 13 years to get far enough out beyond the orbit of Neptune for everyone to say, "We're done with the Voyager's scientific mission. Now let's do this frivolous stuff, like take a picture of Earth." And so with the $4 million, the craft stays online, takes the picture, so now it's 1990. You are now appointed to the imaging team head for Cassini a year after that. That's all correct? Did I get my timeline?

• 18:09Carolyn Porco?

  Yes. Pale blue dot happened Valentine's Day 1990. November 13th, 1990, I get a phone call from NASA headquarters telling me I'm the imaging team leader.

• 18:20Chuck Nice?

  Hmm, I'm sure those people who didn't want to pay overtime were like, "Damn."

• 18:29Carolyn Porco?

  Well, there was, you know, well, anyways, so, and my first team meeting, my first team meeting was, I think, early December of 1990, and that's when I told my, you know, I didn't tell them we wanted, we're gonna do the pale blue dot, but that's where I set my goals for the team. But anyway, so, fast forward a number of years again to 20, I don't know what it was, 2010, 11, and I'm starting to think, where can I find the time or in the, in the, uh, the plans for all the imagery we were gonna do, uh, where can I slot in another pale blue dot? And in doing that, trying to think of where we were gonna put it, it occurred to me how

• 19:11Carolyn Porco?

  great it would be if we just do the pale blue dot with a twist. And that twist was gonna be that, I thought, we'll invite people the world over to participate in this. We'll tell them ahead of time, not after the image is taken, like everybody else had done up until that point, we'll tell them ahead of time, at this certain time and date, we're gonna take a picture of you here on the Earth, that the window, the picture-taking window lasts 15 minutes, we want you all to go out, you know, straighten up, comb your hair, go out, you know, and look up, you know, at the sky, even if you're on the other side of the Earth, look up.

• 19:54Neil deGrasse Tyson?

  Wait, I saw Chuck in that photo, he had like, he had spinach in his teeth. And clearly I was not wearing pants, so.

• 20:04Carolyn Porco?

  Well, anyway, it wasn't so clear Chuck, don't worry about it.

• 20:08Chuck Nice?

  Okay, good.

• 20:13Carolyn Porco?

  So.

• 20:13Neil deGrasse Tyson?

  Okay, so I remember Carolyn, because there were news articles about this, to get everybody to participate. So, do you know, at the end of the day, how many people looked up and smiled?

• 20:22Carolyn Porco?

  I don't really know. I think we estimated tens of thousands. And I really, to be honest with you, I had plans to make it a big event. I even had applied to the TED people, you know, the TED conference?

• 20:35Neil deGrasse Tyson?

  Right.

• 20:36Carolyn Porco?

  They give out a million dollar prize for a big project. And I thought, this is just going to be up their alley. And I applied to them and they didn't, they didn't choose it. But the idea was to just, you know, make it a big event, a teaching moment, all around the globe. And that never happened. But anyway, people did participate. We said, you know, just go out, look up at the sky, think of all of us here on this planet, all of Earth's creatures on one planet. Think of our isolation and the blackness of space. And think of how precious life is and our own lives are on this planet. And just smile at being alive on a pale blue dot. And that was kind of the directive. And we set up a website, people

• 21:20Carolyn Porco?

  wrote in, and it was really moving for a lot of people. So I was very, and the picture, of course, turned out like, just, it's a killer picture.

• 21:28Neil deGrasse Tyson?

  Stunning, with, in the shadow of Saturn. It's one of, one of the more brilliant photos, I think, ever taken.

• 21:34Carolyn Porco?

  I know. And it was the first time we ever had seen the Earth and Saturn and the whole thing together, just like that. So, and I've been told, Neil, literally, people I know who are in your audiences, this has been happening for years, they write me an email, they say, do you know Neil deGrasse Tyson is showing your image right now? And he's saying great things about you. So, anyway, thank you for that. Thank you for that.

• 22:00Neil deGrasse Tyson?

  Yeah, yeah, I call you out every time. I say, Carolyn Borgo. And I also let people know that you're active on social media, so they can find you.

• 22:08Carolyn Porco?

