Transcribed by Planetary Society volunteer Jake Bathman:

[Mat Kaplan]: Lucy in the sky with asteroids, 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. The Lucy mission will leave for Jupiter before long. Before it's done, it will have visited seven different asteroids that may be remnants of our solar system's genesis. We'll talk with three leaders of this exciting mission including Principal Investigator Hal Levison. Rubber asteroids, sure, but rubber telescopes? They'll bounce their way into this week's What's Up segment with Bruce Betts. Happy Space Day of China. April 24th is the anniversary of China's first successful satellite mission launched in 1970. We'll celebrate it by checking in with Andrew Jones, the Planetary Society's Finland-based correspondent who closely follows the progress [00:01:00] of the ambitious Chinese space program. Andrew, welcome back for this quick update on the Chinese mission that appears to be doing very well on the Moon. You wrote about it in a blog post that went up at planetary.org on April 22nd. The title is "Chang'e-4 Updates: Yutu-2 Roves into Overtime, Returns More Images." Well that kind of captures did right there, but I guess these two little spacecraft on the surface are doing pretty well.

[Andrew Jones]: Hi, Mat, good to speak to you again. Yep, absolutely the Chang'e-4 spacecraft are both doing well. We're not getting too many very regular updates. It's normally after Yutu-2 coming out of it nap or the end of the activities for the lunar day. But we're getting some interesting updates that we can see what's going on. So Yutu-2 has now totaled I think it was 170.9 meters which means that it's added [00:02:00] about sixteen meters over the full lunar day. That doesn't sound very much and it is relatively short distance and what that tells us is that they're navigating this complex lunar terrain in Von Kármán crater trying to use this spectrometer which they have which has a very small field of view and so they need to very carefully approach these different specimens, which they want to analyze.

[Mat Kaplan]: Well clearly they are getting good data. You mentioned in the piece that they just had a ceremony for handing off the first of that data to the the international partners on the mission.

[Andrew Jones]: That's right, representatives for payloads from Sweden, Germany, and Netherlands were at a ceremony in Beijing. So they've got their hands on their first data. So Sweden has a small payload on the rover. Germany has the atomic neutrals payload on the lander. And on [00:03:00] the relay satellite the Netherlands low-frequency astronomy payload has also got its first data. So we'll be looking to see what they can return in terms of papers in the coming months.

[Mat Kaplan]: This international angle to this mission is given extra meaning perhaps because of a really gorgeous, a beautiful poster that you have put into the piece. It's worth seeing on its own in addition to lots of great images from the surface of the Moon. It has this English subtitle: "pursue space dream for win-win cooperation." It is it really is gorgeous. It's loaded with iconic and symbolic images, but it seems to also say something about how China hopes to use these missions to further collaboration with with other nations.

[Andrew Jones]: Absolutely. This is a very interesting poster and I recommend you go take a look to see what symbolism and imagery they have on there with a blend of space [00:04:00] achievements and also Chinese history and culture. The phrase "win-win cooperation" is something that China bandies around regarding its international relations with other countries that if you're familiar with China, you might roll your eyes when you hear that once again, but absolutely it's it does give an indication of one way in which China is using its space activities to pursue goals on Earth, shall we say.

[Mat Kaplan]: In the meantime, an American spacecraft overhead, the Lunar Reconnaissance Orbiter, is you put in some pretty remarkable images that it's picked up of this Chinese mission on the surface.

[Andrew Jones]: Yeah. It's just fascinating that we have something in orbit tracking what's going on down on the Moon. Once every month the LRO will pass overhead on its orbit. They seem to be tracking carefully what's going on with Chang'e-4 and the Yutu rover and also now [00:05:00] looking for the remains of the SpaceIL probe as well.

[Mat Kaplan]: Ah, I didn't know that. Before I let you go, very briefly, there is another mission which you mentioned to me is appears to be moving forward. Although you said it's still under discussion?

[Andrew Jones]: That's right. So at the ceremony in Beijing last week, there was a couple of announcements of opportunity for international partners and also for commercial domestic and private actors as well. One relates to Chang'e-6, which will be a follow-up to the Chang'e-5 lunar sample return mission which shoud launch this year, so that will take place sometime in the 2020s, but there's a really fascinating mission called... well, it's not been named officially but tentatively called Zheng He. Named after a Chinese eunuch Admiral from the 14th and 15th century. This mission proposes to visit the near-Earth [00:06:00] asteroid 2016 HO3, collecting between 200 and 1,000 grams of materials, returning to Earth, dropping those off, before heading for Mars flyby, and then going on to analyze the Main Belt Comet with the name 133P/Elst-Pizarro.

