Planetary Radio • Oct 13, 2021

Leaders of the Lucy asteroid mission

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On This Episode

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Hal Levison

Lucy Mission Principal Investigator for Southwest Research Institute

20190424 cathy olkin

Cathy Olkin

Lucy Mission Deputy Principal Investigator for SouthWest Research Institute

20190424 mike sekerak

Mike Sekerak

Lucy Mission Deputy Project Systems Engineer for NASA Goddard Spaceflight Center

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Mat Kaplan

Planetary Radio Host and Producer for The Planetary Society

A delightful exclusive conversation with principal investigator Hal Levison, deputy principal investigator Cathy Olkin and deputy project systems engineer Mike Sekerak on the eve of Lucy’s launch toward the asteroids that share Jupiter’s orbit. Don’t miss the cameo appearance by Ringo Starr! Bruce Betts offers another What’s Up space trivia contest with an extended deadline.

NASA's Lucy Spacecraft
NASA's Lucy Spacecraft NASA's Lucy mission will explore six Trojan asteroids, a unique family of asteroids that orbit the Sun in front of and behind Jupiter.Image: NASA
Lucy encapsulation
Lucy encapsulation Workers inside the Astrotech Space Operations Facility in Titusville, Florida, move the first half of the United Launch Alliance (ULA) payload fairing toward NASA’s Lucy spacecraft.Image: NASA/Ben Smegelsky
Lucy plaque
Lucy plaque The Lucy spacecraft carries a plaque as a time capsule, including messages from prominent thinkers of our time and a diagram showing the positions of the planets on the date of Lucy’s launch.Image: NASA

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Trivia Contest

This Week’s Question:

What two objects that will be visited by Lucy are named after real people?

This Week’s Prize:

A safe and sane Planetary Society Kick Asteroid r-r-r-rubber asteroid.

To submit your answer:

Complete the contest entry form at https://www.planetary.org/radiocontest or write to us at [email protected] no later than Wednesday, October 27 at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

What major political event happened in the USSR while the Voskhod 1 mission was in space?

Winner:

The winner will be revealed November 3, 2021.

Question from the Sept. 29, 2021 space trivia contest:

What moon of a planet has an orbital period closest to 24 hours or one Earth day (sidereal period).

Answer:

With an orbital period of 1.0096 days, Saturn’s moon Methone has the orbital period closest to 24 hours or one Earth day..

Transcript

Mat Kaplan: Leaders of the Lucy Mission, that is about to begin its journey to Jupiter. This week on Planetary Radio. Welcome. I'm Mat Kaplan of The Planetary Society, with more of the human adventure across our solar system and beyond. I lied. Lucy is not going to Jupiter. In fact, it will never be closer to Jupiter, than when it returns to earth in a slingshot maneuver. That's how far the Trojan Asteroids, that share Jupiter's orbit are from our solar system's biggest world. Our last conversation with Hal Levison, Cathy Olkin, and Mike Sekerak, was over two years ago. Now their spacecraft is prepped and ready to begin the long trip to the outer solar system. My exclusive and very fun conversation with them is minutes away. And includes a cameo appearance by a space fan named Richard Starkey. You may know him as Ringo Starr. Afterward we'll check in with Bruce Betts, who has a space trivia quiz with yet another extended deadline. We'll begin with these headlines from the downlink. The weekly newsletter from The Planetary Society. You can get it for free at planetary.org/downlink. The October 8 edition is topped by a photo. You'll hear Bruce and me talk about its mercury image during a brief visit by the European Space Agency's BepiColombo Spacecraft, while it was less than 200 kilometers above the surface.

Mat Kaplan: Five more of these encounters are in store, before it finally achieves orbit in four years. Building on its very successful Emirates Mars Mission, also known as Hope, the United Arab Emirates has announced that it will send a probe to explore several asteroids in the main belt before finally landing on one in 2033. I look forward to welcoming back her Excellency, Sarah Al Ahmed. Chair of the UAE Space Agency for a conversation about this new project. I didn't hesitate when I received an invitation from Mike Sekerak a few weeks ago. He wondered if I'd be interested in getting the gang together again. Based at NASA's Goddard Space Flight Center, Mike is the Deputy Project Systems Engineer for the Lucy Mission. Mike, Lucy Principal Investigator, Hal Levison, and Deputy Principal Investigator, Cathy Olkin, were my guests in April of 2019 when their spacecraft was still coming together. Now, Lucy is sitting on top of the Atlas V, that will help it begin its 12 year mission. The launch window opens on Saturday, October 16th.

Mat Kaplan: It was just a week before that, the four of us gathered online for the illuminating and very enjoyable conversation you're about to hear. Hal and Cathy, both of whom work at the Southwest Research Institute, gathered with Mike around one microphone at Cape Canaveral. Hal, Cathy, Mike, congratulations on reaching this already auspicious date. I cannot believe that we are talking, well, as we speak, it's still what, nine days ahead of the opening of your launch window. But I'm so glad to catch you now, because I have seen some of your schedule for next week. Just the public and media events you're going to be doing. And so, I'm glad to catch you now, when you've got a moment to catch your breath and talk to us on Planetary Radio. Welcome back to the show.

Hal Levison: It's our pleasure to be here.

Mike Sekerak: Happy to be here, Mat.

Cathy Olkin: Thank you.

Mat Kaplan: You got to tell people what you just told me. What just happened this morning, as we speak on the 7th of October. Cathy?

Cathy Olkin: This morning, it was really exciting. We woke up early and got to see the spacecraft lifted onto the booster, at the Vertical Integration facility. So amazing. What an amazing day to finally get here, and have our spacecraft on top of the launch vehicle.

Mat Kaplan: Absolutely thrilling. I did see the two pieces of the fairing as they were being put onto the spacecraft. That was in one of the photos NASA released just the other day. I'm so sorry I wasn't recording when you first told me that, because you were just jumping up and down, in spite of the fact that you've been up since when?

Hal Levison: We got up around 4:00 o'clock to head out to see it. They drove the spacecraft from Astrotech, on surface roads, which is why they do it in the middle of the night, to get it to KSE., and then, starting at around seven, they were beginning the lift.

Cathy Olkin: Yeah. And you mentioned the encapsulation. The spacecraft was put into the fairing. It was a little bit of a bittersweet moment. I love being able to see that spacecraft. And I know that we're not going to see it again. It's going to go on its way. And I was a little sad about not being able to see it in person again. Of course, Lucy will be where it needs to be, in space, where it's designed to be. And of course, where it can capture all the great science. But still, I felt a little sad about not being able to see it in person anymore.

Mike Sekerak: Yeah. We did our final checkouts last week. We got to inspect all the blankets, all the instruments, every little fine detail. And we all put our stamps of approval on it, and wished it goodbye. And we do our first power up on top of the rocket tomorrow for our final checkouts., and then, we're ready to go.