  Okay, good. Good, thank you.

• 22:09Chuck Nice?

  So Carolyn, when I look at these Cassini images, I'm often struck by the colors. And so what makes the different colors?

• 22:17Carolyn Porco?

  The different colors basically come down to...

• 22:22Carolyn Porco?

  Two, two different phenomena. One is just basically different materials, different compositions, okay? Different, in the atmosphere of Saturn, different compounds. Organic materials of one kind or another. They have different colors, right? So, that's, that's what you're seeing in the atmosphere of Saturn. The same thing in the rings. There are impurities in the rings. And they give the rings, even though they're mostly water, largely water, there are impurities and they can, from afar, they can look like color to your eye, okay?

• 23:01Neil deGrasse Tyson?

  Of course, it's frozen water, just to be clear.

• 23:04Carolyn Porco?

  It's ice, yes.

• 23:05Neil deGrasse Tyson?

  It's not, it's not a bathtub.

• 23:07Carolyn Porco?

  Not a bathtub. But there are times when you are seeing a phenomenon known as refraction or diffraction to different phenomena that actually they work. If you're looking at different angles, the object at different angles, you'll see different colors. So, it's, it's just light, electromagnetic radiation interacting with atoms of different types, different types of atoms that can produce different colors. Okay, and as far as true color goes, it was, it's a very hard thing to do to get true color. What you would see, first of all, if you were hanging out, floating above Saturn,

• 23:50Carolyn Porco?

  first, you have to appreciate what you would see would be a hundred times fainter than what you would see here, because Saturn is 10 times farther away from the sun.

• 24:00Neil deGrasse Tyson?

  Uh-huh.

• 24:01Carolyn Porco?

  So, automatically, when we take the picture and we expose the picture, but we leave the shutter open for longer.

• 24:09Neil deGrasse Tyson?

  Long exposure.

• 24:11Carolyn Porco?

  For longer than your eyes' residence time on your retina, we're already cheating.

• 24:16Neil deGrasse Tyson?

  Right.

• 24:17Carolyn Porco?

  So, it's always gonna look somewhat different than it would, would to you if you were there. But we...

• 24:23Neil deGrasse Tyson?

  It wouldn't be cheating, Chuck, if you had huge eyeballs. If my eyes had CCD chips in them.

• 24:30Chuck Nice?

  Collecting all those photons, that'd be good.

• 24:33Neil deGrasse Tyson?

  If you had Elsa-sized eyeballs from Frozen. All right, so Carolyn, so when I look at the, think of the inventory of profound photos, of course, Earthrise from Apollo 8 comes to mind. Can you reflect on that?

• 24:49Carolyn Porco?

  Well, that was, that was the first time the globe of people first saw the Earth from afar. And I mean, there had been pictures like it taken, but it wasn't going to become as popular as the Apollo 8 moon, Earthrise. And it had, you know, in some sense, it can be, you can attribute that, you can attribute the environmental movement to that picture. Because it was the first time we see ourselves as a globe. It's an uncorrupted, unpoliticized view of our planet. And, you know, we know, of course, that we all live on it. And it's, it just, people have such a powerful, as you must know, when you show that picture,

• 25:34Carolyn Porco?

  the day the Earth smiled, and I'd been going around doing the same thing, showing it, people have a very, a very strong response to recognizing where and what we are.

• 25:45Chuck Nice?

  Yeah.

• 25:46Carolyn Porco?

  And just, just knowing what the Earth would look like in the skies of another world.

• 25:51Chuck Nice?

  It's, it's, it's the "you are here" on the mom.

• 25:55Neil deGrasse Tyson?

  That's right.

• 25:56Carolyn Porco?

  And it's not only "you are here," but "you are here on this just insanely small and fragile-looking thing with nothing around it." I mean, just, just complete blackness all around. And that's-

• 26:13Neil deGrasse Tyson?

  Bare-assed in the universe. That's a, that's a title of a book.

• 26:17Carolyn Porco?

  Is that your next book?

• 26:19Neil deGrasse Tyson?