[Mat Kaplan]: Wow.

[Andrew Jones]: So that that mission is looking about 10 years. So let's see if that goes in.

[Mat Kaplan]: Very ambitious plans. Thank you Andrew, glad that you're tracking all of this for us as China continues its busy schedule of missions across the solar system and look forward to talking again.

[Andrew Jones]: Great. Thanks very much, Mat.

[Mat Kaplan]: That is Andrew Jones. He's a Contributing Editor for the Planetary Society. He's based in Finland, but covers the Chinese space program as you've heard. You can follow him on Twitter at @AJ_FI. And his latest as we just said was posted on the 22nd, an update on the Chang'e-4 [00:07:00] mission now exploring the far side of the Moon. The Voyager spacecraft continue their grand tour even as they leave our solar system forever. Their fantastic voyages were enabled by a rare alignment of planets that would enable them to visit multiple worlds. Hal Levison, Cathy Olkin, and Mike Sekerak are preparing for yet another grand tour. This time the targets are much smaller, but the stories they may tell are just as intriguing and revealing. Principal Investigator Hal and Deputy PI Cathy are at the Southwest Research Institute headquartered in San Antonio, Texas. Mike is Lucy's Deputy Project Systems Engineer working out of NASA's Goddard Space Flight Center in [00:08:00] Maryland. They recently joined me in a four-way conversation about their mission to seven asteroids. Hal, Cathy, Mike, thank you for joining us on Planetary Radio. I am thrilled to talk to you about this this mission that's going to take us through where no robotic spacecraft or human has gone before.

[Hal Levison]: It's a pleasure to be here.

[Cathy Olkin]: Thanks for having us. Excited to be here and tell you all about the Lucy mission.

[Mike Sekerak]: Thank you very much, this is exciting.

[Mat Kaplan]: Cathy and Mike, I'm going to welcome you for the first time to the show. Hal, I don't know if you remember it, but you were on quite a few years ago back in 2010. We talked about the Oort cloud and those comments that were captured by the Sun, which was a fairly new thought I guess at the time. We won't spend more than a minute on this but has that held up pretty well?

[Hal Levison]: Yeah, I think it has, at least in the in the sense that it's a model that can still work. They observations have changed a little bit and so as a result, it's not clear that we actually [00:09:00] need the process but we suspect that this kind of dynamics happens all the time and star clusters and so a significant fraction of the Oort cloud could be comets that were captured from other stars.

[Mat Kaplan]: Excellent work. Let's get on to Lucy. Are you on track for launch in October of 2021?

[Hal Levison]: Absolutely. We've... we're halfway between what we call the preliminary design reviews and our critical design review. That is in the fall. So far, everything is looking good and we should be there in October 2021 for the launch.

[Cathy Olkin]: Yeah, so it's just about 30 months until we launch which is going to go really quickly. And as Hal said we're coming up to our critical design review. And so we call it CDR season. We have many design reviews for our subsystems. And [00:10:00] peer reviews leading up to the mission CDR.

[Mat Kaplan]: Does this also mean that you're actually bending metal or spacecraft itself is beginning to come together?

[Hal Levison]: Let's let Mike answer that question.

[Cathy Olkin]: Yeah, go ahead, Mike.

[Mike Sekerak]: Yeah so because we have to hit our planetary launch window, we have a very aggressive schedule that we're sticking to and with that while we're going through a critical design review as we are starting some early fabrication and some long leads for some of our components to make sure that we hit that planetary launch date. So yes, we are starting to actually get hardware in right now.

[Mat Kaplan]: We know from past experience how difficult it is to pull together a spacecraft, especially one that is taking on a mission that has never been attempted before. I'll just mention one more thing in connection with the preparations and I'll address this to you Hal, but again anybody can jump in. You must also be relieved to see that it looks like you are assured of a ride into space because that was somewhat in question when SpaceX protested the selection of your launch vehicle.

[Hal Levison]: Yes. You know the now that that's [00:11:00] resolved we're moving ahead. It was resolved in a timely enough fashion so that we weren't really impacted on our schedule. We're in fine shape and moving ahead with that. By the way, it's an Atlas V 401.

[Mat Kaplan]: Let's talk about this mission and what you hope to accomplish. It's a seven for one, it seems to me, since you're going to be visiting seven asteroids, two of those that are in a binary system. That's... nothing like this has ever been done before, has it, Hal?