Mat Kaplan: Wow. And you were not the first people to tell me that was kind of a feeling of mixed emotions, as you saw your spacecraft with your own eyes for the last time. So, Mike, it sounds like everything is in good shape.

Mike Sekerak: Yeah. Absolutely. Technically, the spacecraft is ready to go. And we put it through a lot of environmental testing, and a lot of other simulations and other verification procedures throughout the whole last, basically, year and a half. All the way through the normal shock and vibration and thermal vacuum testing. But because of our unique mission, we've had to do some unique tests to help simulate those Asteroid encounters and flybys. Which is required to really look at the Lucy unique aspect of our mission to define and execute some specialized testing. And the spacecraft all passed with flying colors. And we feel she's ready to go.

Cathy Olkin: Yeah. I'd like to mention one of those specialized tests. We have an instrument pointing platform, on the spacecraft. It has our scientific instruments, and it has a two axis gimbal, so we can move and point at the Trojan Asteroids as we fly by. That gimbal, of course, is designed to be working in space. But we need to test it here on earth. And so, there's a huge helium balloon that we use to off-weight the weight of the force of gravity pulling down on the instrument pointing platform, so that we can do deployment tests. I think that's really cool that all the different ways, that there's ground support equipment to be able to test this spacecraft on the ground, that's meant to work in space.

Mike Sekerak: Yeah. And another one really amazing test, was we deploy these solar arrays, the largest ultraflex arrays that ever flown, will be the furthest solar-powered mission that's ever operated. And seeing those arrays deployed off the spacecraft for the first time was really, really exciting. But it takes a huge amount of ground support equipment. And we can deploy one wing at time because it's so big fitting into that area. But they work just great so far on the ground, and we have confidence that they'll work in flight as well. But it was quite the engineering feet to get them tested, both in the vacuum chamber on their own, as well as on the spacecraft, and tested on the ground.

Hal Levison: I just want your audience to understand what these solar arrays are. They're made out of cloth. Well, the cells aren't made out of cloth, but the support is made out of cloth, and they own-fold like oriental fans. So, they're actually quite beautiful to watch deploy. I encourage your listeners to go off and watch some of the videos that are on YouTube. It really is quite beautiful.

Mat Kaplan: We will put the link to that video of the test deployment of those magnificent solar panels, those fans, on this week show page, at planetary.org/radio along with some other stuff that I think will be talking about. So, you're going to be taking that record away from Juno, the current record holder for farthest out flight by a solar powered spacecraft. Tell me, if you would have the chance, if NASA had said, Hey, look what we found. There's a radioisotope thermal generator we forgot we had. Would you like to substitute that for your solar panels? I don't know. Might you have tried to take advantage of that? I mean, I assuming it was years ago.

Hal Levison: Yeah. And it depends on the details, right? One of the things that are really special about our solar arrays, is we got a lot of power for the mass, right?

Mat Kaplan: Mm-hmm (affirmative).

Hal Levison: And so, that's not necessarily true, for any kind of nuclear power. So, we'd have to look into the cost benefits of it.

Mike Sekerak: Yeah. So, our arrays are going to produce half kilowatt of power, all the way out of 5.7 AU.

Mat Kaplan: Wow.

Mike Sekerak: That's why we have the big solar arrays. And so, one RTG won't be nearly enough to give us that amount of power out of that distance.

Mat Kaplan: Isn't that amazing? I mean, we went from, Oh my gosh, is Juno going to be able to do this from so far out, to now, actually seen other advantages. Not just the core availability of RTGs, but they may actually offer the advantages that you're talking about.

Hal Levison: One another aspect of these things is, when they're folded up, they're only four inches thick.

Mat Kaplan: Mm-hmm (affirmative).

Hal Levison: So, that gives you some feeling for how special these things are, and how innovative they are.

Mat Kaplan: I wanted you to know that all of us at The Planetary Society, were ready, a couple of weeks ago, to start screaming if the budget circus in Washington DC had prevented you from beginning your mission within this launch window that opens on the 16th. Now, thank goodness that that worked out. But were those anxious moments for any of you as well, Cathy?

Cathy Olkin: Well, it something that we had our eye on, but we were planning and putting in contingencies in place. And trying to figure out how we would best work around things, if we needed to. So, it was something to pay attention to, but I wasn't worried yet. And luckily, it didn't end up being something that we had to worry about.

Hal Levison: I was pretty confident that we would be okay. The people at headquarters are supporting us every which way they can. And I'm pretty certain that they would have gotten us exemptions and whatever we needed to do, to finish our job. They really were on top of all that.

Mat Kaplan: I would like to think that, someone told all the members of Congress, we might have to delay the Lucy Mission. And they said, What? We can't have that.

Mike Sekerak: We already had one other government shutdown, during earlier, part of our development. And then, of course, we had to deal with COVID obstacles. So, they get so close to the end to be tripped up by this. And we're going to make sure that didn't happen.

Cathy Olkin: Well, just like we've done all along. Things have come up. We work around them. We make plans. We look at our contingencies. And we move forward. Because it's not like we haven't had challenges. Of course, being in at load during COVID was challenging, and we are here. And on track for the opening of our launch period. So, I'm confident, because we've had a lot of experience in working as best we can, to stay on track.

Hal Levison: If you don't mind me saying, our team has been amazing. The innovative way they had to look at scheduling and budget during COVID, the flexibility, every day they had to replant things occasionally. And yet, they got us here where we needed to be. They're really an amazing group people.

Cathy Olkin: Yeah. And we had a plan at first, when COVID happened. And it was the fast plan. And then, we had the faster plan.

Mike Sekerak: Mm-hmm (affirmative).

Cathy Olkin: And then, the next plan, you might think it would be the fastest plan, but no, that's when we pivoted to peace and love.

Mat Kaplan: Peace and love. Well, that's going to come up in a few moments as well. Hal, this may be as good a time as any, to let you give some additional kudos to, if not the individual members, or other members of the team, but the other organizations and companies that have helped us reach this day.

Hal Levison: Well, there's no doubt that we have gotten tremendous amount of support from our partners. They've been there, not only with financial support when we needed it, but every time that we needed help, we got the A team. And that is why we ended up being where we are. So, it's a combination of Goddard Space Flight Center, who's been managing this, and Lockheed Martin has been amazing at getting all this done in time. It's been a great collaboration that has allowed us to get here.

Cathy Olkin: Yeah. And I'd like to also call out some of our other partners. Our instruments were built at Arizona State University, and the Johns Hopkins Applied Physics Laboratory, and Goddard Space Flight Center. And our navigation team comes from Kinetics. And our Science Operation Center is at Southwest Research Institute. So, it takes a number of different institutions, all across our country, to be able to build and fly a spacecraft. And it's because of all the hard work of the people of those institutions that we are where we are today.

