 to the September NASA Night Sky Network member webinar. We're hosting tonight's webinar from the Astronomical Society of the Pacific in San Francisco, California. We're very excited to welcome our guest speaker, Dr. Joseph Lazio from NASA Jet Propulsion Laboratory in Pasadena, California. Welcome to everyone joining us on YouTube. 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 Night Sky Network and the Astronomical Society of the Pacific, check the links in the chat. Before we introduce Joseph, here's Dave Prosper with just a few announcements. As I've unmuted myself. So just so you know, it's that time of year, we've got our first year of home report in our inboxes that turned out to be the star of Fomalhop, which reminds me that we should have the new Night Sky Notes out tomorrow and now you have a little hint about what it's about. We have been crushed with work and even though it's the technical deadline, I like to get it out a little earlier. So in case you didn't know, we make a monthly article called NASA's Night Sky Notes. It kind of like took the baton from NASA Space Place for their monthly article for Astronomy Club Newsletters and you can use it for yours for free. And of course, you could also edit out my excessive exclamation points if you so wish. I try to do that myself, but I'm a little too enthusiastic at times. Anyway, we link to these notes in our own newsletter every month, which you also get, it probably drawn here already. And sample articles are on our front page and you can find the latest edition and sign up for alerts when the new newsletter comes out and access our past archives at bit.ly slash Night Sky Notes and I'll put that link in the chat right there. Also, just so you know, we have another little announcement, but they're not ready to order yet, but they've just arrived, the Night Sky Network Outreach Pins for this year. And here's a little peek. I gotta turn off my auto focus to hopefully get a better view. Whoop, there we go. You can see that beautiful JWST mirror there. So yeah, we believe they should be ready. We already sort of accepted orders around sometime in October and we'll send it an announcement in the newsletter and in the special extra announcement as well, just to make sure you all know that it's time to order. And of course, just a reminder, of course to order the pins, you need to report on your events and make sure that they're already scheduled so you can report on them. And we needed at least five for 2022 for your club to qualify. And every club gets three free pins that does do the reporting. Extras will be a little extra. And we'll have the details of all that in October. Can't wait to tell you all about it. And yes, you must be at Night Sky Network Member Club to order the pins. And Vivian has another announcement for Eclipse Ambassadors. Vivian. Hi everyone, thanks Dave. Those pins are really beautiful. I'm excited about them. I just want to let you all know that we are recruiting for the Eclipse Ambassadors off the paths for the next two upcoming Eclipses in 2023 and 2024. It's a really fun program. You partner amateur astronomers with undergraduates and you can mentor them a little bit and get them to know about the astronomy community in your community. And then you'll be trained together to offer really wonderful outreach as you all already do, but we'll send you a big package of lots of materials. You can do all of the outreach before the Eclipses. You do not have to be anywhere in particular for the Eclipses themselves, of course, because we know many of you, hopefully will be traveling to the path at least for 2024. So we encourage you to sign up. I've got a link right here I'll put in the chat. And it's a pretty quick application just about 15 minutes and we will, we're selecting people right now for the pilot workshop that's happening in October. So if you'd like to get a head start and lots of great materials, a very cool NASA partner badge akin to the Solar System Ambassador badge, I think that you'll have a good time at it too. So I'm putting the link with lots more information in the chat. Thanks for letting me share it. All right, thanks Steve, thanks Vivian. For those of you on Zoom, you can find the chat window and the Q&A window in a button at the bottom edge of the Zoom window on your desktop. Please feel free to greet each other in the chat window or to let us know if you're having any technical difficulties. And as always, remember to select everyone in the chat window. Otherwise, the only people that see your greeting are those of us on your screen. Put all of your questions that you have for our speaker in the Q&A window. That helps us to not lose track of them. If you do have a technical issue, you can drop that into the chat or you can send us an email at nightskyinfo at astrossociety.org. And let me hit the record button here. If I can find it, there it is. So welcome to the September webinar of the NASA Night Sky Network. This month we welcome Dr. Joseph Lazio to our webinar. Joseph is the Interplanetary Network Directorate Scientist at the Jet Propulsion Laboratory, California Institute of Technology. He received his PhD from Cornell University, was a National Research Council Research Associate at the U.S. Naval Research Laboratory and was a radio astronomer on the staff of the Naval Research Lab before joining JPL. He's a project scientist for the Sun Radio Interferometer Space Experiment Mission and he has served, you know, I'm always amazed at all these missions. I swear that everyone decides what the acronym is gonna be before they name it and then they give it these long names, the sunrise mission. And he has served as project scientist for the Square Kilometer Array or SCA or maybe it's SCA, the Deputy Director of the Lunar University Network for Astrophysics Research, Lunar, part of the NASA Lunar Science Institute and the project scientist for the U.S. Virtual Astronomical Observatory. He also observes routinely with the world's premier ground-based radio telescopes including the expanded very large array, the very long baseline array and the Green Bank Telescope. So please welcome Dr. Joseph Lazido. Greetings, sound check, you can hear me? We can. Excellent, okay. Yes, thank you for that introduction. Gives me great pleasure to be here. Thanks for the invitation. And I will, this worked before, so it will work again. You should see my slides. So I'm gonna... And they're beautiful. Excellent. I'm going to describe to you the Deep Space Network, a