Planetary Radio: Space Exploration, Astronomy and Science - Cassini Project Scientist Linda Spilker With a Saturn Mission Update

Episode Date: June 4, 2012

Planetary Radio's most frequent guest returns with the latest news from the great ringed world, its moons, and its rings.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Cassini's Linda Spilker, reporting from Saturn, this week on Planetary Radio. Welcome to the travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. She's back. Our most frequent guest, the project scientist for the Cassini mission, will give us yet another update from one of the most interesting, provocative, mysterious, glorious neighborhoods in the solar system. My conversation with Linda Spilker at JPL begins right after we hear from Emily Lakdawalla and Bill Nye.

Bruce Betts will join me a little later for this week's What's Up. But before all that, here's a brief quote from someone who may have been the happiest man on or above Earth a few days ago. This has been a fantastic day. I'd like to again thank NASA and the whole SpaceX team for an amazing job. I'm really proud of everyone. This really couldn't have gone better. Yeah, I'm just overwhelmed with joy. It's been 10 years to have done this, and to have it go so well is incredibly satisfying. We look forward to doing lots more missions in the future and continuing to upgrade the technology and push the frontier of space transportation.

Elon Musk of SpaceX, barely an hour after his Dragon capsule safely splashed down in the Pacific and after it delivered cargo to the International Space Station. We congratulate everyone at SpaceX for what is just the start of something big. Here is Planetary Society Science and Technology Coordinator, Emily Lakdawalla. Emily, welcome back. Where was that that you were hobnobbing with all those astronauts? It was in Tucson, Arizona. Balmy

Tucson, Arizona, or maybe hot as the surface of the sun. Tucson, Arizona. I was there for Space Fest 4, which is a gathering, really, of space artists and astronauts. It's a kind of strange merger of two worlds. But fun, I'm sure, as was a trip that you and I and Bill Nye made

out to the desert to see something else that is going to turn a lot of people into astronauts. Yeah, I was so excited to have this trip to see White Knight 2 and Spaceship 2 under construction at Scaled Composites. We were, of course, invited there by Virgin Galactic. I actually got to poke my head inside the cockpit, which was pretty cool. Those spacecraft, they're made of very thin, multi-layered carbon fiber, and it's kind of hard to imagine that that thin a layer is going to protect you from space, but supposedly it will. As our boss Bill Nye said, wow, spaceships made of plastic.

Well, yeah, pretty much. But apparently they're going to work, and I wouldn't refuse a ride. Well, all of this is in a May 29 blog entry in Emily's blog that you should check out. And pretty soon it'll be here on the radio show and probably some video as well, as soon as we get that material all back from Scaled Composites as they're reviewing it right now to make sure we don't give away any secrets. Emily, just briefly, what's up in the month of June?

Well, it's a pretty active month. Opportunity is finally rolling across Mars again. It's been like six months since she parked with a northerly tilt so she could get some better sun for the winter, but now she's rolling again. She's got her wheels on top of some gypsum veins, which should be very interesting to check out because those are most definitely associated with water moving through the subsurface on Mars. And then out at Saturn, Cassini is getting its first good views of Saturn's rings for two and a half years. It's been in the plane of the rings for a long time, which let it get really good views of moons, but it's lousy for observing the rings, of course. So now we're getting fewer moon views, but more ring views, and they're absolutely

spectacular. But we still are getting the occasional moon flyby, and this month there's going to be a MIMAS one, which I'm looking forward to. And there is much more in Emily's monthly update, What's Up in the Solar System, for June. It's a May 31 entry in the blog at planetary.org, our beautiful new website. Take a look. Emily, thanks. I'll talk to you again soon. Thank you, Matt.

She is the Science and Technology Coordinator for the Planetary Society and a contributing editor to Sky and Telescope magazine. Up next is the Planetary Society CEO, Bill Nye. Bill, I know we catch you in montreal and maybe we'll have time to find out why you're up there but first i wanted to get your impressions of that trip that emily you and i made out to uh the desert uh just a few days ago to see virgin galactic and and more in the town of mojave california fantastic thing giant buildings Javi, California. Fantastic thing. Giant buildings, giant molds. These would be tools to make airplanes and rockets out of plastic. So instead of being fiberglass, like you might think of a boat, these are airplanes made of carbon fiber. Fantastically strong stuff. And the thing they

