Planetary Radio: Space Exploration, Astronomy and Science - Exploring Saturn With Cassini

Episode Date: February 23, 2016

Cassini Mission Project Scientist Linda Spilker returns with the latest discoveries at the beautiful ringed planet, 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.

Exploring 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. We're back with one of our favorite and most frequent guests this week, Cassini Mission Project Scientist Linda Spilker has the latest science and wonder from that great ring planet. The space above our own planet just gets busier and more business-like. That's according to Bill Nye the Science Guy.

The family that stargazes together stays together, at least if they are the Herschels. at least if they are the Herschels. And that's just one thing that we'll learn from Bruce Betts in today's What's Up segment that includes a chance to win OK Go swag. We begin with the Planetary Society's senior editor, Emily Lakdawalla. Emily, a couple of things for us to talk about today, including a reference to some stuff that you're tracking for the rest of us in your Twitter account. that you're tracking for the rest of us in your Twitter account. First, what are these photos, these crazy rolling images of Earth that you posted to the blog at planetary.org on the 19th?

Well, I'm always on the lookout for odd images of Earth from space. We have lots of spacecraft that are supposed to take photos of Earth in Earth orbit. And then there's deep spacecraft that sometimes take photos of Earth as they fly by or depart. But this was a new one for me. This was from a spacecraft called Cluster, which has been in orbit for 16 years. Actually, it's four spacecraft and they have wonderful names. Their names are Roomba, Tango, Salsa, and Samba. And they have- No Cha-Cha? No Cha-Cha. There could have been a lot of other dance options, but let's not get distracted.

So we're talking about the Cluster spacecraft, which had these basically webcam cameras on them in order to watch their deployment. The spacecraft were launched in pairs and they needed to be separated once they got to space. And they had this little tiny camera on the spacecraft to watch the separation. The European Space Agency has put cameras like this on a lot of spacecraft, including Mars Express. They reactivated that camera on Mars Express a few years ago and are taking really fun images of Mars with it. So it suddenly occurred to the Cluster team, hey, I wonder if these 16-year-old cameras still work. And it turns out they do. The only thing is that

Cluster is a spinning spacecraft design. And so the images of Earth that they get are just kind of whirling around and around and around the field of view. It's kind of mesmerizing. It's really hard to stop watching. Frankly, I was more impressed with the animation watching the Earth roll around the frame than with the individual images. They're not exactly sharp, but it's still really fun to watch. Now, on to something you're sort of giving us some insight

into your writing process as you prepare your book about the Curiosity mission. Well, for the last couple of weeks, I've been working really hard on the chapter that goes into the launch, cruise, approach, entry, descent, and landing phases of the mission. Curiosity was many spacecraft. Curiosity is not just the rover. There was this descent stage and heat shield and backshell and cruise stage. And all of these very complicated spacecraft were developed for the sole purpose of that nine-month journey to Mars. The descent stage is just as complicated as the rover. And so it's taken me a lot of research, but I've finally begun to understand what all the parts are and what they were for. And I just want to give some credit to this amazing piece of equipment

that had one job to get Curiosity onto the surface and then was unceremoniously dumped onto the Martian surface to make a crash site. And good job, engineers, on making those things work. Also, good job doing all this labeling. It's great fun. And if you do not follow Emily's Twitter account at eLockedAwala, this is a good time to start. And you will find this stuff there. Thanks, Emily, very much.lachtawalla. This is a good time to start, and you will find this stuff there. Thanks, Emily, very much. Thank you, Matt.

She is our senior editor, the planetary evangelist for the Planetary Society, and a contributing editor to Sky and Telescope magazine. And that book's going to come out before too long, a book tracing the Curiosity mission, the Mars Science Laboratory rover. Up next is the CEO of the Planetary Society, Bill Nye the Science Guy, with a lot of ground to cover this time, or a lot of space to cover. Bill, I guess if there's a theme, it's simply that space is a very busy place. Oh man, there's so much going on. I mean, in the background that will one day be in the sky,

you know, Boeing had its CST-100 capsule splash down. They did a splashdown test like the good old days, let it fall into water, and it worked. This is like an Apollo-shaped capsule or a dragon-shaped capsule, but they got it working. And this is an important step not to have not work. That is to say, you'd expect it to work, and it did. So that's good. And then they're still fighting about this upper stage for the space launch system. SLS is an acronym for the new

NASA rocket that would be big. And we at the Planetary Society are excited about it because it could not only take humans up deeper and farther into space, but it could take interplanetary spacecraft farther into space. And the great thing for us about that is it would lower the cost of these missions and speed them up. And then I cannot help but notice that the ARM asteroid redirect mission is still going way in the background. It has a new R. Instead of arm, it's arm. They've added the word robotic. This is an idea that kind of emerged, how to say, emerged from nowhere, from the background of NASA a few years ago.

