Planetary Radio: Space Exploration, Astronomy and Science - Zibi Turtle and a Mission to the Ice Giants

Episode Date: September 22, 2015

They are the most neglected planets in our solar system, but that status may be changing. Planetary scientist Elizabeth “Zibi” Turtle celebrates NASA’s announcement that it will study a mission to Uranus or Neptune.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Ice Giants with Zippy Turtle, 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. Planetary scientist Elizabeth Zippy Turtle wants a mission to Uranus or Neptune. She'll tell us about good news from NASA in a few minutes. Have you read The Martian? Bill Nye has, and he'll tell us why good news from NASA in a few minutes. Have you read The Martian? Bill Nye has, and he'll tell us why it's so much fun. And Bruce Batts will prepare us for a lunar eclipse.

First, though, we'll talk with Senior Editor Emily Lakdawalla about her latest update on the Curiosity rover, now rolling across a red planet near you. Emily, love this new Curiosity update. Obviously, time to dig out the red-blue 3D glasses. Yeah, it's always fun to dig into the 3D data captured by the HiRISE camera on Mars Reconnaissance Orbiter to get a sense of the landscape that Curiosity is driving through. And it's getting much more interesting.

There's ridges and valleys and sand dunes, and the mountain's getting closer, and it's pretty fun. Why is this looking for the next drill site proving to be more challenging than was originally thought? Well, it has to do with trying to find a place to drill where the scientists are sure that they really understand the scientific context. And context is really what it's all about. If what you want to do is tell a story. They have already drilled a couple times in this mudstone layer called the Murray Formation. And now they're interested in drilling into the next rock type that's sitting on top of it

called the Stimson, which is an Aeolian sandstone, a wind-blown sandstone. But they've had a hard time finding a good place to drill where they understand where they are in the stratigraphic section. And then as they've been driving along, they've been getting distracted by these halos around these fractures on the ground. And they're taking a pretty close look at those things too. Halos? You mean these bright areas around these fractures we can see in the images? That's right. Pretty much all of the rocks that Curiosity has seen are sedimentary rocks that are all split by these fractures of different kinds. And back in the Murray Formation, those fractures formed these bright, brilliant white veins absolutely filled with calcium sulfate.

But now that they've gone into the Stimson Unit, there are still fractures, but they have a very different character. You don't see that bright fill. Instead, you see this kind of bleached appearance going out many centimeters away from the original fracture. And they don't know what's causing that. It could be the deposit of a mineral. It could be the taking away of a mineral.

It could be some kind of chemical alteration or none of the above. And they're struggling to figure that out, but it's pretty cool looking. Well, some great analysis ahead, I guess, once that drill point is found. And also ahead, looks like Curiosity's future is full of sand. Yeah, it's pretty cool. After the Stimson, they're finally going to get to those sand dunes, these black basaltic sand dunes that rim the edge of the mountain and are really what have been preventing Curiosity from reaching the mountain in the first place. And so they've been driving southwest for a really long time to get to a point where they can get around the dunes. But before they do that, they're going to drive right up to one of these things, which is pretty cool because these dunes

have actually been observed to be in motion from orbit. And so it'll be the first time we've actually explored an active sand dune on Mars. Yeah, you can actually see those dunes moving in that one sort of flicker image that you posted. All right, we'll close with consideration of the wheels. I was interested to see that the Curiosity team does a good vehicle maintenance, checking the tires, or rather wheels, on a pretty regular basis. They do. And I have been very worried about this part of the mission since the wheels started having problems, because Curiosity is driving on very sharp exposed rock right now, but the rover drivers are doing a really good job carefully steering around dangerous hazards, and so far

the wheels seem to be holding up pretty well. Emily, much more in store. We certainly hope for this mission, and look forward to talking to you about that in the future and again for our regular segment next week. Thank you, Matt. Senior Editor for the Planetary Society. She's our Planetary Evangelist, a contributing editor to Sky and Telescope magazine. That's Emily Lakdawalla. Bill Nye, the CEO of the Planetary Society, comes in now. Bill, how about that Martian? Planetary Society, comes in now. Bill, how about that Martian? Love the Martian.

