 I know there's these quirky things about zoom and we're talking about that earlier we. It's confusing sometimes. Then they fix one thing and then they mess up something else. That's right you get used to it one way and then they change it. It's like a class. One from Colorado. I'm in Colorado now. Clark Colorado where's Clark. I'm not sure where Clark is. Kansas City. Hello. Yeah. We were just having a chat right beforehand. We're comparing smoke and weather patterns around the country. Since we're in all certain, we're in three different spots today. Hopefully this guy's are a little less smoky and nice and clear for you all. I'm about to get some wet weather myself, but at least it gets the smoke out. So. I'm in Northern. Yep. It's pretty smoky here outside of Boulder. Oh yeah. I can bet. Oh, someone from lowland. Yeah, that's not far from here. Well, that big fire up in the Dixie fire is now well over 600,000 acres, which is. It's crazy. And it's pretty much burned about a third of. Lassen National Park. And so our good friend. Kevin. Sweeney. Who. Has run the Lassen dark sky festival. And so he's been dealing more with. Smoke and fire issues then with doing some of the interpret interpretive things. Was he a dark sky ranger? One of the. He was dark sky. He was one of the, he went through the sky rangers program once upon a time. I shouldn't say it was. Cause you always are. If you've got once a dark. Once a ranger always a ranger. You know, you know, You know, I'm sure for the national parks and possibly for Babylon five. Seven o'clock. Oh, good luck with the tornado and tornado and severe storm warnings. Sue. Yeah, where are you at, Sue? I heard that there were some in Pennsylvania earlier with the. Kind of the remnants of. Friend. Well, let's go ahead and get started. Okay. So, August NASA night sky network member webinar. We're hosting tonight's webinar from I'm in San Francisco, California at the astronomical society of the Pacific. And we have Dave and basically almost Canada. And in way up in New York. And we've got Kathy from Boulder, Colorado. We're very excited to present this webinar with our guest speaker, Dr. Kathy all can the deputy principal investigator for NASA's night sky network. Welcome to everyone on YouTube for we're very happy to have you with us. These webinars are monthly events for members of the night sky network for more information about the NASA night sky network and the astronomical society of the Pacific. And just a couple of moments. I'll put some links into the chat. But before we introduce Kathy, here's Dave prosper with just a couple of announcements. My announcements are a little stuff tonight. So I'm going to try and get through this pretty quickly and clearly because I want to focus on the Lucy mission to the Trojan asteroids. And I'm assuming everyone else who does too. So first I got a fun item for everyone just a hint. I just sent out the request to get our pins formally. Designed and manufactured. So the hint is the design this year may feature everyone's favorite rover helicopter duo. But that's not official official until I get the final stamp pin. So look for official announcements in next month's newsletter. Just a reminder, we bumped up some of the dates on the pins when we did the date change last year. So I'm hoping to have them available for order for you all by September, October. So I'm getting them out to you right after that. So more to come with that next newsletter. And we also have a big giant astronomy survey. We want you all to take. You may have already heard about it from us or someone else. But please, we would love if you have not taken us yet to take it and share it with anyone who might be interested. It's about 10 to 15 minutes of your time, but it is time well spent because this is a sort of a state of amateur astronomy in 2021 survey. And it'll inform our next few years of planning with the public and basically means we want to help better serve your club's needs. And to make that happen. We want to know what you think and the survey is a great way to do that. And I'll stop talking about the survey and put the link in the chat so you can take it later. Hopefully enjoy the talk now. And it is also at a bit.ly slash astro survey 2021. I want to hear from the people who aren't interested in taking it there. Actually might be more important than all of you who are enthusiastic users of the night sky network. Actually, that'd be great. Send it to some folks that may have a drop from your club, but you're still hanging out with. Maybe you get to know. That's not the survey. So it's not awkward. Oh, just a quick reminder too. If you're going to be posting any moon related events on October, post them to the end of your NSN club calendar soon. Because international observe the moon night is coming on October 16th this year. And if your club posts any public events in the NSN calendar between October 8th and 24th with the word moon anywhere in the title, you'll have your events synced up with the event calendar for the international observe the moon night folks and their setup. So you got to do this by September 1st to qualify for a packet of fun moon related outreach materials to be sent to your club. So that's why you need you to submit the events by September 1st to give us time to ship these goodies to you for your October events. And if you don't want your events synced just don't put moon in the title or make it a club or private event only in that will skip the same process. The last thing. I may be seeing many of you at this, which is Alcon virtual, which starts tomorrow. And it's free. It runs through Saturday and has some really excellent guest speakers and topics and guests like you and me. And you can join them for free on their streams at Alcon virtual.org. And that is all from me. Back to you, Brian. All right, thanks, Dave. So for those of you on zoom, you can find the chat window and please make sure that you go down to the bottom and zoom fix it. It now says everyone. If you've done an update lately, it now will say everyone instead of all attendees and and panelists. And so make sure you select everyone so that everyone can see your greeting. You'll also find the Q&A window. If you scroll down at usually on the bottom edge of your zoom window on your