Planetary Radio: Space Exploration, Astronomy and Science - Black Cats and Other Mysteries--Cassini-Huygens at Saturn's Moon Titan

Episode Date: November 1, 2004

Black Cats and Other Mysteries--Cassini-Huygens at Saturn's Moon TitanLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Just in time for Halloween, a black cat on Titan. All will be explained on this week's Planetary Radio. Hi everyone and welcome back to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan. As it zipped past Saturn's moon Titan on October 26, the Cassini spacecraft peered downward with the best instruments ever to visit the outer solar

system. The images sent back were astounding and, at least so far, baffling. We'll relive the flyby and talk to one of the mission's creators. Bruce Betts has finished his Halloween treats, but isn't out of tricks. He'll have a new space trivia question on What's Up.

We'll get underway with a handful of space headlines. NASA has scheduled the return of a space shuttle to orbit. If preparations continue to go well, Discovery, or one of its two remaining sister ships, may lift off in mid-May 2005. The date has been delayed several times, in part because of damage caused by the recent string of hurricanes that buffeted the Kennedy Space Center in Florida. The European Space Agency's Smart One spacecraft is healthy and on course. The ion-propelled probe will go into orbit around the Moon on November 15.

Check back with Planetary Radio for more coverage soon. Looking for something to do on Saturday, November 6? Why not drop by the high school athletic field in St. Louis, Missouri, where the Ansari X Prize will be awarded to Burt Rutan of Scaled Composites. Yes, it's time for Burt and sponsor Paul Allen to pick up their $10 million check. Spaceship One pilots Mike Melville and Brian Binney will be signing autographs. I'll be back with our special coverage of Cassini's Titan flyby after Emily sheds a little light on this mysterious moon. Stay with us. Hi, I'm Emily Lakdawalla with questions and answers.

A listener asked, If Titan is so far from the sun and it has thick clouds that you can't see through, wouldn't it be too dark to take any pictures of the surface? It is rather dark underneath Titan's clouds, but not too dark to take pictures. Saturn and its moon Titan lie about 10 times farther from the sun than the Earth does. Because of the inverse square law, that means the sun is a hundred times weaker at the top of Titan's atmosphere than sunshine is at Earth. Titan's atmosphere is thick and hazy, but it's not completely opaque. About 10% of the light that gets to the top of its

atmosphere trickles down to the surface. So, in all, the Sun is a thousand times fainter on Titan's surface than it is on the Earth's surface. For comparison, the light of the full Moon is a million times fainter than the light of the Sun. So while Titan's surface is dark, it's much brighter than a moonlit night, which is more than enough to take pictures of the surface. It's actually much more difficult to see Titan's surface from orbit. To find out why, stay tuned to Planetary Radio. Tonight, the Cassini spacecraft has its first close encounter with Saturn's largest and most intriguing moon, Titan. That was NASA TV's Gay Yee Hill,

kicking off live coverage of the Cassini-Huygens close brush with Titan on October 26. The bus-sized spacecraft will fly by Saturn's largest moon 44 more times over the next several years, and it may take that many to figure out what's going on down there. Other than images from Earth-bound telescopes, our best views of Titan prior to Cassini came from the Voyager spacecraft years ago. But those otherwise very successful probes turned out to have a serious vision problem when it came to Titan. Cassini imaging team leader Carolyn Porco explains. The Voyager investigators were very eager to study

Titan because even back before the days of Voyager, we knew that Titan had organic materials in its atmosphere, and so it was a very intriguing object, yet the Voyager cameras were exactly mismatched to the scattering and the absorbing properties of the atmosphere, so where the cameras became blind is where the atmosphere, as you go to longer wavelengths, the atmosphere became more transparent. So it was just an unfortunate situation that the Voyager cameras could not really see down to the surface, and they saw this fuzzy globe instead. But Cassini-Huygens is an entirely different story.

Its designers figured out how to allow the spacecraft to peer through the smoggy layer of hydrocarbons surrounding Titan, utilizing infrared imagers and radar. So confidence was high as the probe passed less than 750 miles above the surface of our solar system's second largest moon. Carolyn wasn't disappointed when the first images began popping up on screens at the Jet Propulsion Lab near Pasadena, California. Oh, look at that. That is the northern region. Boy, that is gorgeous. We're looking at a body that is active and has a surface like none other we've ever seen. So it's got to be good. It's remarkable.