Mat Kaplan: A great collaboration, as so many missions, basically, all of missions are nowadays.

Cathy Olkin: Yeah.

Hal Levison: You couldn't do something like this without collaboration like that.

Cathy Olkin: Yeah. It takes a great team, right?

Mat Kaplan: Mm-hmm (affirmative).

Cathy Olkin: There's no single person who could build and fly a spacecraft. That would be crazy. But it also takes a lot of people with different talents and different skills all coming together, for a single goal. That's part of the reason I love doing space exploration.

Mat Kaplan: I promise I'm going to come back to the mission and what's ahead, even though we've talked about that in the past. By the way, you were last on the show in April of 2019. So, two and a half years, a lots happened since then. There are so many other wonderful things that are wrapped around this mission. I watched the video the other day, made of the dedication ceremony for the plaque, that has now been attached to Lucy. And is going to sail with Lucy for what, 10s of thousands of years?

Hal Levison: Well longer.

Mat Kaplan: Good.

Hal Levison: Way longer. So, our estimates is, if Lucy is left alone, that it's average lifetime before it either hits the sun, or gets ejected from the solar system, is roughly two million years.

Mat Kaplan: Wow.

Hal Levison: We had this thought, that we go back to the pioneer plaques, remember those, back in the 70s. I was in middle school, right? And I remember thinking how cool that was. Made me feel like I was connected to the Galaxy in a way that I had never thought of before. And it probably had a lot to do with why I'm doing what I'm doing today. The pioneer plaque is heading out to the stars, so we put messages to aliens about the human race on that here, since it's remaining in orbit around the sun for such a long period of time. It's easy to imagine that some Astro archaeologist sometime in the near or distant future, will come across it, looking for our junk, trying to learn about us. So, this plaque has inspirational messages to our descendants on it. It's really an honor to be able to do that. We're leaving a record. I mean, if you look at most of our lives, even the three ours, this thing is going to outlive everything that we've done. And so, it's really our legacy that's sitting on that spacecraft.

Cathy Olkin: Yeah. And I really like thinking about the long term, the eons that you're talking about, right? I think it takes a long time to explore the Trojan Asteroids will be in flight for 12 years. But that's nothing compared to the millions of years that the spacecraft could go on. And also, it's nice to look back to the Australopithecus fossil, Lucy. That was millions of years ago as well. Ad so, we're spanning millions of years in either direction. And hopefully when our descendants go and find Lucy in the plaque, they'll say, Oh, it's based on the fossil that we know from our ancient records. So, that would be very cool, but millions of years is a long time.

Mat Kaplan: One of the really charming things about that ceremony, that we will link to, as I said, is that you actually have the anthropologist who discovered the Lucy remains, right? The Lucy skeleton.

Hal Levison: Yes. Donald Johansson gave us the honor of attending that. He's also going to be attending launch, giving a press conference about the synergy between the fossil and Lucy, the spacecraft. He has an interesting story to tell. His hypothesis is that, what makes human beings human, is our ability to be able to collaborate, so that as a group we can accomplish things that are greater than any individual can do. So, that's his definition of human. And in that way, what we're doing building a spacecraft, is sort of, the ultimate expression of that.

Mat Kaplan: That's just perfect, isn't it?

Hal Levison: Yeah. It really is.

Cathy Olkin: Yeah. And I'm really excited to take the Lucy spacecraft to go explore the asteroid Donald Johansson. When we were doing the mission design, there was an opportunity to fly past an asteroid. And that asteroid had its typical license plate designation, not a given name. We realized the opportunity, and asked the person who discovered that asteroid, Bobby Bus, if he could name it after Donald Johansson. And now it is asteroid Donald Johansson. So, we'll be taking Lucy out to visit Donald Johansson.

Mat Kaplan: That's just wonderful. I want to go back to the plaque. And it includes these wonderful wise messages from people like Einstein, and Carl Sagan, poet, Rita Dove, novelist, Kazuo Ishiguro. I'm a big fan. And many others. Even Amanda Gorman, who blew so many of us away with the reading of her poem at the Presidential Inauguration earlier this year. And then, there's this, I'll read it from the wonderful Dava Sobel, who I was in touch with a couple of days ago. We, the inquisitive people of earth, sent this robot spacecraft to explore the pristine small bodies orbiting near the largest planet in our solar system. We sought to trace our own origins as far back as evidence allowed. Even as we look to the ancient past, we thought ahead to the day you might recover this relic of our science. Gosh, she's great. She's just wonderful.

Hal Levison: Dana's really great.

Cathy Olkin: She is great.

Mike Sekerak: Beautiful words.

Cathy Olkin: Yeah.

Mat Kaplan: How did you choose among all of the possible candidates to, basically, make very nearly immortal on this plaque?

Hal Levison: I must admit, it was just coming up with the type of person we would like to represent us. We've reached out to all Nobel laureates. We reached out to US poet laureates. We then just started coming up with a bunch of names that we thought would really represent us well. Dana came to the front of the list really quickly, because she understands what we're doing so well, right? A lot of the people on that list, they think what we're doing is profound, they really don't understand very well the community that we're part of. And I've always been impressed with Dana, with her ability to be able to truly understand what we're doing and why. And her words reflect that.

Cathy Olkin: Yeah. Dava's books are just amazing.

Hal Levison: Yeah.

Cathy Olkin: And the way that she can convey the science and exploration, and I'm thinking of longitude.

Mat Kaplan: Yeah. Yeah.

Cathy Olkin: Is just amazing. And so, she really brought that insight with that quote. But there are so many people who come from different backgrounds, and it was wonderful to see their take on this request.

Hal Levison: Yes. Another group that we've included is, we reached out to people from the pop culture.

Mat Kaplan: Pop culture?

Hal Levison: Yeah.

Mat Kaplan: I got one for you. Let me see if you can hear this.

Ringo Starr: A little noise, but I'm so excited. Lucy is going back in the sky with diamonds. Johnny, I love that. Anyway, if you meet anyone up there Lucy, give them peace and love from .

Speaker 7: Peace and love man.

Speaker 8: Peace and love.

Mat Kaplan: The one and only, Ringo Starr. You actually have messages on the plaque from all four of the of The Beatles, speaking of pop culture. Pretty, pretty darn cool.

Hal Levison: Well, after all, the spacecraft is named after the fossil, right? And the synergy there is Donald Johansson and his collaborators were trying to unravel the history of the human race with the fossil. We're trying to unravel the history of the solar system. Both of which are origins questions, with the spacecraft. But the fossil was named after the song, Lucy in the sky with diamonds. So, there is a connection there. And if you look carefully, you'll notice that our logo for Lucy is diamond shaped.