[Hal Levison]: No. This is a survey of what we call Trojan asteroids which are objects that lead or trail Jupiter in its orbit by 60 degrees.

[Mat Kaplan]: And that's a very specific amount right? Because we're talking about LaGrange or LaGrangian points, which I bet a lot of our listeners have heard of particularly L5 the one that's near Earth but they might be surprised to hear that these points of equilibrium are not exclusive to Earth.

[Hal Levison]: Yeah, these [00:12:00] asteroids are in stable equilibrium points called the LaGrange 4 point and the LaGrange 5 point, and the way to think about this from a dynamical point of view is if you put an object in a three body problem right, Jupiter and the Sun and put it down an asteroid at that, exactly at 60 degrees from Jupiter, the gravitational attraction of the Sun and Jupiter plus the centripetal force of rotation cancel out. You've put an object there. It'll stay there forever. And as a result, there's this population of asteroids there that date from the beginning of the solar system.

[Mat Kaplan]: Does this mean that it's a little bit like a gravity-based butterfly net that has been collecting these objects over billions of years?

[Hal Levison]: I think that's a good analogy.

[Cathy Olkin]: Not only Jupiter has these LaGrange points as Hal said it's a result of a three body [00:13:00] problem. And so we know of other objects that are in the LaGrange points of other planets. Neptune, for example, has asteroids in its LaGrange points, but we only know about a few of them. There's thousands of asteroids in the L4 swarm and thousands in the L5 swarm that we know of, there's many more smaller ones that we will probably discover in the future.

[Mat Kaplan]: Cathy, you've just described. What was the biggest surprise for me because I didn't realize I'd heard of a Trojans but until I saw the kind of hypnotic computer animation of these asteroids orbiting ahead of and behind Jupiter. I had no idea there were so many of them. It really is a pretty stunning little animation or computer model.

[Cathy Olkin]: It really is there's I think 4,000 in one of the swarms and 5,000 known objects in the other swarm, at least that many, and so this is really a concentration of these [00:14:00] objects that are left over from the evolution of our solar system. And that's part of the reason we want to go visit them. We want to understand where they came from and they're a diverse set of objects and that indicates that maybe they had different experiences in the past either forming at different locations or having different evolutionary paths. And so that's why we're visiting seven asteroids with just one spacecraft six of them are Trojans and one is the main belt asteroid that we kind of get the free on the way there we'll be able to use as a rehearsal.

[Hal Levison]: So you can find that movie at our website, which is lucy.swri.org.

[Mat Kaplan]: And we will put that link on the episode page for this week at planetary.org/radio so people can find it from there as well. Why are they called Trojans?[00:15:00]

[Hal Levison]: [laughing] You know, I've been asked that that question a long time... several times that have no bloody idea. So I think we should just pass on that question.

[Mat Kaplan]: We will because I have lots of others. Cathy you started to talk about the how diverse these asteroids are and I saw on the website that there are basically... you expect to encounter three different types, is that correct?

[Cathy Olkin]: So there's different ways that our targets are diverse and one way is looking at the spectral type. And so that's looking at the light you see reflected from the surface in the visible and in the near-infrared spectroscopically and so there's three different types. They're called C, D, and P types and that's just one axis of diversity in the objects. Also, there's diversity in the size of the objects and in the color of the objects. [00:16:00] And as you mentioned before one of them is a binary pair and another one our smallest target we expect to be a fragment so they have the diversity in many different ways that you look at them.

[Mat Kaplan]: How have we learned what we know so far about these thousands of objects?

[Cathy Olkin]: What we've learned so far is really from ground-based observations. These are points of light. These are not resolved objects. So you can look at it... their position against fixed stars. You can look at the amount of light that you see reflected from the surface. You can look at how that light changes over time as they rotate. But we haven't been able to see detailed images of the surface and what the surface geology looks like and what the surface composition looks like at a resolved level. And that's what Lucy's going to give us. It's going to really revolutionize our view of these objects by giving us the first close-up looks at them.

[Mat Kaplan]: Are you pretty [00:17:00] confident? I mean, do you know enough to say that of these seven you'll have representatives of all three of these types that you've just mentioned?

[Hal Levison]: Yes. Well we don't know is what that actually is telling us about how they formed, right? The overall goal of the Lucy mission is trying to put real constraints on our theories of planet formation and the evolution of the outer solar system and I can talk a little bit about that. That's the goal of Lucy. What we're going to use is information about the geology, about the cratering, about composition to try to constrain the models of planet formation. The analogy I like to use with regard to why small bodies are some important to unraveling our formation model is—it's a little gross but I think it's appropriate—is all of a murder scene. Sometimes the blood [00:18:00] splattered on the wall can tell you more about what happened than the bodies laying on the floor. And these small bodies represent the blood splattered on the wall and particularly the Trojans because they're out near the orbit of Jupiter really are going to allow us to understand how planets like Jupiter formed.