portion of what you see here. It's always a pleasure and a privilege to talk about the Deep Space Network or the DSN. But I have the pleasure and privilege of talking about it. A lot of the credit, most of the credit, goes to the engineers and the technicians that are at the various complexes which you'll see momentarily or literally all around the world. They keep these antennas working 24 hours a day, seven days a week, 52 weeks a year and almost 60 years running. So it's a real credit to them in the field that I can actually talk about this to you. Okay, however, let me actually start by, there's this really neat mission called Lucy which is going to the so-called Trojan asteroids. This is a mission actually launched earlier this year. It's going to the Trojan asteroids which are a set of asteroids that are captured in orbits such that they're at the same orbit as Jupiter. They're either ahead of Jupiter or behind Jupiter in the orbit. And if you can see in sort of the upper right hand of this image, you can see a picture or a rendering of Jupiter to indicate that they are this. The motivation for this mission is that we think that these asteroids probably are some of the primordial remnants of what actually formed Jupiter and the other planets or the planets in the solar system. And so these are in some sense true primordial remnants of the solar system. The mission actually owes its name. It's named in the same sense as the Australopithecus fossil that was found in 1974. They both owe their name in some sense. Well, the Lucy mission owes its name to the sense that these primordial asteroids are thought to be remnants of early formation just as the skeleton, the Australopithecus skeleton is of our early ancestors. But then of course they both owe their name to a Beatles song. We earlier also saw a reference to the James Webb Space Telescope. So it is flying now. I hope you've all been ogling over the images much as those of us here at JPL have been really astounding. Of course, these are just the first look images in many cases. Once we start getting many deeper images and many more objects, it really is gonna help repostrates. The deep space network is three complexes of antennas spread about equidistant around the world. And if you imagine you can understand immediately or I hope understand intuitively why there are three complexes, if you imagine that you're at some, pick your favorite planet or pick your favorite place in the solar system, what you can see is as the world turns, you can always see one or more of these complexes. So that means essentially all the time we have one or more antennas that can send a command to a spacecraft or receive data from it. The bottom pictures show the complexes or pictures of the complexes you can see again that at each complex there are multiple antennas. Now, in fact, these pictures are, the pictures of the bottom are slightly out of date. Earlier this year, we welcomed one of the new antennas into the network. So this is one of the newest, this is the newest antenna that was welcomed into the network. It was constructed at the Madrid complex in Spain. The importance of this can be seen by the fact that the King of Spain actually showed up for the inauguration ceremony. And again, going back to my earlier statement, it's a real testament to the engineers and technicians in the field because of course this antenna was constructed largely during the pandemic. It was commissioned during the pandemic. So it made everything much more complex in terms of dealing with health and safety, but nonetheless, the teams brought it online. And in fact, it's being used. This is actually, we are in the process of constructing another antenna. This is now at the Goldstone complex, which is actually about sort of three hours over my shoulder or something. I did take a look. You can see the picture here is dated from July. I did take a look this afternoon at the picture. There's a webcam that we can watch the progress, the construction progress. You could barely tell that there was any difference. There's a little bit more of the foundation or upper level, so there's some gold. Actually, if you can see my cursor, there's a little bit of gold support structure that's been added here, gold colored support structure. But essentially there is another antenna that is being constructed. It'll come online in a couple more years. So we're constantly adding antenna, well, constantly, we are continuing to add antennas to the network in an effort to expand the capability and essentially enable more missions across NASA. Okay, and in fact, you can watch. So this is, in fact, you can sort of tell that this is an outdated view of, this is an outdated screenshot. So if I stop sharing and I now reshare, if you go to say to, whoops, share, well, you should now be able to see, oh, the wait, sorry, I've got to stop the screen and go to my web browser. What I hope you can actually see now is this is a real time view of NASA's Deep Space Network. This is DSN now. So in fact, if you just go after this clock, go to eyes.nasa.gov. You should be able to find the real time view of NASA's Deep Space Network. So again, I'm hoping that you are actually seeing my screen and you can actually see what antennas are operating currently, which ones are bringing down data from which spacecraft and on the right hand side of the panel, you can actually click on either the antenna or the mission to get more details. An important aspect of what this shows is that at each complex, there are multiple 34 meter diameter antennas. So those are the smaller ones and then there is one 70 meter antenna and you can see the importance of the 70 meter antennas right now as I'm talking as this webinar is going on. The 70 meter antenna out at Goldstone is sending commands to or receiving data from the Voyager 1 spacecraft. So if I now go back to the actual presentation, so again, now you should be back in seeing, I gotta get this out of my way. Wait, okay, that's, hang on a sec, technology works wonderfully when I get it to work, right? And, okay, just a quick confirmation, I'm back where I'm supposed to be, you're actually seeing the PowerPoint screenshot of a previous DSN now. That's what it looks like. Excellent, okay. Okay, so now the first question is, I just said 34 meters and 70 meters. Let's do a quick sort of, you don't have to shout out the answer, but what does 70 meters actually mean? So if you were just to pick ABC, note to yourself, it'll be on your honor