Planetary Radio: Space Exploration, Astronomy and Science - Ralph Lorenz and Titan Unveiled

Episode Date: June 16, 2008

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Ralph Laurenz and Titan Unveiled, 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. We leave Mars and head hundreds of millions of miles outward to Saturn, where the great Cassini spacecraft continues to explore that beautiful ringed planet and its moons. Our specific destination is Titan, and our guide is planetary scientist Ralph Lorenz,

a major contributor to the Huygens probe. We'll talk about that frigid yet weirdly Earth-like world and his new book, Titan Unveiled. Emily Lakdawalla will take us back to the Red Planet in this week's Q&A segment, and we'll wrap up with a particularly sweet edition of What's Up. Sweet as the candy we'll enjoy as we examine the night sky and give away another Planetary Radio t-shirt with Bruce Betts.

Discovery is back from its trip to the International Space Station. The picture-perfect mission delivered another big hunk of the Japanese Kibo lab. Note that's Kibo translated as hope, not Kaibo. Let's put the kibosh on that. We thank Rick Sternbach for the correction, a terrific artist and designer, and he knows a little Japanese. Live long and prosper, Rick. Have you heard? Pluto is now queen of the Plutoids.

The story is at planetary.org, where you'll also find Phoenix Mars mission updates. Titan Unveiled. It's a great read with a very accurate title, but it could as easily have been called Planetary Exploration Unveiled. Co-author Ralph Lorenz is now a planetary scientist with the Johns Hopkins Applied Physics Lab, but as Cassini-Huygens got underway, he was a young British engineer who got the chance to join what may have become the most ambitious robotic mission ever. We learn how Titan has literally emerged from the mist that hid its amazing surface. We also get Ralph's personal story through his log entries that pop up regularly throughout the text. These elements and lots of illustrations make the book a grand

journey to a new world and an exploration of how science gets done around our solar system. Well, that's really one of the aspects of the story we wanted to get across, is just how science gets done, how these large international space projects come together and get executed. Because it's not something you kind of learn about in school, you know, the nitty-gritty of how these things come together. We're glad to have had the opportunity to convey some of that. The fact that science isn't always uniform progress. There's a lot of false starts and false trails.

We end up making some wrong guesses and maybe following up on those guesses, and only later, after a lot more work, finding out they were wrong. So it's been a pleasure to try and retell that. This isn't the first book that you've written about Titan with Jacqueline Mitten. Yeah, Jacqueline and I collaborated on an earlier book called Lifting Titan's Veil. That was the first book I'd ever written. And I was glad to have Jacqueline's help. She's an accomplished author. And the collaboration worked very well. And so we decided to reprise that six years later, once Cassini had arrived and a lot of its findings were in.

And so it was a natural title for the sequel, if you like. But it's a standalone book. You don't need to have read the earlier book to appreciate the new one. No, I can attest to that. I have not seen the original book, and this one was really delightful. It's a very well-told story, very well written, and it is really a fascinating accounting of where we started with Titan prior to the Cassini mission, and where we are now. And we've learned a lot, haven't we? It's true. I was looking the other day at the Smithsonian's database of astronomical and planetary science

journal papers, and now it's getting close to 100 different papers a year about Titan, just Titan by itself. There's an enormous amount to catch up on, but even before the spacecraft era, Titan was recognized to be an interesting planetary body. I mean, its atmosphere was detected spectroscopically in the 40s, and there were hints of an atmosphere even before that time. So it's always been an object of interest and something that can be learned about from the ground as well as by spacecraft. So kind of building that story up from the ground-based work through the Voyager encounters of the 1980s

up to the sort of crescendo of activity we have right now with Cassini and indeed the sort of build-up towards contemplation of possible future missions. There's really a lot to talk about. I'm confident this won't be the last book about Titan either. So we might be looking at a trilogy here at least? Well, not for another few years, I think. You know, we're just busy just trying to make sense of all that Cassini is telling us. And right now there's a busy activity involving both NASA and the European Space Agency

to consider a possible future mission to Titan, an orbiter and balloon and lander kind of combination. My day job, if you like, is taking a lot of time. So it'll probably be another six years before we get around to doing a third one, if indeed we do a third one. How did you become involved with this mission long ago? Well, I remember actually as a kid and as a teenager watching Voyager encounters on TV and for myself being a Brit growing up in Europe, the Giotto encounter in 1986 with Comet Halley, which was sort of the first real European-led planetary science endeavor. So I sort of knew I wanted to work in these fields and understand the exploration of the planets by spacecraft.