clearly have figured out, Matt, is the manufacturing techniques. They lay it up, as they say, just perfectly with no bubbles, no voids. And it is astonishingly strong. And then the rocket cabin, where the pilot and you and I will sit when we have our $200,000 for the rides, and the airplane cabins are all the same mold. They're all the same size and shape, just with different tail pieces on them. It's amazing. It's really a very impressive thing. And the other thing, Matt, let me say, as a guy who did manual reversion on commercial airplanes, if all the engines go out, all the hydraulics quit,

the pilot is able to fly the plane. Quite a cool thing. Yeah, I hope we can share more of that trip very soon. Where did you go after that? Well, I went to Washington, D.C. for the ExploraVision Awards. This is something I participated in for 11 years. It's sponsored by the National Science Teachers Association and Toshiba. And, you know, the planetary side, I got a little funding from Toshiba. We made those videos that are hilarious and charming, and those are part of this consortium of the NSTA, Toshiba, and us, the Planetary Society. That was really good.

And while I was in Washington, I took a few minutes and met with three people from the White House. These will be staffers who work for the current administration, and we are much closer together than I realized. They're very supportive of Congress adding back. That's a verb in Washington, adding back money for planetary exploration. And of course, the whole thing could fall apart again, but we're hoping that the funding for planetary exploration is kept in the budget so that we can continue to reach out farther into the solar system and make discoveries that will change the world, Matt. And SpaceX landed back in the water. Yes. It's been an exciting week. It really has. A good week

for space development and space exploration. Okay, really fast, what are you doing there in Montreal? Oh, Matt, apparently, through the efforts of my academic colleagues, I am receiving the Ralph Coates Rowe Medal honoring my mechanical engineering ability. Now, what's funny about that? You are a mechanical engineer, and you've probably done more to boost engineering than anybody else I can think of. Well, now you're talking, Matt. It's just very exciting because I was a member of the SME for

many years when I was working full time. And it's the kind of thing you read the magazine now and then, but I guess they've stayed in touch with them enough that they're giving me this award. It's really, it's going to get to me, I'm sure. It's exciting. Congratulations, Bill. Thank you, Matt. He is the CEO of the Planetary Society.

We catch him in Montreal, as you heard, and we'll talk to him again next week. Up next, though, is Linda Spilker, the project scientist for the Cassini mission. We'll get another update on that amazing trip among that big planet, its rings and its moons. Linda Spilker of the Jet Propulsion Lab is project scientist for Cassini the Magnificent, the spacecraft that has revealed so much of Saturn and its companions. She has spent nearly half her life working on the mission.

We like to check in with her several times a year. It's time for another of those visits. Linda, back at JPL, the little conference room off the Visitor Center. Thank you for reserving this for us. Oh, you're welcome. And congratulations on this award that you and your team have received from the National Air and Space Museum in Washington. Thanks, Matt. It's a great honor to receive that award. And well-deserved, I must say. So you're coming up June 30th this year, eighth anniversary at Saturn, studying that incredible system. And you still have, amazingly, at least to me, a pretty healthy spacecraft.

Yes, the spacecraft is very healthy. In fact, we had one instrument that we turned off briefly to try and understand it caused sort of voltage changes on the spacecraft. The Cassini plasma spectrometer is now back on, turned back on in mid-March, and working very well. And the spacecraft is healthy. And it never broke. It was just scaring you a bit, and you wanted to take some action. Right. We wanted to study it further.

Something called little tin whiskers were growing that were causing little mini shorts. They're smaller than the size of a human hair. Turns out that they really don't cause us problems. If there's enough current that goes through, they just burn out. Tin whiskers. Sounds like a rock band. Yes, it sure does. The whole team has been busy. Lots of new discoveries. I want to mention something that just recently, Emily Lakdawalla put in the blog, and we talked about here during her segment of the show, and that's this odd little moon that looks like an egg. Yes, that little tiny moon

called Methone. It's only about two miles across. And we flew within 1,200 miles of this tiny moon just a little over a week ago. And it's very smooth. Methone is one of three moons Cassini discovered. We discovered Methone, Pallene, and Anthy, and they all orbit between Mimas and Enceladus. And Enceladus is this tremendous source of particles and water vapor coming out of the jets at the South Pole, and we think that's why Methone looks so smooth. It's coated in E-ring particles. I think I said to Emily, it's sort of an interplanetary dust bunny, maybe. It could be. That's a good analogy.