type of thing. What does 70 meters actually mean? Well, 70 meters, to illustrate what 70 meters means, I put it in the context of a local Pasadena icon, the Rose Bowl. So what you can see here is that a 70 meter antenna is large enough to essentially play a football game, whatever flavor of football you favor in the dish itself. And the reason that these antennas are so large, even 34 meters, we think of as the small ones in the network, but they're still impressive sites. The spacecraft are distant, right? Voyager 1 is outside the solar system. And so the signals that we receive from the spacecraft are incredibly faint. In fact, one of those factoids is if you were to add up, how long would it take the Voyager 1 spacecraft, all of the power that we've ever received, you really couldn't run the refrigerator, the little light in your refrigerator, you couldn't run it for more than a second because the spacecraft signals are so faint, the amount of power that we are receiving on Earth is really small. And it takes these really big antennas to collect enough power to actually get the data or get the images back. In fact, it would be a completely different, I'm gonna talk of very high level. It's an entire engineering lecture or series of lectures describe the antennas. There's a lot of still cutting edge electronics and related aspects that go into one of these antennas. Okay, so now I've said deep space network is integral to enabling NASA space missions, space exploration of the solar system and beyond. Again, on your honor, how many missions do you think NASA, the deep space network is enabling to say this week? So we should queue up the Jeopardy music here, but the answer is, this is the current NASA deep space network mission suite. So these are all of the missions, if you were to look over the course of a week, you would, on average, see all of these missions showing up. Not all of them have the same amount of time and there are some interesting aspects like Voyager 2, you only see it because of where it's located in the sky. Those of us in the Northern Hemisphere can't actually see the location of Voyager 2, so it's only the Canberra complex. But essentially, in a typical week, the deep space network is enabling about three dozen missions. The other thing is, and I've sort of already given this part of the talk away, if you look in the upper left, of course, not all of these missions are inside the solar system. Voyager 1 and Voyager 2 are outside the solar system. New Horizons is currently what we say in the solar system, but it's headed out as well. It's on an escape trajectory, it's going, it'll never come back. So, I don't remember exactly how many years, but given enough time, New Horizons will also be outside the solar system. The other thing that, the other reason I really like this figure of, again, the kind of space exploration that deep space network enables. Well, so Voyager 1, Voyager 2 and New Horizons, they're on their way out of the solar system, they're outside the solar system. So they're kind of exploring nearby interstellar space. You can see the Mars armada in the upper right-hand corner. You can see various planets, but if you also look, for instance, sort of toward the bottom left, Tess, Chandra, JWST, XMM Newton, these are space telescopes. These are astrophysics, they're in some, actually with the exception of JWST and Gaia, they're all in more or less Earth orbit, but they're looking out into the universe. So they're one of the ways that we study the universe, and it's really a case of the DSN enabling everything from studying like LRO, which is at the moon, studying our local satellite to the most distant reaches of the universe. It's also a case that, although it's NASA's deep space network, in some sense it's enabling space exploration for all of humanity. So if you look at the Mars armada in the upper right, there's, for instance, MRO, the Mars Reconnaissance Orbiter, and I'm sure you're familiar with Curiosity and Perseverance Rovers, those are NASA missions, but Mars TGO, Mars Trace Gas Observer, that's a European mission. If you look in the lower left, the Gaia mission, this is essentially, this is one of these missions is rewriting the astronomy textbooks. It's a European mission. It's a European Space Agency mission. If you bounce back to the upper right, you see this mission that affectionately seems to be called MOM, the Mars Observer, Mars Orbiter Mission. That's an Indian Space Research Organization mission from the nation of India. You can also see in the sort of, again, part of the Mars armada, the Emirates Mars mission. So that's the Emirates, the United Arab Emirates. They've sent a mission to Mars that is orbiting Mars now and is using the deep space network. And in the lower right, I don't have the image or I don't have the icon in there yet, but KPLO is the Korean Pathfinder Lunar Orbiter from South Korea. It's their most recent mission and in fact it has launched and I can't remember if it's actually in lunar orbit now or not, but essentially, yes, it's NASA's deep space network, but in a very real sense, it's enabling exploration. Oh, and I forgot to mention, sorry, I forgot to mention. I'm now remembering Akutisaki, which is in the middle there. That's a mission around Venus that is from the Japanese Aerospace Exploration Agency or the Japanese Space Agency, as is on the far left, the Hayabusa-2 mission. So again, yes, it's NASA's deep space, but in some sense it's for all of humanity. We're really enabling space exploration and discovery for all of humanity. Okay, so that's deep space network. That's the standard description of it, what it does. It's integral for again, almost every image that you've ever seen from another planet in our solar system and some number of the astrophysical discoveries that you've heard about have come through one or more of antennas of the deep space network. Now, I said earlier that one of the, I've talked about delivering data, so it actually recovers the data from these various spacecraft or it receives the data. It also sends commands up. So I'd like to now switch to one of the science uses for the deep space network that is a standalone use and it's represented by the icon of the lower right, this thing called the GSSR. So you can imagine, if I can send a command, so I can send signals on a radio wave to a spacecraft somewhere in the solar system, I could also target other things in the solar system and in the case of a spacecraft, it receives the commands and it