And they're still trying to get funding for it. I don't know how it's going to work out. Now, this sounds like an insignificant story, this next one, Matt. The Viasat-2 satellite will not be launched on a SpaceX Falcon Heavy because of the concern about schedule slips. They're going to an Ariane, a European-built rocket. This is a very interesting thing to me, that space is so international now that you can change countries and nobody says anything about it. Meanwhile, the U.S. Congress, all excited about whether or not to enable RD-180 engines, which are all made in Russia,

that are fitted on an Atlas V. And we love the Atlas V, Matt. That's what LightSail was launched on. And how. There's a lot going on. Speaking of which, there's a lot of satellites that are going to start running into each other. You know what it says to me?

Space, I mean, the marketplace extends into well into orbit now and maybe beyond. Whoa. No, you're right. It does. It extends beyond orbit, beyond geosynchronous orbit. It's way out there. Man, it's a wild time. Stay tuned, everybody. We're just trying to change the world here. Let me just add that the conversation that I had with Casey during what would have been your slot last week about the president's budget request for NASA, that long, very wonky but fascinating discussion with Casey and Jason Callahan, the other space policy guy for the Planetary Society, it's now available at planetary.org slash radio and all kinds of other places. A fascinating discussion with those two smart guys. If you're into it.

I hope you are out there. No, it's good. So the Planetary Society, Matt, we used to just argue about space policy at the end of board meetings. It was a heated discussion. Now we have two people that analyze it full time, think about space policy full time. And it's made us, I think, a lot more effective. Am I allowed to use the word effective? Yes, I believe you are. We're a lot more effective. And indeed, the planetary science budget is now up at being proposed at 1.7 billion. That would be huge.

It would be a huge increase. Is that right? I thought it was 1.5. It's 1.5 is the goal, but people are throwing 1.66 around like it's a real number. So we're all hopeful. But anyway, hiring these two guys full time has really been effective. We've been able to make friends in the right offices and engage people in the importance of our mission to advance space science and exploration. It's an exciting time. If I ever run into the guy who runs the place, I'm going to congratulate him.

Oh, he's odd. It's an odd duck now. I've got to fly. Bill Nye the Planetary Guy. Is the CEO, the guy who does run the place at the Planetary Society, who joins us most weeks here on Planetary Radio. He's the science guy. Up next, a conversation, one of our regular updates from Linda Spilker, the project scientist for the Cassini mission at Saturn.

Cassini mission at Saturn. I've lost track of the number of times we've been joined by Linda Spilker. Linda has been the Cassini project scientist since 2010. She was deputy project scientist in the 13 years before, taking that position in the same year Cassini began its voyage. The great spacecraft will celebrate 12 years at Saturn this coming June. It will have just one year left before it ends its journey of discovery with a dramatic plunge into the giant planet's atmosphere. Linda always has new discoveries to tell us about. This time we sat down at a picnic table on the sprawling Jet Propulsion Lab campus set in the hills above Pasadena, California. Linda, it's been too long. It is a great pleasure to get you back on Planetary Radio and in this terrific setting. I just love being at JPL and

to be sitting outside on a beautiful winter day here. You can't be beat. It's great to be back, Matt. You've had a busy morning. It's great to be back, Matt. You've had a busy morning. We actually had to delay this conversation a little bit because you had a celebrity space enthusiast visitor. Right. Sir John Hurt was here to see JPL. He came with his wife and a friend. Sir John Hurt, the famous actor.

Right. And he was just phenomenal and curious about all the things going on. I talked with him about Cassini. And he's just one of a number of people that really are curious and come here for tours. Nothing new, because we're all curious about the stuff that goes on at this place, and certainly about Cassini, which is why we're happy to talk to you on a regular basis. By the way, you also told me that from now on, the incredibly popular open houses here at JPL, you're going to have to issue tickets because it's just outgrown what the lab can handle. That's right, Matt.