Mat Kaplan: Oh.

Hal Levison: Where we were making your connection there with that. So, they were natural to reach out to when we were putting the plaque together. And, of course, the living ones got very excited about being able to contribute, as you heard from Ringo.

Mat Kaplan: So, let's talk about the mission. Which we've done before, but it bears repeating. So, seven asteroids, five flybys, you just mentioned to me. Some of these are double or binary asteroids. There's a lot to see out there. Remind us why these objects have generated so much interest from scientists in so many fields, Cathy.

Cathy Olkin: What's really interesting to understand the diversity of the Trojan Asteroids, and that's really where we started. With a list of asteroids that had similar properties. So similar sizes. Similar inclinations. But different spectral types. Telling us that the composition was different. And then, starting with those matched pairs, finding sets that the mission designer could get to. And that's how we got two Euripides and Oris in our mission design. That was the first objects that we started on. And then, we built from there. With Patroclus and Menoetius, we were looking at what would happen when we continued the trajectory out further, right Hal?

Hal Levison: Yes. So, the amazing thing about our trajectory, and let me just say, Cathy had it exactly right. That we started off looking for pairs. It turns out that that was difficult enough to find a pair of asteroids we could go to. The fact that we have such a large number is a combination of hard work by the team that designed the trajectory, and a lot of luck. For example, our last one which, to me, is the most interesting scientifically, which is this near equal mass binary just so happens that we happen to be floating by at the right time, to be able to visit it. And so, that luck really has led us to this amazing set of objects, that allow us to compare, not only spectral types, which is what we were set out to do, but a wide range of different directions and parameter space. We have everything from an object that's less than a kilometer, up to optics that are 100 kilometers across. We have objects that have very different collision on histories. We have an object that we know was involved in a major collision, right? Because it's part of an asteroid family. And the binary, we believe, is pretty pristine, and has been left alone. So, we can, by seeing this multi-dimensional space, it really makes the signs that much more compelling.

Cathy Olkin: Yeah. And I'd like to build on what Hal was saying, about the luck before. Because with Patroclus and Menoetius, they're on an inclined orbit. And so, it just happened to be that not only were we drifting by at the right time, but Patroclus and Menoetius were crossing the ecliptic plane or nearby at that time, allowing us to get to them. So, there was a lot of luck in getting this amazing set of diverse Trojan Asteroids.

Mike Sekerak: There was a lot of luck in finding the opportunities. In facts, dynamics team has been spending a lot of server time over the past four and a half years, crunching this trajectory thousands and thousands and millions of times, to be able to fine tune it. We have three earth gravity assists. Five deep space maneuvers. Over 30 trajectory correction numbers, in order to thread the needle to do these flybys at just the right distances, to make sure that we're able to get the other images, and the science that we want to get. So, it has taken that flight dynamics team a lot to make sure that we have robust, have accounted for all the unknowns, because we're going to them, because they're not what they look like. Which also means, there's other challenges that we don't know exactly what's out there. So, we have to look at the statistical variation to make sure that we are well within the margin of the spacecraft. Which we comfortably are. But from that first luck of finding those, and then, really, really drilling down in those details, and putting all that in simulations, and putting that on more spacecraft, and testing it, has taken a whole team, from the engineers and the scientists as well working together, of what do you know about the targets? Okay. Let's take that and put that into the simulation. That has taken a lot of effort for that to converge. But it has.

Cathy Olkin: Yeah. Exactly. And some of those details are really interesting, at least to me. We do a deep space maneuver as we're leaving the L4 swarm that targets are third earth gravity assist. Which sets us up, than to fly by Patroclus and Menoetius at the time that we want. And so, this is all carefully orchestrated, as Mike was saying. And really quite an accomplishment of mission design.

Mike Sekerak: Another part of that, that I find so intriguing, is big science fiction fans. We'll be the first mission to go all the way out past Jupiter distance, and come back to the vicinity of earth.

Cathy Olkin: And come back.

Mike Sekerak: I mean, you read all these books about humans criss-crossing the solar system. It's all a science fiction. We sent these probes out to great distances, is really the first one that goes out and comes back. We do that third earth gravity assist to set ourselves up for the Patroclus and Menoetius, sort of, binary encounter.

Mat Kaplan: Some of the people who found the trajectories, those magical trajectories that resulted in the Grand Tour by the two voyagers spacecraft, are still around. And they went through some of these long nights of sweating over the numbers. Computers are a little more advanced now, fortunately for you guys. But you have to be thinking of Voyager. Which, to some degree, with this ballet that Lucy is going to be doing, it appears to me that in some ways you're actually out doing the Voyager spacecraft, at least in terms of trajectory. now, I know, that sounds like sacrilege. But still, it is a wonder to look at this path.

Mike Sekerak: So, obviously, the Grand Tour four Voyager, visit all these planets and gave us great images to help understand what these large bodies in the solar system look like. What they had to do with inventing a lot of that when they did, was truly amazing. Computers and our knowledge of special mechanics has improved since then. But our targets are so much smaller. So, it's so much harder, versus a big planet, versus NASA that, at most, is a little over 100 kilometers across to our smallest ones, as Hal was saying, the [inaudible 00:28:56] is 20ish or so kilometers across. That's a much, much finer needle that you need to thread there. And we want to make sure we get just the right aim point, to be able to do this this careful choreography of actually imaging those asteroids. So, it is a much finer window that we need to hit, the images of small asteroid, versus a large planet. Not to take anything away from the Voyager Mission, which is, and I think most amazing missions. But we have new technology and we've used that to be able to do this really, really fine work.

Mat Kaplan: Stick around. Hal, Cathy, Mike, and I, will have much more fun talking about the Lucy Mission in just a minute.

Bruce Betts: Hi, again everyone. It's Bruce. Many of you know that I'm the Program Manager for The Planetary Society's Light Sail Program. Light Sail two, made history with its launch and deployment in 2019. And it's still sailing. It will soon be featured in the Smithsonian’s new futures exhibition. Your support made this happen. Light sails still has much to teach us. Will you help us sail on into our extended mission? Your gift will sustain daily operations, and help us inform future solar sailing missions like NASA's NEA Scout. When you give today, your contribution will be matched up to $25,000 by a generous society member. Plus, when you give a $100 or more, we will send you the official LightSail two extended mission patch, to wear with pride. Make your contribution to science and history at planetary.org/S-A-I-L-O-N. That's planetary.org/sailon. Thanks.

