Planetary Radio: Space Exploration, Astronomy and Science - Shedding New Light on Saturn

Episode Date: December 28, 2009

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New light shines on Saturn, this week on Planetary Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. Linda Spilker is back. The Cassini Mission Deputy Project Scientist has news from Saturn and its mysterious moons and rings. We'll check in with her in a couple of minutes. Bruce Betts has end-of-year tidings of the night sky and a new space trivia contest.

And we'll finish with something special from Emily Lakdawalla, a solar system version of a classic holiday poem. And speaking of both Emily and Cassini, take a look at her image for day 27 of the solar system advent calendar. It's a brand new and quite striking shot of Saturn's little ring moon, Prometheus. We've got the direct link at planetary.org slash radio. Prometheus. We've got the direct link at planetary.org slash radio. We've also got four spectacular movies of Cassini's moons swinging past each other and the great planet's rings. They are a wonderful late Christmas present. I'll be right back with Linda Spilker with his own wishes for the new year. Here's Bill. Hey, hey, Bill Nye, the planetary guy here,

vice president of the Planetary Society. First of all, scientists have found super-Earths on nearby stars. Right over there at 61 Virginus, they found a planet that's Earth-sized. And sooner or later, they're going to find Earth-sized planets that are in the zone where there'd be liquid water. And then we're going to go looking for life. And that's going to be exciting. Excuse me, Bill. I know you haven't introduced me to your special guest so far, but it's actually double Earth sized, not Earth sized.

Wait, are you from the future? We'll get back to that. Wow. In the meantime, coming up in January, there's going to be a luncheon with people who have helped blaze the way for us to explore the stars. Buzz Aldrin will be celebrating his 80th birthday and Stephen Hawking, the man who helped so many of us understand our relationship with time and the universe, will also be at the luncheon. And with us also is someone from the distant future, the Doctor from Star Trek Voyager.

Please state the nature of your year-end emergency. That's right, Bill. I am here to wish you all a very happy new year and to tell you that 2010, some pretty cool things will happen. I, of course, know what they are. I'm not at liberty to share because I do not want to affect the timeline in any way. Wow. Jeez, Doc. That's exciting. Now, Robert Picardo is here with me on the advisory board of the Planetary Society. And this is going to be a big year.

These big discoveries made in space, space policy is going to be figured out in the United States. And we are going to change the world. Well, Robert and I've got to fly. Bill Nye, the planetary guy. to fly, Bill Nye the Planetary Guy. The Cassini-Huygens mission continues to return some of the most spectacular images and science in the history of space exploration. Regular listeners know that we turn to longtime Deputy Project Scientist Linda Spilker for her insightful and enthusiastic reviews of the latest from that spacecraft that has been touring Saturn, its rings and its moons for five and a half years.

She has lots to report this time. We didn't even get to the marvelous movies of Saturn's aurora in action. And don't miss the just as great videos of the ring planet's moons that I mentioned a few minutes ago. The links are at planetary.org slash radio. Linda, I think I may be visiting with you a little bit earlier than we normally would, but really there has just been so much going on. Just in last week's show, we talked with Emily Lakdawalla about this, well, I guess it's confirmation of a lake on Titan?

Yes, it's very exciting, Matt. It turns out that we've seen for the first time a glint of sunlight reflected off a lake called Croc and Mare. It's a huge lake in Titan's northern hemisphere. It's about 150,000 square miles, and that's larger than the Caspian Sea. And what this glint does is it confirms the presence of a liquid in this large northern lake. And what's very interesting is we didn't see this glint at visible wavelengths, much like you'd see a glint as you're flying in an airplane over a

lake or something if the conditions are just right, see a bright flash off of the lake. But instead, we saw this glint at five microns, and that's a wavelength much longer than you can see with your eyes. It's in the near infrared, and it's where Titan's atmosphere is clear enough that it absorbs little enough sunlight so it could get to the surface and reflect back up to us, causing this glint. The spectra that were taken as we flew over this lake were the very brightest when we were actually on the lake and then not bright at all when we were off the lake. And so we were able to take radar images of this region of Titan and map the VIMS spectra onto it.