So it just, from flying through these particles, it's picking up all this stuff, and we don't really know what the surface looks like. No, probably not. It just appears to be coated from what we can see in this very nice image that we got with Cassini. Speaking of Enceladus, you've been spending some time there as well. I mean, I was just telling you before we started recording about this amazing picture on the website. Well, they're all amazing. Uncalibrated, so I couldn't really tell how close it was,

but it looked so close, like you were right, you could almost touch the surface. Yeah, that's actually a wide-angle image, but as close as we were to Enceladus, it's like a postage stamp on the surface. It was taken in the south polar region, and you can actually see, I think the resolution's about six meters per pixel, you can actually see tiny icy boulders sitting on the surface near some of these tiger stripes. And this flyby was actually a trio of flybys where we were flying directly under the south pole, almost parallel to those linear tiger stripes, and basically mapping out in situ what the material is like coming out

of each of those jets, seeing if there are slight differences in composition, any changes in the volume of the flow between the various flybys, and so it was a very nice set of flybys of Enceladus. And now we're actually having a period where it's going to be about three more years until our next flyby of Enceladus. Okay, but certainly not the last flyby. Oh, no, we have several more in mind. And we'll talk about, we'll get to what's in store in the next few months.

Let's go to this other moon that you thought we ought to bring up in this very brief overview of recent happenings out there by Saturn, and that's Phoebe. Yes, Phoebe is a very interesting object. We know it's a captured moon. It's the largest of a class of captured objects. It now looks like Phoebe is a class of what we call planetesimals, objects from which the planets formed. It probably got its start out in the Kuiper Belt and was warm enough early on in its history to actually shrink or differentiate a little bit. And its density is about 40% higher than any of the other Saturnian moons that formed at the same time that Saturn did. It's about the density of Pluto. And then there's this very chaotic period in the solar system where objects

were thrown in. Phoebe was then captured by Saturn. And it's in a retrograde orbit. In other words, it orbits backwards relative to the other moons in the system. So a very interesting, very unique object. And you say that it's differentiated. So it's layered more like we would expect. Yes, it got warm enough that actually the porosity sort of condensed a little bit. So it's maybe slightly differentiated.

the porosity sort of condensed a little bit. So it's maybe slightly differentiated. When it formed, there were radioactive materials still around that aluminum CAIs that could actually heat it up. And then we think that's what happened with it. You're a ring person. We can say that because that's your field of study, although you have to take into account the entire system as project scientist. But there certainly have been things happening there. In fact, maybe more for you ring scientists to be happy about in the last few weeks than you've had for a while.

Right. There's been some exciting activity. In particular, we've taken a close look at the F ring. This was actually, it's been two and a half years since we've actually seen the rings. We've been in Saturn's equatorial plane. But in looking back and having a chance to study our data in more detail, we find that the F-ring is particularly fascinating. It's shepherded by two tiny moons, Prometheus and Pandora, on either side. Prometheus gets very close to the F-ring every once in a while and actually creates jets and streamers and causes

little objects to form. You can imagine snowballs kind of building up in the F ring. And some of these objects, maybe a half mile across, actually have slightly different orbits of the F ring, and they punch through the F ring, pulling a glittering trail of particles behind them, mini jets, we call them. And so we're looking for these mini jets, very tiny, hard to see in the images, but very, very beautiful. I wonder what those would look like up close. You know, this just occurred to me.

The old Star Trek Voyager series, you saw a Voyager pass through this thin ring of material and pull some material out with it. And that's what this makes me think of. That's the image in my head. Right, like just a glittering trail of particles that come out with these objects that penetrate the F-ring. Linda Spilker, project scientist for the Cassini mission at Saturn. We'll rejoin her at JPL in a minute.

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That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. It's officially known now as the Cassini-Solstice mission, as the great spacecraft nears its eighth anniversary orbiting Saturn. We're talking once again with the mission's project scientist, Linda Spilker. In addition to her own research, she coordinates all the science efforts of the Cassini team. Another five years of exploration are ahead, ending with a spectacular 2017 plunge into the planet.

Of course, Cassini began returning data long before it reached the ringed world. You mentioned looking back at the data, and I came across something else on the site, which talk about looking back. This goes back to your Jupiter flyby in the year 2000, something that just came out. And I think this has something to say about the value of the data collected across particularly a long-duration mission like yours. Right, say about the value of the data collected across particularly a long duration mission like yours. Right. And in the case of Jupiter, we can actually go back now as we learn more about Saturn and compare those two planets that we had. Even though it was just a flyby, we had a very rich data set from that Jupiter flyby. We used Jupiter's gravity to

actually swing us on to continue towards Saturn. And so, yes, it is fascinating. In fact, the Cassini team still goes back and looks at Voyager data. We go back and look at Voyager ring data, the planet, the moons, and that was 30 years ago. So these data sets last for a long time. All right, now I want to jump back to the rings and other things happening with the spacecraft because there are some big changes underway already for Cassini. You're kind of changing your attitude.