It's really just a remarkable time right now. Right now. We will never again be so innocent and so ignorant. But even as the unprocessed images flowed in, becoming ever sharper, revealing new detail, the scientists began to realize that they really were looking at a new kind of world with features unlike any we had seen elsewhere in the solar system. When asked to describe the newly discovered region christened Xanadu, Carolyn could only express wonder.

I would love to tell you about Xanadu, but I don't know what to say, and nobody knows what to say. We're having a very challenging time trying to interpret the surface features of Titan. It's looking like a body, I mean, it's looking like nothing anybody's ever seen before. There are parts of it that look familiar, there's boundaries that look very sharp, and it's enticing to think that it could be fluid creating a shoreline or it could be lava. Figuring all this out has practical as well as intellectual value. In mid-January, the Huygens probe, detached from the Cassini mothership, will descend through Titan's thick atmosphere in exactly the areas surveyed in

this first flyby. This flyby is in some sense like conducting reconnaissance for the Huygens probe. The Huygens probe will get the exquisite detail on a part of the surface that we're going to be imaging during this flyby. After five and a half hours, the flyby was over. But it may take months to fully process and analyze the data collected. And then there are all those other encounters to look forward to, as Carolyn acknowledged the next morning in a press briefing.

The imaging team is looking forward to a wonderful four years of exploring Titan and also working with our colleagues to figure out what this great mystery is all about. One thing was for sure. Cassini had revealed a lot of new mysteries. Carolyn Porco's colleague Bob Brown got his turn to speculate at the press briefing. Brown is the team leader for the VIMS instrument. That's V-I-M-S, or Visual Infrared Mapping Spectrometer, which has proved to be a surprisingly effective imaging tool.

Consistent with what Carolyn was saying earlier, there's a lot of complex structure on Titan's surface, a lot of strong margins between bright and dark regions. We're not exactly sure what the composition of the bright and dark regions are, but some of the preliminary indications that we've gotten from VIMS suggest that even though there are differences between bright and dark, which are roughly a factor of two, that the composition of those bright and dark regions are not all that different, which is not what we expected. We're looking at this more closely, but the first cut suggests that these things are very

similar in composition. Jean-Pierre Le Breton also attended the morning press briefing. He serves as team leader for the Huygens probe built by the European Space Agency. He was delighted by what he had seen of the landing spot for his instrument-packed capsule. We did not select the Huygens landing site because our main constraint is the entry. And we are going to land where we land. And I think it's the best place we could have selected if we had selected it. So I will not do some more guesswork myself.

I leave it to you. But it looks like it's a very, very interesting place. So I'm really looking forward to visit it at very close range in less than three months from now. You said this is a great place to go. And so my question is, what makes that a great landing site? Diversity. Very politically correct. Politically correct, yeah.

As the briefing drew to a close, Carolyn Porco was asked if she was surprised by how few answers Titan had delivered. I'm not surprised we're having such a difficult time interpreting what's on the surface, because remember, this is an environment that we've never seen before. It's not like we're visiting another icy body and we've got a lot of airless body and we have a lot of experience interpreting airless bodies. And we've got all the techniques that we've used for interpreting airless bodies like looking at shadows and looking at high phase angles and all those all those methods of examining solid surfaces from planetary spacecraft that we, this community has learned over the last half century. OK, we can't use that on Titan because it's a different, very different environment. As we've said many times, its environment is in some respects close to the environment we have here

on earth and yet the materials it's made of are alien so i'm not at all surprised the next big event for cassini hoygens is a second titan flyby on december 13 then on christmas day or christmas eve in the americas the hoygens lander will separate from Cassini for the first time since well before the 1997 launch of the mated spacecraft. This will put Huygens on its way to a perilous descent through that thick Titan atmosphere on January 14, 2005. Lowered by parachute, it will take no more than two and a half hours to reach the surface. Will it survive? Will it splash down in a sea of liquid hydrocarbons, bobbing back up to the surface for a few minutes of life on that alien moon? No one yet knows. Oh yeah, that black cat we mentioned at the beginning of the show? Well, that's the name just given to one region of Titan that was revealed by the imaging radar

system. The wonderfully detailed mosaic represents about one percent of Titan that was revealed by the imaging radar system. The wonderfully detailed mosaic represents about 1% of the Big Moon's surface. One researcher's young daughter pointed out that a noticeably darker area looked like a cartoonish feline. Not surprisingly, the name stuck. JPL director and head of the radar team, Charles Elachi, wonders if the black cat isn't one of those liquid hydrocarbon seas we heard him talk about on this program two weeks ago. By the way, you can learn much more about Titan and Cassini-Huygens on our website, planetary.org. You'll also find links to related sites on the webpage where you can download this show.

on the web page where you can download this show. We'll continue our Titanic encounter coverage with planetary scientist and Cassini-Huygens mission designer, Toby Owen. That's right after this break. This is Buzz Aldrin. When I walked on the moon, I knew it was just the beginning of humankind's great adventure in the solar system.