  No, no, I don't know. So Carolyn, can you foresee a photo yet to be taken that might have, be as impactful as those that have come before?

• 26:31Carolyn Porco?

  Um.

• 26:33Neil deGrasse Tyson?

  That sounds like a no.

• 26:34Carolyn Porco?

  I'd have to think, I'd have to think about it. I'd have to.

• 26:37Neil deGrasse Tyson?

  Okay, while you're thinking, let's go to questions.

• 26:39Chuck Nice?

  Okay.

• 26:39Neil deGrasse Tyson?

  Chuck, you got some questions from our Patreon members?

• 26:41Chuck Nice?

  Yes, we do.

• 26:43Neil deGrasse Tyson?

  All right. Line them up. What do you have?

• 26:45Chuck Nice?

  Let's start off with Casey here and actually, uh.

• 26:51Neil deGrasse Tyson?

  And each of these members have been told that we would be speaking to you today, Carolyn. So these are tuned, these are bespoke for your presence on this program.

• 26:59Carolyn Porco?

  Okay, okay.

• 26:59Chuck Nice?

  Absolutely. So Casey says, Dr. Tyson, Lord Nice, Dr. Porco. Uh, Casey here from Florida with a question for Carolyn. What was the most interesting thing you learned from the Cassini mission? And what upcoming mission has you most excited?

• 27:16Neil deGrasse Tyson?

  I like that. All right.

• 27:17Carolyn Porco?

  Oh gee, I mean, what we learned so many things, so many.

• 27:21Neil deGrasse Tyson?

  Okay, pick your favorite child then.

• 27:27Carolyn Porco?

  Okay, I'm gonna give two. Can I get two?

• 27:29Chuck Nice?

  Go ahead.

• 27:30Neil deGrasse Tyson?

  Two, I'll give you two.

• 27:31Carolyn Porco?

  One, it's what everybody expects me to say, because really is the thing that has grabbed me ever since we found it. And that was learning what, what exists on Enceladus. It's the ocean that has got just in a complex or gatic compounds on it. Has hints of hydrothermal activity that presumably is taking place on the seafloor of Enceladus. As an ocean underneath it, that's what I'm trying to say.

• 27:56Neil deGrasse Tyson?

  Right.

• 27:56Carolyn Porco?

  And, and it's expressing itself into space in the form of geysers and a plume that we can flew, fly through. Cassini flew through it to sample it. And we know a lot about it now and, um, and it's just, it really is, despite what anybody else tells you, it is the low hanging fruit in our solar system to go search for life.

• 28:19Neil deGrasse Tyson?

  Whoa.

• 28:20Carolyn Porco?

  And to be, to be at the forefront of that, I mean, we took the pictures. We were the ones who found the hundred geysers, you know, lofting into space. Uh, and there's, um, there's good reason to believe that, uh, very good reason to believe that that ocean, uh, with it, that's the geysers are coming out of four fractions of the south polar terrain. And there's good reason to believe that the liquid water from which those, uh, geysers are created comes all the way up to the surface. Literally is like, it could be like old faithful, except not with an intermittent kind of character. But water that comes all the way up to the surface. And I mean, it just doesn't get any more exciting than that.

• 29:05Carolyn Porco?

  So that was...

• 29:06Neil deGrasse Tyson?

  Well, if there's fish down there, then some of the fish might have come up in the geyser. You could have freeze dried fish on the surface of Enceladus.

• 29:13Carolyn Porco?

  No.

• 29:14Neil deGrasse Tyson?

  Why not? No, not my story. That's a good story.

• 29:17Carolyn Porco?

  It's bad.

• 29:18Neil deGrasse Tyson?

  Carol, let me keep my story.

• 29:19Carolyn Porco?

  Bad, bad, bad. It's bad. It's bad because it's bad because there's very, it's not likely there's complex life down there. You need more energy that is, than is available there. But microbes, hey, microbes are cool. Don't disrespect microbes.

• 29:36Neil deGrasse Tyson?

  Okay, so microbes float up in there on the surface?

• 29:39Carolyn Porco?

  I said, I've always said it could be snowing microbes in those geysers.