[Mat Kaplan]: I think you're watching too many CSI shows.

[Mike Sekerak]: [laughing] I've heard it before and I laugh every time.

[Mat Kaplan]: How is Lucy... what will it have on board? What instruments are going to be able to reveal so much more about these these asteroids once were up close to them?

[Mike Sekerak]: We have three primary instruments on board the spacecraft and they're L'Ralph, L'TES, and L'LORRI. We will also be using some of our engineering cameras for some of the science for the asteroids as well. The Ralph instrument has both color panchromatic as well as near-infrared imaging of the [00:19:00] asteroids that will give us high-resolution pictures over will give us good pictures as well as compositional knowledge. The LORRI instrument, which is similar to New Horizons' LORRI, is long range reconnaissance imager and that'll give us our high-resolution pictures of the asteroids as well as it will help other optical navigation as were navigate her way into the asteroids. And the L'TES instrument is thermal emission spectrometer that will help tell us the temperature for the far-infrared for the bodies that will give us information about their thermal properties.

[Mat Kaplan]: Cathy there's a lot of legacy for all of all three of these right? I mean definitely New Horizons, which you are a Deputy Project Scientist for but, also for TESS.

[Cathy Olkin]: That's right. These instruments all have a lot of heritage from past mission. There is a Ralph instrument on New Horizons. And that's what gave us the color images that are so beautiful on Pluto. And then there's the LORRI instrument which fulfilled the same [00:20:00] role on New Horizons as it does on Lucy doing optical navigation and really our highest resolution imaging and then L'TES has heritage from OSIRIS-REx. And there's also a variant of the Ralph instrument on OSIRIS-REx called OVIRS, which is the infrared part of the Ralph instrument. So there's a lot of heritage that helps to build the instruments and we can just keep making them better and better so we get the data that we need when we go to the Trojans.

[Mat Kaplan]: I guess another similarity to New Horizons is you're not going to be orbiting any of these objects, are you? These are flybys, like the flyby of Pluto and and the much more recent more distant object.

[Cathy Olkin]: That's right. These are all flybys and we are flying by at a velocity of approximately five to nine kilometers per second, which is really quite fast. It's not a speed that we [00:21:00] really deal with here on the Earth, very much. But it's slower than the New Horizons flybys and it will allow us to get the data that we want as we fly by and also to accomplish our mission objectives in a timely way. We get to our first target in 2027, our first Trojan target, we get to Donald Johanson, our main belt asteroid in 2025. So you have to have a lot of patience to be exploring the outer solar system.

[Mat Kaplan]: Ain't that the truth.

[Hal Levison]: If you think about it, this is a 12 year long mission, but most of the critical science is going to be collected within a few hours.

[Mat Kaplan]: Wow.

[Hal Levison]: So a lot of this time is spent just getting from one target to other. And it's the velocity obviously allows us to do that. But that means the encounters don't last very long.

[Mat Kaplan]: Yeah.

[Mike Sekerak]: You could do a mission like this with like propulsion and and that most certainly has been looked at. [00:22:00] The trajectory that we able to find for Lucy to do it without electric propulsion though is really an amazing trajectory with our three Earth gravity assists, 5 G space Maneuvers, and as you see on our website how we're kind of zigzagging across the solar system if you will.

[Mat Kaplan]: It's quite a dance, really.

[Mike Sekerak]: It really is and that's a real fun part of the mission is this trajectory design and navigation where we start out in a in essentially a one year orbit around the sun we go straight to heliocentric trajectory right off a launch. We never orbit the Earth at all. We do an Earth gravity assist about a year later to gets us into two year orbit. Another Earth gravity assist that then gets us into our approximately six year heliocentric orbit that allows us to swing out to the L4 Trojans, then we come back in for Earth gravity assist number three and then that then swings us out as well as does a plane change to get us to the L5 Trojans. So there's a lot of time cruising in between as we as we hit these different swarms, but we will be the the [00:23:00] furthest out solar-powered mission so actually going out past Jupiter's orbit, so past Juno, so we'll be the furthest out solar mission that's ever been flown.

[Mat Kaplan]: So that explains the humongous, the two circular solar panels that you'll be unfolding once you're up there?