That's why I'm a member of the Planetary Society, the world's largest space interest group. The Planetary Society is helping to explore Mars. We're tracking near-Earth asteroids and comets. We sponsor the search for life on other worlds, and we're building the first-ever solar sail. You can learn about these adventures and exciting new discoveries from space exploration in The Planetary Report. The Planetary Report is the Society's full-color magazine. It's just one of many member benefits.

You can learn more by calling 1-877-PLANETS. That's toll-free, 1-877-752-6387. And you can catch up on space exploration news and developments at our exciting and informative website, PlanetarySociety.org. The Planetary Society, exploring new worlds. Toby Owen was there when it all started. The planetary scientist began planning a mission to Saturn almost 23 years ago.

He had already made major contributions to the Viking, Voyager, and Galileo efforts when he joined American and European scientists and engineers to get the ball rolling. Now he's having a ball as the Cassini-Huygens spacecraft continues a perfectly magnificent tour of the ringed planet and its moons. The University of Hawaii professor was at JPL on October 26, watching the images and data arrive during the Titan flyby. We talked to him just a few days later. Toby Owen, thank you very much for joining us on Planetary Radio. Thank you. I'm happy to be here. So, how do you think your little mission is doing so far?

It's doing brilliantly. I think we're all just thrilled at the level of performance. Everything is working very well. We're getting a lot of exciting data, and we're looking forward to four more years of the same. I don't think there are too many people who are still involved with this mission, to the degree that you are, who were there apparently at its genesis. There are a few of us, and of course we're especially happy to see our dreams being realized, so to speak. It's very nice. And I should stress that one aspect of us, and of course we're especially happy to see our dreams being realized, so to speak.

It's very nice. And I should stress that one aspect of this which may not be coming through to people is that this is a strongly international mission, and it was from the beginning. So we had a European team and an American team working to plan this from the very start back in 1982. from the very start back in 1982. Let's talk about some of the results that you folks have found so far as this data flows back into the Jet Propulsion Lab. Charles Zalachi just said that studying Titan is like reading a mystery novel, and there's still, I take it, many, many mysteries left to solve.

That's absolutely true. The simile I also like is the one Winston Churchill used describing the Soviet Union about being a riddle wrapped in an enigma. And in the case of Titan, the enigma that it's wrapped in is this universal smog layer, this thick layer of photochemical smog that hides the surface from view. chemical smog that hides the surface from view. The Voyager cameras, although they brought us wonderful pictures of other satellites and planets, were not able to see Titan's surface, with the result that it's the largest unexplored surface in the solar system at this point. And we just got our first taste of it with the radar that, of course, penetrates the smog layer easily, and the infrared cameras on the spacecraft that can also get through the smog at certain wavelengths and show us the surface.

But even the camera goes to long enough wavelengths that the Voyager camera could not reach that give us some glimpses of the surface. So we're getting a lot of new information. Now, speaking of the radar instrument, that, of course, one that Charles Elachi has had so much to do with, did you guys, when you were deciding what should be aboard this big spacecraft so many years ago, did you realize then that with an infrared imager and with a radar system, you would have a much better chance of getting down to the surface of this mysterious moon?

Absolutely. That's why we put the radar on there. This is the first time that radar has been taken to the outer solar system. And the reason it's there is that we wanted to be absolutely sure that we could sense the surface. Indeed, we are. Now, I should quickly point out to people that we have just one very narrow stripe across the surface of Titan so far from the radar. About 1% of the surface, sir. That's right. We can't claim that we can tell you what Titan is like. All we can tell you is what that little strip is like.

And we know from past experience, I think especially Mars, where we had three flybys of Mars, which completely missed the volcanoes and the channels that told us so much exciting stuff about Mars that we have to be a little modest about what we're learning from Titan. There's a lot more to come. Well, if I could ask you to take the small and very tantalizing amount of data that you've gained so far, what speculations are running around about these interesting features that are seen, streaks on the surface that people are wondering about the nature of, and that radar image that gave us such a sharp picture back?