• 29:43Neil deGrasse Tyson?

  Okay.

• 29:44Chuck Nice?

  All right.

• 29:45Neil deGrasse Tyson?

  You like my fish? All right, I'll give you the microbes.

• 29:47Carolyn Porco?

  Give me a, give me a microbe. I'll take a microbe any day.

• 29:49Neil deGrasse Tyson?

  Okay. I still like fish, but all right.

• 29:51Carolyn Porco?

  That's all right.

• 29:52Neil deGrasse Tyson?

  And, and, and what upcoming space mission, planetary mission do you most look forward to?

• 29:57Carolyn Porco?

  Uh, well, okay, so I'm, I'm, I won't be around for it, but when we go back to Enceladus, land on the surface and we can do the whole, the whole kit and caboodle. We can measure the geophysical activity underneath the surface, seismically. We can, uh, we could stand there and just have the stuff fall on us. We could collect to our heart's content and we could really do a bang up job, uh, searching for life in that.

• 30:24Chuck Nice?

  So how do you know when you land?

• 30:26Neil deGrasse Tyson?

  Apparently you expect to be dead. You expect to be dead.

• 30:29Carolyn Porco?

  Well, it's gonna take so long before that happens.

• 30:31Chuck Nice?

  How do we make sure before we go back that when we land, we don't contaminate, if there are microbes there?

• 30:37Neil deGrasse Tyson?

  Ooh.

• 30:38Carolyn Porco?

  Good question. Good question. Good question. And this brings up, boy, this brings another topic. I don't know if we want to do it this time or another time. Uh, you know, NASA treats this as, for all the criticisms people have about NASA, they treat planetary protection very seriously. So we would have to go back with an absolutely like... pristine, clean spacecraft contaminated with no microbes from Earth. Or else, you know, we could be measuring our own, our own, you know, scum.

• 31:14Neil deGrasse Tyson?

  Viruses.

• 31:14Carolyn Porco?

  So we don't want to do that. So, but, but it just puts, it puts before us the specter of having the people from the commercial space side of things now just crazily flying into space with what will be hundreds of thousands of satellites of lower Thorbait. They're talking about missions to go to Enceladus. They want to, they, I've heard plans done to go land on Enceladus or fly through its plume. I doubt any commercial enterprise will ever be able, would want to spend the money, you know, actually fork over the bumps to ensure the cleanliness of a spacecraft.

• 31:54Chuck Nice?

  Hmm, yeah, okay.

• 31:56Neil deGrasse Tyson?

  So, so it's got to be NASA to lead this. Otherwise, we worry about forward contamination of what it is we're trying to observe.

• 32:03Carolyn Porco?

  That's what I was trying to say.

• 32:04Chuck Nice?

  Yeah.

• 32:05Neil deGrasse Tyson?

  Yeah.

• 32:05Chuck Nice?

  Well, no, yeah, that makes sense. NASA cares and, you know, everybody else just wants the money.

• 32:11Carolyn Porco?

  You're, you're.

• 32:12Neil deGrasse Tyson?

  And Carolyn.

• 32:13Carolyn Porco?

  You'll be right.

• 32:15Chuck Nice?

  Yeah.

• 32:15Neil deGrasse Tyson?

  Carolyn, is one of the plumes from Enceladus make one of the rings of Saturn? Isn't there some ring made by a plume?

• 32:22Carolyn Porco?

  It's not just, well, all the, there's geysers, there's hundreds, there's a hundred that we counted, my research group, actually, this is my own research. We counted about a hundred individual geysers, but if you had higher resolution, there's probably more. All those geysers make a plume. So don't get confused. There's hundreds of geysers, they all make a plume. But another thing that my research group did, we showed that those geysers, the biggest among them, the most, you know, pronounced, actually, most of that stuff falls down, the solid stuff falls down on the ground, back on Enceladus, but some 4% of the material ends up going into the E-ring. It forms the E-ring.

• 33:08Chuck Nice?

  Wow, that's very cool.

• 33:10Carolyn Porco?