Mat Kaplan: Mike, I know you did some pioneering work on electric drives, ion engines basically. I was just talking about a week ago on this show with Mark Raymond, who did so much with the Dawn Mission. With that, because of its ion engines, you don't have that. I mean, I want to make sure everybody understands, yeah, of course, you've got thrusters to make some adjustments now and then, but you don't have a main engine, much less an ion engine, that's going to make sure you thread the needle as you're saying. And yet, this is all looking pretty good. Do wish you had an ion engine scrapped on there?

Mike Sekerak: Well, as an electric repulsion person, of course, I was going put an ion there, but Hal said no. When you've got big arrays like this, that can fit in earth orbit, the tens of kilowatts of power, if we had really strong solar cells differently.

Mat Kaplan: Yeah. 500 watts. Yeah.

Hal Levison: You're getting that to work in five AU, is almost impossible.

Mike Sekerak: Yeah. You have to have a very throttable drive, which engineers and my friends and colleagues are working on. But we are able to, just with the trajectory, we're able to do alone. The thing about Dawn, is that they did over 12 kilometers per second at Delta V change, using the NSTAR ion engines. And that's really amazing. Allowed them to change things in orbit. They weren't really using a lot of gravity. They were using the impulse from those ion thrusters. Whereas, for us, we're only doing at 1.7 kilometers per second of Delta V. A small correction, we do have a main engine, [inaudible 00:31:54] 1C by prop engine that will be doing those deep space maneuvers. It's a chemical propulsion system to give those burns, which does the major orbit tweaking. But we do have a main engine, but it's really the oral mechanics that's allowing us to get that, versus. So, we don't have a lot of flexibility. For example, we are launching here shortly, and it puts us on a one year earth gravity assist, and then, two years later, another earth gravity assist. If, for some reason, we don't go here shortly, which[crosstalk 00:32:23]

Cathy Olkin: We're going.

Mike Sekerak: Our teams also, if we have to launch next year-

Hal Levison: Don't even say that, Don't even say that.

Mike Sekerak: The next opportunity would launch us, in what would have been our first earth gravity assist, to get us on the exact same trajectory. So, that's how special and unique this trajectory is. So, ion engines would definitely enable more options here, but we managed to find this trajectory that we are getting on.

Cathy Olkin: Yeah. And that's what I think, is that we found a solution to all of these design challenges that we had, within the technology constraints that we were working in. And so, I wouldn't change anything. I wouldn't want to change their propulsion system. I wouldn't want to change the power system, because we've managed to find this beautiful solution. I mean, Lucy is an amazing and beautiful spacecraft. And it all works well together. Pivoting so many different Trojan Asteroids. One thing that I think is interesting is that, the first two Trojan Asteroids we fly past, your Eurybates, with its small satellite Queta. And then, Polymele, we fly-past them just about one month apart. And so, we're really setting that up. And almost thinking about playing billiards and shooting pool, and flying right down that line. I think the orbital mechanics of that is just beautiful. Because it's, kind of, so pure.

Mat Kaplan: It is. It is. I mean, I guess it's a cosmic dance. I called it a cosmic ballet. And thank you for the correction, Mike. You know I look at Cassini, which tooled in and around the Saturnian system for so long, which also had just those chemical main engines to make it's a huge success. Hopefully Lucy will see the same kind of success.

Hal Levison: Well, we certainly plan that to be true, right? And we're doing something that, building on what Cassini did. Because really, the earth is doing all the work, right? When it comes to setting up our encounters, right? The main engine is doing some tweaks. And the thrusters, a little bit smaller tweaks. But the earth is doing all the heavy lifting. And to me, that's a very elegant solution.

Mat Kaplan: Unfortunately, earth has some momentum to spare to [crosstalk 00:34:39]

Hal Levison: Yeah. Sure.

Mike Sekerak: We'll seal just a little bit of it.

Hal Levison: Yeah.

Mike Sekerak: That posed some interesting engineering challenges from the standpoint of, so we had three years gravity assists, but depending on when we launch in the launch period, our first earth gravity assist could be as low as 300 kilometers. That's low earth orbit, type of distances. So, even in space gravity had to be designed for deep space operations, we had to take into account what would typical low earth orbit spacecraft do, bypassing that low with aero-torque, aero-thermal heating, electrostatic discharge. So, we've had to deal with those kinds of complications, which is very unusual for deep space mission.

Cathy Olkin: Right. And with these really large solar arrays.[crosstalk 00:35:15]

Mat Kaplan: Oh, right. Sure.

Mike Sekerak: That's goes a whole course of that. I mean, we had to go, I had to take a sample of the arrays to a special facility NASA, Glenn, and expose it to a plasma art to help the simulated electrical discharge to make sure they went short themselves out going through the atmosphere this low. Which again, is not normal when you think of for a deep space mission. And we also, we go as close to the sun as .83 AU. So, we're within earth's orbit for part of the mission. So, we had to account for the thermal extremes there as well, as past Jupiter. That beautiful revolution has posed some technical challenge to engineering team, that we definitely met and overcame. But, definitely it required some special thinking.

Mat Kaplan: Didn't occur to me till now, but with those giant arrays, I suppose, as you continue to adjust your trajectory, you got to take into account that you're going to be a bit of a solar sail as well.

Mike Sekerak: The solar radiation pressure that is going to be coming from these arrays is something we definitely had to take into account. We've known that from the beginning. And yes, that is something we certainly had to factor in, because they are a big solar sail out there. But you guys [inaudible 00:36:16].

Mat Kaplan: Hal, a lot of us, I'm one of them, would have been thrilled even if you went all this way and did this amazing trajectory. And didn't do any science. But, of course, you're going to. Can you talk a little bit about what you hope to discover, and maybe about these instruments that you hope to make those discoveries with. They have this illustrious and very reliable history fortunately.

Hal Levison: Yeah. Indeed they do. So, we have three main science instruments. All our instruments are L apostrophe. And a little bit of a frankle file. Right. So, we have the L'LORRI instrument, which is a clone of the LORRI instrument that's on the horizons. Narrow Field High Resolution, basically panchromatic telescope. That's really a beautiful design. There's no focus mechanism, right? So, it's designed so that the thermal expansion will keep it in focus throughout the temperature range that we're going to be observing with. We have a instrument called L'TES, which is a thermal infrared spectrograph, that will be used to measure the surface properties. We're going to measure the temperature of the surface as we go by. And as the temperature warms up or cools off across the terminator, that'll tell us how fluffy the surface is. For example, we have an instrument called the L'Ralph, which is based on, again, on the new horizon's Ralph, which is really two instruments in one. It's a color camera. And an imaging near infrared spectrograph. So, we're going to get three dimensional data cubes out of it, of position, and of spectrum. We're hoping that that's going to tell us a lot about the chemical makeup of the surface of these bodies.