[Mike Sekerak]: Yes, we have 7.2 meter diameter ultraflex arrays, which also be the largest ones ever flown. The ones in the crew resupply vehicle for from Northrop Grumman are only three point seven meters in diameter and the Phoenix InSight ones are only a little over two meters in diameter. So ours will be the largest ones ever flown it also the only ones that have flown through deep space in this environment. So that's an exciting but fun challenge that we're up to.

[Hal Levison]: These things are really huge. The spacecraft from tip to tip is 50 feet...

[Mat Kaplan]: Wow.

[Hal Levison]: ...when the solar arrays get deployed.

[Mat Kaplan]: It's really remarkable because when I was looking at one of the artists concepts, it looked like it was all all solar panel and and there was the spacecraft way down below. It was... they really dwarf the [00:24:00] spacecraft and its I guess being able to see that this has been accomplished by spacecraft like Juno that far out must be encouraging.

[Mike Sekerak]: We're definitely pulling from some of the same power management strategies that Juno had used with different lengths of strings, the different low intensity low temperature testing for the cells. So we're really capitalizing that experience which our spacecraft vendor Lockheed Martin has with with Juno.

[Mat Kaplan]: Hal, I want to go back to talking about the real purpose of this mission, what your goal is, and I believe that's to help us understand the origin of our solar system and maybe by extension other solar systems? Is that fair?

[Hal Levison]: Absolutely fair. This mission, first of all, is designed to help us understand how the outer planets formed right? They study of asteroids in the main belt has allowed us to understand how the terrestrial planets, the rocky planets [00:25:00] formed. So this is again another step out that will concentrate on the giant planets, but it's also is going to tell us a lot about how the Earth train things that we have learned in the last 20 years studying how planets form tell us that planets like the Earth don't form if you'll excuse the pun in a vacuum, right? They form as a part of a system where the growing planets can move material between them and the planets themselves are moving around and interacting with one another which not only determines the physical characteristics of the planets, but there orbits as well. The Earth is sculpted in a way by Jupiter and the growing giant planets and so we're going to understand what the giant planets have been doing, which will help us understand [00:26:00] how the Earth formed. Another aspect of this mission that I think is very important is that there are theories for the formation of the Earth which suggests that it formed dry and that the volatiles and organic from which were made came in late in the planetary process. And the Trojans and the asteroids in the outer asteroid belt are probably the source of Earth's oceans and organics.

[Mat Kaplan]: And would you include comets within that as well?

[Hal Levison]: I would. So for example, remember I said this mission is going to be used to constrain theories of planet formation and evolution. One of my favorite theories, which is called the nice model is a model for how the planets moved around after they formed. The nice model would predict that the comets that we see particularly what we call the Jupiter family comets and the Trojans are basically the same population [00:27:00] and the way that works is that the nice model hypothesize that the four giant planets formed in a much more compact configuration than we see them today. So Jupiter is five astronomical units, currently Neptune is at 30, and then this model would say that the four giant planets formed all within 12 or 13 astronomical units of the Sun. Surrounding those planets is a disk of planetesimals that extend just outside the orbit of the giant planets out to roughly 30 AU where Neptune is today. And the nice model hypothesized that that system is actually not stable for long periods of time, that the orbits of the planets actually dynamically go nuts. They cross each other, they gravitationally shoot each other around the solar system. And in particular Jupiter and Saturn [00:28:00] chuck Uranus and Neptune out to near their circular current orbits and the dynamical interaction between the planets and that planetesimal disc circularizes their orbits and puts the planets on the orbits we see today. If that's true then both the Kuiper belt that is supplying us the comets and the Trojans should be remnants of that disc. And so that's one of the things that we're going to be testing with Lucy. Another thing is that's relevant to the nice model is that that disc I was talking about the objects in that disk formed at a range of heliocentric distances, therefore the range of temperatures. And so one of the hypotheses were going to check is whether the diversity that we see in the Trojans are due to the fact that this disc had members in it [00:29:00] with very different formation temperatures.

[Mat Kaplan]: Cathy anything to add?