  Yes, it was very cool. We showed that we did modeling simulations of these tendrils that you see coming off Enceladus at long distances, tens of thousands of kilometers away, and we could show that they were created by the geysers. So it was like a slam dunk. It was really cool.

• 33:29Neil deGrasse Tyson?

  And so what is it I hear recently, Carolyn, about tasking the James Webb Space Telescope to look at this very phenomenon?

• 33:38Carolyn Porco?

  Yes, the James Webb Space Telescope, which by the way, I'm sure it's blown your mind, it's blown my mind, it's blown everybody's minds. It's just fantastic, the way that whole thing has been working perfectly. And it also took a look at Enceladus, okay? We'd never seen the plume from, you know, anywhere other than Saturn. Actually, Voyager also saw the plume, but faintly. And here we have, James Webb now has the ability to look at this plume and monitor it. And there's a collection of scientists, they were the team that did this, and they're, you know, they're gonna keep looking at it. It means that we can monitor it from, is it okay to say the vicinity of the Earth?

• 34:22Neil deGrasse Tyson?

  Yes, that's fine.

• 34:26Carolyn Porco?

  I guess what I'm saying, it means that we can continue to monitor it before the mission goes back long after I'm dead. That's what I mean.

• 34:34Neil deGrasse Tyson?

  Okay, there you go. Unless you live forever, which might still happen.

• 34:49Neil deGrasse Tyson?

  All right, so Chuck, time for a couple more questions.

• 34:51Chuck Nice?

  Okay, here we go. This is Samuel Tomka, and Samuel says, hello, Dr. Porco. Greetings from Slovakia. My name is Samuel, and I was wondering, will the day come when we can livestream video as our probes allow us to watch in real time flybys of celestial bodies? Why don't we already have such a system in place?

• 35:18Neil deGrasse Tyson?

  Yeah.

• 35:19Carolyn Porco?

  So, videos, um, well, okay, so what are we, the question is, you know, you're not gonna have somebody out there taking a video of a spacecraft flying, like, a planet. So he doesn't mean those kind of videos. Uh, and we actually have sort of done things like that. I mean, to, you know, remember, video is lots and lots of data volume, and you have to get that stuff down to the ground. And, and we have lots of instruments that wanna take data and get their data down to the ground. So you, we can't take an indefinite amount of data volume, even though it would be cool to do. So videos take a lot of, uh, space, uh, lot of downlink, we call it.

• 36:02Carolyn Porco?

  So, uh, but we have, we did take imagery, uh, we did this. You could look at the cyclops.org website, and we have a little page called theater, uh, where, and video clips or whatever. Well, we made video clips, for example, when we flew by Iapetus. And we put together some imagery. It's, you know, it's kind of clunky, but we were able to show what it looked like as we went by.

• 36:26Neil deGrasse Tyson?

  Cyclops, uh, is the name of what?

• 36:28Carolyn Porco?

  It stands for Cassini Imaging Central Laboratory for Operations. So it's C I C L O P S. And it was the center, it was the center where we, we, the imaging team, actually, my staff members and I, uh, set up the uplink and downlink operations for the imaging team. Okay. And now, since that's disbanded and there's no more of that, cyclops.org is the website. That's my website, where all the, uh,

• 36:57Neil deGrasse Tyson?

  Okay.

• 36:58Carolyn Porco?

  The Saturn imagery is, and lots of other stuff is put.

• 37:01Neil deGrasse Tyson?

  We can find it there. Excellent.

• 37:03Carolyn Porco?

  Yes.

• 37:04Neil deGrasse Tyson?

  Excellent.

• 37:05Carolyn Porco?

  Yes.

• 37:06Neil deGrasse Tyson?

  All right. Chuck, give me more.

• 37:08Chuck Nice?

  Okay. This is Captain James Riley, and he says, hello, Dr. Porco. I've heard that the Hubble Deep Field image was used, uh, was a use of director's time aimed at an empty point in space. Since that worked out so well, are we doing more at aiming at empty spots? Or are there telescopes scheduled to pretty much lock up on things that we just wanna better look at, like nothing?

• 37:34Carolyn Porco?