Hal Levison: In addition, we're going to be able to measure the Doppler shift as we go by, and so get the measurement of the mass. Remind me Cathy, what the Delta V is going to be.

Cathy Olkin: So, the delta V that we're measuring the Doppler shift of, is about six millimeters per second, on top of our base velocity that's between six and nine kilometers per second. So, we really have very precise ability to measure the Doppler shift to determine the mass of the Trojan Asteroids as we fly-by.

Mat Kaplan: And I'll just remind everybody, that's using the spacecraft radio, and the clock that's built into it, to make these ultrafine measurements of just the shift in the signal that's coming back to earth. Well, going to the spacecraft, and coming back to earth. Fascinating.

Mike Sekerak: Which means we can't use a thrusters during that time. So, we have to plan that into our concept of operations, because any small thruster fryer would make it hard to pull out that measurement. So, that's a very part of that carefully choreographed con-ops there is we got to take that into account.

Hal Levison: Certainly true.

Cathy Olkin: Yeah. It's very much like a dance. Everything has to work together. And we also are using our terminal tracking cameras for science. We have two terminal tracking cameras on our instrument pointing platform. And they're there so that we can make sure that we're pointing at the Trojan Asteroid as we fly-by. They'll be able to take images of the Trojan Asteroid, and on board, do state estimation, and point the instrument pointing platform at the Trojan Asteroid. Effectively collapsing the uncertainty ellipse between the relative position of the spacecraft and the Trojan Asteroid. That's why we have the terminal tracking cameras. And these are very wide field cameras. And we realized that these images would also be useful to determine the shape of our targets. As you heard before, we are measuring the mass, and then, you combine the mass with the volume. And that's how we'll get density. Which is really a very diagnostic feature of the origin and evolution of small bodies in our solar system.

Mat Kaplan: Hal, you use the word pristine, which takes us back to one of the justifications for this mission, right? Because we expect, at least, some of these objects, probably will be able to take us back to the earliest era of the solar system.

Hal Levison: Yeah. If you look at what NASA and the other space agencies have been doing, they've been spending a lot of time studying the small bodies, asteroids, comets, and things like that. In a real sense, these populations were affected and sculpted during the planet formation process. And relatively, have been unperturbed since then, right? So, the best way, I think, and I've pretty much dedicated my career to do this, to understand the history of the solar system, is to study these small body populations.

Mat Kaplan: Mm-hmm (affirmative). Did you have to take Planetary Protection into consideration, as of so many other missions have to, Mike?

Mike Sekerak: Yeah. So, all of the missions we have to work with headquarters to make sure that we meet our requirements, and the cost bar agreements for Planetary Protection. Even though these are the Jupiter Trojans, because of the ground points are 60 degrees in front and behind Jupiter, and its orbit, in space is a big place, the closest we ever get to Jupiter and Europa, which, of course, is concerned, is actually on launch day. And then, because we are going on this basically six year heliocentric orbit around the sun, that gets us to the L4 and L5 swarm, space is a big place. So, we did the analysis and we don't have any concerns for Europa or Mars.

Hal Levison: Turns out, at the first DGA, we're closer.

Mike Sekerak: Oh.

Hal Levison: So, the statement is not. Oh, right, I don't know if you want to read. Say that, but-

Mat Kaplan: That's okay.

Mike Sekerak: Earth Gravity assist. So when we do our first earth gravity assist, which will be next fall, well, we're actually is for a little bit closer to Jupiter. [crosstalk 00:42:25]

Hal Levison: We're a little bit closer to Jupiter. But it is true that the spacecraft is closest to Jupiter when it's sitting right near the earth.

Mat Kaplan: Just fascinating. And it give us just a good idea of just how huge the orbit of Jupiter is.

Hal Levison: That's right. That's right. So, I don't know if you want to restate this.

Mike Sekerak: Yeah, let me restate that real quick Mat.

Mat Kaplan: You can. I don't mind. I mean, that was, kind of, entertaining actually, what we just went through. And it's, kind of, splitting hairs. I would keep it. I would say, you don't need to worry about it.

Hal Levison: All right.

Mat Kaplan: If it's okay with you.

Hal Levison: That's fine.

Mat Kaplan: But I got to do it-

Mike Sekerak: I'll do it. I do have paperwork from headquarters that says, we don't have to worry about Planetary Protection. You had to get that signed.

Cathy Olkin: That's right.

Mat Kaplan: Maybe this is another one for you Mike. But everybody jump in if you like. Give us an idea of what's ahead. I mean 12 year mission, primary mission at least, with any luck, we're going to see a beautiful launch on Saturday, October 16th. What are the next big milestones as we look out across this mission profile?

Mike Sekerak: After we launch, of course, we're going to have several weeks of checkouts, making sure that everything is working properly in the spacecraft, deploying an instrument point platform, because it's in a lock position right now. And doing some calibration checkouts on the instruments in the spacecraft. Like I said, about a year later, we're going to do our first earth gravity assist, basically next fall. And then, again, stealing a little bit of energy from the earth. We'll go onto a larger orbit. Two years after that, is when we'll do our next earth gravity assist. And that will give us enough energy to get out to the L4 swarm. Before we get there though, in 2025, is when we do our flyby the Donald Johansson main belt asteroid, and that is going to get its own science end of itself. We will be using that to help test some of our sequences, and basically use that as a rehearsal for the Trojan Asteroids. And then, from 2027 through 2028, is when we're in the L4 swarm. And that's where we encounter Polymele, Eurybates, of Lucas Norris. And then, we come back around for a third earth gravity assist, that then tilts our orbit a little bit, that gets us out to the L5 swarm to do that Patroclus Menoetius binary in 2033. I hope your calendar is clear all the way out.

Mat Kaplan: Well, I mean, that does bring up what we've heard from so many other people on other missions. Exploring the solar system requires the greatest of patients, doesn't it?

Hal Levison: There's no doubt. One interesting fact, I think, about Lucy is, we're going to be traveling for 12 years. It's the length of the mission, but all our important science is going to be collected within a total period of 24 hours.

Mat Kaplan: Wow.

Hal Levison: Right. That tells you how fast these encounters are. So, each one is basically the two-hour stretch. I mean, obviously we're taking data on approach and leaving. But all the important science really is in that two hour approach, or egress, depending on which encounter it is. So, there's going to be a lot of sitting around. And the spacecraft is going to be waiting. We're not going to be waiting. We're going to be busy planning the next one. But it is true that the spacecraft will be just waiting for a long period of time.

Cathy Olkin: That's right. We have a lot of science planning to do, to make sure that we're really have the best and robust science return, that we'll be able to get from the Trojan encounters. As Hal says, they're very fast. And so, time is a critical commodity. And we're going to have to spend a lot of time planning that to really optimize what we get back scientifically. It's interesting, because I've been thinking a lot about your question, what's next. And it almost seems to me that this mission has been, basically, a trilogy. So, first we had volume one, which was the proposal.

