Planetary Radio: Space Exploration, Astronomy and Science - Lucy in the Sky With Asteroids

Episode Date: April 24, 2019

A rare alignment of planets and other objects will enable the solar-powered Lucy spacecraft to examine seven asteroids, six of which are among the thousands of Trojan asteroids that orbit ahead of and behind Jupiter. The mission team, include Hal Levison, Cathy Olkin and Mike Sekerak, hope to unlock secrets of our solar system’s origin through these ancient artifacts. Planetary Society correspondent Andrew Jones helps us celebrate China’s Space Day with an update on the Chang’e 4 lunar mission. The space trivia contest returns as just one cog in the universe-spanning machine called What’s Up. You can learn more about this week’s guests and topics at:  http://www.planetary.org/multimedia/planetary-radio/show/2019/0424-2019-lucy-levison-olkin-sekerak.htmlLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Lucy in the Sky with Asteroids, this week on Planetary Radio. Welcome, I'm Matt 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 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 and U-22 roves into overtime, returns more images. Well, that kind of captures it right there, but I guess these two little spacecraft on the surface are doing pretty well.

Hi, Matt. Good to speak to you again. Yep, absolutely. The Chang'e 4 spacecraft are both doing well. We're not getting too many or very regular updates. It's normally after U-22 coming out of its nap or the end of the activities for the lunar day. But we're getting some interesting updates so that we can see what's going on. So U-22 has now totaled, I think it was 178.9 meters, which means that it's added about 16 meters over the fourth 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 Bon Carmen crater, trying to use this spectrometer, which they have, which is a very small field of view. And so they need to very carefully approach these different specimens, which they want to analyze. 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 international partners on the mission. That's right.

The 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 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. 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. images, but it seems to also say something about how China hopes to use these missions

to further collaboration with other nations. 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 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, so that if you're familiar with China, you might roll your eyes when you hear that once again. But absolutely,

it does give an indication of one way in which China's using its space activities to pursue goals on Earth, shall we say. 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. 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 orbits. They seem to be tracking carefully what's going on with Chang'e 4 and the U-2 rover, and also now looking for the remains of the Space IL probe as well. Ah, I didn't know that.

Before I let you go, very briefly, there is another mission, which you mentioned to me appears to be moving forward, although you said it's still under discussion. That's right. So at this 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 and one relates to chang'e 6 which will be a follow-up to the chang'e 5 lunar sample return mission which should launch this year so that

will take place sometime in the 2020s but there 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 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. Wow. So that mission is looking about 10 years, so let's see if that goes in. 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 I look forward to talking again. Great. Thanks very much, Matt. 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 at AJ underscore FI. And his latest, as we just said, was posted on the 22nd,

an update on the Chang'e 4 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, Kathy Olkin, and Mike Sekarik 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 Kathy 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 Maryland. They recently joined me in a four-way conversation about their mission to seven asteroids. Hal, Kathy, Mike, thank you for joining us on Planetary Radio. I am thrilled to talk to you about this mission that's going to take us where no robotic spacecraft or human has gone before. It's a pleasure to be here. Thanks for having us. Excited to be here and tell you all about the Lucy mission. Thank you very much.

It is exciting. Kathy 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 Earth cloud and those comets 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? Yeah, I think it has, at least in the sense that it's a model that can still work. The observations have changed a little bit.

And so as a result, it's not clear that we actually need the process, but we suspect that this kind of dynamics happens all the time in star clusters. And so a significant fraction of the Oort cloud could be comets that were captured from other stars. Excellent work. Let's get on to Lucy. Are you on track for launch in October of 2021? Absolutely. 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. 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 peer reviews leading up to the mission CDR. Does this also mean that you're actually bending metal? The spacecraft itself is beginning to come together? Let's let Mike answer that question. Yeah, go ahead, Mike. 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 our critical design reviews,

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. 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're assured of a ride into space because that was somewhat in question when SpaceX protested the selection of your launch vehicle. Yes. And now that that's 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 5 401. Let's talk about this mission and what you hope to accomplish. It's a 741, it seems to me, since you're going to be visiting seven asteroids, two of those that are in a binary system. Nothing like this has ever been done before, has it, Hal? 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. 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. Yeah, these asteroids are in stable equilibrium points called the Lagrange four point and the Lagrange five 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 centrifugal force of rotation cancel out. If you 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. 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?

I think that's a good analogy. Not only Jupiter has these Lagrange points, as Hal said, it's a result of a three-body 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. Kathy, you've just described what was the biggest surprise for me because I didn't realize, I'd heard of the 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 a computer model. 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 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 a main-veiled asteroid that we kind of get for free on the way there that we'll be able to use as a rehearsal. So you can find that movie at our website, which is lucy.swri, for Southwest Research Institute dot org. And we will put that link on the episode page for this week at planetary dot org slash radio. So people can find it from there as well. Why are they called Trojans? You know, I've been asked that question a long time, several times, and I have no bloody idea. So I think we should just pass on that question.