  I think, I think there are, there are telescopes on the ground, and Neil probably knows this better than I do. Telescopes that are on spacecraft, or plan to be on spacecraft, that will do surveys of the entire sky. So they're not just looking at one tiny little bit. They're doing entire surveys. And this reminds me to bring up the fact that they're...

• 37:57Neil deGrasse Tyson?

  Well, just to be clear, it's not a survey of known objects. It's just a survey of areas of the sky, no matter what's there.

• 38:04Chuck Nice?

  No matter.

• 38:04Carolyn Porco?

  It's a survey of the sky, the entire sky. Okay, so that's better than just, you know, looking at one little spot. And this brings up something I would love to talk about if we can. And that is that there are plans for enormous telescopes, ground-based telescopes. The Giant Magellan Telescope, the Extra Large Telescope. These are just enormous telescopes to be built on the ground, to be able to look at the heavens from the surface of the earth. And I am deeply concerned about all the, the traffic that will be in low Earth orbit. That is going to, all these satellites, these internet constellations,

• 38:48Carolyn Porco?

  that are going to impair ground-based observations. Not only in the visible, because they'll be streaking across fields of view. And there's going to be many, many more of them in the future. But also in the radio region of the spectrum, it's going to harm radio observations, even search for extraterrestrial intelligence.

• 39:08Neil deGrasse Tyson?

  And you know what else it'll do? It creates signatures of moving objects in the sky. When you might be trying to find an asteroid that has our name on it, headed towards us. And if the noise level of imagery goes up, you could possibly lose one of these killer asteroids.

• 39:25Carolyn Porco?

  There's lots of bad things that could happen. And right now, the whole thing is just, it's poorly, if at all, regulated. There's insufficient monitoring, tracking. There are protocols for what happens in the event of an imminent crash. But really, I think the...

• 39:44Chuck Nice?

  I'll say it again, NASA cares. Everybody else just wants the money.

• 39:49Carolyn Porco?

  Well, NASA, NASA is supporting this. I was very, very disturbed to find out that they're, you know, they want to encourage this, and I think it's a bad thing. 400, let me just put this number out there. As of about, as of about nine months ago, and it could very well have changed. There were proposed and approved satellites totaling 430,000.

• 40:19Chuck Nice?

  That's insane.

• 40:20Carolyn Porco?

  And there's now, no, actually, as of about six months ago, there was 6,000 up there. And in order to appreciate what this means, before the 2019, which was the first launch of the Starlink, SpaceX Starlink satellite, before that, six and a half decades of exploration by nation-states had left an accumulation of 3,700 satellites in orbit around the Earth. About half of them were alive, about half of them were dead. And as of about, what did I say, six months ago, I think it was?

• 40:59Chuck Nice?

  Six months.

• 40:59Carolyn Porco?

  Maybe nine months ago, there were 6,000. And there are proposed, and maybe already approved and proposed, 430,000. That's 70 times what's up there now. So we...

• 41:13Neil deGrasse Tyson?

  It's the end of the night sky.

• 41:15Carolyn Porco?

  Oh, that's another thing I want to say, is the night sky, the night sky belongs to all of us. It's the only thing you can lay your eyes on that's 13.8 billion years old. I go to the night sky to check in on the meaning of my life. I mean that. Where else can you find that kind of perspective? You know, and it will be ruined. It will be ruined, not only for professional astronomers, it will be ruined for people who just love to look up and remember where they really are.

• 41:47Chuck Nice?

  Wow.

• 41:47Neil deGrasse Tyson?

  Yeah, you know, my ending comment on every show is keep looking up. And now it's like, keep looking up and look at all the satellites. That's all you're gonna see.

• 41:59Carolyn Porco?

  Yeah.

• 41:59Neil deGrasse Tyson?

  Chuck, we might have time for one more question.

• 42:01Chuck Nice?

  All right.

• 42:02Neil deGrasse Tyson?

  Got one more to slip in there?

• 42:03Chuck Nice?

  Yeah, wow, that was disturbing, what we just talked about.

• 42:07Carolyn Porco?

  It doesn't fit in with your humor thing, so I don't know if you'll use it, but...