does something and then transmits it back. But if it's a natural object, say the moon or Venus or Mercury or Mars or an asteroid, the target will naturally reflect the signal and that's what we call radar. So in fact, the virtual antenna behind me or my virtual background is the 70 meter, I already referred to it, it's the 70 meter out at Goldstone. But one of its other uses is it's used in planetary radar. So we call it, when it's used for that, we call it the Goldstone Solar System radar. And it's been used actually to study Mercury, Venus, the moon, essentially all of the objects out to Saturn all of the major, all of the objects in the inner solar system with solid surfaces and then some of the major moons of both Jupiter and Saturn. And again, the idea is very similar. You send, instead of sending specific commands to a spacecraft, you target a natural body and you look for the reflection and then you study how the body reflects it to learn some science. Now, why would you wanna do this? So the Goldstone Solar System radar, there are actually three reasons that you'd wanna do this. One is just a science aspect. It's complex and costly to send a mission to say an asteroid or to another body in the solar system. If we can study it from the ground, it may be less expensive and we can get some good information and less. So in fact, the little animation that you see repeating to the left on the screen here, this is a Goldstone Solar System radar or Goldstone radar image of a near-Earth asteroid. And what you can tell is it's actually a sequence of movies so you can actually see this object rotating. You can get some sense of actually how big it is. And in fact, if you look at it, you watch, you see that the surface doesn't reflect uniformly. There are parts that are brighter and some parts that are dimmer. Like as the movie comes around, if you could see my cursor, like there's this little bright spot or bright wedge that shows up. So that's probably some kind of real structure, a cliff or something on this asteroid. We're actually getting some indication of what the structure of this, the surface features are on this asteroid from the ground without actually having to send a spacecraft there. The other reason that radar is important, so let me back up a couple of slides. I've talked about these various missions. All of these missions, these three missions here, Hayabusa II, Cyrus Rex and Dart, are missions to asteroids and Psyche, which is in the lower right. It hasn't, it was supposed to launch this year, but it's been delayed. It is also a mission to an asteroid. All of the targets for those missions were identified on the basis of radar observations. In fact, it was radar observations of the asteroid 16 Psyche, to which the Psyche mission is going to travel, that helped identify it as a promising target for study. And one reason for using radar to study these objects is just to understand, is it a good target? But the other reason is the orbit determination. So by lighting up an asteroid with radar, we get a very precise orbit determination and it's a precise enough determination that we can actually send a spacecraft to that target. In fact, the very first use of the precursor to what is today's Goldstone Solar System radar was to figure out how far away Venus is because in the very early days of space exploration, think late 50s, early 60s, we didn't actually know how many meters it was to Venus with enough precision that we could send a spacecraft to it. And once we did that, then we could send spacecraft all over the Solar System. The final reason for wanting to do radar, and this has kind of been one of the major reasons that the Goldstone radar has been operating over the past decade or so, is planetary defense. In the upper right, you can actually see what is really the contrail from an asteroid that hit the earth in 2013. So this was a relatively small asteroid. It was about 20 meters in diameter. And as you can sort of see from the contrail, it came in at a glancing blow. And I don't have a picture of it here, but a fragment of the asteroid was later recovered from a lake in Russia. So the earth is hit, in fact, all the time by these relatively small ones, small objects. We would like to, of course, understand their orbits well enough that we can predict what is the risk that they will hit us in the future. This particular object is interesting. It's a good lesson. It's sort of like if you're near an ocean and you start to see the ocean go out, recede, that may be an indication of tsunami and you should not follow the ocean, you should run for high ground. So if you see a contrail like this or a bright light and a contrail like this in the sky, don't rush for the windows to gaze because lots of people in Russia did that. And this asteroid, the subsequent shockwave blew out, some blew out windows across the trajectory, sent many, maybe hundreds of people to the hospital with various cuts from the flying glass. And ultimately it would cause something like $1.6 billion in worth of damage. So the radar system, one of the key targets is these asteroids in an effort to understand or determine their orbits precisely enough to then make predictions in the future. And in fact, just by illuminating one of these asteroids, we can often extend how far into the future we can predict its orbit two centuries. But again, let me focus in on the science. Here's an example of some of the science and why the power of doing ground-based radar with the Goldstone Solar System radar. This was an object you can see here, 2017, a DQ, I think six from a few years ago now. The press release that came out compared this asteroid to a Dungeon and Dragon die. You can see that it has very sharp, almost angular features or facets. And I'm not a geophysicist or a geologist, but how do you get an asteroid with these sharp features and how do they stay well-defined potentially over a cosmic time? My understanding is nobody actually understands why this asteroid looks the way it does. And yet here's the power of the radar by taking the sequence of images. And you can actually again see it rotate in this or see the effects of its rotation. You can actually just make, we don't understand how this object formed or why it survived like this. Ask very basic science question about these objects. Another, again, on your honor, what do you think are asteroids likely to have moons? Queue up jeopardy music and you've got a 50% chance. Well, the answer is in fact that asteroids do