Literally, literally. What we're doing is we're using Titan for gravity assist and raising the inclination of the orbits. And for the ring scientists in particular, the saying is the rings are back. That just means that now, once again, with Cassini, we can start to look at the F ring. How has it changed in the two and a half years since we've been able to observe it? Look at the gaps. Search for moonlets. And so there's a lot of activity.

Over the next three years, we'll get up to an inclination of about 62 degrees. And spectacular views of the rings. Imagine them just spread out in front of you, being able to sort of encircle Saturn as you look down and study them. So that's very good. Now we'll get good views of the poles of the planet. We'll get to see good views of the north polar hexagon, which is so peculiar on Saturn. How can it maintain the shape of a hexagon with straight sides, this hurricane-like storm? How can it do that?

We're still puzzled. And also there's a more typical hurricane in the south polar region of Saturn. Great views of the auroral regions as well. Measure the magnetosphere at higher inclinations. What we don't do as much of is fly by the icy satellites. Those are best done when you're in orbits that are in Saturn's equatorial plane. So we'll have fewer flybys. We have, I think, a Rhea flyby coming up in the next couple of years, and then get back to Dione and Enceladus and so on in about three more years.

Can you say a little bit more about Titan? Because really, this world that was largely a mystery until the arrival of Cassini, you're revealing more and more of it. And I guess more of that is yet to come with these upcoming flybys. Yes, the seasons are changing on Titan. We saw an equivalent of a giant rainstorm in the near equatorial region. And now we're seeing the lakes being illuminated by the sun for the first time, the lakes in the north polar region of Titan. So we'll be looking to see, can we, we've looked with radar

because you don't need sunlight to view them, but are the lakes changing, the lake levels changing? We've noticed that the north polar hood on Titan has basically changed and gone away. Will it reform in the south because it tends to follow the winter pole? Will it now reform in the southern polar region of Titan? So lots of seasonal changes. It's spring on Titan, and we're busy watching those changes.

Incredibly dynamic place. Yes, very dynamic. How about the planet itself? Or really, anything else that you would want to call attention to that maybe we should be watching for in the next, you know, few months? Well, for Saturn, back in December of 2010, we saw the start of a huge storm, a storm that grew and actually encircled the planet. The storm came back around, and you could say the head of the storm bit its tail.

There's now still a very turbulent region left around that latitude on Saturn. And there's also high up in the stratosphere a very hot beacon that there's something going on. We hadn't anticipated, perhaps dredging up or forming new compounds. So we're basically going to be watching as the storm continues to die out and watching for new storms. We have a radio and plasma wave spectrometer. It's our first, you know, guardian to tell us there might be a storm because it hears the lightning coming from the storm as it starts. In fact, back in December 2010, we heard the lightning, and then within a day had a picture of a tiny little spot forming on Saturn.

And it's been a great adventure because the amateur astronomers have been very interested in helping us track the storm because, of course, Cassini isn't looking every day, whereas the amateurs can really help us keep track and have watched with us as the storm has dissipated. I've got to ask, with just a few seconds left, that beacon that you mentioned, you said it's hotter and there may be new compounds forming there? Hotter and there's compounds or more certain compounds than we've seen before. It could be that the atmosphere as the storm, as the thundercloud rose up,

and then now as it's sinking, as the storm, as the thundercloud rose up, and then now as it's sinking, as the storm has subsided, the sinking atmosphere heats up. And that may be what's going on in the stratosphere, causing perhaps some new chemistry with the compounds that are there. Absolutely fascinating. As always, Linda, thank you so much. And of course, if people want to learn more, you can go to the Cassini website. We will put up a link to that at planetary.org slash radio, but it's easy enough to find. And I hope that we can continue. We've been doing this for years now, Linda. You still have the record for the number of appearances on this radio show talking about this amazing mission. Well, thank you, Matt. Linda Spilker is the project scientist

for the Cassini mission, as we said earlier, coming up on its eighth anniversary, spinning around through the Saturnian system with its rings and moons and the beautiful planet itself. Much more to learn out there as this mission continues very successfully. And we'll be learning some more from Bruce Betts in just a few moments when we join him for What's Up. Here's Bruce Betts, the director of projects for the Planetary Society. It's What's Up. And still got a lot going on up there, don't we? We do.