We were so popular last year that by 10 in the morning, we didn't have parking and we had to close the gates. So we're going to have to hand out tickets so we can have people visit in a more controlled fashion. Not sure of the details yet, but it'll be a different format than we've had in the past. Just another sign of the popularity of planetary science. I agree. It's great. I got to mention one other thing. The last time that I did any recording out here was also because of Cassini. It was because there were hundreds of us out here waving as Cassini took a photo of us. Yeah, what a wonderful event to everyone be waving at Saturn. And so those photons were reaching Cassini at just the right time for Cassini to take those pictures of Earth. Really a lot of fun. I was out there waving too. I saw you.

I'll put up a link to that past show. It was such fun. But let's talk about what's going on with the mission. And as usual, there's probably much more science than we will have time to talk about. But first, the health of the spacecraft. How's it doing? The spacecraft is healthy. Everything is working just fine. We haven't had any changes since the last time we talked. All right. Let's start with the moons because you've, in a sense, had to say goodbye. Right, right. We've basically been in the equatorial plain for not quite a year, and that's a great time to have flybys of the moons.

We had flybys of some of the tiny moons, including Atlas, which kind of looks like a little flying saucer, Epimetheus, Prometheus, these really odd-shaped little moons. And then we had our final three flybys of Enceladus. And that was really sad, to say goodbye to this fascinating world with the active geysers coming out of the south polar tiger stripes. So that just happened in the last several months. Also, since we last talked, isn't there now much better evidence

confirming the existence of that ocean under the ice on Enceladus? Right, for Enceladus, and it came in a very unusual way. It's the tribute to having a really long mission like Cassini. They took images over about a decade, saw how much Enceladus would wobble back and forth in its orbit. Our moon wobbles too. And if Enceladus had been frozen solid all the way through, or mostly frozen, it would have wobbled only a little bit. And the amount of the wobble told us that there had to be a global ocean underneath the icy crust. So here's an ocean, maybe six miles thick underneath an icy crust, 15 to 20 miles in size. And so it allows Enceladus to slosh back and forth, riding on that global ocean.

And so that was a big finding just in the last few months that we've made. So it's not a perfect comparison, but I'm thinking of spinning a raw egg compared to spinning a hard-boiled egg. Right. By how much it wiggles around, you'll get evidence of what the state is on the inside of the moon. And so this was our first confirmation of a global ocean. We knew there was liquid water underneath the South Pole from gravity flybys, but we didn't know how extensive, whether or not you had a global ocean,

and now we know. It's a global ocean, hydrothermal activity on the seafloor of Enceladus, so a very exciting place. Just waiting for a return visit by some other spacecraft. Oh, absolutely. And, in fact, as part of this series of flybys, on October 28th we had our closest pass ever underneath the South Pole coming within just 50 kilometers of the surface

and actually sampling the particles and the gas. And we're still busy analyzing those data. Part of what we were looking for in the gas is a signature of H2, hydrogen, because that would tell us another piece of evidence about the hydrothermal vents and how active they might be. But it's a very delicate measurement carefully being calibrated so we don't have any of the results out for that yet. Amazing to think of a human-made device flying right through those plumes

barely above the surface of this great world. Right and since it was so close a lot of us gathered in the room waiting for that first signal back from Cassini to let us know that everything had gone well and that we were getting the data back. And so there were lots of cheers and applause as a number changed from zero to just the right number. We knew that the signal from Cassini was good and it was sending data back and it had survived that fly through. Let's move on to another moon, one that you got some color pictures of and has some amazing and beautiful features that are mysterious. Right, that moon is Tethys, and it has these red streaks on its surface looking like someone maybe spray-painted graffiti or used lipstick to just cover and make these long, arching features on the trailing and leading sides of Tethys. So we decided, okay, we've discovered them. Let's get in as close as we can with the remaining flybys we have,

take some pictures, and see if we can look for fractures or cracks or is it some internal source for these red streaks. And so we did that. We got in very close. And what we saw is that these red streaks just go up and down over craters and hills, and there's no evidence of fractures whatsoever. So it's still a big puzzle, but they're so narrow and in such a confined region, we're beginning to think something's going on on the inside of tethys that's putting this material on the surface. When I see red, and a fairly

brilliant red, although I think the color was a bit enhanced. Enhanced, definitely enhanced, Matt, yes. But just the same, when I see red, I think organics, maybe? Exactly, exactly. We have a few spectra that are being analyzed. The visual and infrared mapping spectrometer took spectra at the same time we took images, and there are no definitive results about that yet. They look very red in the near-infrared filters.