Love it. For those of you who don't know, it's a novel about a guy stranded on Mars, a NASA astronaut, and he has to innovate. He has to come up with things to keep himself alive. Now, there's some license taken. You talked to Andy Weir, the author, about it, right? A little bit. Yeah, but it's cool.

It's just cool. He's constantly figuring. And what we all love about it is that fighter pilot swagger. I mean, things are troubling, but he maintains his sense of humor. I don't want to give it away for a long time on Mars. It's cool. I'll just say one word. Potatoes.

Potatoes. There's a lot of potatoes. And even that's unreasonable. Would you show up with a – never mind. Everybody enjoy the book and the film. Yeah, it is absolutely marvelous. And he's going to join us for our celebration of the 35th. He'll be at the 35th with all the cool kids here in Pasadena, California. Come on out.

It's going to be a fantastic party. He'll be here. And here's – Matt, I'll just tell you. It's going to be a fantastic party. He'll be here. And here's – Matt, I'll just tell you. I feel that the success of this book, movie with Matt Damon, who is required to be in every movie now, is part of this resurgence in interest in science. You know, Neil deGrasse Tyson talks about this all the time, where the Big Bang Theory is the highest-rated show on television. Not the highest-rated sitcom.

Highest-rated show. And it's cool to be a nerd now. It's cool to be smart again. And that's the way it was in the few years leading up to the moon landings, the human moon landings. And so I hope that this gets everybody excited about science. This is a part of the bigger effort to get everybody excited about science so that we work hard to change the world. Well put. And it's just great fun.

Oh, it's just cool. I have so many leaders. So many days. So what that means is I did the math for you. I have 30 days of oxygen. Yay. But I don't have anything beyond that. Boo.

It's just brilliant. It finds a way to communicate with Earth in a very cumbersome way. And it just adds to hilarious comedy charm. I'm glad you didn't give that part away either. Yeah, well, I'll just warn everybody, things go wrong. It ain't so simple to survive on Mars with nobody coming to rescue you, all right? Mars is hard. Mars is hard. Mars is hard. And I also, frankly, hope this reminds everybody of how harsh Mars is.

Oh, yes, you can live in a rubber Teflon canvas bubble for a while, but it's not a high quality of life. That's all I'm saying. Thank you, Bill. Thank you. He is the CEO of the Planetary Society, a fan of The Martian. I can't wait to see it. The book was fantastic. Also, to have Andy Weir on stage at our 35th anniversary celebration coming up in October.

Up next, Zippy Turtle, pretty happy about at least a chance to send a mission to Uranus and or Neptune. Outer planets rule. Yeah. So many of the scientists we talked to are juggling involvement in multiple missions and projects. Elizabeth Zibby Turtle is no exception. She's part of the science team working Cassini at Saturn. And she's deeply involved in the upcoming mission to Jupiter's ocean moon Europa, as you'll hear toward the end of our conversation today. When she recently spoke to me from her office at the Johns Hopkins Applied Physics Lab,

it was primarily to celebrate a small step by NASA toward one or both of the most neglected planets in our solar system, beautiful worlds that are full of mystery. Zibi, welcome back to Planetary Radio. Thanks for joining us today. Thank you. I was excited, I bet maybe not as excited as you, to see this announcement from NASA, Jim Green, the Director of Planetary Science, that he's directed the Jet Propulsion Lab to start looking at or developing a study, something that will tell us whether we ought to seriously consider going back to Uranus and Neptune. Is that something you were pleased to see? I was very excited to see that announcement. It's great to be really seriously starting to look at potential mission concepts for the distant outer solar system. Yeah, that's great.

