Ep. 697 – Mission Roll Call Part 6: Outer Solar System

Finally, we reach the end of our tour through the missions in the Solar System. Out beyond Mars, to Jupiter the Kuiper Belt and Beyond. Recorded live during the CosmoQuestX 2023 Hangout-a-Thon.


(This is an automatically generated transcript)

Fraser Cain [00:01:48] Astronomy Cast episode 697 Mission Roll Call part six The Outer Solar System and Beyond. Welcome to Astronomy Cast, our weekly facts based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. I’m Fraser Cain, I’m the publisher of university. With me, as always, is Doctor Pamela Gay, a senior scientist for the Planetary Science Institute and the director of Cosmic Quest. Hey, Pam, are you done? 

Pamela Gay [00:02:11] I am doing well. This is one of two very special episodes of Astronomy Cast that’s going out during the Cosmic Quest. Hang out. Atheism. We’re spending 32 hours, not contiguous. We’re going to sleep, trying to raise money to keep all of our programs going, all of our people fed. And we just want to give all that we create away for free. And I was a little slurred at ads than Fraser, so we have to beg right now. So thank you everyone who’s here and is enjoying everything we’re doing. We’re now going to get on and go strictly science and science. 

Fraser Cain [00:02:51] All right, let’s get into it. Finally, we reached the end of our tour through the missions in the solar system, out beyond Mars to Jupiter, the Kuiper Belt and beyond. So this is the final episode where we talk about all of the spacecraft that are in the solar system. We’ve reached Mars, and now we push out beyond Mars. And the first spacecraft that I guess we’ll reach is the one that actually dropped a bunch of news just a couple of days ago before we are recording this episode. And that’s Lucy. 

Pamela Gay [00:03:22] Lucy knocked all of our socks off. I, I’m Facebook friends with doctor Stuart Robbins at Southwest Research Institute, and I saw this like, I don’t know, supposed I don’t know what you call it. Where he’s like, okay, so Lucy’s going to have images tomorrow and, and then just facial expressions in, in emoji. I’m paraphrasing terribly. And I was like, okay, so something’s coming. Something’s coming. I rearranged our news plans for this week to make sure there was space, and I was expecting it to be like another rubble pile dog bone. Just some weird shape. But no, no rubble pile for us. But instead, we got two asteroids. The main asteroid dink smash. Am I saying this halfway right? 

Fraser Cain [00:04:26] I think that’s right, dink. I always think Dinklage, but, you know, one is an actor in Game of Thrones. The other is the name of an asteroid with deep cultural heritage. 

Pamela Gay [00:04:35] So, exactly. 

Fraser Cain [00:04:36] Think missions, right? 

Pamela Gay [00:04:38] Most people call it dinky. 

Fraser Cain [00:04:40] Dinky? Sure. 

Pamela Gay [00:04:42] All right. 

Fraser Cain [00:04:42] What do you call the moon? Like if dinky is the main asteroid. Dinky moon. That makes sense. All right. Yeah. 

Pamela Gay [00:04:47] So? So dinky is about 700m across. It’s a bit bigger than Bennu. And they just. They noticed that the variations in brightness were more than they were expecting. We know it varied in brightness. This was thought previously to just be its rotation rate. But the variation have them thinking, well, what if this is actually a binary system? And sure enough, there’s a 220 meter companion. And during closest approach image, they got this wonderful suite of the bigger one in the foreground and the smaller one just slightly peeking out. Well, it’s just slightly overlapping with the foreground one. So you have this great perspective of just how closely they’re orbiting each other. And, I love just how much we’re finding. No one really likes to be alone in space. Yeah. It’s planets. Yeah. Things grew up. 

Fraser Cain [00:05:48] And, like, the question is starting to be like, how do you get these things? Are you are you getting are they spinning up because like, back to Dimorphos and Didymus, which the dart mission slammed into, into Dimorphos, like it’s really starting to look like Dimorphos is a piece of mass that some event causes an asteroid to spin. Maybe the your you know, the interactions with the sunlight makes them spin faster and faster, and then chunks start to shred off. And we saw even with with Bennu, it was spinning at pretty much the maximum speed that there are rocks that were lifting off of Bennu going into orbit and then finding their way to more northern or southern latitudes, and then being attracted again and landing on the surface. And then, in fact, that asteroid is shedding material at its equator and then pulling it back in to the northern and southern parts of the of the asteroid. So, like this dynamic is really fascinating. And you sort of wonder we can see more and more of this. I mean, I think we’re up to 11 objects seen or that Lucy will visit known so far with many of the objects having additional moons are they all can have moons. 

Pamela Gay [00:06:58] And they only thought they were going to see nine. 

Fraser Cain [00:07:01] Yeah. They’re really. Yeah, exactly. And now we’re up to left. Are they all going to have moons? 

Pamela Gay [00:07:05] Yes, please. 