But I ended up actually getting an undergraduate degree in engineering, aerospace engineering, and I was very fortunate in that my first job straight out of college was with the European Space Agency. And this was in 1990, just when Cassini and the European end, Huygens, was starting up. So I was not a particularly experienced individual at that point, but got involved right at the beginning. And it gave me an opportunity to see how the project was put together, how the cooperation between NASA and the European Space Agency worked, and how the different scientists from different universities and other institutions

worked with ESA and NASA and with the industrial contractors that actually, you know, built the hardware. So I could see how all this sort of came together. And then I shortly after had the opportunity to do a PhD back in the UK, building, you know, physically with my own hands, building and designing part of one of the experiments on the Huygens probe, which is just a once-in-a-lifetime opportunity. I mean, this thing was still all paper at the time, and it was still five or six years before it was even going to be on the launch pad, let alone the another seven years that it would take to get to Titan. But the opportunity to build that and be involved from the beginning, and then over the years

learn more and more about Titan and then finally see that instrumentation do its thing a billion miles away. It was just an amazing opportunity, and I feel really privileged to have had that chance. Would you talk a little bit about that instrument that you had great responsibility for, the penetrometer? Well, it's not a terribly highfalutin instrument as these things go. You know, while I can understand the search for structure and order in the universe that people look for with magnetometers and plasma spectrometers and things like that, this is actually a very, very literally down-to-earth experiment. The Huygens probe was going to

reach the surface of Titan, but we had no idea what kind of surface that would be. There was actually a lot of speculation that perhaps it might be a global ocean of liquid hydrocarbons. But there was a chance it was going to be solid, too. And to that end, we included this instrument called a penetrometer, which is just a little instrumented rod about the size of your little finger that pokes out of the bottom of the probe, and when the probe lands on the ground under its parachute, and it's only going at about 10 miles an hour when that would happen, this thing gets rammed into the ground and records a little force

signature, just for one twentieth of a second as it gets driven into the surface. And from that force signature, you can tell whether the material is a sort of plastic fluid, you know, like a tar or something like that, or a gravel, or whether it's dry sand. Or it's, you know, the sort of thing you might do as a kid on the beach, just kind of poke your, you know, close your eyes and poke your hand, poke your finger into the ground and try and guess what it is just by how it feels. So it's a very sort of easy-to-understand, kind of familiar kind of experiment. But, you know, it's one that has to tolerate a certain amount of space radiation and work at 180 degrees below the freezing point

and do all that after seven years flying in space. So, you know, it has a challenge all of its own. And building one of these instruments, I guess it's kind of like if you're an Olympic athlete doing a high dive or something like that. The crux of the event itself is just a short time, but you're building up to it for years and years, and you sort of hope to anticipate all the things that could go wrong. So it was very gratifying when the thing actually worked at the end of all that. We'll continue our conversation with Ralph Lorenz, co-author of Titan Unveiled, when Planetary Radio continues.

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The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. Titan Unveiled is the aptly named book co-written by our guest, Ralph Lorenz. Ralph is a planetary scientist with the Johns Hopkins Applied Physics Lab in Maryland. Preparation for the Cassini-Huygens mission was just getting underway back in the early 1990s. The 22-year-old engineer and PhD candidate was given responsibility for developing the penetrometer that would almost literally stick a finger into Saturn's moon Titan. It is quite stunning to think that you spent all those years developing this device,

and then it did its job in one twentieth of a second. What did we learn about the surface of Titan from your penetrometer that was corroborated by many other instruments and images? This is the fun thing about planetary science. There's a lot of different ways of learning about a place, but all of them are incomplete. And so you're sort of looking at little pieces of the jigsaw puzzle. And this instrument really is just one small piece of the jigsaw. The sort of challenge during the night of the encounter and the Planetary Society's own Emily Lagdawalla was sort of embedded at the European Space Operations Center to sort of report in real time. And so she

will remember this. All the individual experiment teams were just looking at their own data initially just to make sure that their experiments had worked and so on. And so we were looking at our data without, for example, having seen the pictures that are now sort of so familiar to everyone. You know, the Huygens landing site looks like this. Everyone knows that now. Everyone's seen those same pictures. But in the few hours before those pictures were processed and released, you know, we were just looking at the squiggly lines on our screens.