So very exciting to see another body. This makes Titan the only other body in our solar system with a liquid on its surface. And this liquid is methane on Titan. Methane plays the same role that water plays on the Earth as a liquid. It can be a liquid or a solid or a vapor. And so you have weather on Titan with methane. And a lot of the same kinds of things that water does on Earth to form the geology that we

know of our planet. That's exactly right. You get stream beds and rivers. You get the methane actually carving the surface or eroding down the mountaintops and creating a surface that's in many ways very much like the Earth's surface. Now, Emily talked about this having taken a lot longer for Cassini to catch this glint than anybody expected. Why was that? Well, it turns out that when Cassini arrived at Saturn, Titan's northern hemisphere was in darkness.

And most of the lakes are in the north. There are just a couple of lakes in the south. And so as we went through equinox and as the sun was rising and it started to become spring And so as we went through equinox and as the sun was rising and it started to become spring and the sunlight hit those northern lakes, that gave us the first opportunity to see it. And actually it was just a lucky find. We weren't looking at the time for a specular reflection, and conditions were just right when we took that VIMS image of Titan to see the specular reflection. And we're certainly going to keep on looking for more of those as the mission continues.

Now, is this discovery, is this going to help find more of these reflections and discover additional lakes? Yes, as the sun continues to rise, and we now have more of the north in sunlight, we'll be looking for those special geometries where you can get that specular reflection or that glint from the sun and then continue to use it to probe other lakes and see if we have liquid there and also especially going along the lake edges to see what we might be able to find. All right, let's jump over to another moon of Saturn, and that's Iapetus,

which has been one that has been full of mystery for a very long time. I take it some of this mystery has maybe been solved. We're bit by bit trying to understand this very unusual moon, Iapetus. It's sort of the yin-yang moon. It has one very bright side and one very dark side. It turns out that the leading side, the side that faces forward as it orbits Saturn, is much, much darker than the trailing side. In fact, the bright material is about a factor of 10 times brighter than the dark material.

And both the north and the south poles of Iapetus are bright, too. I think of it as the black and white cookie moon. Right, right. Well, one side is very dark and the other side is very, very bright. The leading hemisphere has both the bright and dark material that's present there is redder, as though there's some kind of a dust that's coating the leading side of Iapetus. And in fact, just recently in Spitzer data, there's a new giant ring discovered out around the orbit of Phoebe and going inward, and perhaps dust from those tiny moons that orbit outside the main Saturn moons might be contributing dust that's coating Iapetus.

And then Iapetus is another interesting thing. It takes 79 days for Iapetus to turn once on its axis, so it has a very long day. days for Iapetus to turn once on its axis, so it has a very long day. And what this allows is that the sun has a long time to warm up the dark material. In fact, it can warm up the dark material enough that the water vapor, any water, is volatilized and moves to the bright regions. You can kind of think of the warm region like a blanket. Any water material there sort of evaporates and moves toward the bright regions and then freezes out again on the bright regions both at the poles and on the trailing side of Iapetus. Let me make sure I understand.

Iapetus is tidally locked and that's why it always has this leading edge that is gathering all the flotsam possibly from the rings? Right. That's exactly right. Since it keeps one side facing Saturn, it always has been one side leading or sweeping up the dust in the Saturn system. So we're pretty confident now that we understand why this moon presents such a contrast, quite literally? Yeah, in fact, Iapetus might be undergoing sort of a runaway feedback loop

where the dark material as the water ice goes away and freezes out on the bright regions, there's more dark material, which means it can get even warmer. If you've had a really dark sweater on on a warm day, you know that with a dark sweater you warm up even more than you would if you had on, say, a white t-shirt or something. More from Cassini Deputy Project Scientist Linda Spilker when Planetary Radio continues. I'm Robert Picardo. I traveled across the galaxy as the doctor in Star Trek Voyager. Then I joined the Planetary Society to become part of the real adventure of space exploration. The Society fights for missions that unveil the secrets of the solar system. Transcription by CastingWords voyages, and I hope you'll consider joining us. You can learn more about the Planetary Society at our website, planetary.org slash radio,

or by calling 1-800-9-WORLDS. Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Our nearly 100,000 members receive the internationally acclaimed Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. We're in the middle of one of Linda Spilker's regular reports on the Cassini-Huygens mission. Linda is Cassini's deputy project scientist and has been with the mission since well before its 1997 launch. She spoke with me from her office at the Jet Propulsion Lab near Pasadena, California. Let's go down to the big

planet. And lots of curiosity. In fact, we've had a couple of listeners write to us about how could this hexagon, this polar hexagon, be a natural formation and there must be something mysterious going on here. Well, maybe not so mysterious, but certainly magnificent. And I guess you've gotten back some really, I don't guess, I've seen them, some beautiful new images. Right. Again, as the sun has been illuminating the North Pole of Titan, the same thing has been happening at Saturn. And it turns out there's this North Polar hexagon. We have really no good idea of