It's interesting. Jim Green applied a phrase that I think is very appropriate to these planets. He said they are mostly ignored. It kind of reminded me of the Hitchhiker's Guide to the Galaxy's description of Earth, mostly harmless. They really have been mostly ignored, haven't they, at least by spacecraft? Yeah, they've been, well, each of them has been visited once by the Voyager 2 spacecraft. So there was a single flyby of each of them has been visited once by the Voyager 2 spacecraft. So there was a single flyby of each of them. In particular for Uranus, because of its orientation, where it's rotated and kind of end on to the sun,

the Voyager flyby was during the northern winter. So we saw the southern hemispheres of the satellites and not the northern hemispheres at all, because they were in darkness. Yeah, so we don't even know what the northern hemispheres look like and the activity was very different in the atmosphere because of the illumination. So they really haven't been explored very thoroughly at all. Now, there have been, since the Voyager flybys, the advent of space telescopes with HST in particular, and improvements to technology for Earth-based telescopes. There's been a lot of surveys

of Uranus and Neptune to study primarily the planets, but there's some other studies you can do as well from these assets. But of course, we're very far away, so there's only so much you can resolve. But we've got brilliant movies of the dynamics of the Uranian atmosphere, for example, during the equinox period when the illumination was very different from the Voyager flyby and the atmosphere was behaved completely differently. And we have been able to monitor that from the ground. There have been some really spectacular observations of the planets themselves. The other aspects of the system, especially the satellites,

are just too small to really observe the satellites and certainly can't see their geology from Earth-based assets. So that's why we've got to get back there. Expand on that. What is it that a spacecraft will be able to do that is not likely to happen, even with the much more powerful Earth-based and space-based telescopes that are going to be coming online in the next few years? A mission that would go to either of these bodies, ideally one would want to go into orbit around

the planet, the same way the Galileo mission did at Jupiter and the Cassini mission did at Saturn, or is doing at Saturn still. With a flyby mission, there's just a limited amount of time, and you can take as much data as you can and then play it back after the flyby, but you don't get to see aspects of the system, temporal changes, for example. You don't get to see those the way you do with a mission that stays in orbit for a few or several years. You're just limited to the duration of the flyby. So one of the flyby. One of the things that you gain by having an orbital mission is temporal observations.

You get to observe daily, monthly cycles, obviously. It would be a short portion of the Uranian or Neptunian year because those are very long. You'd be limited in the seasonal changes you'd be able to see, but nonetheless, you'd be able to look at temporal dynamics in the rings, for example, and certainly in the atmospheres. You also get in-situ information about the magnetic fields of the planets, which are very different than the magnetic fields of the gas giants. They're tilted at great angles to the rotation poles. There's a lot that's different about the magnetic fields.

Potentially, if one's able to do an atmospheric probe, obviously in situ data about the atmospheres of Uranus and Neptune would be very valuable. Uranus and Neptune as planets are very different from the gas giants from larger Jupiter and Saturn. These differences are things that we need to understand to constrain the formation of our solar system. Right now, the formation models tie very strongly to the larger outer planets, but we don't know the details of the interiors of Uranus and Neptune. So being able to study those in situ would give a lot of information about that. In addition, a lot of the exoplanets that have been discovered are Uranus and Neptune

sized. Understanding these planets that we can explore in our own solar system may inform us about planets of this nature in other solar systems. And obviously for the satellites, other solar systems. And obviously for the satellites, being able to observe the Uranian satellites up close in detail and the Neptunian satellites as well as the ring systems, these are things we can't do in detail

from Earth-based or space-based telescopes. When we return, Zibi Turtle will tell us which of the ice giants, Uranus or Neptune, gets her vote for a visit from Earth. This is Planetary Radio. Bill Nye the Planetary Guy here inviting you to the Planetary Society's 35th anniversary celebration. It's Saturday, October 24th in our hometown of Pasadena, California.