[Cathy Olkin]: Yeah, one of the tools in a planetary scientist toolkit is comparative planetology. So being able to look at the Trojans and compare them amongst each other but also comparing against the latest New Horizons target, 2014 MU69 is going to be very interesting. 2014 MU69 is a cold classical Kuiper Belt object, which means it formed out in the outer part of the solar system likely at the edge of the protoplanetary disk, and it's had its whole existence there. And so it's been relatively unchanged and being able to then compare that object with the Trojan asteroids is going to be very interesting, because the one hypothesis is that the Trojan asteroids have been scattered from the outer solar system to their current location and captured [00:30:00] there. Comparative planetology is very interesting. NASA has many interesting small body missions going on right now. We have OSIRIS-REx which is at the asteroid Bennu. Also launching similar time as Lucy is the Psyche mission which is going to go to a metallic asteroid. And being able to compare all these bodies is really going to inform our understanding of the solar system.

[Mat Kaplan]: For both of you, would you say that we are closing in on an understanding of how our solar neighborhood came to look the way it does and why it appears to be relatively stable?

[Hal Levison]: Oh, I would like to say that, I'm hoping that that's true. But as you know with these missions quite often, you see something that you don't expect that can actually overturn a lot of the current thinking. That would in a way from a scientist point of view overturn these ideas that we've been developing over the last 20 years would be[00:31:00] more interesting and more fun than confirming that they're true.

[Cathy Olkin]: And I'd like to add that. I think we're in a golden age of planetary science, understanding not only our solar system, exoplanetary solar systems. So solar systems around other stars besides our own and being able to now have this huge zoo of different solar systems to think about when we're trying to understand formation and evolution. It's very exciting.

[Mat Kaplan]: Cathy. That's exactly what we call it. The golden age of planetary science. And I'm glad you mentioned the Psyche mission. Are you folks in touch with them as well? And and how will you complement each other in what they learn about this this very strange object that they'll be visiting that maybe in entirely made of metal?

[Cathy Olkin]: We are definitely in touch with people in the Psyche mission. In fact, some of our Lucy team members are also on the Psyche mission team, [00:32:00] and so we're well aware of the synergy between the two different missions. I like to think of us as sister missions. We were selected together. It's very exciting to have to planetary spacecraft in development at the same time that are discovery class.

[Hal Levison]: And also by comparing them, right, you can see the range of the kinds of science that small bodies will allow us to do. Lucy will be studying what I like to call very primitive objects, objects the probably date from the very earliest times in the solar system's history. Psyche is going to the remnants of a differentiated planet. So it actually formed quite late in the evolution of the solar system as a planet and went through a lot of the same plant processes that the Earth did and the mantle got blown off in some kind of impact we [00:33:00] think and as a result we can study both the differentiation process that occurred in the Earth, and the formation of the most primitive objects in the solar system with the small body missions.

[Mat Kaplan]: Extremely exciting and very cool. Mike, you at Goddard get to work on lots of different missions with lots of different partners. What is the nature of your work on on this one as the Deputy Project Systems Engineer?

[Mike Sekerak]: So the role of the product system engineering team is to make sure that all elements of the mission are working together. We are overseeing both the the spacecraft development through the prime contractor of Lockheed Martin, the instrument development, which is a partnership with SWRI, as well as NASA Goddard, John Hopkins Applied Physics lab, as well as Arizona State, and then of course the launch vehicle provider as you said is going to be ULA with their Atlas V 401, as well as our ground system and our navigation teamwork KinetX will [00:34:00] be doing will be worth part of our navigation team with us. The role of system engineering is to make sure all those elements are working together and everything comes together as one mission for when we launched in October of 2021.

[Hal Levison]: Cathy and I are called the Principal Investigators and we sort of thought up the mission concept, we put together the team, worked on things like this beautiful trajectory that we found, set the goals for the mission. What Mike does is making sure it's all going to work. So a good analogy for all this is that Cathy and I are the composers of let's say a symphony, but Mike does is he's the conductor. He makes sure all the parts are working together so that you can actually produce the music that Cathy and I conceived of.

[Cathy Olkin]: I really like that.

[Mat Kaplan]: I love that. That's delightful.

[Mike Sekerak]: That's an excellent analogy. [00:35:00]

[Mat Kaplan]: How long has this been mission been coming together? I mean, when did it first occurred to I assume to you Hal or maybe was you Cathy as, gee wouldn't it be great to visit the Trojan asteroids at Jupiter?

[Cathy Olkin]: So we really first started working on a mission to the Trojans in about 2008. And the first time we put in a proposal for Lucy was in the 2010 round for Discovery. We did quite well there but we didn't quite win. There were other mission proposals on the along the way that we were part of that included New Frontiers mission proposals. Those weren't selected either. And this is really a message of you need to keep trying and refine your message. When the more most recent discovery AO came out in 2014, the one that we proposed the Lucy mission, over the years the [00:36:00] architecture of the mission has evolved. Because there's different decadal surveys that you're responding to. The decadal survey is the voice and direction of the planetary science community to say what they think the direction of planetary science should be for the next decade.