what's causing its shape. It was first seen by the Voyager spacecraft almost 30 years ago, and that's the last time that the north polar region was in sunlight. And it turns out that Cassini's visual infrared mapping spectrometer could see it in darkness because it was looking at infrared light and the heat coming up from Saturn. But for the very first time at Equinox, we had a chance to see it with the cameras as well and get very, very detailed images of this hexagon. It's wider than about two Earths, and the hexagon jet stream whips around at about 220 miles per hour. And so it's quite a large structure, and the fact that it's lasted for 30 years when weather or hurricanes on the Earth

have such a much shorter lifetime is a real puzzle. It's powerful strange to see what appears to be a more or less regular polygon at the top of this planet. I mean, are we beginning to understand why something like this would form? Well, we're not sure why it formed, and in particular, why it has this particular shape. There's lots of ideas,

and perhaps we'll get better clues with these images. At the corners of the hexagon, you see little waves, little curlicues coming off. There's a multi-wall structure along each of the six sides that go all the way up to the top of Saturn's atmosphere. So perhaps we can put some of these clues together. But we don't have a good story yet for exactly why the hexagon formed and what's keeping it in the shape that it has today.

Lots of mysteries left to go as Cassini continues to circle that planet. You mentioned the discovery of that very dim, that very faint ring, and I know you are something of a ring specialist, a ring scientist. Is there anything that you'd like to add about what we've learned in the last few months about the rings and what we've seen?

Well, we've gone through a very interesting period of time called equinox at Saturn, and it allowed the rings to go from sort of a two-dimensional flat structure to a third dimension. As the sun got very low, anything big in the rings would cast shadows, and we saw some very magnificent shadows cast by larger objects in the rings. Some of the edges of the gaps actually have structure that makes it stick up above and below. And so it gave us a chance to study Saturn's rings in a new way.

And that's been very exciting. And we're still looking through the data, trying to understand all that we've discovered there. But equinox proved to be as exciting and informative as all of you had hoped. Oh, I think even more so. We saw some things we expected, and always what's the most fun is to find the unexpected. Good scientist. What's ahead? Every week I get the regular reports in my email, and it always starts out with, Cassini is in excellent, an excellent state of health, which is awfully nice to hear because there's so much more left to do.

What should we be looking forward to over the next few months? Well, over the next few months, we'll be having additional flybys of some of Saturn's moons. And in particular, we'd like to find out if Enceladus is the only moon in the Saturn system that's active. There are tantalizing hints that perhaps Dione and maybe Rhea might be active in looking at some of the magnetic field data. And so we will be on the watch for any signs of activity on some of these other moons in the Saturn system. And of course, we'll be getting great views of the planet.

We're going into a series of orbits that are more nearly equatorial. And if you're a planet scientist, that means that the rings form a thin line at the equator and we'll get some great views of the planet itself. You know, we should have probably talked more about Enceladus, because that little moon continues to fascinate, and I guess we're beginning to understand it a little bit better, too. Right, right. We had a couple of flybys in November where we saw some of these jets. In fact, we saw perhaps as many as 30 jets, some of them very tiny, as we saw the South Pole now going into shadow. And so some of these jets were in contrast against the dark part of Enceladus.

And so we're trying to put together the pieces of just where along some of these tiger stripes the jets might be active. And now we've seen a few more that we have to explain. And there's a great animation that we'll have to link to once again. We did it a few weeks ago. As the spacecraft was actually approaching those vents and these geysers of material springing out of this moon that we once thought was much too small for this kind of activity. Exciting stuff going on. Yes, absolutely, and a lot more to look forward to.

We have many more Enceladus flybys coming up and some more cuts through the plumes. With the recent November flybys, we actually noticed individual jets with the in-situ instruments, the ion and neutral mass spectrometer and the cosmic dust analyzer. Both could see discrete jets as we crossed through them as we flew very, very close to Enceladus. Linda, how long have we got left on the current extended mission of Cassini? Well, the current extended mission ends on October 1st of 2010, and we have a proposal in to NASA for a possible seven-year extension,

something we call the Cassini Solstice Mission, because what we'd like to do is to go from equinox to solstice on Saturn, where it would be summer in the northern hemispheres of both Saturn and Titan. Wow. Best of luck with that. I think you know how I and I would suspect most of our audience feel about that opportunity. And thank you once again. We love these regular reports from you on Cassini, and we'll talk to you again in a few months. Okay, thanks, Matt. I look forward to it. Linda Spilker is the longtime Deputy Project Scientist for the