We will, because I have lots of others. Kathy, you started to talk about 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? 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. 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 diversity in many different ways that you look at them. How have we learned what we know so far about these thousands of objects? What we've learned so far is really from ground-based observations. These are points of light.

These are not resolved objects. ground-based observations. These are points of light. These are not resolved objects. So you can look at 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. Are you pretty 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? Yes. What 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. try to constrain the models of planet formation. The analogy I like to use with regard to why small bodies are so important to unraveling our formation models, it's a little gross, but I think it's appropriate, is of a murder scene. Sometimes the blood 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. I think you're watching too many CSI shows. Heard it before and I laugh every time. How is Lucy, what will it have on board? What instruments are going to be able to reveal so much more about these asteroids once we're up close to them? We have three primary instruments on board the spacecraft. And they're LaRalph, LaTess, and LaLaurie.

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 asteroids, and that will give us high-resolution pictures, or it 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'll help with our optical navigation as we're navigating our way into the asteroids. And the LATES instrument is thermal emission spectrometer that'll help tell us the temperature for the far infrared for the asteroids. And the LATES instrument is thermal emission spectrometer that'll help tell us the temperature for the far infrared for the bodies that'll give us information about their thermal properties. Kathy, there's a lot of legacy for all three of these, right? I mean, definitely New Horizons, which you are a deputy project scientist for, but also for TESS. That's right. These instruments all have a lot of heritage from past missions. There's 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 role on New Horizons as it does on Lucy doing optical navigation and really our highest resolution imaging. And then Lattes has heritage from OSIRIS-REx. And there's also a variant of the Ralph instrument on OSIRIS-REx called OVIIRS, 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 that we get the data that we need when we go to the Trojans. 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 the much more recent, more distant object. 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 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 got to get to Donald Johansson, our main belt asteroid in 2025. So you have to have a lot of patience to be exploring the outer solar system.

Ain't that the truth. 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. Wow. So a lot of this time is spent just getting from one target to the other. And it's the velocity, obviously, that allows us to do that. But that means that the encounters don't last very long. Yeah. You could do a mission like this with electro-pulsion, and that most certainly has been looked at. The trajectory that we're able to find for Lucy to do it without electro-pulsion, though, is really an amazing trajectory with our three Earth gravity assists, five deep space maneuvers, and as you see on our website, how we're kind of zigzagging across the solar system, if you will. It's quite a dance, really. 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 a heliocentric trajectory right off the launch we never orbit the earth at all we do an earth gravity assist about a year later that 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 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 hit these different swarms, but we will be the furthest out solar-powered mission. So we'll actually be going out past Jupiter's orbit, so past Juno's. we'll be the furthest out solar mission that's ever been flown.

So that explains the humongous, the two circular solar panels that you'll be unfolding once you're up there? Yes, we have 7.2 meter diameter ultraflex arrays, which will also be the largest ones ever flown. The ones in the crew resupply vehicle from north of Grumman are only 3.7 meters in diameter, and the Phoenix and InSight ones are only a little over 2 meters in diameter. So ours will be the largest ones ever flown, and 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.

These things are really huge. The spacecraft from tip to tip is 50 feet when the solar arrays get it deployed. It's really remarkable because when I was looking at one of the artist concepts, it looked like it was all solar panel and there was the spacecraft way down below. They really dwarf the spacecraft. And I guess being able to see that this has been accomplished by spacecraft like Juno that far out must be encouraging. Yeah, we're definitely pulling from some of the same power management strategies that Juno had used with different length 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 Juno. 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? Absolutely fair. This mission, first of all, is designed to help us understand how the outer planets formed, right? The study of asteroids in the main belt has allowed us to understand how the terrestrial planets and rocky planets formed. So this is, again, another step out that will concentrate on the giant planets. But it's also going to tell us a lot about how the Earth formed, right?

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 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 their 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 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 formed. Another aspect of this mission that I think is very important is that there are theories for the formation of the Earth, which suggest that it formed dry, and that the volatiles and organics 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. Now, would you include comets in that as well? I would. Okay. 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. And the way that works is that the Nice model hypothesizes that the four giant planets formed in a much more compact configuration than we see them today. So Jupiter is a five astronomical units.

Currently, Neptune is a 30. And the Nice 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. Uranus and Neptune out to near their current orbits, and the dynamical interaction between the planets and that planetesimal disk 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 Trojan should be remnants of that disk. 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 NIS model is that that disk I was talking about, the objects in that disk formed at a range of heliocentric distances, therefore at a range of temperatures. And so one of the hypotheses we're going to check is whether the diversity that we see in the Trojans are due to the fact that this disk had members in it with very different formation temperatures. Kathy, anything to add? 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. 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 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. all these bodies is really going to inform our understanding of the solar system. 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? 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's point of view, overturn these ideas that we've been developing over the last 20 years would be more interesting and more fun than confirming that they're true. 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. Kathy, 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 how will you complement each other in what they learn about this very strange object that they'll be visiting that may be entirely made of metal? 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. 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 two planetary spacecraft in development at the same time that are discovery class. 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 that 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, it went through a lot of the same processes that the Earth did, and the mantle got blown off in some kind of impact, we 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 these small body missions. 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 this one as the Deputy Project Systems Engineer? Well, so the role of the Project System Engineering team is to make sure that all elements of the mission are working together.