have moons. So let's see. So this particular nicely called 1998 QE2, you can see the little speck there as the, excuse me, as the movie continues. So that little bright spot that is moving toward the bottom of the image is a moon of this asteroid. And in fact, something like one in five, actually maybe it's one in six or seven, but somewhere in the neighborhood of 15 to 20% of all asteroids have moons. And most of them are detected from the radar properties. So when they light them up, it's like, oh, look, there's a second reflection, if you will. That's the moon and the power, I mean, part of it's just nobody kind of expected asteroids to have moons. Didn't think, well, do they have a strong enough gravity field to actually retain a moon? The other reason is a very basic celestial mechanics. If you have a moon, then you actually have a very powerful way of determining what the mass of the asteroid is. And in fact, one of the very basic questions of an asteroid is, are these like in some sense solid chunks of rock, or are they really just lots of little boulders that barely hold themselves together by their own gravity? And having the mass, having the mass determined from the orbit of a moon, it's one of the really the few ways that we can address that question. Okay, now the big news, so you're gonna hear a lot more about this asteroid Apophis, this sequence of images, this was taken earlier this year, or the sequence of radar images, and you might say, well, geez, this kind of doesn't look like much. It doesn't look that impressive. Apophis is a 380 meter diameter asteroid, and you're going to hear a lot about it, because on Friday, the 13th, in the year 2029, this asteroid is going to come really, really close to the Earth. So if you're in the right spot, I think the right spot is kind of in the middle of Atlantic, so maybe book your cruises now, but if you're in the right spot, this object will be a naked eye object, it certainly you'll be able to see with binoculars, and it will move across the sky. If you know what the geosynchronous belt of satellites are that orbit the Earth and provide a lot of our telecommunications infrastructure, it's going to come within the geosynchronous belt, so it's gonna come within something like 30,000 kilometers of the Earth. And you can see here, this sequence shows how it approaches, how its orbit is predicted to change as it goes by the Earth. All these little green, let me see if I can run this movie again, or this little animation again. So these are the opportunities, Goldstone is of course our workhorse radar, and then we have a second possible facility down in Canberra, so it's actually, it's a slightly less powerful, but still very useful. You can see these are all the opportunities to get looks at the asteroid. And part of the, among the questions are going to be things like just how much does the Earth change the orbit of the asteroid? Do we see because of the tides, this asteroid is gonna come close enough. We're going to get much better images than this. Does the surface feature change as a result of say the tides or essentially the side of the asteroid that's closer to the Earth is gonna be pulled a little bit more strongly to the one that's on the far side or the farther side of the asteroid. So are there essentially landslides on the asteroid? So this is gonna be a really big deal. You're gonna hear a lot about it. In fact, maybe you've already heard about it if you read the right British tabloids. And the reason that I can state with such confidence that it will not hit the Earth is that the sequence of radar images have now determined the position of the asteroid within 10 meters. So the room in which I'm sitting is something probably five meters in size or something like that. So this 300 meter, 380 meter asteroid, we know it's orbit to sort of a little bit bigger than the size of the room in which I'm sitting now. Or maybe if you're at home, a typical room might be say five to 10 meters, depending upon the size of the room in which you're sitting, you might be sitting in a room that's 10 meters. You can just sort of look around and say, we know the orbit of this asteroid because of these radar observations to something like 10 meters. And so we can predict with complete certainty, it will not hit the Earth in 2029. One of the other questions was, is it going to hit the Earth in 2036? Cause it does another pass by and the answer is no. So we can predict it decades and maybe even a century into the future if it will not hit the Earth. Nonetheless, you're gonna hear a lot about it. You're gonna hear a lot about it. And I'm sure that you will hear some from the British tablets as well. Okay, so I intentionally did not have a long presentation. I wanted to leave some time for other questions or conversation, but I've, please do not leave the Earth without the Deep Space Network. And I've also tried to give you a hint of the Deep Space Network is not only integral to the space exploration, but it's a science instrument in its own right by providing this unique information on solid bodies in the particularly inner solar system with a lot of emphasis on asteroids. And I now see something like a dozen questions queued up in the Q and A. So I'm happy to turn to Q and A. Yeah, we do have quite a few questions. And so thank you very much. This is a really great. So let's start off at the top. We had a couple of questions having to do with the Trojan asteroids and they're curious whether or not Earth has any Trojan asteroids and if we have given any thought to a mission to those? The Earth has, and I'm trying to remember if it's one permanent or one temporary Trojan asteroid, there's been at least one object that has been identified as an Earth Trojan. I think it's kind of not my field. And so I'm sort of, I'm hesitating to say much more other than I honestly don't remember if it's a big mystery of why the Earth doesn't have more Trojans or not. So I'd better leave it at, there's been one, I'm sure there's been one that's been identified as an Earth Trojan, or it has nowhere near the number as Jupiter. I could speculate that it has to do with just the various gravitational forces on Earth Trojans versus Jupiter Trojans, but I don't remember enough to say much more than that. I just wanted to note here too, is that over the last couple of years, we've had quite a few of these webinars have been with about asteroids and we had one on Dart, not particularly long ago and then a year ago in August, we had Kathy