I'll lead the party with special guests. A great many of them. No kidding. These people are the real deals. You can't believe how much fun this is going to be. The details are at planetary.org slash 35th. That's easy, right? Planetary.org slash 35th.

Join us as we change the world. Hi, Mary. Can I borrow a couple of eggs? Sure, Marge. I'll get them from the fridge. Oh, darn. Look at this mess. All my refrigerator magnets have clumped together again. Mary, you need magnetic monopole refrigerator magnets from the Roswell Wonder Company. They're guaranteed to never clump. Gee, thanks, Marge.

I'll order my magnetic monopole refrigerator magnets today. The Roswell Wonder Company, putting alien technology to work for you. Not an actual company. Welcome back to Planetary Radio. I'm Matt Kaplan. NASA will study a major mission to the so-called ice giants in the outer solar system, and that suits planetary scientist Elizabeth Zibby Turtle just fine. That mission may be many years away, if it happens at all, but Zibby is also deeply involved with plans to investigate Jupiter's moon Europa,

a mission that will, we hope, happen much sooner. We'll get to that in a few minutes after we talk with her a bit more about Uranus and Neptune. If you had to pick between the two, if you could only send an orbiter to one of them, do you have a preference? I'll probably get in trouble for having a preference, but I do, actually. I mean, they're both fascinating bodies, and they both have their own interesting systems. But I, as someone who's studied icy satellites, and in particular the icy satellites of Saturn, the Uranian system, which has a group of these mid-sized icy satellites,

is particularly interesting to me, especially because we only saw half of them during the Voyager flyby. One of the things we've learned from Cassini is how little we understand these small icy bodies. The larger satellites we have a better handle on. The variability between Mimas and Enceladus, for example, is not something one would predict, that Mimas is an ancient cratered surface and Enceladus has active cryovolcanism right now. That's not something we would have predicted. And I don't think we understand these bodies. And so as someone who studied icy satellites, I find the features that Voyager revealed on Miranda, the incredibly tectonically deformed surface of Miranda,

the fact that there might actually have been cryovolcanic flows on the surface of Ariel, which is something we have had a lot of trouble finding we expect to see on icy satellites, but haven't been able to identify in detailed analyses. see on icy satellites but haven't been able to identify and detail the analyses. You know, whether those hold up as cryovolcanic flows when we get to explore them is something that is particularly interesting. So there's just a lot we don't know about those bodies and I think from my perspective, being able to explore the Uranian system and understanding its satellites, their histories would just be spectacular.

And the Uranus itself as well is very puzzling in the Uranian ring system. And as I said, Neptune 2 and the big satellite, Triton, are fascinating bodies. But my preference is the icy satellites of Uranus. Well, I hate to make people pick favorites. I mean, obviously, wouldn't it be great if we could send one to each? That's the way to do it, yep. All right, now Jim Green of NASA made it very clear that this is just the first of many, many steps toward a mission, if that ever happens. And he talked about it relying on a recommendation that will come out in the next decadal survey,

also something we've talked about on this show in the past, which is not due for a few years yet. I mean, do you think that this is the sort of mission that will be given a high priority in, what, 2022, I think? I would certainly hope so. It really is the next step for understanding the outer solar system, I think, to understand the ice giants. Both Uranus and Neptune mission concepts were studied for the last decadal survey, actually. And there were a lot of mission studies done in support of the previous decadal survey. And in fact, a Uranus mission is on the list that was recommended by the decadal survey for potential future missions. Obviously, flagship missions, there's a limited number of those that one can develop and fly at the same time.