Yes, I guess that the most intriguing aspect of Titan from the, gosh, what an interesting place to visit point of view, is the possibility that there can be liquid hydrocarbons on the surface. We know that there's methane in the atmosphere, and we know that the photochemistry is producing ethane and propane, and all of these things would be liquids at the very low temperature of Titan's surface. So we're looking for things like lakes and rivers and, who knows, rainstorms, waterfalls, all driven, of course, by hydrocarbons. We can think of it as liquid natural gas instead of water. So the dark spots that Dr. Elachi has found in the radar,

he has proposed might be some of these lakes, but we don't know yet. And we're trying to find ways of identifying them in the other images as well. I saw in at least one write-up some speculation that some of the streaks that I guess have been seen in the visible light or infrared images, some speculation that those could also be hydrocarbon, but hydrocarbon glaciers? that those could also be hydrocarbon, but hydrocarbon glaciers? Well, the streaks, we think, could be formed by wind-blown dust, but the dust in this case is the aerosol material, which is constantly precipitating out of the atmosphere,

what Carl Sagan liked to call manna from heaven, dropping down on the surface. And this stuff, of course, is rich in organic material, and it would settle to the surface and then could be blown around by the wind. So we may have drifts of these organic aerosols, even banks of them. Who knows? But that's what we think would be there rather than, say, the sand on Mars. In fact, maybe it's worth pointing out that since people have been seeing a lot of

Mars imagery lately, that Titan is almost the antithesis of Mars. On Mars, you could cover the whole surface of the planet, and you wouldn't find anything that would burn. It's completely oxidized, whereas on Titan, almost everything burns. It's a flammable world. And, of course, the reason it hasn't blown up is simply because there's no free oxygen there. So almost as if everything is already burned on Mars and nothing is at a chance to on Titan. Exactly right. Fascinating. We know that this is only the first of many, many, many flybys of Titan. Do you have any inkling from the data that you've seen so far, have a feeling

that once we have made a few more of those flybys, or maybe a lot more of them, we will have a better understanding of this moon? Absolutely. I'm looking forward to the additional flybys because the instruments are working so well that I'm sure that as we gradually build up a picture, we're going to have a much stronger sense of the place. And I should point out that in January, we're going to send a probe into the atmosphere that will land on the surface after taking a lot of measurements, including pictures on the way down. And putting that probe material together with the orbiter material, I think,

is going to give us a very good picture of what this mysterious moon is all about. And we hope that a lot of our audience today heard our show last week with Chris McKay, which, of course, is still available at planetary.org, where we talked at some length about the Huygens probe. And, of course, Planetary Radio will be focusing on that very exciting event when it takes place in January. Dr. Owen, I will let you go, but I hope I can do that with the promise that you'll rejoin us again to talk about your long career in planetary exploration.

Well, I'd be happy to. Thank you. Thank you very much. Toby Owen has been our guest, wrapping up what we know so far about this Cassini flyby of Titan. Indeed, a very mysterious place, becoming ever so slightly less mysterious with the promise of many mysteries yet to be solved. I'll be back with Bruce Betts and what's up right after this return visit from Emily. I'm Emily Lakdawalla, back with Q&A. Seeing the surface of Saturn's largest moon, Titan, is very difficult to do

from an orbiting spacecraft. When photons of sunlight pass through Titan's atmosphere on the way to the surface, they can bounce off any number of other molecules and bits of haze and fog on the way. This process is known as scattering. The same scattering happens to photons that are reflected by the surface and travel upward and out of the atmosphere. So only 10 to 20% of the photons that leave Titan's surface make it to the top of the atmosphere without being scattered and changing direction. What an orbiting camera sees is a small number of photons that come directly from the surface, plus a big number of photons that come in from every direction, making Titan look diffusely fuzzy. number of photons that come in from every direction, making Titan look diffusely fuzzy.

In order to see anything of the surface, a hefty amount of computer processing has to go into subtracting this diffuse general brightness out of camera pictures. That's why the European Space Agency's Huygens probe is so important. As Huygens descends deeper and deeper into Titan's atmosphere on January 14th, it will get a better and better view of the surface. Scientists believe Huygens will actually pass through the bottom of Titan's cloud layer and get the first ever unobstructed views of Titan before the plucky probe crashes on the ground. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Dr. Bruce Betts is here, the Director of Projects for the Planetary Society, which must mean that it's time for What's Up.

What's up, Bruce? Hi. Hi. Hey, how you doing? Good. Good. Well, what's up in the pre-dawn sky, if you can get up for it, is Jupiter and Venus nuzzling up close to each other. Very, very interesting, fun-looking, two brightest naked-eye planets out there. Jupiter and Venus getting within a degree apart on November 4th and 5th. We will have Jupiter to the lower left of Venus before the 4th and 5th, and then they will switch places, and Jupiter will be to the upper right of Venus, Venus being the brighter object, and both looking very, very bright.