And it was, frankly, a bit of a puzzle. This record that we had from the penetrometer didn't look like anything we'd done in the lab all those years ago. It didn't look like dry sand. It didn't look like clay. It didn't look like dry sand. It didn't look like clay. It didn't look like gravel. But when we started to sort of break it down bit by bit, we saw that there was sort of a spike at the beginning. And then it was sort of more or less constant resistance. And that kind of constant resistance is typical of sort of wet or plastic materials, or maybe like packed snow. And we sort of laid out these possibilities and just sort of for fun, myself and a colleague kind of thought, well, you know,

it's got a plastic kind of soft material with a hard crust, sort of like creme brulee, which is my favorite dessert. And Principal Investigator John Zanecchi, who had been my PhD advisor all those years ago, announced the first findings at the first press conference that night and mentioned, you know, just kind of in passing the creme brulee thing. And the press just literally ate that up. They thought that was a great sort of familiar analogy. It turns out, after all that, that it probably wasn't anything like creme brulee at all. But really, it looks like when we take the data from the various experiments into account,

probably it was basically wet sand. That's wet sand-sized particles of ice moistened with liquid methane. It's very different materials, but in terms of how it sort of behaves physically, it's a lot like wet sand. And probably that spike at the beginning was one of the cobbles that we saw in the Huygens images shortly thereafter. I'm glad you mentioned Emily, my colleague at the Society, and I already alerted her to the quote you have from her.

She is a geologist by training, and she looked out and saw what looked like rounded boulders, and the first thing that she thought was, there's been liquid flowing here. Well, that was one of the really big surprises of the Huygens thing. First, we got pictures from the surface at all. I mean, there was no guarantee the probe would have survived. We were lucky it landed right way up. It landed in something relatively soft, but there could have been many scenarios where we wouldn't have had pictures from the surface at all.

One of the reasons that Titan is interesting is the fact that it has an atmosphere, and in particular the surface conditions may be close to those that allow liquid methane and ethane, natural gas on Earth, to be liquids at these conditions. The notion that the landscape should be substantially modified by rainfall and river flow, just as the Earth is, was completely speculative. We had no idea whether it might just kind of, you know, just always be foggy or something and there wouldn't necessarily be rivers and stream channels the same way there is on the Earth. But that was just graphically clear from the Huygens data and that just made that sort

of new picture of Titan ironclad. Of course, since the Huygens encounter itself, Cassini has been continuing to map other parts of Titan's surface with radar and in the near infrared. Now, we've seen that there are indeed some places on Titan that are like this, that are sort of gravelly and covered in little rounded boulders. But there are others that are vast sand seas, I mean, full of sand dunes. And then as you go to the poles, we find lots of lakes. So it's a very diverse place, and Huygens only saw one little

bit of it. Isn't this really one of the great wonders of this big moon, that it is at the same time so much like Earth in its terrain, and yet it remains such a strange and exotic place? Well, that's it. It seems that the physical processes that shape Titan are very much the same ones that shape the Earth. They are probably occurring at very different rates. For example, just based on the amount of sunlight that there is at Titan, which, you know, since it's 10 times further from the sun, is about, you know, 100 times less than Earth, and the haze in tight atmosphere gets in the way of a lot of that.

So just the amount of solar heating only gives you, say, one centimeter of rainfall per Earth year. That's something like 100 times less than a rainfall on the Earth. So the rates are different. The materials are very different, of course, because the temperature is lower. I mean, water as a material is literally rock hard on Titan's surface. Methane, which is, you know, here on Earth is natural gas, is cold enough to be a liquid. And so you have different materials participating in the same processes, albeit at different rates, and they seem to result in the same sort of landscape. So it's a very familiar place, but very exotic, as you say. And I think Titan is going to prove to be an outstanding laboratory for a lot of processes that affect us here on the Earth

that we can learn a lot about because we can't sort of, at least within limits, we can't change the conditions on the Earth too much. But by going to Titan and seeing how these same processes work under very different conditions, we can learn a lot, I think, and have a lot more confidence in our ability to predict how, say, the Earth will change as conditions change. The wonderful thing about Titan is because it has this thick atmosphere, it's very easy to deliver instrumentation to the surface, very easy to soft land things by parachute. to deliver instrumentation to the surface, very soft land things by parachute. And also there's the opportunity to fly, which is actually easier at Titan than basically anywhere else in the solar system.