Fraser Cain [00:07:06] Yes, please. Yeah, exactly. All right. Now, I actually don’t know where this spacecraft is, but let’s talk about juice. 

Pamela Gay [00:07:16] Juice is on it, and this is going to come up a bunch during this mission because, like, you would think, Lucy, in the asteroid belt, going to Jupiter is like straight line in it, but no, Lucy’s going to turn around, come back. The next thing it’s going to see is us. Well, maybe not us, but our planet. And then it’s going to head back out after a gravitational assist. So these outer solar system missions in you pull up NASA eyes on the skies, which, if I did right now, would destroy our streaming set up. Yeah. You can’t keep track of where they are. And juice is on its way to Jupiter. And and so this this is yet another of what will be many on its way, but not quite there yet. Missions in the outer solar system. Because we finally realized these things need to be visited. Yes, but things haven’t got there yet. 

Fraser Cain [00:08:16] Yeah. And I mean, juice is great. I, I am really excited about juice. I mean, I’m excited about the Europa Clipper. I’m excited by all of them. But with juice, they’re going to do these flybys of each of Jupiter’s icy moons Callisto, Europa and Ganymede. And they’re going to do like a few flybys of Europa and Callisto, but then it’s going to go into orbit around Ganymede and stay there. And and like the more they learn about Ganymede, the more excited I get about this world. It is the largest moon in the solar system. It is bigger than Mercury. It has a magnetosphere. It has a thin oxygen atmosphere. It has that same issue of an ice shell with a liquid water ocean underneath, around a rocky core mantle. So there’s probably the raw ingredients for life mixed in with the water, but it’s larger, has more gravity. And it’s farther away from Jupiter, so it doesn’t have that same radiation load on the surface. And so I really think Ganymede is the new Europa. 

Pamela Gay [00:09:21] And and Ganymede doesn’t have that really weird alien look that Europa has. It looks much more like just a beat up gray ball. And so it’s going to be amazing to see just what do we learn when we finally get truly high resolution images. And June is great. Juno I think we now need to pay attention to. In this episode, you should have already been paying attention to it in real life. The Juno mission is already at Jupiter, and 2023 is the year of io. As it goes round and round. It is almost on a monthly basis, getting a little bit closer and a little bit closer as it passes IO on a converging path, such that later in the year it will make its closest approach, and with each pass, it’s giving us a little bit more of IO and a little bit more detail, with amazing images coming from the the folks like Ted strike who are processing in this image to bring out the features, and others are doing what they can to enhance them. There is an overlay enhanced version on Astronomy Picture of the day the other day. Go get the stuff directly from Ted. 

Fraser Cain [00:10:45] It’s amazing the the images of IO. 

Pamela Gay [00:10:49] Yeah. 

Fraser Cain [00:10:50] Yeah. 

Pamela Gay [00:10:51] But we’re not going to get what we’re going to get with juice. Jesus. Dedicated. It’s there for the ice, not the world. 

Fraser Cain [00:10:59] Yeah. And with the Juno mission, like the original goal was to do imaging of Jupiter, to study its upper atmosphere, to measure its magnetosphere and the radiation environment around Jupiter. All of these, these things and and, of course, the amazing story that we’ve talked about with Juno is that they weren’t originally planning to put a visible light camera on it and. 

Pamela Gay [00:11:26] Then EPO camera. It’s for education and public outreach. Yeah. The science that’s doing. 

Fraser Cain [00:11:33] Yeah. I mean, I mean, so it was a bit of an afterthought, but they were able to put it on and it’s able to do visible light as well as near infrared. And so you get these really great images of Jupiter. And like all of these, the, the cool pictures of Jupiter with the swirling clouds and the incredible structures that you see, this is all coming from Juno. And and as you said, it’s an EPO camera. You’ve got all of these citizen scientists who are who are watching every time genomics flyby of Jupiter, downloading all the fresh images, processing them using all of their skills and just producing amazing images. And like some of my favorite citizen scientist people are working on this and they’re making discoveries at Jupiter with with their work polar vortices. 

Pamela Gay [00:12:20] Word. Discovering the clouds of Jupiter are swirling and interacting and chemically interesting in ways we just didn’t know. It’s amazing. 

Fraser Cain [00:12:31] Yeah, yeah. And so on that most recent flyby of io, astronomers were able to measure 266 volcanoes in the pictures of io between from the flyby now, and probably has some more, but that’s how many they were able to to see. And what’s amazing about that is they, you know, they they they’re really starting to think that there’s this global magma ocean underneath the surface on io and that all of these volcanoes are connected and that you’ve got this, this magma flowing and then erupting in various volcanoes. And it is the most volcanic place in the solar system, way more volcanic than Earth. That flyby that they just did. The one that was about a month ago, they came within about 15,000km of io. They’ve got another one planned later on this year, and the one that’s coming in 2024 is going to be 1500km away from io. Like this is a this is going to be quite the flyby and the spacecraft is still doing fine. I mean, you know, they’ve brought it close to Jupiter to try and go through, you know, just to and they’re risking it in this radiative environment, but still amazing. 