desktop, that's where we want you to put all the questions that you have for Kathy during her presentation and then we'll have time at the end that we'll be able to get to those. If you do have any technical difficulties, you can drop something into the chat or you can always send us an email at night sky info at astro society.org. And so with that, let me. Start my. Okay, I want to welcome everyone again to the August webinar of the NASA night sky network. This month we welcome Dr. Kathy Olken to our webinar. Dr. Olken is a planetary scientist at Southwest Research Institute in Boulder, Colorado. Her main topic of research is the outer solar system, specifically planetary atmospheres and surfaces. She carries out ground based observations to learn about the size and atmospheres of small worlds. She's worked on the NASA's New Horizons mission as the lead of one of the scientific instruments, the color camera and the composition mapper. NASA's New Horizons mission provided us with the first close up images of Pluto and its moons in 2015. In 2019, the New Horizons spacecraft made the most distance encounter of any solar system object, Aracoff, and I probably didn't pronounce that right. Kathy is also the deputy principal investigator for NASA's Lucy mission. The Lucy mission will be the first spacecraft to visit the Trojan asteroids, asteroids that share an orbit with Jupiter. In her free time, Kathy mentors first robotics programs, which I know many of you have done that as well. And so robotics programs are great, providing hands on STEM education for students from fourth to 12th grade. And so having judged some first competitions, it's a lot of fun. And I'm sure that Kathy's had a very rich, very rich experience with that. So please welcome Dr. Kathy Alkin. Hi everyone. I'm delighted to be here today and tell you about the Lucy mission. So let me show you some slides about Lucy. Looks great. Thank you. All right. So today I'm going to tell you about NASA's Lucy mission. This is the first mission to the Trojan asteroids. So we've never sent a spacecraft to the Trojan asteroids before. And this is going to be a first. So I can't wait to get there and see what these objects look like. First, a little overview. Lucy is a Trojan tour. It's a robotic spacecraft that travels out to the Trojan asteroids. And we're going to fly by seven different Trojan asteroids through the years 2027 to 2033. We actually are going to launch in October of this year. The spacecraft is down in Florida at Cape Canaveral, getting processed right now and getting ready for launch. And it takes a long time to get to the outer solar system. And on our way out there, we're going to do a rehearsal at a main belt asteroid in 2025. So that's what we have coming up. We're going to fly by these objects and learn about them. As we go, and I'm going to tell you some about the motivation and what we'll be learning about these Trojan asteroids. And I should say here for those who are maybe not familiar with Trojan asteroids that in this top down view of the solar system, you see the sun in the middle. And then the inner planets and Jupiter is the outer kind of circle. The green dots are the Trojan asteroids. They are in two swarms, one that's ahead of Jupiter in its orbit and one that's behind Jupiter in its orbit. These are the L four and L five Lagrange points of Jupiter. And these are stable zones. So if you put an object there, it will stay there. And there's other Trojan asteroids as well. The outer planets like Neptune have known Trojan asteroids, but this mission is going to the Jupiter Trojan asteroids. So the science motivation is really kind of two fold. The first one is to boldly go where no one has gone before. We, as I said before, we've never seen one of these objects close up. And we really want to understand what they look like and what their properties are. And part of the reason we want to understand that is because these are the leftovers, the remnants from solar system formation. They're near neighbors would have, might have gone into making up the giant planets. And so we want to look at these objects to really understand what these building blocks of solar system formation were composed of. And the Trojan asteroids are really interesting population because they're not homogeneous. As you saw it in the last figure, they're located in a very confined area in the solar system right now. But we think that might not have always been the case. And they have a pretty significant variety of albedo or the reflected light from the surface. Here at the, and the bottom left, you see the visible albedo versus a three micron wise mission albedo. And the albedo is really range from four to 15%. And then if you look at their spectral slope, so this is an indication of color in the visible. There's two specific. It's a two different populations, a red population and a less red population. And so it's not just a random distribution. It's two distinct populations. Also, in not being a homogeneous population, they have different spectral types. The different spectral types really tell you about the spectrum as a function of wavelength from about 0.45 microns out to 2.45 microns. This is a region from the visible into the near infrared. And there's a taxonomic classification system. There's been a number of them. One of them is by bus and the Mayo. And this classification system basically is a way to look at the surface properties. And they have different reflectance as a function of wavelength. As you can see over in the left here, there's C types and D types and P types. And they have different slopes in the spectral range. And we have those three types of asteroids present in the Trojan swarms that I showed you before. And you could imagine perhaps if the Trojan asteroids formed in the location they're at today and had their whole existence there, they would have formed out of the same materials. And they would have been processed in the same way. So you would expect them to be more homogeneous. And instead we see these different spectral types. We see, and the different spectral types depend on what size the objects are. So in the 20 to 50 kilometer size range, you have mostly P's and D's with a little bit of C's. And in the 50 to 100 kilometer size range, you have mainly