Alken, I think her name was, did one on the Lucy mission. And so you could go back into the Night Sky Network website and find some of those old webinars and learn more about these actually fascinating objects out there. And since you made reference to Dart, I didn't really highlight it, but yeah, Dart, the subtext of what the second title, the alternate title for Dart is Earth Strikes Back. And of course, one of the big targets for the Goldstone Solar System radar is going to be looking at the asteroid Dynamos after the impact to figure out what happened to its orbit. And so that's kind of another thing too, is that when you're talking about asteroids having moons, is that they're not actually hitting, they're actually going to smack it into the moon asteroid. And so that's actually a good question, is are you going to be monitoring that with the Deep Space Network radar-wise or just waiting for the data that comes back? Both. Both. So Dart, if I scroll back, you'll see that Dart was one of the missions that is enabled by the DSN. So it's actually retrieving data, but then it's also a target for the Goldstone radar. Okay, fantastic. So we had a question here and this is interesting. And so it has to do with the different comms signals and there's kind of three questions here, but let me see if I can combine them. And so the Deep Space Network, are you basically using a single frequency? Are there any interference problems and what do you do about, you're probably able to be listening to several different satellites or missions at the same time. And so what do you do about the interference and if it's on the same frequency or multiple frequencies? That's a great question. So the spacecraft, the various missions have, they do have well-defined frequencies and that's done intentionally to try to avoid them essentially interfering with each other. There's a bigger picture question, which is the range of frequencies that Deep Space spacecraft use is a particular band, which is agreed to by an international body called the International Telecommunications Union that sits under the United Nations. And that's done internationally to coordinate so that because these signals are so faint, we have to be very careful about somebody else at a different frequency, unintentionally broadcasting some of the power that they're transmitting at a different frequency could still spill into the bands that are used. So there's an issue of both interference and we try very hard and we coordinate internationally to avoid that. The spacecraft themselves have well-defined frequencies. Almost think of it as if you go to an FM or an AM radio dial, you step between various stations, you can think of an analogous feature for the spacecraft. Now, the interesting thing, I didn't really highlight it but it is, if I flip back to this, actually this one shows it. So if you're still seeing the display, this is again an out of date, but it shows at the time I took this screenshot, one of the antennas in Madrid was actually communicating with that's Mars Odyssey, Maven and the Mars Reconnaissance Orbiter simultaneously. So at Mars, and sort of it was tongue-in-cheek, the Mars Armada, but there are enough spacecraft at Mars that we've actually worked out with Deep Space Network, engineers have worked out a way that we can monitor multiple spacecraft at the moment it's up to four, monitor or receive the signals from four of them, up to four of them simultaneously. And in fact, actually you can see here, this would have been in a hand-off period. So probably Madrid was getting ready to hand off to Goldstone, these spacecraft were being tracked by Madrid, but you can see Goldstone was getting set up to do the same, including also the Mars Science Laboratory or Curiosity. So I hope that's answered the question of, yeah, well-defined frequencies, we try to ensure that nobody else interferes with us, they're well-defined so as to not to interfere with each other and then at Mars, because there are so many spacecraft, we can actually communicate with multiple ones. So that actually kind of brings up an interesting question is, are the signals encrypted at all? Is there the possibility that somebody could decide to construct their own antenna and grab the signals before you guys do or at the same time? They are certainly coded. So there's a whole literature and a whole field of how to encode the signals, certainly on the downlink. And this is more for error-checking purposes. So the signals are very faint. You wanna make sure that if, you wanna make sure that the data coming down, you've actually received it accurately. And so what is typically done, there are various ways to do this, of encoding in a way that you have not only the data, but then some amount of error-checking as well. And they're both ways to do that efficiently, but it's also just an error-checking of, yeah, I really did get down the signals that I thought I would get down just for an error-checking. And that's just from the basic, I'll gloss over some of the underlying physics, but there is some underlying physics that goes into, there's some amount of always noise in the system, you can't get rid of it. And so there's always the possibility that some bit will get flipped and something will look bad. So you always have some error-checking. That's just from the physics. More recently, there is an effort to encrypt the signals so that you can actually ensure, in some sense, security of the command. That if we send a command to the spacecraft, we know we're the ones sending it, not somebody else. Yeah, that seems like a wise thing. How about the data coming back? I mean, I know that scientists are interested in openness, but countries aren't necessarily interested in openness. And so is there, let's say if I decided that I wanted to construct an antenna in my backyard, could I tap into the signals myself? In principle, yes, but without knowing how they're encoded, I think, or you'd spend a fair amount of time trying to figure out how they exactly the coding and all of that kind of thing. So we also have a question, and does China or Russia use the deep space network? I know that they have fairly robust space programs of their own, or do they have their own networks that they use? They have their own networks with a certain number of similarities, but they have their own networks. As I should add, Europe has its own network, but we have a sharing agreement between NASA and ESA in which, or the European Space Agency, they can use