So if you look just at a visible picture of Tethys, they'd be very subtle and you'd probably miss them. Project scientist Linda Spilker will share more with us about Saturn and the Cassini mission when we return. This is Planetary Radio. This is Robert Picardo. I've been a member of the Planetary Society since my Star Trek Voyager days. You may have even heard me on several episodes of Planetary Radio.

Now I'm proud to be the newest member of the Board of Directors. I'll be able to do even more to help the Society achieve its goals for space exploration across our solar system and beyond. You can join me in this exciting quest. The journey starts at planetary.org. I'll see you there. Do you know what your favorite presidential candidate thinks about space exploration? Hi, I'm Casey Dreyer, the Planetary Society's Director of Space Policy. You can learn that answer, and what all the other candidates think, at planetary.org slash election2016. You know what? We could use your help. If you find

anything we've missed, you can let us know. It's all at planetary.org slash election2016. Thank you. Welcome back to Planetary Radio. I'm Matt Kaplan. As project scientist, Linda Spilker oversees and coordinates all science activity for the Cassini mission that has been revealing Saturn and its rings for nearly 12 years. Let's not forget the planet's fascinating and unique moons, worlds unto themselves that Linda was talking about just before the break. All right, yet another one of these worlds. You had some beautiful images of, it's pronounced Dione, isn't it? Right, right, yeah.

Another very fascinating and tantalizing world. And we had our last close flyby of Dione, got some good color mosaicing, covering the parts of the surface we hadn't seen previously now that the sun is shining down on the North Pole. And that was basically, we're now saying farewell to the major moons of the Saturn system. Although toward the end of the mission, as we pull that closest approach in to about the F ring, as we orbit just outside the F ring, we'll get a chance to look at some of those tiny ring moons that are basically shepherding one side of the F ring or the other,

or Atlas just at the outer edge of the A ring. So we'll have a chance at least at some of the smaller moons in those orbits. Anything new to say about Titan before we leave that cloudy place? Yeah, well, Titan is just, we're continuing to monitor the lakes and seas on Titan, trying to see if we might see waves on the seas. There's some hints that that might be true. For Titan, perhaps something new, there's a very narrow channel between two of the great seas, and we've actually seen flow

through that channel that actually connects them up. And just yesterday, we had an observation to take a radio occultation of the atmosphere of Titan and then bounce a radio signal off the surface. And if you hit a liquid, you get a strong, what they call, bistatic signal. And so we're going to be analyzing those data, and that just happened yesterday. I should have worn my Surf Titan t-shirt. Appropriate, yeah. You've mentioned the rings. What are we learning about them? What's come up in the last few months?

Well, the rings are turning out to be very interesting. The B ring, which we thought contained the bulk of the mass, it does. We thought it would be much more massive than we're finding out. We found a very clever way to add up stellar occultations, add a number of them together, line them up the way they should be, and look for spiral density waves. And lo and behold, when we did that, getting them phased just properly, we found these spiral density waves in the B ring. They're controlled by tiny moons outside the ring.

Gravitational interactions force these waves. And the structure of the waves, the spacing between them, is determined by how much material you have in the ring. And here we found the B ring, which is very opaque and you really can't see through it, had only a few times more mass than the A ring, which we can see through very easily with occultations. So it's an interesting puzzle. Are the particles different in some way? Are they more transparent? Are they bigger? Is there some difference about the

particles that's giving this apparent large opacity and yet not more massive? So it's a puzzle. At the end of the mission, we'll be able to directly measure the mass of the rings, and that will help perhaps solve the puzzle. I remember early on, and even before Cassini, the discovery of how complex these rings were, the braids and so on. And now, as you've mentioned, you have these little moonlets that are basically hurting the other ring particles. How far has it come since those early days, looking even back to Voyager? Right. I mean, with Voyager, we were amazed at how thin the rings appeared to be, maybe only 100 meters thick. Now, with Cassini, it's more like maybe 10 meters or less thick across a lot of the rings. And the particles have gone from individual particles floating around, is our idea, to now the fact that most of the particles tend to clump together,

at least temporarily, and then could be broken apart. So our understanding and the dynamics and the processes in the rings have grown by leaps and bounds by looking at them. I don't think a science fiction writer could have come up with these if we didn't have, you know, ringed planets in our solar system. Who would have thought of millions, billions of particles? Billions, probably, of particles, yeah. Ten meters thick. It's just mind-boggling.