We are overseeing both the spacecraft development through the prime contractor of Lockheed Martin, the instrument development, which is a partnership of the SWERI, 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 our Atlas 5401, as well as our ground system and our navigation team, where Kinetics will be doing, will be 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 launch in October of 2021. Kathy 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 Kathy and I are the composers of, let's say, a symphony. What 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 Kathy and I conceived of. I really like that. I love that. That's delightful. That is an excellent analogy. How long has this mission been coming together? I mean, when did it first occur to, I assume to you, Hal, or maybe it was you, Kathy, as, gee, wouldn't it be great to visit the Trojan asteroids at Jupiter? 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 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 most recent Discovery AO came out in 2014, the one that we proposed the Lucy Mission, over the years, the 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. Yeah, something that comes up quite frequently on the show. 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 rich scientific return that we're going to have. So I'm really excited that this Lucy mission was selected. The trajectory that we have, this amazing ability to go to these diverse, interesting objects, and a number of them, is a matter of luck. And so the universe, the planets are aligning to 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. Do you think of it in terms of the Voyager missions, Voyager 1 and 2, and their grand

tours, which were also once inin-many-lifetime opportunities just because of the trajectory they were able to follow. I think it's an excellent analogy. And I just hope that we can have the impact that they did. 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 orbit as Jupiter, but quite separate from it. I've just got one more question. Why Lucy? Why that name? Well, Kathy was actually one of the developers of the name, so I'll let her answer that.

The Lucy mission is named after the Australopithecus fossil 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 we're 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 Johansson, who was one of the discoverers of the Lucy fossil. It's going to be very exciting to take the Lucy spacecraft past the asteroid Donald Johansson. 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 in 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, its 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 Kathy and Hal and all the other scientists can get their work done.

Most certainly. It was a pleasure. Thank you. Thank you very much, Matt. Our guests have been the principal investigator for the Lucy mission to the Trojan asteroids of Jupiter, Hal Levison, like the deputy PI, Kathy 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 Sekerik, 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 get back to doing trivia contests,

which we now will answer the question that we gave a couple of weeks ago, but that's still to come. Welcome. Thank you, Matt. 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. 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, Eta Aquarius 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 lineup 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 in the pre-dawn is bright Jupiter. So a lot to look at. Don't feel bad for the southern hemisphere. They've got the Southern Cross. They've got the Magellanic clouds. All right, we move on to this week in space history. In 1990, amazingly, 29 years ago, Hubble Space Telescope was deployed. Amazing.

Still working, making the universe beautiful and scientifically cool. We move on to... Space Fact. move on to space fact well i thought that motor wasn't going to turn over for a moment there so pluto our friend pluto its orbit is quite non-circular quite elliptical how elliptical is it well if you you gotta stick with me on this 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. Wow. That's a lot.

There it is. We didn't have to wait long for that. That's a lot. There it is. We didn't have to wait long for that. 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,

Quarararara, Sedna, Orcus, and the soon-to-be-named 2007 OR-10. How'd we do? 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.

Cool. Not only a poem, it got all the key points. It's the Samuel Ocean Telescope at the Palomar Observatory. That, according to our winner, James Shields of Scarborough, Maine. Congratulations, James. I think he's a first-time winner, and he has picked himself up a 200 200 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 there'll be a few of those flying around next week outside of Washington, D.C. More about that in a moment. We also got this from Jordan Tickton.

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. He dedicated his wealth to building low-cost housing in conjunction with the federal government until his retirement. So good on you, Samuel. Nice. Good facts. 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 slash radio contest. 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 and I will be on stage to do another live version of Planetary Radio Live and What's Up. And we'll have a, I bet, won't we have a live trivia contest for people who join us there at the University of Maryland. Exactly. And we'll have asteroid experts and NASA's chief scientist and the Planetary Society's chief scientist.

It'll be great. It's going to be great fun. And you are the overall host. So I will follow your lead, sir. It's the first time for everything. your lead, sir. It's the first time for everything. For this one,

you again will have a chance to win yourself a Planetary Society rubber asteroid and a 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. Telescopes.

Rubber telescopes. The best kind. Deformable mirrors built in. All right. A little adaptive optics humor. Very well done. We're done. All right, everybody, go out there, look up the night sky and think about how

non-circular you are. Thank you, and good night. 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, California, and is made possible by its grand voyaging members. Mary Liz Bender is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser. I'm Matt Kaplan, Ad Astra.