Depending on when people are hearing this, if they catch it right away, there's still the Venus transit. Tuesday, June 5th, in the afternoon, our time, Pacific time. Starting a little after 3 o'clock in the afternoon, Pacific time, and continuing for about 7 hours. So the sun will set while we're looking at it. If you missed the Venus transit and you're listening to this afterwards, well, there'll be another one in 2117. So hang in there. But I'll have some good news for you in the random space facts segment. Good.

We also still have fabu planets up there in the evening sky, even though Venus, of course, has gone bye-bye, hanging out in the area of the sun. We do have Saturn making still quite a lovely pair high in the south in the evening sky, with Saturn being the yellowish-looking star-ish object, and Spica being an actual bluish star. And they're both about the same brightness but different colors. We've also got the Mars hanging out in the southwest in the early evening. So Venus being close to the sun now, that's not going to interfere with the transit on Tuesday? I don't think so. I think, in fact, we might say it facilitates it. Ah, okay.

Well, I've always wondered, though wondered those during a transit does venus go behind the sun or in front i always forget relative to never mind go on anyway it goes in front of the sun uh and i will mention on the venus transit i'm they they foolishly they've given me my own blog on the planetary society site now so there's a blog up there with some of the why the heck should you care about Venus transits, as well as some observational ideas and tips. We move on to this week in space history. It was this week in 1985 that the Soviet Vega-1 spacecraft deployed a balloon in the atmosphere of Venus, as well as a lander, although the balloon did a lot better than the lander.

Venus, as well as a lander, although the balloon did a lot better than the lander. 2003, Spirit was launched on its way to Mars for its fabulously successful roving journey. Yes, and as we heard from Emily, it's sister opportunity now, crawling across Mars again. Random space fact. Whether you saw the Venus transit or not, even though one of those won't occur for over 100 years, Mercury transits the sun an average of about 13 to 14 times per century. And the next one takes place less than three years from now on May 9th, 2016. It will be visible for us here in North America. I'll get you more details as we get closer to that event.

You do need to do more because it's a smaller little black spot on the sun that day. It's still kind of spiffy. We watched the last one in 2006. Beats 2117 anyway. It does. It very much does. And in fact, there'll be several more Mercury transits before then. All right, we move on to the trivia contest.

Who performed the first known observation of a Venus transit, and in what year? How'd we do, Matt? Lots of correct answers. Lots of people who also provided additional information, like John Gallant, who said that first observer, he used this transit to estimate the distance to Venus, and he was only off by about uh 50 million kilometers but it was the best guess until then i bet you talk about this kind of stuff on your blog i do indeed he indeed did make an approximation that was better than anyone else had done and

in driving distance to venus and then and then extrapolations to distance to the Sun. But people got a lot better at it when they got crazed using the transit of Venus to really get better calculations of the distance between the Earth and the Sun during the 1700s and then the 1800s because it's the yardstick. You get that or the meter stick and then you can scale it to the whole solar system. So here's our winner robert dickinson a first-time winner i believe from cedar city utah who said it was jeremiah horrocks jeremiah horrocks and his buddy william crabtree in get this i love these towns in britain much hool or much hoolie? Much hool. They have a lot of hoolie there. In Britain, they did this on December 4th, 1639. They did indeed. As we mentioned before, there were

some vague predictions of the 1631, the first in the Venus transit pair in the 1600s, but nothing that was visible from the places the people were. So Horrocks nailed it with his buddy Crabtree in 1639, at least got that first observation. So, Robert, we're going to send you a Planetary Radio t-shirt. Congratulations. And next time. Okay, we've given you the year, but some people want to make plans right now. So for those people, I want you to tell us, what is the date of the next Venus

transit of the sun? This is after the 2012 one, just to be clear, what is the date? Uh, go to planetary.org slash radio, find out how to enter. And you'll have until the 11th of June, uh, this year, 2012, not 2117 to get us that answer. Just one more thing. Did you get the secret package that is your gift from JPL? Because I always buy you something in the JPL gift shop. You're so nice.

No, I don't have the secret package. Oh, no. Well, we'll just wait until next week, I guess. Hopefully it'll be delivered. I'm sorry to keep you in suspense this way, but something to look forward to. Alright, everybody. Go out there, look up at the night sky, and think about dark circles. Thank you, and good night.

Dark circles, as in that dark disk that's going to be crawling across the surface of the sun. He is Bruce Betts, the Director of Projects for the Planetary Society. He joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California and is made possible by a grant from the Kenneth T. and Eileen L. Norris Foundation and by the members of the Planetary Society.

Clear skies. Thank you.