our antennas, we can use theirs, and we keep track of sort of making sure that everybody's getting fair use. Japan has a much more limited, but it's the same arrangement. They can use our antennas, we can use its antennas, and there's not an official agreement that India has, at least one antenna, and there can be some cross-sharing there. So we had a couple of people as the question is, and so we're using the radar, is there any thoughts about using optical or laser type things to communicate with the spacecraft? Yes, in fact, one of the aspects is that the psyche mission, I talked about it from the science perspective of going to study an asteroid, where'd it go? There, I talked about it from the standpoint of the science. One of the technical demonstration aspect of psyche is that it is carrying a laser-com terminal, a laser communication terminal. So during, once psyche launches, as it's going to the asteroid, there will be a test part of the campaign or a test portion of its trajectory in which the onboard laser communication terminal will beam a laser signal back to Earth. And actually, this antenna here, this is the antenna that's being constructed at Goldstone, the idea is that an inner part of that antenna will be removed and replaced with mirrors, although the time scales don't quite work out, but the idea is to enable this in the future. Now, in practice, this is probably not something for the near term for these kind of deep space missions, Earth-orbiting missions, maybe missions to the moon, almost certainly you're gonna see a lot more laser communication because it can have higher data rates and lasers are not regulated the way radio is. So you can actually use it without having to work, there's much less fear of interference. And so you can use it with far fewer concerns about interfering with somebody else or somebody else interfering with you. So the advantage of that is that you'd be able to pull out your cell phone and tweet about something in proximity to the receiving antenna then. Yes, yes, yeah, because the receiving antenna, well, in fact, it's not on here. There was an earlier laser communication demo from a spacecraft orbiting the moon and the ground terminal, trying to remember there were multiple, the ground terminal was either 20 centimeters or 40 centimeters. So it's the ground terminal was something that, if you're an amateur astronomer or if you're no amateur astronomers, you may know amateur astronomers who have larger telescopes than was used in this earlier demonstration. The key thing is, of course, you probably don't have a near infrared detector that was such as what was used, but in terms of just raw glass or a mirror, it's something an amateur astronomer could easily construct or there may be amateur astronomers with telescopes today that could be used in laser com if they had the appropriate back-end detectors. So here was a question. It was asked very early on, have any repeater antennas been used either in Earth orbit or in solar orbit or all of these antennas are on the ground. You haven't put anything in space yet, right? Well, actually, that's an excellent question. I didn't touch on it. Most of the data, in fact, you see here the insight mission and what was the one before? Phoenix, was it Phoenix? Yeah. Most of the data from curiosity, insight, and perseverance doesn't actually come directly through the deep space network. They are relayed through MRO or through MAVEN. I'm trying to remember what Mars TGO does in many of this now, but essentially in Mars orbit, there are at least a couple of these orbiters that serve as both their science orbiters in their own right. So they do science observations, but then they also collect data from one or more of the ground-based assets, one of the rovers, and then relay it back to Earth. So it is being done at Mars. Again, at Mars, they're enough spacecraft and it's complicated enough and costly enough to put stuff on the surface of Mars that it warrants doing relays. It's a big topic going forward for the moon, but at the moment, Mars is the only place where this is really done in earnest. Okay. So, but there aren't any necessarily around Earth, and so it's the relay that, you know, because sometimes the rovers are on the opposite side so they can continue to communicate with something that's in orbit. Yeah. There seems to be questions keep coming up, some other additional questions come up about the directionality of the antennas and getting the signals from various projects simultaneously or various missions simultaneously. And so I know that you had that graphic that showed that you had four missions that you were talking to. And you had mentioned that, I think that they're on different frequencies, but do they stagger those at all so that the equipment is, so how does that work? Well, so the, if you, so first off, the antenna, if you think about what part of the sky the antennas can see, they can see enough of the sky that let me take the specific case of Mars. All of Mars and all of the spacecraft, all the orbiters around Mars are essentially in the same part of the sky as seen by the antenna. So the way it works is that connected to the antenna, you can think of it as there are four different receivers. So the signal comes in and then it's copied four different times. And each one is set to a frequency specific to the spacecraft that's being received. It's very much, again, the analogy would be if I go, if I could, I could take my car's antenna, car's FM or radio antenna, and I could actually connect four different receivers to it and have four different radio stations being received simultaneously because they're all broadcasting simultaneously. And it's just a matter of picking out using the appropriate frequency. Okay. Actually, because I talk about frequencies and sometimes radio frequencies, maybe another way to think about it is if I had four different lights, and say they're turning on and off, they're, in fact, they're coded. Suppose I'm using lights to send Morris code and one of them's blue and one of them's green and one of them's yellow and one of them's red. Well, our eyes can see those four different colors simultaneously, those four different wavelengths or there's four different frequencies simultaneously. Now, it might be a bit much for our brain to figure out, oh, here's the Morris code from these four different things simultaneously, but if I had a telescope that was looking at these four different lights, I could easily say, well, okay, you