D type asteroids. And in the greater than 100 kilometer, it's P's and D's. And these are basically telling you about the different surface features on the surface composition on the Trojan asteroids. And this diversity is really the result of accretion and the evolution in the outer planets. There's theories that the outer solar, the solar system as it was forming that the giant planets migrated outward away from the sun. And they reached a resonance, a two to one resonance where Jupiter would go around the sun twice for every one time that Saturn went around the sun. And this resonance caused a chaotic disruption of the small body populations in the solar system and would have ejected some small objects away from our solar system and some from the outer solar system into the inner solar system. And that's one possible explanation for how the Trojans became located where they are today. And so one of the goals of the Lucy mission is really to understand the diversity of these Trojan asteroids so that we can learn about their history. And these are the targets that we're going to go to in order to learn about the diversity of these objects. We have five objects in the L4 swarm. That's the one that leads Jupiter in its orbit. And two in the L5 swarm. I'll tell you a little bit more about these objects, but you can see the color. So first of all, I'll say that these are artist's conceptions of what the asteroids look like. We don't have anywhere near this level of surface detail about what the Trojan asteroids look like. That's why we need to send the Lucy spacecraft there so that we can see how many craters on the surface, what does the geology look like, and what kind of variation in the surface color and composition exists. We do know that Lucas and Oris are both D type asteroids. Remember I showed you the spectral types before. They are more red than the other objects in our sample that we'll be visiting. And then there's P type or kind of primitive objects. And that is patroclus, menaceus, and our small object, polymaly. And then there's urabates in its small satellite, Keta. So urabates is a pretty interesting object. This is going to be the first one we fly past. And it is a remnant from a previous collision. We can look at the orbits of Trojan asteroids and also main-belt asteroids and identify families. Families are a group of asteroids that used to be one object that was then disrupted, and those pieces didn't coalesce back together, but went on their own independent orbits. And so from the orbital elements, you can look and understand which asteroids had this history, was a collisional family. And the only collisional family in the Trojan asteroids is the urabates family. It's named after the largest remnant from that disruption, the one that we're going to visit. And here is a simulation of what that disruption might look like. And you can see the, how the objects coalesce in the rightmost panel. So that's going to be a very interesting object to go visit. And then I want to call attention to Patroclus and Manecius. This is a really interesting pair of objects. They orbit each other. So they orbit a common center of mass between the two of them. And you can see the animation of the objects. Which is once again an artist conception of what the objects would look like going about their common center of mass. And the scale of the size of Patroclus and Manecius relative to its orbit is correct in this animation. And I really wanted to point out the little inset box here that says Hubble Space Telescope, HST on the right, because that's a little bit different. The inset box here that says Hubble Space Telescope, HST on the right, because that's what the data looks like that we have on these objects. So when I said before that these are artist conceptions, you can see how much liberty was taken in showing you what these objects might look like from what we really know. As you can see from the Hubble Space Telescope images. And I wanted to share, since this is the night sky network, I thought you would all like seeing the way that astronomical observations inform the mission planning. So we have made extensive use of ground based observations, particularly occultations and light curve data. So photometry from the ground. Looking to see how the light varies with time that we see from our Trojan asteroids. And right here I'm showing you one of our targets. It's called Lucas. It was one of the more red ones that I showed you previously. And before we started this campaign of stellar occultation observations, of which we've had five events that we've all observed. I'm showing you four of them here. We didn't have a good shape for what Lucas looked like. So we really wanted to understand that. And it was important to understand the shape of Lucas, because it's a very slow rotator rotates, takes about 400 hours for it to rotate on its axis. And as you do a planetary flyby, that means we're not going to see one side of Lucas as well. So to really understand the mass properties of Lucas, we need to get solid understanding of its shape from the start. So we've invested a lot in stellar occultation observations of Lucas. And like I said, also combining that with light curve data. And you can see these are stellar occultation light curve cords. So each line here is an observer in the path of the stellar occultation. So we're watching Lucas pass in front of the star. And you can see the dots on the lines, which are where the light dimmed out as Lucas was passing in front of the star. And if you can see really carefully, there are little ticks there that indicate the uncertainty in that time of where the light curve draw the flux from the combined light of Lucas and the star dropped to just the light from Lucas. And so we have all of these great cords. You can see this event, which was really well sampled here. And from this data, we're able to fit a shape model of Lucas. And this is on the right here is the shape model shown you from different views of what we believe Lucas looks like. And we could still get very surprised when we fly pass because this type of modeling only gives you convex shapes. So concavities, you really can't get from this retrieval method. And you can see the resolution of the facets that we have used to fit the data. And