Right, that Saturn's just so oblate that it just keeps those particles very carefully confined. And then there's the F ring, just an amazing, amazing puzzle. This ring that has lots of small particles but appears to have now a dense central core. It appears as the moons interact, they cause collisions that puff out all of this dust, and these dust form in streamers and all kinds of very interesting structures.

The F ring is one of those rings that never looks quite the same every time you look at it. There's always something new and different going on in that ring. Speaking of dynamics, the planet itself, I don't know how much news there is out of the last few months, but isn't the focus increasingly going to be on the planet and somewhat the rings? Right, definitely as we get toward the end of the mission, especially when we get in those final orbits that when we dive between the innermost ring and the planet,

we'll get really great measurements of the gravity field of the planet, the magnetic field, and really begin to understand the internal structure of Saturn, how it might have formed, how it's evolving. Although, you know, the rings are a great detector for some of the things going on in Saturn. It turns out that a recent paper found some waves in the rings. Some of them were actually seen by Voyager,

but we didn't know what was causing them. And it must be that there's some kind of a lumpiness, perhaps, inside Saturn that's creating the equivalent of spiral density waves, but instead of propagating outward, they propagate inward, telling us that this extra mass is inside Saturn in some way. Maybe the equivalent of a Prometheus or a Pandora, one of the F-ring shepherds,

of redistribution of mass that can create these little waves. So an interesting story there that the rings are actually good detectors of Saturn not being completely homogeneous. Fascinating that we can use the rings as a science instrument. Right, that's what we're doing, like a seismic detector. Saturn itself, there hasn't been a lot of change in the planet, no giant storms coming out,

although we're finding that Saturn's upper atmosphere appears to breathe. We saw it from early in the mission expand out, and now it appears to be contracting again. It might be a seasonal effect, and we're watching this very carefully with stellar and solar occultations because we want to fly at the very end, the last five orbits of the mission, very close to Saturn. Basically, dip our toe in, sniff the upper atmosphere with our ion and neutral mass spectrometer, and directly measure the composition of the upper atmosphere. So we're watching to see just what might happen over the next year or so with Saturn's upper atmosphere.

So we're in good shape as we build toward this grand finale, which is now just a little more than a year away. Right. It's amazing to me how quickly this grand finale is approaching. It just appears to be coming too fast. You know, it's been a wonderful mission, and it will be very hard to see it end. I'll say. I know that the Planetary Society and others around the world will be looking for ways to celebrate that finale and this tremendous accomplishment by you, the entire Cassini team, the spacecraft, when that time comes. But fortunately, we still have some months ahead of a year and a half to go. New science, new revelations. Right, exactly. Linda, it is a great pleasure as always. Thank you so much. Thank you, Matt. It's a pleasure to be here. That's Linda

Spilker. She is the project scientist for the Cassini mission. She's had that job since 2010. But I noticed, let's see, you started as a Cassini assistant study scientist 28 years ago. That's right. 1988. 1988, yes. I was transitioning from Voyager to my next job, and that just happened to be Cassini. And I've enjoyed it so much, I've stuck with it. And we'll be right back with this week's edition of What's Up?

and Bruce Betts, and I have to go to the JPL store and figure out what I'm going to buy him this time. Time for What's Up? with Bruce Betts, the Director of Science and Technology for the Planetary Society, who is on the Skype line with us once again, which is a shame because it means I can't give you your gift from JPL, where I talked to. I know, I talked to Linda there last week, and of course I stopped at the shop on the way out, and it'll just have to wait. Maybe we can do something in person for next week. I hope so because because i know you're gonna love it just like i'm gonna love the night sky what a segue wow that was a beautiful segue yes you will matt talk one more time about five planets in the sky mercury's getting tough particularly depending on when

you pick this up but in the pre-dawn, low in the west, still some Mercury, but definitely low in the west, but higher, the much brighter Venus. And then as you work your way all the way across the sky in the pre-dawn, you follow a line that goes to Saturn, which is yellowish. There's also not that far from Saturn, the reddish star Antares in Scorpius. And then farther across the sky is Mars and Jupiter over low in the west, which also means Jupiter's rising fairly early in the evening sky over in the east. So you can pick up bright Jupiter in the early evening east.