• 42:11Chuck Nice?

  Well, no, believe it or not, we've had Morbajah, who is a... Uh, he, what he, uh, what's he, he deals-

• 42:19Neil deGrasse Tyson?

  An orbital dynamist specializing in-

• 42:21Chuck Nice?

  Cleaning up the space environment.

• 42:22Carolyn Porco?

  Oh, good.

• 42:23Chuck Nice?

  Yeah, so-

• 42:24Neil deGrasse Tyson?

  He's in the Department of Aerospace Engineering at University of Texas at Austin.

• 42:28Chuck Nice?

  Absolutely.

• 42:29Neil deGrasse Tyson?

  So, yeah. More about Jah.

• 42:30Chuck Nice?

  More about Jah.

• 42:31Neil deGrasse Tyson?

  His name J A H.

• 42:32Chuck Nice?

  So, check out his work. Uh, okay, here we go. This is Mohammed Saif, and he says, "Hello, Dr. Tyson, hello, Dr. Porco, and hopefully Chuck." Well, thank you, Mohammed.

• 42:44Chuck Nice?

  He says, "My name is Saif from the land down under, and my question for Carolyn is, as a part of your association with Cassini, Voyager, and New Horizon, what is the least known but most fascinating thing you have seen or noticed?"

• 43:06Carolyn Porco?

  Oh, my goodness.

• 43:08Chuck Nice?

  So, yeah. What's, what's the thing we would never see or know that you know?

• 43:13Neil deGrasse Tyson?

  She can't talk about that, she only knows- But, okay, the second most fascinating.

• 43:20Carolyn Porco?

  Well, okay, so here's something that, um, I, I think is fascinating, and most people don't know about it. Um, we found, again, this is my research group, we found in the rings of Saturn, a type of, um, wave in, near the outer edge of the B-ring, which I had done my thesis on many, many years ago. So, I was anxious to look more closely at this. And we found evidence of these free, uh, normal modes of the rings, where these waves are sloshing back and forth, uh, from the place where they get self-excited. These are not waves that are excited by an orbiting satellite.

• 44:02Carolyn Porco?

  They're self-excited, they slosh up again, they, they, they travel up against the B-ring, the outer edge of the B-ring, which is held by a resonance with memus. It's held sharp. They reflect off the outer edge of the B-ring, they travel inwards, they reflect off their inner, uh, origin point, they go back and forth and back and forth, and they can be amplified. And they're spiral waves, they can be amplified, and you can, uh, see them actually in the motion of the outer edge of the B-ring. And the reason why this is so exciting is because these kind of waves are predicted to exist- In protoplanetary discs around, protostellar discs around stars,

• 44:46Carolyn Porco?

  and even in spiral galaxies. In fact, they can be responsible for the spiral arms in galaxies. And you can't measure their motion in a galaxy, because the orbital, the periods, the rotation periods in a galaxy are like 200 million years. But we found the smaller version of them, the Saturn ring equivalent in Saturn's rings. So it really was so thrilling to find something that really exists on a galactic scale, and we found evidence of it in Saturn's rings.

• 45:19Neil deGrasse Tyson?

  Wow. Love it. Love it. In fact, that's a scientist's great dream, to discover something in their own field that affects other fields as well.

• 45:29Carolyn Porco?

  Yeah.

• 45:30Neil deGrasse Tyson?

  In this case, it's all astrophysics, but it's not often that the planetary folks talk to the galactic folks.

• 45:35Carolyn Porco?

  I know. Well, we made it, we put it out there, so it's there for people to know.

• 45:39Neil deGrasse Tyson?

  Yeah, well, congratulations on that.

• 45:41Carolyn Porco?

  Thank you.

• 45:41Neil deGrasse Tyson?

  Very cool. And one last thing, I'm gonna ask, I got this. I'm gonna end with this question. Go ahead. What's up with that hexagon on Saturn's south pole?

• 45:49Carolyn Porco?

  Everybody loves a hexagon, whenever we...

• 45:51Neil deGrasse Tyson?

  I don't, hexagons don't belong in a gas.

• 45:54Carolyn Porco?