if any of you are interested, this is described in a paper by Matola et al. That was published in 2020 in the planetary science journal. And that is open access for anybody to read. And this data, the light curve coupled with the occultations allow us to estimate where Lucas's spin pole is. And so you can see a probability map here or a chi-squared map showing the likely location of the spin pole where you have the darker colors. So before this, we didn't know the axis that Lucas rotated around. So we're learning more and being able to constrain that better and getting a better shape all from astronomical observations. And I wanted to share some of these pictures with you. These are pictures from our team in the field. And two of the people who have been helping with our stellar occultation observations are night sky network members or coordinator Christopher Erickson and Roxanne. You can see them here. And I saw that they were online tonight listening to the webinar. So good to see you virtually. And they've been participating in our stellar occultation campaigns. Next I want to show you the trajectory of the spacecraft. We launched on October 16th, 2021 on an Atlas 5-401 from Launch Complex 41 at Cape Canaveral. And this is the type of rocket that we will be launching on. And we orbit in a one-year orbit about the sun and come back and do an Earth gravity assist just about a year later. And the actual exact details of our first Earth gravity assist depend very much on when we launch in our launch period. So this is a demonstration of what it would look like when we launch on the first day of our launch period. And we have a very sporty EGA. We're flying just 300 kilometers from the surface of the Earth. So under the space station, under many satellites. And so this will be a sporty flyby. And that allows us to increase our app helium. And we go out about twice as far away from the sun as we had been previously. You can see there. And now we're coming back closer to, we're going to come back towards the Earth. When we're at app helium, we actually do a burn that allows us to slow down. And this will increase our velocity when we fly by past the Earth at EGA too. Orbital mechanics are a funny thing the way things work. You slow down to go higher and it has lots of different implications. So we have a second Earth gravity assist in 2024. And this will allow us to boost our orbit all the way out to the Trojan asteroids. So now at this point, we're going about 34,000 miles per hour, which is about 19 times faster than a bullet. So we're really cruising by the Earth very fast. And then we do a flyby of a main belt asteroid. This is a small main belt asteroid. It's probably about five kilometers across. And we will fly by in 2025. And what we're doing at Donald Johansson, that's the name of the asteroid, is a rehearsal. We're going to be rehearsing for the Trojan asteroid flybys that are still there to come. We want to make sure that everything on the spacecraft works the way we expect. We've done many systems level tests here on the ground. We will do lots of tests in flight, but there's nothing like an actual flyby to test and make sure that we have got everything working the way that we want it. Donald Johansson is also an interesting scientific target as well. Remember, I told you that your babies was a collision family member. Well, Donald Johansson is as well. So this is a remnant from a previous collision. It will be very interesting to see what it looks like. And the last thing I'll tell you is that we were able to name Donald this asteroid. We named the asteroid after the discoverer of the Lucy fossil. This is an Australopithecus fossil that was formed that was found by Donald Johansson and his team back in 1974 in Ethiopia. And the Lucy fossil that you can see in the upper right of my slides, that is really transformed our understanding of the evolution of hominids. And just like the Lucy fossil transformed our understanding of human evolution, we plan to have the Lucy mission transform our understanding of solar system evolution. So we're going to fly by Donald Johansson. And from that, from there we go out to the L4 swarm. I'm only showing you selected objects in the L4 swarm, just the ones that we're going to fly by. So there's many other objects in the area. And even though I say there's many objects in the area, the area is very large. So we're not worried about hitting one accidentally. From here we get to fly by our first Trojan asteroid target. And this is your babies and it's small satellite KEDA. And we're going to fly by in 2027. So we've launched the mission in October of 2021. And it's going to take almost six years to get to the Trojan asteroids. So we have to be very patient to get there and exploring the outer solar system takes a lot of time. After your babies, just 30 days later, we fly past polemily. This is another one of our targets. It's one of our smaller targets. I'm excluding KEDA because we're targeting the fly by of these larger objects. And we're going to fly pretty close to polemily. We're going to fly about 600 miles away from most of our targets, but polemily is smaller. And so we'll be going closer, just 270 miles away, closest approach. And the reason we're doing that is so that we can kind of weigh the Trojan asteroid by measuring the Doppler shift of the spacecraft as it flies by. I'll tell you more about that in a little bit. Next, we fly past Lucas. And that's the one that I showed you the occultation light curves of. And about seven months later, we fly past Oris. And this is our last of the L4 Trojans. From Oris, we fly back and past the Earth again. We do another Earth gravity assist. And this Earth gravity assist sets up our aim point to get to Petroclas and Menecius. Petroclas and Menecius are the final targets in our prime mission. You can see them here. And that fly by occurs in 2033. So quite a long time from now, but it's going to be so exciting to see what these objects look like. And then from there, we just continue out and we continue circling in this manner. So we're going to go forward and then back out to the Trojan asteroids. And we'll be transmitting our data all along, but the Trojan, the Petroclas and Menecius data will be the last data that comes down in our prime