[Mat Kaplan]: Yeah, something that comes up quite frequently on this show.

[Cathy Olkin]: Major mission proposals need to be responsive to the decadal survey. So our mission concepts have evolved over time and it's really quite exciting because this one is outstanding with its diversity of targets and the the rich scientific return that we are going to have so I'm really excited that this Lucy mission was selected.

[Hal Levison]: The trajectory that we have this amazing ability to go to these diverse interesting objects and the number of them is the matter of luck. And so the universe mechanics are aligning to [00:37:00] allow us to get something that is this exciting. And cover the diversity that we see. So one advantage that we happened to have in this round is that we found this amazing trajectory.

[Mat Kaplan]: Do you think of it in terms of the Voyager missions Voyager 1 and 2 and their grand tours which were also once in many lifetime opportunities just because of the trajectory they were able to follow?

[Hal Levison]: I think it's an excellent analogy. I just hope that we can have the impact that they did.

[Mat Kaplan]: Well all of us, of course at the Planetary Society and I'm sure everyone listening to this show look forward to the beautiful music that you will be making as the Lucy mission progresses and makes its grand tour of these mysterious objects that are in the same [00:38:00] orbit as Jupiter, but quite separate from it. I've just got one more question, why Lucy? Why that name?

[Hal Levison]: Well Cathy was actually the one of the developers in the name. So I'll let her answer that.

[Cathy Olkin]: The Lucy mission is named after the Australopithecus fossil of Lucy that was discovered in East Africa and just like the Lucy fossil revolutionized our understanding of hominid Evolution, the Lucy spacecraft mission will revolutionize our understanding of solar system evolution. So there's a lot of great synergy and analogies between the Lucy fossil and the Lucy mission. Also the main belt asteroid that were flying past when we were originally formulating the mission it didn't have a name. And so we decided to have it named after Donald Johanson who was one of the discoverers of the Lucy fossil. It's going to be very exciting to take the [00:39:00] Lucy spacecraft passed the asteroid Donald Johanson.

[Mat Kaplan]: I love the romance of thinking that we are going to be learning about these ancestors of our solar system through a mission that has the name given to one of our own human ancestors. Maybe Lucy was an Explorer and her time as well. Folks it has been delightful I very much look forward to talking to you again as we reach the time when Lucy will begin its long journey, it's 12 year mission. What would that be almost two and a half times longer than the Starship Enterprise the original one? I wish you the best of luck. And Mike for you, I hope that that spacecraft keeps coming together in exactly the way that you want it to so that Cathy and Hal and all the other scientists can get their work done.

[Mike Sekerak]: Most certainly.

[Hal Levison]: It was a pleasure.

[Cathy Olkin]: Thank you.

[Mike Sekerak]: Thank you very much, Mat.

[Mat Kaplan]: Our guests have been the Principal Investigator for the Lucy mission to the Trojan asteroids of Jupiter, Hal Levison, [00:40:00] the deputy PI, Cathy Olkin, who is also from SWRI, the Southwest Research Institute, and a little ways away from them across the country the Deputy Project Systems Engineer for this mission, Mike Sekerak at the NASA Goddard Space Flight Center. Time for What's Up on Planetary Radio. Bruce Betts is the Chief Scientist for the Planetary Society who has joined us once again to talk about the night sky and and get back to doing trivia contest, which we now will answer the question that we gave a couple of weeks ago, but but that's still to come. Welcome.

[Bruce Betts]: Thank you, Mat. Welcome to you too. Well, we'll start with an above average average meteor shower the Eta Aquarids, which is capable of producing up to 60 meteors per hour at its peak if you have dark skies, and if you're in the southern hemisphere, [00:41:00] so here's a bone for the hemisphere that I accidentally don't cater to as much. I'm sorry to all of you. Now, you've got a beautiful meteor shower peaking I've arranged for it peaking on the night of the 6th and 7th. Also visible from the northern hemisphere but you'll see fewer meteors. It's good in terms of the Moon, the crescent Moon will set early in the evening. So May 6th, 7th, 8th, Aquarids meteors. While you're out there, hey, if you're out in the evening check out Mars still hanging out not far from the also reddish Aldebaran and Taurus. In the morning sky we've still got that line up going from the East down low is super bright Venus and you might catch Mercury near it. And then to the upper right getting farther and farther away is Saturn and then farther all the way in the South and the pre-dawn is bright Jupiter. So a lot a lot to look at.