And Uranus is further down on the list. But it is actually on the list from the previous decadal survey. Starting the mission studies now gives more time to really do more analysis of the mission concepts. In the previous decadal survey, a lot of mission studies were done in a very short period of time. And this time, I think they're looking at doing some of these mission studies, starting them at least in advance of the decadal survey, and that way there can be more time to do the detailed analyses of the mission concepts that can then support the decadal survey decisions and

recommendations. We've got a minute or two left, and in that time, I thought maybe we could talk about a mission that is much farther along, and I was very pleased to see. I guess I should congratulate you once again, because you are the principal investigator for an instrument that will be on the Europa mission, still known to many people as the Europa Clipper. Tell us about the Europa imaging system. Thank you, yes. It's very exciting to have a Europa mission being planned at this point. It's exciting to be selected as part of that payload. It's a very capable payload, and it's going to be really great for exploring Europa in detail, understanding Europa as a body. That camera is a dual narrow-angle camera and wide-angle camera, the NAC and the WAC.

These are designed to study a wide variety of aspects of the surface and interior of Europa. One of the really exciting things about working with a camera system is that we get to study Europa at the very, very highest resolution. In the close 50-kilometer altitude flybys. We'd get half-meter pixel scale images. Wow. So we really get to see the surface in detail, but we also get to map Europa globally. And so we get the big picture and the really high-resolution picture, and we get to put those together in context and in the context of the other instruments

that have been selected, and it's just going to be an absolutely spectacular data set. I'll say, very, very exciting. We have to talk more about that as that mission progresses, also something that a lot of us are very, very excited about. Sabi, we're out of time. Thank you so much for covering all of this, a somewhat more immediate mission, and hopefully one that will be seen, well, it may be the late 2020s or early 2030s, but at least we're talking about Uranus and Neptune.

Thanks again. Thank you. Elizabeth Zibby-Turtle is a researcher, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory. She is part of a Cassini team at Saturn and, as you heard, is also the PI, the principal investigator for the Europa Imaging System, one of the instruments that will be on the mission going to Europa sometime in, let's hope, the early 2020s. And very interested, as you heard, in seeing a mission to these ice giants that are really unique in our solar system and well deserving of study. We'll do some studying of the night sky with Bruce Betts when we are back in a few seconds for this week's edition of What's Up with Bruce Betts, the Director of Science and Technology for the Planetary Society. We are back in the studio here at Planetary Society HQ.

Good to see your smiling face, Matt. Thank you. I'm having a good time. There's a bunch of good stuff going on today. There is indeed. Would you like to hear what's going on in the sky? Ooh, ooh, that too? Yeah, I've specially arranged another total eclipse of the moon. You are so kind.

I know I am, but it's the last one for a couple years, so make sure you go see it. That's on September 27th or 28th, depending on your time zone. So the night of September 27th, Sunday night, visible from the Americas, Europe and Africa. It will rise already in eclipse at sunset for us in Western Americas and set in eclipse around dawn in Eastern Europe. Everyone in between gets more of it. So the start of the partial eclipse, the umbral part, the dark shadow that you can easily see with your eye, is 107, September 28th, UT. So just an hour after midnight UT, you'll have to convert to your own time zone. But for you, Matt, that's 1807 Pacific Daylight Time.

607 p.m. Okay. Yes, yes. 607 Pacific Daylight Time. 607 p.m. Okay. Yes. Got it. Yes.

That's when the partial eclipse starts, and the rough way to look at it is about an hour of partial eclipse, about an hour of total eclipse, and about an hour of follow-on partial eclipse as it moves out of the shadow. So check it out. Also up are our planets. We'll get back to them more next week. But you can check out Saturn in the evening sky, Mars, Venus, and Jupiter in the morning sky. Rolling on. On to this week in space history.

Forty-five years ago this week, Luna 16 returned lunar soil samples, becoming the first robotic sample return from another world. It kind of got lost in the Apollo headlines, though, didn't it? Well, yeah. It did not beat Apollo. And you may remember there were humans involved with Apollo. And they brought back a lot more samples. But the Soviets did do successful robotic sample returns after a number of unsuccessful tries. It was a great engineering achievement.