And one of the really attractive options that's being explored in a present study right now is to maybe use a hot air balloon at Titan. That would be a hot air balloon kept warm by the same radio isotope generator that would give the thing electrical power. But that would just be a wonderful way to explore a world that we know is diverse. And we'd get a sort of new airplane window kind of view, you know, every day. It'll be a real adventure. So that's what I'd really like to see happen. And you have a very nice color plate, an artist's rendering of just such a balloon or dirigible

or blimp exploring the surface of Titan. We are out of time, Ralph. I want to thank you very much once again for joining us on Planetary Radio, and best of work as your investigations of that moon continue, as you continue to digest the data that was

received by both Huygens and Cassini. Great. Well, thank you. Ralph Lorenz is the author, with Jacqueline Mitten, of Titan Unveiled from Princeton University Press. He is a planetary scientist with Johns Hopkins University's Applied Physics Lab. We'll be right back with this week's edition of What's Up, a look at the night sky and a space trivia contest from Bruce Betts. But that'll be after Emily Lakdawalla and this week's edition of Q&A. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, How are the robotic arms on the rovers in Phoenix similar or different? Both the Spirit and Opportunity rovers and the Phoenix lander are equipped with robotic arms that enable them to manipulate and study rocks and soils on Mars.

Both were built by the same private company, Alliance Space Systems, and they're operated with similar software and commands. But the similarities pretty much end there. The Mars Exploration Rover arms are about the size of a human's and, like a human arm, they have five degrees of freedom, being able to rotate freely at shoulder and wrist and bend at the elbow. The rover arm is designed to place a handful of instruments gently onto the surface of soils or rocks. Stopping its motion once contact switches on the hand tell the Rover that the arm is in contact with its target. The Phoenix arm is designed for much harder work.

It has only four degrees of freedom, being able to rotate freely at the shoulder but not at the wrist. Unlike a human arm, the Phoenix arm's elbow is double-jointed, being able to bend freely at the shoulder but not at the wrist. Unlike a human arm, the Phoenix Arm's elbow is double-jointed, being able to bend both up and down. The tip of the arm does have two instruments, a camera and a soil temperature and conductivity analyzer, but the main purpose of the arm is not to measure but to do physical labor, digging and scraping at the soil and ice, possibly trenching up to a meter down, so it doesn't have sensitive contact switches like the rover's arm does. Probably the biggest difference between the two is that Phoenix's arm is almost three times as long as the rover's.

Operating Phoenix's arm has been compared to trying to use a fishing pole by remote control. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Live and in person, it's Bruce Betts, the Director of Projects for the Planetary Society. He's back for a new edition of What's Up? Going to tell us about the night sky, and we have some other fun stuff to talk about today. Candy. We have candy. You do. You've brought packages.

Well, it was sent. You have things. I'll come back to that. I'll come back to that. All right, well, it'll be harder to concentrate, but I will try to talk about the night sky, Mars, Saturn, growing closer together. Look over in the west in the early evening. Look, you know, third to halfway up the sky. You'll see Mars being the reddish-orangish thing down below. left. You next come to Regulus, the brightest star in Leo, which will be slightly brighter than Mars, but dimmer than Saturn, which will be farther to the upper left. They're roughly forming a line

right now. And Saturn looking kind of yellowish. They'll keep getting closer and closer till they snuggle up in the night sky around the middle of July. Then we've got Jupiter, giant brightest star-like object up there now because Venus is off playing with the sun. Jupiter is looking really bright coming up at 10, 11 in the evening in the east, and you'll be able to see it the rest of the night, brightest star-like object up there. I just want to say that your hand gestures are enormously helpful to my understanding of the night sky, and I hope the rest of the audience is appreciating them as well. I'm glad I could help.

Just follow where I'm pointing. Oh, wait. Maybe it's reversed in the southern hemisphere. Oh, that's true. Okay. All right. I'll have to think about that. We'll come back to the southern hemisphere, too.

All right. Here, wait. Let me point for them. Okay. Watch. Okay. Jupiter will be over there. All right.

Moving right along. Do-do-do. Do-do-do. We go on to this week in space history. It's Women's Week in space history. We had, see, it's one of those big anniversary dates. 45 years ago, Valentina Tereshkova became the first woman in space in 1963 and still the only solo space flight by a woman.