Cassini-Huygens mission, which continues to explore and reveal more and more of the Saturnian system, and much more to come if the past is any indication of the future. We will move on to the future of this radio show by going

to our weekly What's Up segment. That means Bruce Betts will be here in a minute. Don't go away. Time for another holiday What's Up with Bruce Betts, the director of projects for the Planetary Society. It's good to be with you again. I'm sorry that I couldn't record you at lunch, the Planetary Society lunch last week, because I had left at home the name of our trivia contest winner. But here you are, and now I have the name in my hot little hand. Well, I just don't feel like doing it now.

No, we will. Don't worry. We have a lovely T-shirt for some lucky winner out there who is yet to be revealed. Tell us about the night sky. All right, fine. In the night sky, in the evening, we've got Jupiter still very bright in the first two or three hours after sunset. Over in the west, before it sets, looking like an extremely bright star. In the west, before it sets, looking like an extremely bright star. We're also getting Mars down there. You can see it quite easily by 9 p.m., probably by 7 or 8.

And it's going to be over in the east, other side of the sky. On January 2nd, you can see it near the full moon. And it is hanging out in Leo at the moment and getting brighter and brighter until January 29th when it reaches opposition, opposite side of the Earth from the sun. That means the brightest it's going to get for another couple of years or even more in this case. It's getting quite bright and looking kind of reddish, and it's quite lovely. You can also, by the way, when you're looking over there, look kind of a little bit farther south. And we mentioned Orion last week. Well, it's indeed up there. And if you take Orion's belt, a little trick for you, Matt, you probably know.

And you'll have to wait till the mid-evening, 9 p.m., say, 8 p.m., 9 p.m. to do this. You take Orion's belt and you point downward toward the horizon and you will find Sirius, the brightest star in the sky, looking kind of bluish. Beautiful. Yeah, that's what I thought. Orion itself is looking very beautiful, as it does this time of year, but just a couple of nights ago, it was just a beautiful, reasonably clear night, and boy, it was pretty.

Yeah. Yeah, it's good stuff. Saturn, speaking of good stuff, rising middle of the night, high in the east before dawn. Check it out with a telescope, see some rings. Let us move on to this week in space history. Hard to believe, Matt, it was five years ago this week that we held the Planet Fest Wild About Mars to celebrate the landing of Spirit on Mars. So that was five years ago. And also the fly-by-and-fly-through of the coma of Comet Wild 2 by Stardust.

What a party we had. That was really swell five years ago. We move on to Random Space Fest! And then Happy New Year to you, too. Happy New Year, everyone. STS-129 space shuttle mission that returned to Earth just a few weeks ago, slated to be the final space shuttle crew rotation flight to or from International Space Station, final to deliver or remove astronauts or cosmonauts. So from here on out, no more shuttle.

All Russian Soyuz doing the job of cycling astronauts and cosmonauts to the space station. Yeah, working our way toward the end. I was just reading today about NASA bought some spare solid rocket boosters just in case a rescue mission is needed for the very last scheduled shuttle mission in September of 2010. Coming up, coming up, coming up, to retire the shuttle. Jeez, almost 30 years after it started its work. Good long run. Let's go on to trivia.

We asked you a popular primate question. Who was the first chimp to orbit the Earth? How'd we do, Matt? Well, orbit the Earth, by the way. Yes. Remember what I said a week ago about dogs and chimps, dogs and monkeys? All true. Huge number of responses. And as I said, here it is. It's in my hand. The winner of a Planetary Radio t-shirt this week is our old friend Tom Hendricks, who enters every week, and he said he believes, and he's correct, the first chimpanzee to orbit the Earth was Enos aboard Mercury Atlas in November of 1961. He's actually off by a couple of months here, but he got the name right, and that's what we asked for.

really off by a couple of months here, but he got the name right, and that's what we asked for. Interestingly enough, a couple of Soviet men had already orbited the Earth by the time Enos did, Gagarin and Titov. So he was only the third hominid in orbit, as someone pointed out, and he had a bad time of it. It was hot up there. And someone else said he was electrocuted whenever he touched a control panel, which, you know, might have been on purpose now that I think of it. Gosh, I hope not. Anyway, Tom, we're going to send you a Planetary Radio t-shirt. Anyway, he did come back at least alive. By the way, Lindsay Dawson mentioned that the first mouse in space, suborbital, August