  Okay.

• 45:55Neil deGrasse Tyson?

  So what, it's like a perfect hexagon made out of gas. If I'm made out of gas, I ain't giving you a hexagon. Gotta tell you, I am made out of gas, and I'm letting you know right now, no hexagons here.

• 46:09Neil deGrasse Tyson?

  So take us out with what the hell that was.

• 46:11Carolyn Porco?

  Okay, so I just wanna say, though, whenever we posted anything about the hexagon on our website, the hits went through the roof. Because people couldn't get their head around this. And people, really, there were people who genuinely thought it was crystal energy. There must be something inside Saturn creating this. It is a jet stream. Just like the polar jet stream we have here on the Earth, it is a, just a river of gas that if you took it and stretched it out, so it's circling the pole, right? We'll just take it, stretch it out, it would be a six... Six waves, six conjoined waves, crests and troughs, just like that.

• 46:55Carolyn Porco?

  But when you take it and you wrap it around a globe, it gives the impression that it has sides. But that's just because you're stretching out the, what are you stretching out? You're stretching out the crests. The crest suddenly becomes stretched out, and so that's what it is. And it's, um, and the reason, the reason why we found it on Voyager, it's still screaming around at something like 220 miles an hour, going around Saturn, you know, 30, 40 years, whatever it is since Voyager, uh, went saw it at Saturn. It's because any atmospheric systems on Saturn or any of the giant planets that get started

• 47:35Carolyn Porco?

  up, they don't run down because you don't have a solid surface underneath the atmosphere of any of the giant planets. So there's no friction to run them down. Once they get started, they continue. It's the same thing with the Great Red Spot.

• 47:48Neil deGrasse Tyson?

  Jupiter, right.

• 47:49Carolyn Porco?

  The Great Red Spot has been doing that for hundreds of years.

• 47:52Neil deGrasse Tyson?

  Right.

• 47:52Carolyn Porco?

  At least on, at least hundreds of years.

• 47:54Neil deGrasse Tyson?

  At least, yeah.

• 47:55Carolyn Porco?

  Yeah, so. Yeah.

• 47:56Chuck Nice?

  I'm gonna, I'm just gonna say that's a, that's awfully convenient there, Carolyn. That's all I can say.

• 48:02Carolyn Porco?

  What's convenient? What's convenient?

• 48:06Chuck Nice?

  Uh, you just have a perfect little explanation for straight lines in, in nature. Okay.

• 48:12Neil deGrasse Tyson?

  I can tell you, here's how to say that, Chuck.

• 48:14Chuck Nice?

  Go ahead.

• 48:15Neil deGrasse Tyson?

  Chuck, here's how to say that. Say, Carolyn, if it's so obvious, why wasn't it predicted to be there before anyone found it?

• 48:21Carolyn Porco?

  Uh, there are a lot of things that are obvious in hindsight that no one took the time to predict, so.

• 48:27Neil deGrasse Tyson?

  Okay, that's the answer. So Carolyn, thank you for being on StarTalk once again.

• 48:31Chuck Nice?

  Always great.

• 48:32Neil deGrasse Tyson?

  You're a good friend of our show. In fact, you even hosted StarTalk All-Stars back when that was a running, uh, part of our portfolio. So I want to thank you for your service.

• 48:40Carolyn Porco?

  Oh, thank, thank you for having me. I love being here. It's fun being with you guys.

• 48:44Neil deGrasse Tyson?

  And, and I need affirmation, it's okay if we call you Madame Saturn? That's okay?

• 48:48Carolyn Porco?

  Continue calling me Madame Saturn. Like, you know, you know, like, like you, Saturn is probably my favorite planet after the Earth. Neptune is a close third.

• 49:00Neil deGrasse Tyson?

  Nah, not for me.

• 49:01Carolyn Porco?

  A close second, I'm sorry. Neptune would be a close second, but anyway.

• 49:06Neil deGrasse Tyson?

  All right, all right. Chuck, always good to have you, man. Always a pleasure. This has been StarTalk, and I'm Neil deGrasse Tyson, bidding you to keep looking up.