Mat Kaplan: Mm-hmm (affirmative).

Cathy Olkin: And that had one cast of characters. Volume two, we're coming to the end. This is nearing the conclusion of our volume two. Where we built this great team, and built the spacecraft, and developed it. And then, we have the closing book in the trilogy, is about to start with our operations phase. And we'll transition. And some of the team will roll off to other projects. And we'll be with our operations team for the next 12 years. So, it's really like a series of three volumes, with different characters.

Mike Sekerak: After the 12 years though, the spacecraft should still be in good health. Should still have her Palatine board.

Cathy Olkin: [crosstalk 00:46:59] Oh yeah, it could be like the foundation series, and go on and on and on.

Mat Kaplan: All right. Are you watching? I'm pretty impressed with the episodes I've seen so far.

Cathy Olkin: I haven't had time.

Mike Sekerak: [crosstalk 00:47:09] I haven't had time either. After launching, check out the tie in the list.

Cathy Olkin: Exactly.

Mat Kaplan: It's a good update to classic science fiction. Hal, I am thinking back to you, talking about being in junior high during the pioneer missions. And now I'm thinking of a 12 year old who may be out there right now. Who, by the time this mission is ready to end, or move on to whatever it moves onto in 12 years, that 12 year old might be a grad student or even a post grad, working with Lucy data.

Hal Levison: There is no doubt, right, that this is a multi-generational mission, right? We have built into our plans, for session plans, right? So, as people age out, and retire, bringing in new people in, and that's expected to continue to the very end. So, for people that are in college now, or even in high school now, should think about coming and joining us sometime. There is plenty of opportunity.

Mike Sekerak: Yeah. I gave a talk at my son school. My son's in elementary school. And halfway through my talk on Lucy, it dawned on me that these elementary school kids I was talking to were going to be in college when we did the PM binary flyby. And it really is, again, these long duration missions really. And he said to multi-generational endeavor.

Cathy Olkin: Yeah. And I think about it from our student collaboration perspective. When we were selected, we didn't have a student collaboration, and Dr. Thomas [inaudible 00:48:40] suggested that we think about it. And we really thought how can we reach the most people. We were fortunately brought in folks from Arizona State University to help lead that effort. And we've reached, I believe it's over 6000 students over the course of our offerings. We have virtual academies. This can lead two internships. We have instrument incubators. We have a Lucy ambassadors program. These students who are in college now, can easily be working on the mission in the future, in that time frame, in their career. And so, I think that's a really exciting thing to look forward to.

Mat Kaplan: And Cathy, that's exactly what I was going to ask you about next, because I saw some activities on the website. I think you probably are reaching a lot more than 6000 young people, because I mean, one project was encouraging kids to make time capsules that they can add things to over the years. And then, open them up in 12 years. There's some really fun stuff to get kids involved, that everybody can find on the Lucy website.

Cathy Olkin: That's right. That's right. The time capsule idea, I think is just outstanding, because like Mike said, this time scale is different than most people's regular experiences. And so, being able to capture what we're doing in October of 2021, and then, look at it again in 2033, is going to be remarkable. And in fact, I put together a collection of items for my own time capsule. And it'll be interesting? What was it important for?

Mat Kaplan: That's part of the fun of a time capsule.

Cathy Olkin: That's right.

Mat Kaplan: Listen you three, you've been very generous with your time, in what I suspect might be a, kind of, busy period. Let me just finish with this. Where will each of you be when that, I think it's an Atlas V lifts off with Lucy in just a few days? Hal?

Hal Levison: I'll actually be part of the pulling for launch. So, I will be in the Control center, called ASOC, at ULA during the launch.

Mike Sekerak: Yeah. And I'll be in the test Control Center, where we'll be monitoring the telemetry from the spacecraft. So, we have a lot of family and friends coming down, but we actually won't get to see the launch ourselves.

Hal Levison: You'll be working, yeah.

Mat Kaplan: You'll be working.

Mike Sekerak: We'll be working, watching a computer monitor, making sure that everything is healthy with the Lucy Spacecraft all the way through the solar[crosstalk 00:51:09]

Hal Levison: I'm going to run outside, watch the launch, and then run back inside. There's no way anybody's going to stop me from seeing the launch.

Mike Sekerak: Yeah, you [crosstalk 00:51:16].

Cathy Olkin: Okay. I'm going to try and be in two places at once, basically. I'm held back up for the polling, so in the beginning of the night, I'll be in a place called Hangar AE. It's one of our control areas. And then, I will drive across the Causeway to a building over at Kennedy Space Flight Center, and give a briefing to some people about the mission, and watch the launch from there with them. And then, I will scoot quickly back over to Hangar AE, to see if the telemetry will come back down. So, I'm going to be very excited to, kind of, be everywhere all at once.

Mat Kaplan: I only wish that I could be there, at the Cape with the three of you. It is going to be so exciting. Just know that a lot of us out here at The Planetary Society, and many other listeners to this show, are also thrilled. And I know that I speak for them when I wish you the greatest of success, and the greatest of science ahead from the Lucy Mission. And thank you for this time today, all three of you.

Hal Levison: Go Lucy.

Mike Sekerak: Yeah.

Cathy Olkin: Go Lucy.

Mike Sekerak: Go Lucy.

Cathy Olkin: Peace and love.

Mat Kaplan: Go Lucy.

Hal Levison: Peace and love.

Mat Kaplan: Peace and love.

Mat Kaplan: Lucy, Principal Investigator, Hal Levison, Deputy Principal Investigator, Cathy Olkin, and Deputy Project Systems Engineer, Mike Sekerak, of the Lucy Mission.

Mat Kaplan: Time for What's Up, on Planetary Radio. Here is the Chief Scientist of The Planetary Society. Wait a minute, I got something to read to you. I almost forgot. It's from our longtime listener, Elijah Marshall, in Australia. I'm loving listening to Bruce. Is he as much fun in the office as he is on the show? Well, I'm sure the answer is, I don't know, because I haven't been to the office in a year and a half. Much less been there with Bruce. Are you fun in the office still?

Bruce Betts: No.

Mat Kaplan: There you have it, Elijah. Straight from the mouth. Yeah. Right. What's up?