mission. So now I want to turn and tell you a little bit about the hardware that we have. We have this beautiful spacecraft you see on the right. And it has on the top of it an instrument pointing back towards the spacecraft. And it has a large range of motion. Basically it can point down back towards the spacecraft. And then all the way over and towards the high gain antenna that you see here. And it has a small range of motion in the cross-track direction. So the way it can rock kind of towards one of the solar arrays, either one of them. And the scientific instrument, the scientific instruments mainly sit on this instrument pointing platform. We have a high resolution imager called LORI. And this is very similar to the LORI instrument on New Horizons that brought you the highest resolution images of Pluto. And next to LORI, we have two terminal tracking cameras. These cameras are part of our guidance navigation and control system. And they allow us to track the asteroid with the pointing platform. So to take images and then line up our instruments so that we're pointing at the Trojans the whole time we fly past. We're flying past at between six and nine kilometers per second. So that's very fast. If any of you have run a 10K race, that's like doing it in just a little bit over a second. Which is crazy. So we're going to fly by really fast and we need to keep our instruments targeted on the Trojans as we do that. La Tess is this instrument right here. And it's like a remote thermometer. It allows us to get the black body curve in the infrared, which allows us to determine the temperature of the surface of the Trojan asteroids. And we're interested in understanding the temperature at different times of day so that we can understand the properties to retain heat in the regolith on the asteroids. And then on the furthest right in our instrument pointing platform we have this big behemoth of an instrument here called the Ralph. It is a color camera and infrared imaging spectrometer and it's based on the Ralph instrument on New Horizons. So it'll be what gives us our color and composition information. And the radio science will be able to do a radio science experiment like I mentioned previously where we can look at the Doppler shift of the signal as the spacecraft lies by to get an estimate of the mass of our Trojan asteroids. So we're going to do a geology investigation and the geology is really going to provide data on the shape of the target. How many craters there are on the surface? And what are the characteristics of the surface? Do we see mass wasting or mass that's slumping downhill in a crater? What type of ridges do we see? And that can tell you about the internal structure on the Trojan asteroid. And all of these data that we're looking for from a geologic standpoint are diagnostic of the history of these targets. And here you just see three very different examples of small bodies in the outer solar system or in the solar system from a main belt asteroid to Comet to a small moon of Saturn. And this is a mosaic of the solar system. And this is a mosaic of the solar system. And this is a mosaic of asteroid images that was put together by Emily Lactawalla. And these are basically all the asteroids that we've flown by and have close up images of. And the asteroids are approximately to scale. And the surface brightness that you see for them is also to scale. So over here you can see Matilda and that is very dark. And Lutetia, that Rosetta flew by, the Rosetta mission flew by is much brighter. And our Trojan asteroid targets span the size from approximately Lutetia, which Petroclus amenaceus is about that size, down to the size of Dactyl, which is a small satellite of Aida. And Dactyl is about the same size as Keta, the satellite of your babies. So we're going to be spanning a wide range of sizes and really being able to look at very different objects across the Trojans. In surface composition, we're going to be looking at for clues to where the Trojan asteroids formed and what chemical processes might have affected them. So you can see this diagram here in the bottom left shows you the formation distance in AU, where an astronomical unit, one is the distance between the earth and the sun. And so you can see where Jupiter is here in Saturn and Uranus, Neptune and Pluto. This is the average Pluto distance because it has an elliptical orbit. And these molecules all here, you can see where they get retained or lost. And so it's a function of the size and where they formed. So we're going to be looking for things like water and CO2 and different molecules to understand the history of the Trojan asteroids. We'll also be able to investigate minerals on the surface like olivine, peroxine and serpentine. And that tells you something about their formation and whether they differentiated. You can see a differentiated body down here. And the way we do this is by taking spectra. We'll be taking spectra. We'll get visible images here out to about one micron and then we'll get spectra out to about a little bit past three and a half microns. And you can see all the different species or molecules that have absorption features in this wavelength range. And so this is how we're going to be looking for the fingerprints of these molecules in our spectra. And the reason they have these different dips and undulations in the spectra had to do with the modes of how the molecules move. You can see the vibrational modes in water and you can see three different modes shown here and each of them is diagnostic of a different wavelength. And when we look at the Trojan asteroids from the ground we see spectra that look like this. These are two different examples of a more red and less red Trojan asteroid. And they're feature list generally. There's some features out near three microns. But when we get up closer to the Trojan asteroids with Lucy we'll be able to look at smaller regions on the surface and that will allow us to look and not be swamped by the overall signature from across this whole object but we'll be able to see if there's differences in the surface composition across the object. And that's something that's not possible at all from the ground. And these are some examples from the Dawn mission looking at water exposure or organic materials and you