[Mat Kaplan]: Don't feel bad for the southern hemisphere. They've got the Southern [00:42:00] Cross. They've got the magellanic clouds.

[Bruce Betts]: Yeah. All right, we move on to This Week in Space History. In 1990, amazingly 29 years ago, Hubble Space Telescope was deployed. Amazing, still work in making the universe beautiful and scientifically cool. We move Random Space Fact.

[Mat Kaplan]: I thought that motor wasn't going to turn over for a moment there.

[Bruce Betts]: So Pluto, our friend Pluto, its orbit is quite non-circular. Quite elliptical. How elliptical is it? Well, if you... you get you gotta stick with me on this you'll be amazed if you hang in there. So the difference between its closest point to the Sun and farthest point from the Sun. The difference is about the same as Uranus's regular distance from the Sun.

[Mat Kaplan]: Wow, [00:43:00] that's a lot.

[Bruce Betts]: There it is.

[Mat Kaplan]: Didn't have to wait long for that.

[Bruce Betts]: Okay. All right. We move on to the trivia contest to satisfy you all with an answer to a question. I asked you What telescope was used to discover Eris, Quaoar, Sedna, Orcus, and the soon-to-be-named 2007 OR10? How do we do?

[Mat Kaplan]: Here is the answer embedded in the latest contribution from our Poet Laureate Dave Fairchild in Shawnee, Kansas. A telescope at Palomar is scanning toward the heaven. It was named for Ocean back in 1987. It takes wide-field images of 48 inch Schmidt. And Pluto killer Brown discovered Eris using it.

[Bruce Betts]: Cool. Not only a poem it got all the key points.

[Mat Kaplan]: It's the Samuel Ocean telescope at the Palomar Observatory that according to our winner James Shields of Scarborough, Maine. [00:44:00] Congratulations James. I think he's a first-time winner and he has picked himself up a 200 point iTelescope.net astronomy account from that worldwide network of telescopes operated out of the Southern Hemisphere, so there, and a Planetary Society kick asteroid rubber asteroid. I'm sure they'll be a few of those flying around next week outside of Washington DC, more about that in a moment. We also got this from Jordan Tipton. He said that Samuel Ocean. He's the same guy same philanthropist who gave his name to the Planetarium at the Griffith Observatory a place that is near and dear to many of us in Southern California. But that's not all he did for Mark little in Northern Ireland. He was very much a philanthropist who dedicated his wealth to building low-cost housing in conjunction with the federal government until his retirement. So good on you Samuel.

[Bruce Betts]: Nice. Good facts. [00:45:00] And we've got a new question for you. Ganymede is the largest near-earth asteroid. What is the second largest near-earth asteroid? Go to planetary.org/radiocontest.

[Mat Kaplan]: This is so appropriate because we will answer this question and we will answer it in front of a crowd on May 1st. That'll be Wednesday May 1st at 8 a.m. Pacific time and that night at the Planetary Defense Conference public event, Bill Nye versus the asteroids, you will and I will be on stage to do another live version of Planetary Radio Live and What's Up, and we'll have... I bet won't we have a live trivia contest for people who join us there at the University of Maryland?

[Bruce Betts]: Exactly, and we'll have asteroid experts and NASA's Chief Scientist, and the Planetary Society's Chief Scientist. It'll be great.

[Mat Kaplan]: It's going to be great fun and you are the overall host. So I will I will follow [00:46:00] your lead sir.

[Bruce Betts]: There's a first time for everything.

[Mat Kaplan]: For this one you again will have a chance to win yourself a Planetary Society rubber asteroid and 200 point iTelescope.net account. I bet we'll have a few to throw out to the audience that night as well. Not telescope accounts, asteroids... rubber asteroids.

[Bruce Betts]: Telescopes.

[Mat Kaplan]: Rubber telescopes.

[Bruce Betts]: The best kind. Deformable mirrors built in. Little Adaptive Optics humor.

[Mat Kaplan]: Very well done. We're done.

[Bruce Betts]: All right, everybody go out there. Look up the night sky and think about how non-circular you are. Thank you and good night.

[Mat Kaplan]: I'm a little less elliptical than I used to be but just as eccentric. That's Bruce Betts, the Chief Scientist for the Planetary Society who joins us every week for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, [00:47:00] California and is made possible by its grand voyaging members. MaryLiz Bender's our Associate Producer. Josh Doyle composed our theme which was arranged and performed by Pieter Schlosser. I'm Mat Kaplan. Ad Astra.