I won't even charge that against random space facts. And 20 years later, Sally Ride became the first American in space. It was about that long for the Russians to fly another woman as well. Soviets. Let us move on to random space facts. Oh, much better. You're feeling a lot better, aren't you? I am.

I'm much better, yes. Much better than last week's poor performance. Proper motion of stars. Stars, they seem fixed up there, not moving around. That's why planets were called wanderers. But if you watch them over years and decades or eons, eons, eons, they move. Not only are they all, most all of them, receding rapidly, flying away from us, but they also have proper motion. That's right, kids.

Definition time. Proper motion, that's kind of roughly how it's moving across the sky not forward or backwards relative to where we are but across the sky that's the the rough definition and uh we'll we'll come back to that but i do want to give you an extra besides the definition extra little space fact 1992, Ro Aguilay became the first star to, at least in historical observation, to move out of its own neighborhood. Named after one constellation, but it actually slid into Delphinus. So go figure. You're kidding.

Really? I'm not kidding. Don't look forward to much, you know, nothing. They don't expect anything like that to happen again for another 2,400 years. Had one of those subprime mortgages? It had to get out. It moved to the cheaper Dolphinius neighborhood. It's a little rough, but at least, you know, they've got a place. Anyway, moving right along to the trivia contest. And we asked you before Phoenix, what was the highest latitude successful Mars landing? How'd we do, Matt? You know, this is great because everybody, there were so many people who came up

with slightly different answers. And I'm sure they found every one of them in some authoritative source. But they all centered around 48 degrees north. 48 degrees north. As Kevin Hecht, listener Kevin Hecht said, kind of like Southern Canada, eh? Well, the guy who won is Michael Newell, first time winner. He's applied, I think, many times out of, how appropriate, Calgary, Alberta, Canada. So Michael, he said 48 degrees north, and it was Viking 2. Indeed, Viking lander 2. Got to see a little extra frost formation there. But now all the way up to 68 degrees north latitude of Phoenix.

Michael, we're going to send you a T-shirt, Planetary Radio T-shirt, and let's talk about how we're going to give away another one, although this may be the last T-shirt for a little while because we're going to give away some other stuff. So if you've been holding off, you want a shot at a T-shirt, now's your last chance for a while. All right, we return to proper motion. What is the star with the largest proper motion? The star with the largest proper motion. In other words, it's moving across the sky more than any other star, you know, out there.

Yeah, not down here, out there other star, you know, out there. Yeah. Not down here. Out there. Not down here, but out there. Uh-huh. Yeah, because I'd say, you know, maybe Tom Cruise or somebody like that down here. Yeah, okay. I should be more clear. Not that kind of star.

Okay. Now, Big Ball's a hot, wait. Yeah, you know. Astronomical stars. That's what we're talking about. Largest proper motion, go to planetary.org slash radio and find out how to enter. And you got until the 23rd. Monday,

the 23rd of June at 2 p.m. What is up with this candy? I'm going to open it right now. Okay, what happened was crazy Aussie listener. Is that redundant? Crazy Aussie? Crazy Aussie listener. I thought you were only going to offend one person. Now you've offended an entire country. An entire nation offended an entire country.

An entire continent. Anyway, Lindsay Dawson, who's a regular, sends these wonderful responses. He mentioned something about minties having something to do in the sky. I forget. And I said, minties, is that something like Vegemite? And he said, minties, you don't have minties there in the U.S.? And so what does he do? He says, you can't go through life not knowing about minties. So here's a pack to pass around.

Watch out that they don't stick together. So here is the pack. It says, it's moments like these. You need minties. And I couldn't agree more. So, okay. There goes one right now. That one must be yours.

Flying at me. Okay. So here they go. And it says on it, moments like these, you need minties. It's even sticking to the wrapper. Again, we need these people as sponsors for all the promotion we just gave them. Oh, it's very good. Yeah, I'm going to see if you pass over.

No, it's kind of like a candy cane. I wonder if they have those down there when they're all at the beach for Christmas. There you go. It's very good. Why don't you finish up? I'll go ahead and wait to shove mine in my mouth. Well, thanks, everyone, for joining us. Everyone, go out there.

Look out for the night sky and think about your favorite kind of candy and where you can get one right now. Thank you, and good night. Thank you, Lindsay. And thank you, Bruce. He's the director of projects for the Planetary Society. He joins us every week here for What's Up?

Sweet. Next week, the new shape of the Milky Way galaxy. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great week. Thank you.