can see where they can be mapped across the surface to understand how the geology and composition work together. Next I want to talk about satellites and rings. As I mentioned previously we discovered this small moon KEDA using the Hubble Space Telescope. And if we assume the same albedo or surface reflectance of asuripides we estimate that KEDA is about a little more than a kilometer across. So like I said before about the size of Dactyl. And we have a pretty decent orbit for KEDA even that we just discovered this small satellite. And maybe it's probably not surprising that Eurobates has a satellite. As I showed you before we believe that Eurobates is a member of a family forming collision and there are examples of how satellites could form in such collisions. In addition to being able to look at KEDA because we've discovered it well in advance we're going to be searching for satellites and even rings as we approach the Trojan asteroids with Lucy. So there may be more satellites waiting to be discovered. So here is the uncertainty in KEDA's orbit shown in red. And what you see here are two different plots of the Lucy trajectory in blue. One, the one on the left is looking down from the pole of the solar system. You're looking down and then the other is looking sideways. And you can see how the uncertainty in KEDA's orbit is quite large even though we have a pretty good orbit given it was just recently discovered and how faint it is relative to Eurobates. But we're going to be flying pretty close by but we won't hit it as you can see because over in the right panel we're going to be flying under this the location where it is at some point. It's going to be somewhere in this ellipse. So we're going to continue to improve our knowledge with more observations of KEDA so that we can shrink this uncertainty cloud. And I want to tell you a little bit about naming this small satellite because we discovered it we got to suggest a name and the Trojan asteroids are generally named after characters from Homer's epic poems. But given that there are only so many names in Homer's work the IAU has allowed that now we can name small Trojan asteroids after Olympic athletes. And so we've named KEDA after the first woman to ever light the Olympic torch and she did this at the 1968 Olympics in Mexico and her name is Enriqueta and her nickname is KEDA Basilio. And so we named the satellite after her and it was really very fitting because the character Eurobates in Homer's poems was a herald and the modern Olympics that role is reenacted with the lighting of the Olympic torch. So we really liked all that symbolism coming together. And we're also going to be measuring the mass of the Trojan asteroids using our high gain antenna which operates using just 100 watts of power and by carefully looking at the Doppler shift we'll be able to retrieve that mass we're going to get the mass to better than 25% for all of our targets much better for a number of them the larger ones will be pretty easy and using the imagery data that we have for shape we'll be able to determine the density and there's reasonably that perhaps the Trojans might be very under dense so maybe even less dense than water ice and to give you an idea how big the Lucy spacecraft is from tip to tip with the solar rays fully deployed it's 47 feet and that's about the size of a large semi tractor trailer these are the instruments on board the instrument pointing platform I showed you the CAD model before but I want to show you the real thing and this picture was taken at Lockheed in Littleton, Colorado you can see a person he's kneeling but to give you an idea for scale the person is here and so you can see the instrument pointing platform with all the instruments being prepared for the spacecraft and we do tests we test a lot of testing you want to fly as you test and test as you fly and so you can see a test a deployment test of the solar arrays so our solar arrays are furled up and very flattened they're only about four inches wide when they're fully closed up and we need this configuration for launch to fit in the bearing of the rocket and then we deploy the solar rays kind of like a Japanese fan and they unfurl and this was a test of that unfurling that took place and you can see all the metal structure in the lines supporting the solar rays that's because they weren't meant to deploy under one G of force so that is a structure used to offload that weight so that we can test on the ground before we get into orbit and I encourage you to follow the Lucy mission we have a Twitter channel and Facebook and Instagram and there's both the NASA website and the Lucy project website and this is our cartoon character of Lucy on her journey so please feel free to follow us and see what's going on with the Lucy mission and from here I'll stop and take your questions all right well that's really fantastic and so maybe we could go Dave's got the information in the chat so we might want to come back to a couple of the slides or maybe put that one back up later on so that people can see it so we've got some good questions here and so very early on when you're talking about the different planets and so Paul wonders does Earth have Trojan asteroids as well? So that's an interesting question in the Osiris-Rex mission the one that went to Bennu a sample and is bringing the sample back now they were searching for Trojan asteroids there are some objects that look like maybe they get captured for a short period in Trojan the Earth Trojan points but I don't think there's any long term known Earth Trojans well hopefully before too long we'll have our own Trojan JWST that's right that is true at Earth so there's more than just the L4 and L5 point there's other Lagrange points 1, 2 and 3 and so 1 and 2 could be used to put spacecraft in and that is where the JWST will be going which will be very exciting and the reason it goes there is because it's easier to do station keeping because it's a stability point Excellent Okay so John had a question and I'm going to have to see if I can understand this entirely I think that he's asking so we have the main belt asteroids and we have the Trojan asteroids and so he's asking about the percentage of Trojans maybe it has to do with the types does it match up with the numbers and the