Bruce Betts: No, I'm home almost all the time. And I'm big fun, big fun at home. Always. Always. Let's just jump into the night sky. It's just lovely in the evening sky. You've got, soon after sunset, over in the east, Venus really, really bright. And it is getting pretty darn high for Venus. So, pretty easy to see. You turn over to the other part of the sky, and the other really bright object is Jupiter with Saturn to its right. And over the coming weeks and couple months, they'll all be getting closer together. It'll be a fun festive time. But for now, they're still lovely in different parts of the sky. And I've got Mercury. Mercury making an appearance in the predawn east. You're going to need a nice view of the eastern horizon looking fairly low down, but it's coming up, and will be there for two, three, four weeks. On to this week in space history, it was 1997, Cassini Huygens was launched on its way to the Saturnian system. 2003, Shenzhou five was launched, and Yang Liu became the first Chinese astronaut. And in 2018, BepiColombo was launched. And it's been flying past Venus, and making its way gradually to Mercury.

Mat Kaplan: And just made, what, a couple weeks ago now, that first pass of Mercury, and got some really cool images. Some of which we have had at planetary.org. They're fun.

Bruce Betts: And we look forward to more in the coming years. For now though, we move on to [inaudible 00:54:53].

Mat Kaplan: I don't know what to make of that.

Bruce Betts: I don't either. You've been hearing about the Lucy Mission.

Mat Kaplan: In fact, on this show.

Bruce Betts: Exactly. I know these things. And although I haven't heard the episode yet, but the custom of naming the Trojan Asteroids of Jupiter after Trojan War figures from the Iliad. Johann [inaudible 00:55:21] of Vienna, whose first accurately calculate their orbits. And I don't know if you discussed it, in the leading orbit, leading Jupiter named after Greek heroes. Trailing orbit named after heroes of Troy, but just confused matters. There's a spy in each camp with one Greek and the Trojan, one Trojan in the Greek camp. I don't know if there's a horse involved, but they were named early on before the convention took place.

Mat Kaplan: No. That did not come up. Thank you for those tidbits. Those sub RSFs.

Bruce Betts: We're getting into the details. We've been on the air for a long time. All right we moved on to the trivia question. I asked you, what moon of a... This was such a klugey question, I'm a bit curious how we did. What moon of a planet has an orbital sidereal period closest to 24 hours? So, it takes about 24 hours to go around its parent planet. How did we do, Mat?

Mat Kaplan: We got such a variety of answers on this one. There were some ones that came very close. Some not so close. But the general opinion was, the consensus was, well, it all consolidated in one, and I will let Dave Fairchild, the poet laureate provide it to us. Methone is an egg shaped moon, a ball of fluff, I guess. It lives in Saturn’s E-ring, and is also cratereless. At barely three kilometers, Cassini gave it worth by showing that its orbit time is just the same as earth. Almost anyway. According to Norman Casson, in the UK, and a lot of other people, it's rotational period is exactly, or very nearly, 1.009573975 earth days. sidereal measurement. In fact, I think you specified that actually.

Bruce Betts: I did. And it's actually, I mixed and matched. That's why I say it's klugey. It's the orbital period how long it takes to go around the planet, which isn't necessarily the same as the rotational period, which is what our 24 hours is approximately.

Mat Kaplan: Can I tell Norman Casson that he's our winner?

Bruce Betts: Yes.

Mat Kaplan: Well, it's another one that was the end of a long dry spell. His last win was in January of 2017. So, those of you out there who are still wandering in the wilderness, keep the faith. We're going to send Norman, by the way, a Planetary Society kick asteroid rubber asteroid. How's that? Congrats Norman.

Bruce Betts: Congrats.

Mat Kaplan: And here are some more contributions from listeners. Laura Weller, also in the UK, she says, so, Methone is a moonlet? I didn't know a Moonlet was a thing until this contest. Cute. My new favorite thing in space.

Bruce Betts: I've always enjoyed a good moonlet.

Mat Kaplan: Chris Mills, in Virginia. Please send me a rubber moon instead. Sorry Chris, we only have paper moons. Matthew Easton in Virginia, here's a fun fact, he says, Neptune has both the moon with the shortest period, it's niad at 0.294 days, and the longest period, NASO 9374 days for that little pup to get around Neptune. My gosh.

Bruce Betts: I almost use those as part of the show. Yeah. I love that.

Mat Kaplan: Here's a fairly long one, but it's interesting, from Kent Murley, about the nature of this moon, he's in Washington. Methone rides in a dust ring, a close in partial arc separate from the main IC rings. Her orbit varies, along and around this arc every 450 days, because of a resonance with the dreaded minus. Do you hear the imperial march playing in the background? I really do hear it in the background. So, will we still catalog it as a moon a century from now, or an electrostatic dust storm, rafting a gravitational river?

Mat Kaplan: I think it has a moonlet core in there. I can't handle terror in dust bunnies. I advised not landing there until we know how to handle lunar and Aryan, or Martian dust. Imagine trying to climb out of a bagless beanbag in zero G.

Bruce Betts: Wow. I'm going to have to put that aside to think about later. That's wow.

Mat Kaplan: I loved it. Yeah. I feel it had to have a big thing on it, like there is for a Europa attempt no landings here, because he'll just disappear.

Bruce Betts: Yeah. Methone is a weird place. It's where to looking. I encourage people to pull up a picture from Cassini. It's interesting with it's, sort of, ellipsoidal shape, and lack of craters probably caused by being all fluffy.

Mat Kaplan: Here is a poem to close out with from, Gene Luen, also in Washington. Three sisters of the alkionities are dynamic in their ways. Under the effects of Gaia's son, their orbits tend to stray. But forging on like all good eggs, Methone never cowers orbiting around Saturn's girth in about 24 hours.

Bruce Betts: Yeah. It looks, kind of, like an egg. I get it.

Mat Kaplan: It really does. All right, we're ready to go onto another contest with another special deadline.

Bruce Betts: All right, we're coming back to Lucy. So, most of the asteroids to be visited by the Lucy Mission are Trojan Asteroids named after characters in Homer's Iliad, but what two objects to be visited by Lucy, are named after real people? Go to planetary.org/radiocontest.

Mat Kaplan: Wow. This might be a tough one, but you've got two weeks this time. Not three like last week. In fact, we've got the same deadline we gave you last week, of October 27th. That's Wednesday, October 27th, at 8:00 AM Pacific Time. And we'll have a cool little, maybe it'll be warm, I don't know, a little Planetary Society rubber asteroid waiting for the winner of this contest.

Bruce Betts: All right everybody. Go out there, look on the night sky, and somewhat unfortunately think about macrame. Thank you, and goodnight.

Mat Kaplan: I just don't understand. Why would macrame be unfortunate?

Bruce Betts: All right, we love the macrame.

Mat Kaplan: God. That's Bruce Betts. He's the Chief Scientist of The Planetary Society, who 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 members who, like Lucy, are diamonds in the sky. You can shine with them at planetary.org/join. Mark Hilverde and Jason Davis are our Associate Producers. Josh Doyle composed our theme, which is arranged and performed by Pieter Schlosser. Ad Astra.