It was indeed. Speaking of great engineering achievements, 2007 this week, Dawn was launched. Of course, now orbiting Ceres did great stuff at Vesta. White spots. On to white spots? On to white spots. No, on to... Some cultures viewed a lunar eclipse as the moon being swallowed by other animals, such as a jaguar in Mayan tradition.

Or, according to the internet, a three-legged toad in China. A three-legged toad? A three-legged toad swallowed the moon. I'm trying to come up with some kind of angry disabled toad story. Oh, I got a million of them. Maybe someone can write in with more detail on that. We move on to the trivia contest, and it involved our fabulous flight on SOFIA, the Airborne Observatory. SOFIA's telescope has an effective diameter of 2.5 meters, but it's actually somewhat

larger than that. What is the actual diameter of its mirror? Here's the person that was chosen by random.org. I believe a first-time, might have been a first-time entrant, as well as a first-time winner, definitely a first-time winner, out of Helenwood, Tennessee. It's Stephen Ward. He said SOFIA actually contains a 2.7-meter diameter primary mirror for its beautiful infrared telescope. That is correct. They decided to scrawl in crayon on the outside edge. No, that is not true. Probably not a wise decision.

Oh, not true. Not true. Not true. Because the optical design requires that only about 90% of the mirror's reflecting surface can be used at any one time. So just basically the way the telescope is designed. And so what they get is an effective 2.5-meter telescope with an actual diameter mirror of 2.7 meters. Stephen, congratulations. You have won a Planetary Radio t-shirt and a beautiful Chop Shop Store historic robotic spacecraft poster.

I'm not sure which one, but they're all beautiful. So any of those you will be happy to have on your wall. Chop Shop Store is the place to Google to find out more about those. Do you remember the educators that we were on the flight with, the SOFIA flight? I do indeed. I don't know if you met Eileen Grabowski, but she entered the contest. Oh, that's awesome. She said, I don't know if it's fair for me to enter because I was there after all.

So hi, Eileen. She didn't make it into the show. We just didn't have time. But it was great to be flying with you. Thank you very much. Not only that, Eric O'Day, regular listener in Medford, Massachusetts, he says, I'm part of the team of educators that's working with Sophia, and he may get to fly on her next year. And if you haven't checked out the video that Merck Boyan put together of Tide to Planetary Radio from a couple weeks ago, do so. It's really cool.

And Random Space Fact's coming, right? It is. Yes, there will be a slew of Random Space Fact videos as well as a more in-depth video about the science and technology of SOFIA. This comment from Kevin Hecht in Pleasant Plains, Illinois, another regular. I like this a lot. Did you notice, maybe it's in that little border of the mirror that's not used, there was some print on the mirror and it said, objects in mirror may be larger than they appear. No, I didn't. No, I didn't.

Wow. I didn't know. Because they look at galaxies and, yeah, probably so. Yeah, it all makes perfect sense. Thank you, Kevin. What do you got for next time? What word generally refers to three celestial bodies in a line? So this is general. It could be a solar eclipse, a lunar eclipse, or anything else with

three bodies in a line. And I think it's a funny word. Go to planetary.org slash radio contest. Get us your entry. If it's funny enough for you, it's funny enough for me. You got to get that to us this time by Tuesday, the 29th of September at 8 a.m. Pacific time. I bet you that Dante Loretta would make available to us yet another copy of Extranaut, his game about flying your own planetary science mission across the solar system. So let's go out on a limb and say we'll award one more of those games. They just made their Kickstarter goal, and they're going now for, I guess they have several stretch goals? They do. I think we're done.

All right, everybody, go out there look up at the night sky and think about what it's like to record a radio show in a vault. Or a former vault. Thank you and good night. Fortunately they removed the door. They knew that we'd just get ourselves in trouble.

Let me out! He's Bruce Betts. He's the Director of Science and Technology for the Planetary Society, who joins us every week for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its giant, though not very icy, members.

Danielle Gunn is our Associate Producer. Josh Doyle created the theme music. I'm Matt Kaplan. Clear skies.