On to this week in space history. It was 1966. 50 years ago, the Cosmos 110 launched, setting the record for the duration of dogs in space. At 22 days, the dogs Vedrak and Ugljak. But it all worked out for Vedrak and Ugljak. They came back to Earth, successfully lived a long, happy, I don't know if they lived happy life. They lived. Let's put it that way.

One of the puppies was given to president john to kennedy speaking of good pr on to so mercury when the planet mercury is at its closest point to the sun. The sun appears three times the diameter in the sky than it does from Earth. That's nine times the area. We'll come back to Mercury in this week's trivia contest, but first let's check in on the previous one where I confused matters by asking what was famous astronomer Herschel's first and middle names. How'd we do, Matt? Okay, well, I warned people that there was a little bit of trickiness involved in this because, of course, there was more than one Herschel.

There's a whole dynasty of astronomy-oriented Herschels, very accomplished people. And we got a very big response. Now, almost everybody came up with at least the main guy. I think the guy you were thinking of, the patriarch, right? Yes, yes, indeed. And the only one of the bunch to discover a planet. Oh, yes, Uranus. He was, well, he started out anyway as Frederick Wilhelm Herschel. Upon moving to England, that became Frederick William. Is that what you were looking for? That is indeed.

Planet-discovering dude and the guy who wanted to name Uranus George. That's right. After George III. That wasn't well accepted in the international community. Yeah, I wonder why. Anyway, it was Steve Wienel who was chosen by Planetary.org this week, and he gave us the Friedrich Wilhelm version, which is certainly good enough. So, Steve, out there in Antelope, California, you're getting that prize package,

the Planetary Radio t-shirt, the 200-point itelescope.net astronomy account, and a set of year-in-space wall and desk calendars. Just one more week that we'll be giving those calendars away. Dana Lynn Barnett was one of those who tried to fill in the family for us. She talked about Friedrich Wilhelm, but also his sister, Caroline Lucretia, who helped William very much, was really a partner in what he was doing with his deep sky survey. And then, of course, there was Fred's son, John Friedrich William Herschel, who is a very accomplished astronomer. Dana said, please be sure to mention these folks, especially Caroline.

Let's remember those pioneer women in science. Absolutely. I couldn't agree more, Dana. So thank you for your entry. That came from Haifa, Israel, by the way. Bruce, did you know that he came up with, Frederick, Frederick William came up with the term? I think he went by William eventually. He's commonly known as William.

William, yes, you're right. He coined the term asteroid. I did not know that, Matt. That's a fabulous random space fact. So Alex Carl in Belgium was saying he was kind of the first Neo guy, the first near-Earth object guy. Dave Fairchild, who has gotten into this habit now of composing limericks for us, he actually did a couple. Here's one. He found Uranus, did spectral photometry,

nebulae referencing ice caps of Mars. Caroline worked with him locating comets and galaxies, asteroids, hundreds of stars. Wow. Nice. Thank you very much, Dave, in Shawnee, Kansas. Now we're ready to move on. All right, back to Mercury.

Mercury has the most elliptical or non-circular orbit of any of the eight planets in millions of kilometers. How far from the sun is Mercury at its closest and farthest points in its orbit? Go to planetary.org

slash radio contest. I think that this time we will give you till the 30th. That'll be Tuesday, February 30th at 8 a.m. Pacific time to get us the answer. Okay, and for all of you OK Go fans out there who loved last week's show, here's the prize. An OK Go t-shirt signed by Damien Kulash and Tim Nordwin, those two founders of the band. And we'll throw in a Planetary Radio t-shirt as well. Signed by, oh, I don't know, Bruce.

Cool. If you want it signed at all. So get those entries in. All right, everybody, go out there, look up at the night sky, and think about dogs. Thank you, and good night. He's Bruce Betts. He's the director of science and technology for the Planetary Society.

He joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society. He 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 its Planet Happy members. Danielle Gunn is our associate producer. Josh Doyle created the theme. I'm Matt Kaplan. Clear skies.