You can also see two other planets in the predawn sky if you look around. Now Saturn these days is probably easier to catch in the evening. It's starting to come up in the evening, so around 10 p.m. Saturn will rise in the east northeast. If you have a clear view to the horizon in the predawn sky, you can see Mars to the lower left of Venus. And don't worry, it will be climbing up in the sky, so you'll be able to see it better in a few weeks. On to this week in space history. But before you go on, I got to say that eclipse that you warned us about for a couple of weeks was spectacular. I hope folks who were in the right part of the world got to see it. And it was nice and red. I was out with the binoculars. Oh, good. Good, good, good. I looked

a couple times and it was cloudy. Oh, it was better over my way. I'm sorry. I should have invited you over. Had we known. Sunsets around the world converging on the moon. A moment of silence. How appropriate. All right. Anyway, back to this. Speaking of a moment of silence. Funny you'd mention that.

This week in space history, November 3rd, 1957, Sputnik 2 carried the dog Laika. Laika became the first living creature in space and the first dead creature in space. Laika. We should make Laika the mascot of Planetary Radio, because it's either Laika or one of those squirrels that races around here periodically. But Laika should get some attention, I guess. I guess we give her some attention. I don't know what I'm talking about.

Every year we talk about Laika and feel badly for her plight. But they made postage stamps with Laika on it, so I guess that makes up for... Well, okay, maybe not. Anyway, on to Random Space Fact! I just don't think I had as much energy in that this time. No, I think that was fine. Wait till you hear it with the reverb. energy in that this time. No, I think that was fine. Wait till you hear it with the reverb.

So here's an interesting one as we're pondering Saturn and such these days with the Cassini mission. Did you know, Matt, that it was James Clerk Maxwell, same guy of the famous Maxwell's equations that define electromagnetics and good stuff, that he actually proved that Saturn's rings could not be solid and must be made of an indefinite number of unconnected particles. No, I had no idea. Was that kind of far afield for him?

No pun intended. He got around. When he put it out, people were shocked. Shocked, I tell you. Shocked, I tell you. People were shocked. Shocked, I tell you. Shocked, I tell you.

Anyway, those nerds out there who appreciate Maxwell's equations will undoubtedly be fascinated by this. And the rest of you are waiting for me to get on to the trivia contest. So let's go there. We asked you, what two asteroids did the Galileo spacecraft fly past on its way to Jupiter? Everybody had the right answer. No one got it wrong. We had a ton of entrants, which, you know, it makes me feel bad because we have so many people coming in now. We have not told people that, oh, sorry, you can only win once a year or once every three

months or whatever. And we have people who faithfully enter every week. And I always feel bad. I want to give all of them, Bonnie, Sandy, Mike, Meddy, Hannah, Dominic, Kathy, they're there every week. And I want to give them, you know, shirts every week. But we can't. And that's just the way it is. Life is tough. The winner this week is Deb Healing.

Deb Healing of Bethlehem, Pennsylvania, where she may be listening to us, I think, on WMUH, if not on the web. Deb had the correct answer, 951, Gaspra, and 243, Ida. And, Deb, you won. You're going to get that Planetary Radio t-shirt. Congratulations. For the rest of you, including our faithful entrants, answer the following question to win yourself a Planetary Radio t-shirt. In what year did Christian Huygens discover Titan? In what year did Christian Huygens discover Titan?

Go to planetary.org slash radio. Give us your answer by sending us email. Win your prize. Tell us your t-shirt size. Have fun. When do they need to get that in by, Matt? By Monday, November 8, noon Pacific time. That's the 8th at noon Pacific time, so that you can be eligible for this weekly trivia contest.

Who knows? Maybe you. Even if you've entered before. Even if you've won before. Maybe you'll be the winner of that lovely new blue Planetary Radio t-shirt. Yay, and it's a lovely blue. I really like it. We've had a couple of people say they like the gray ones better, who've won them and have them.

But I think the blue is great. So more reason to keep entering. There you go. All right, are we done? We are completely done. All right, everyone, go out there, look in the night sky, and think about chess. And who came up with those rules. Thank you. Good night.

That's Dr. Bruce Betts, the Director of Projects for the Planetary Society. He joins us each week here on What's Up. That's all the time we have for Planetary Radio. Join us next time for another adventure beyond Earth's atmosphere. Have a great week, everyone.