pick out the blue light, you figure out what the Morris code is from the blue light, you figure out what it is from the yellow, you figure out what one is from the red and you could do that simultaneously and that's what's happening. Okay. And I think that you just answered this question too, but let's toss it out there. And so a couple of people have alluded to the tracking of these objects and whether or not the antennas have to be pointed directly at them and or do the antennas continue? Because these objects, the missions are moving, they're not in a single point. And so do you end up having to track them and how close to perfect pointing do you have to be with the antennas for all these missions? Okay, so the simple answer is yes, they are tracked. So a typical DSN track might be four to six to eight hours. And if, again, if you have any experience with just a typical telescope, you know what, Saturn is now a night sky object, right? So go point your telescope at Saturn and if you don't continuously adjust, or you know if the motor on your telescope doesn't continually adjust, Saturn will drift out of the field of view. So these antennas have to track and for those who know the distinction, that also means they have to track non-siderially, they have to be able to track a planet as it moves instead of just the background stars. Now, I should know these numbers because I've been bouncing around the 70 meter antennas at our workhorse frequency, the blind pointing accuracy. So how well do you have to point it is at the level of something like five or seven million, that people, the engineers here use milli degrees, I'm more accustomed to arc minutes, but the blind pointing, what? Six, it's better, it's sort of what? If I'm doing the numbers correctly in my head, it's something better than an arc minute of blind pointing. So you just point the antenna and then it has to be able to track it, something like better than an arc minute all the time to enable to maintain continually pointing toward these spacecraft. Okay. So one contrast, and we'll probably just go for a couple more questions, but there's been a number of questions about this. And so contrast the strength of the signal that's coming in with the signal that you would then transmit in radar mode. And so what kind of signal strength are you sending out? What kind of signal strength can you detect coming back in? And so if we can kind of relate those two. Yeah, so let's see, there are kind of two answers to that. One simple answer is that so the Goldstone Solar System radar itself, the radar system, the transmitter that is attached to the 70 meter out of Goldstone DSS-14, that transmits at in round numbers, 440 kilowatts. So you can easily, go look at your electric bill. If we run the Goldstone transmitter for an hour, that's 440 kilowatt hours. And go look at how much, in fact, I worked this out once upon a time, how many houses would a typical radar track power? And it's many, you probably, I'm not blanking on, yeah, but go look at your electric bill and then sort of think about a kilowatt hour and think of the Goldstone transmitter as 450 kilowatt hours after it works for an hour. Oh, I'm sorry, go ahead. So the other part of the question though is, the signal goes out, these asteroids are still, they're distant, they're small bodies, they're not perfect reflectors. So the actual received power when the radar signal comes back is actually not that much different than the spacecraft signal. That's one of the reasons that we have to use these large antennas is precisely because the signals, whether it's from distant spacecraft or from the radar reflections, they're really faint, you know, they're measured in many, what, billions of a watt or some ungodly small number that these are really small power levels are being detected. All right, so we are at the top of the hour and so let's do one more question. And so I just kind of want to ask what's the, what's your favorite part about this? And so if you have a favorite memory or something that you particularly, I guess, cherish about, you know, working on the DSN and what's something in your mind that was really important that you were really delighted to have been involved with? I think there, I guess the two that stand, well, first off, you know, I'm just kind of an antenna geek. So I've actually been out to all three complexes at least once and I just get a thrill out of being, I mean, going into the antennas, you know, I've crawled up, I've crawled up to 70 meter at Canberra. And that's, you know, I just like, that's cool. And then we actually had some issues with the Goldstone Solar System radar over the past few years that have now been solved. But we had a period when it was off the air and bringing it back on air and just, you know, finally it's back at full power, it's operational and getting those first images. You know, it's like what I didn't touch on is now, there used to be the AeroCibo Observatory radar, that's now gone, duly departed. So the Goldstone Solar System radar is really the only thing the planet Earth has at the moment. And, you know, it's just been a real relief to see it continue to operate. Okay. Great. We'll go ahead and stop sharing if you, if you would. So that's all for tonight everyone. Thank you very much, Joseph, for joining us this evening. And thank you for tuning in. I'm very sorry that we didn't get to many of the questions that were in there, but we got to a lot of them. So we had a really engaged audience this evening. So you can find this webinar along with many others on the Night Sky Network website and the outreach resources section. Each webinar's page also features additional resources and activities. This presentation is also on the Night Sky Network YouTube channel. And if you're more interested in some of those expeditions or missions to some of the asteroids, you can check out some other webinars that happen to do with those. Thank you so much for joining us for our next webinar on Tuesday, October 18th when Jackie Faraday from the American Museum of Natural History will share with us how JWST will bring new discoveries and insights into low mass stars. So we're kind of going from, you know, human constructed things. Now we're going to go back to thinking about some other things that are out there. So keep looking up and we will see you next month and good night everyone. Thank you so much. Yeah, this is great. Thank you so much. Yeah, and actually I saw one question. I mean, if it's.