31st, 1948, tip of a V-2 rocket. Yeah. Interestingly, the first bilge rat just stowed away on the shuttle one time. Don't you know that the Mars base is going to have rats? It's going to have rats. They're going to make it. Spontaneous generation, even if they don't go. So moving on to the next trivia contest, as I mentioned, Mars opposition coming up January 27th. Here's your question. When is the closest approach of Mars in the next decade? So the closest opposition and how far away will it be from

the Earth? Go to planetary.org slash radio. Find out how to enter. And you have until, ready? Our first headline of the new year, January 4, Monday, January 4 at 2 p.m. Pacific time. We wish you all the luck in the world. In fact, all the luck in the solar system. All right. Happy New Year, Matt. Happy New Year to you, Bruce. Thanks for another good year.

Happy New Year, all of you out there. Go out there, look up at the night sky, and think about fun things you did during 2009 and fun things you hope to do in 2010. Thank you, and good night. He's Bruce Betts, the Director of Projects for the Planetary Society, and he joins us every week here for What's Up. And now for something almost completely different.

The Planetary Society's Science and Technology Coordinator usually joins us to review the best of her blog. But Emily Lakdawalla also reads and contributes to UnmannedSpaceFlight.com. That's where she found a special posting by forum member Astro Zero Emily Lakdawalla also reads and contributes to UnmannedSpaceFlight.com. That's where she found a special posting by forum member Astro Zero on December 24, Christmas Eve. Astro Zero took a few out-of-this-world liberties with a classic holiday poem many of you will recognize. It's The Night Before Christmas, published anonymously in 1823. Emily liked it so much, she recorded it. Here is her and our gift to you, our listeners.

Twas the night before Christmas when all through the stars not a creature was stirring, not even on Mars. The rovers were driven by drivers with care in hopes new discoveries would soon be found there. Earth children were nestled all snug in their beds while visions of dust devils danced in their heads. With Oppiett Marquette and Spirit in a sand trap, we just had to settle our brains for a long winter's nap. When out on the dunes there arose such a clatter, and Odyssey watched to see what was the matter. All the way to Earth flew a new data flash.

JPL opened the files and threw was the matter. All the way to earth flew a new data flash. JPL opened the files and threw out the trash. The fines on the rovers from new fallen dust gave the objects below the color of rust, when what to my computer screen should appear but a miniature sleigh and eight tiny reindeer. With a little old driver so lively and quick, I knew in a moment it must be St. Nick. More rapid than rockets, his coursers they came, and he whistled and shouted and called them by name. Now Viking, now Phoenix, now Pathfinder and Sojourner, on rockets, on airbags, on chutes and retro burners, from the red of the sky to the rocks in the wall, now dash away, dash away, dash away all. As dry soil that before the dust devils fly when they meet with an obstacle

mount to the sky, and up to the ops room the engineers flew with drivers full of tricks in new software too. And then in a twinkling they heard on the roof the prancing and pawing of each little hoof. They drew in their heads and turned right around, down the corridor St. Nicholas came with a bound. He was dressed all in fur from his head to his foot, and his clothes were all tarnished with red dust on his boot. A bundle of rocks he had flung on his back, and he looked like a peddler just opening his peck. His eyes how they twinkled, his dimples how merry. His cheeks were like roses, his nose like a cherry. His droll little mouth was drawn up like a bow, and the beard on his chin was as

white as Mars' snow. The stump of a pipe he held tight in his teeth, and the smoke it encircled his head like a wreath. He had a broad face and a little round belly that shook when he laughed like a bowl full of jelly. He was chubby and plump, a right jolly old elf, and they laughed when they saw him in spite of themselves. A wink of his eye and a twist of his head soon gave them to know they had nothing to dread. He spoke not a word, but went straight to his work and filled all the stockings, then turned with a jerk, and laying his finger aside of his nose

and giving a nod, up the chimney he rose. He sprang to a sleigh, to his team gave a whistle, and away they all flew like the down of a thistle. But they heard him exclaim as he drove out of sight, Happy Christmas on Mars, and to Earth a good night. Emily Lakdawalla with Astro Zero's rewrite of The Night Before Christmas. Thank you for another wonderful year. We look forward to exploring the new one with you.

Planetary Radio is produced by the Planetary Society in Pasadena, California. Keep looking up. Happy Holidays from the Planetary Society! Редактор субтитров А.Семкин Корректор А.Егорова