percentages in the main belt asteroid or what are the sheer numbers like you know what are we talking about how many Yeah so right now there's 9,000 known Trojan asteroids but we believe that there's hundreds of thousands of actual Trojan asteroids many of which we haven't discovered yet just from looking at size frequency distributions and projecting what should be out there I'm very much looking forward to the Vera Rubin Observatory coming online because many more Trojan asteroids and other small bodies in our solar system will be discovered with Vera Rubin when it's online and so the question about basically types of asteroids compared to the main belt you see a gradient in the main belt asteroids of spectral types and you'll see basically different you don't see the same types of Trojan asteroid distribution of spectral types as you do throughout the main belt so that one graphic that you showed with the little pie charts those would look significantly different for the main belt asteroids they would they'd look different for the main belt asteroids and they'd look different at the inner part of the main belt versus the outer part of the main belt okay because I was wondering and this was I guess my question is that I was looking at that and in the description that noted that the least common type that you had in the Trojan asteroids were the ones that we've actually sampled and so I was wondering if the compositional percentages held true there as well or is it that we're sampled the least prevalent types so a really good point is that we don't expect that we have any samples of the Trojan asteroids in our meteorite collection because they are generally constrained in those Lagrange points so they're not coming in and impacting the earth and so that's another reason to send the Lucy spacecraft there is because we don't have a sample from the Trojan asteroids in our meteorite collection and it is true that basically when you look you see a lot more sea types further in the asteroid in the asteroid belt okay great so Michael asked will the spacecraft be visible to amateur astronomers at any of the earth passes or particularly the closer one yes and I expect that at EGA1 that Lucy will be visible as it flies by we've got a large area and there's going to be a point in time when it will be in dark sky but still illuminated by the sun and I look forward to sharing that with the amateur community and the professional professional astronomer community as well because I think it would be really exciting to take a picture of Lucy flying by and also for us to go out and look I think it might be a visible sky object perhaps as well but as I said before the exact altitude and circumstances of our first earth gravity assist really depend on when we launch in the launch window the altitude goes up as we get later in the launch window so after we launch I can let people know alright thank you that was an interesting idea and so he wonders if the redness of the asteroids might be coming from the IO volcanoes or whether there's some sort of interaction that's going on there yeah that's an interesting question so IO is really far away the closest that Lucy gets to Jupiter is actually just after one of our earth gravity assist and that's one of those things that's hard to fathom it's just that Jupiter's orbit is very large and the Trojan asteroids are quite far away so they're associated with Jupiter because they share an orbit but they're nowhere near each other so the red color would not have to do with IO at all it could have to do with space weathering so over time you can perhaps get reddening but then some people have seen some evidence that things can get more blue over time with cosmic rays and irradiation so I think it really depends it's a combination of what materials you start with and then how you weather them impact from cosmic rays or solar radiation so there's a lot of interesting work still to done there so many questions that's right I love that though I mean that's the whole point of this when I was a kid in school I learned science from my books and so often I learned what we knew but not what we didn't know yet and I think it's just really important for all of us to keep in mind what we don't know and where all these questions are and because each question that we eventually get an answer to is going to spawn even more questions which is lovely so are you hoping for questions that you don't know that you have yet after Lucy gets out there oh I hope so I think that would be great I'd love to have a new set of questions I didn't even know to ask before there you go so speaking of questions so Paul asks what makes scientists think some of the asteroids were formed or affected by collisions so you know what kind of insight are you seeing yeah we see craters on the surfaces of many objects that we across the solar system you know the moon asteroids so I would expect that we would see craters on the Trojan asteroids and in fact we have a science objective to map the craters over two orders of magnitude in size and the reason we want to do this is so that we can understand the age of the surface by looking at the cratering rates you can get an idea of how young or old the surface is there's different models for how many craters you would expect to see over time at different parts of the solar system so craters are the remnants of an impact and if you have a large enough and energetic enough impact you're going to have catastrophic disruption and we can see evidence of disruption like that in these asteroid families so there's lots of interesting evidence for collisions throughout the solar system all right thank you so let's see we've got so we were wondering can you compare the lorry instrument on lucy to the one on new horizon and they're almost exactly the same they have the same aperture they have the same detector they they let's see with the lorry instrument on lucy we added redundant electronics and some some capacity to store the images so on new horizons the data from lorry go directly to the spacecraft on lucy they'll go on to a recorder that's part of the lorry instrument and then be transferred to the spacecraft but you know optically it's really the same and yeah so it's going to be great because lorry was great at Pluto well we certainly were delighted at all the images that we got back from there and so we've got to look forward to yeah and we'll be using the lorry instrument on lucy for optical navigation just like we did at Pluto excellent okay so steven notes or asks the density of quite a one gram per cubic centimeter and so are you indicating as ice or water what's the indication that you're thinking um well so I don't I'm not sure what the density of these objects will be but um some measurements of trojan asteroids and their densities based on binary systems that would lead you to believe that they'd be less dense than one gram per cc and so it'll be interesting to see what we find and there's a there tends to be a general trend across the solar system that things are less dense further out and so that'll be another indication perhaps of where these objects formed so let's see what we got here okay let's go up to this question and so rando asks will the spacecraft have thrusters to enable you to adjust the trajectory as it approaches the trojans it does we have a by prop system on the spacecraft and we can do large maneuvers like deep space maneuvers where they're much more uh velocity change and we can do small maneuvers we have smaller thrusters for that uh with and we have planned trajectory correction maneuver 30 days before we get to the trojan asteroids and then another one seven days before we get to the trojan asteroids so that we can hit that aim point that we're going for just right and so that's definitely part of our plan and that's why we need the optical navigation as well as the radiometric data type so we'll get through the deep space network okay so uh back to the lorry instrument then for just for a moment since you brought that up again and so um so we have a question so we can probably expect more detailed images of the trojans since lucy will be closer to them than it was to Pluto is that yes yes and and so uh the highest resolution uh that we have uh we have requirements for the science images that we plan to take to accomplish our science objectives and the highest resolution one is tied to that uh imaging the crater uh populations that I mentioned and so we expect to get 14 meter resolution so that we can map craters down to 70 meters in diameter you want to have multiple pixels per crater to be able to identify the crater and we're uh um conservative in saying we want five pixels across so so 14 meter resolution uh which is in fact uh higher resolution than uh new horizons okay we're going to go for two more questions here then we're going to call a good I apologize to those that were not quite getting to your questions so uh Cria asks um are the instruments on Juno completely powered by solar power how large is the solar array I know you showed us the graphic with the semi truck how does that compare with Juno since they're basically at the same distance from the sun yes so the solar arrays are 7.2 meters in diameter I don't know what the area comes to off the top of my head um I should look that up but you can you can get a rough idea from the 7.2 meters in diameter uh and uh the Juno uh spacecraft solar arrays are actually larger in area than the Lucy ones are uh um and that's because the Juno spacecraft uh needed more power than the Lucy spacecraft does um the Lucy spacecraft will be the furthest operating spacecraft from the sun um because we go a little bit further away than uh uh Juno is from the sun all right so last question here and so John it's a different John and so we've got about four different Johns that we've had questions today I should have numbered them all and we have more than four different Johns on the project too a very popular name so uh so this John says uh what happens to Lucy after 2033 or when the planned portion of the mission ends and and I think you had one graphic that kind of alluded to that but what's the what's the plan for data acquisition and things after that yeah so after that Lucy will continue on and it will sweep into the inner part of the solar system and then back out to the Trojan clouds over and over again the Trojan swarms and so uh you know I look forward to putting in an extended mission proposal 2033 and hopefully be able to continue doing uh science on the Trojan asteroids we put a plaque on the Lucy spacecraft um and that plaque is a plaque to our future selves you know how the pioneer and Voyager spacecraft had plaques because they're leaving the solar system and so you know some civilization not in our solar system could potentially find those space those plaques and read them well the Lucy spacecraft is going to stay in our solar system and rattle around for a very long time so we put a plaque on there for future explorers in space and uh quotes from many different poet laureates about uh basically what they would say to our future selves and uh so I think that's kind of a fun thing to think about Lucy being out there um yeah and I should mention that um so Lucy's named after the fossil the fossil is named after the song Lucy in the Sky with Diamonds and we actually have diamond on the spacecraft because one of the optical elements in the test instrument is a culture diamond it's a beam splitter for our uh interferometer and uh so we will be taking uh Lucy to the sky with diamonds oh very cool I love it all right so thank you everyone and thank you Kathy for joining us this evening and so you can look forward to our next webinar on Tuesday September 21st when Dr. Paul Abel will share with us NASA's plans for the dark mission here's another asteroid mission this one will demonstrate a potential of technique for actually changing the motion of one which would be kind of an important one for things that aren't stuck in a trojan um um you know position um we kind of want to know what to do with those at some point so also join us on Wednesday September 8th when Andrea Jones will return and help us prepare for this year's international observe the moon night all of these webinars you can find on the night sky network website in the outreach resources section and you can also find them on the night sky network YouTube channel so keep looking up and we will see you all next month so good night everyone bye everyone thank you thanks for joining us all and thank you