Pamela Gay [00:13:42] Yeah. Yeah, yeah. We’ve run out of adjectives occasionally, folks. 

Fraser Cain [00:13:47] Right, right. Well, it just tells us that we really just need more at the outer solar system. Like, unfortunately, we don’t have a lot to talk about today. We’re almost halfway through. All right. So were there any spacecraft that were on their way that we missed to the outer solar system? 

Pamela Gay [00:14:05] So what do we say about ibex? I mean, it’s just like hanging out. 

Fraser Cain [00:14:12] It exists. It functions. 

Pamela Gay [00:14:15] Yeah. This is the least exciting, most exciting mission ever. There is a mission called ibex. On a journey to the outer solar system, where it will hang out in basically a kind of solar ish orbit looking at the outskirts of our solar system. That’s all I’ve got. I don’t know what else to say about. 

Fraser Cain [00:14:40] I don’t have anything additional for that. Whoo! It’s a NASA mission, right? 

Pamela Gay [00:14:44] NASA mission, and it’s. 

Fraser Cain [00:14:45] Been around for a while. 

Pamela Gay [00:14:46] It’s been around since, well, since 2008. It launched in 2008. Yeah. It launched on a Pegasus rocket dropped from an aircraft, which you don’t get. Outer solar system explorers that usually launch on anything other than extremely heavy lift vehicles. Yeah. 

Fraser Cain [00:15:14] All right, well. Moving on. Where do you want to go next? I guess you horizons that work is Rosetta is rosette. Rosetta is dead, right? 

Pamela Gay [00:15:24] Rosetta is not returning data at the moment. I never found a mission. Is dead until, like, it burns up somewhere. 

Fraser Cain [00:15:32] Right? Right. But it is in. It is no longer returning data. Yeah, yeah, I think it’s. Yeah, well, let’s move out to New Horizons. 

Pamela Gay [00:15:39] And so New Horizons, as many of you probably know, launched prior to the 2006 decision that Pluto is no longer planet. In 2015, it made its historic pass of Pluto and Sharon. It has since gone on to visit two different. Is it still only two there? 

Fraser Cain [00:16:02] Just one. 

Pamela Gay [00:16:02] Just missed one, I lied, okay, and it has since gone past Eric Roth, which I guess it changed names enough times that I decided that it was two different objects. Which is a, basically conjoined icy blob, the snowman in the outer solar system. And at this point, NASA has decided that rather than continuing the mission to visit additional Kuiper Belt objects, they will instead focus on healio science and looking back in to the inner solar system. There’s a lot of thoughts being vocally stated. Senior review meetings right now where the planetary science community would still love to keep their hands on this mission. Still love to send it off to anything that we can manage to find out there, and just keep trying to get more data on these objects that we have nothing else we can visit with. 

Fraser Cain [00:17:17] You know, the extended it to 2029, right? 

Pamela Gay [00:17:19] Right. But the funny thing is, do helium science hmhm. 

Fraser Cain [00:17:24] But that still gives them an option. If, say, Veer Rubin finds another Kuiper Belt object that is. 

Pamela Gay [00:17:30] In. 

Fraser Cain [00:17:30] Their flight path and they could still swing towards it. I mean, obviously, like, I mean, you horizons like we all, you know, for all of the planets in the solar system, we had closer pictures of all of that. We had pictures. 

Pamela Gay [00:17:43] Of. 

Fraser Cain [00:17:44] Thanks to the Voyager spacecraft, which we’ll talk about in a second. We had close up images of Uranus and Neptune, but the one that we the you know, for us, growing up in our picture books, Pluto was an artist’s illustration, or it was eight pixels from the Hubble Space Telescope, and it just was an unsatisfying image. And then in 2015, they did the flyby. Look like it’s been a while since they actually did the flyby of Pluto in 2015. And we yeah, yeah. And we got to see these close up images of of these two worlds for the first time ever and revolutionized. Yeah, Pluto was such a different place than I think anyone, anyone expected. It’s going to be so far it’s going to be this cold ice ball. But no, it’s got mountains of ice. It’s got glaciers made of methane and ammonia that did shift across the surface. It probably got cryo volcanoes. Yeah. In fact, astronomers recently think they might have seen a supervolcano, which I know you like about cells. Yeah, yeah. And and they’re catching plural in this time when it is starting to shift away from the sun, that its atmosphere is about to freeze off onto the surface of the world. But you got these incredible pictures moving away, seeing this thin blue atmosphere around Pluto, and then sharing itself is such an interesting object as well. 

Pamela Gay [00:19:08] So vast chasms. 

Fraser Cain [00:19:10] Yeah. What a huge update. 

Pamela Gay [00:19:12] Like, you can see the these when you look at a world and you see a notch taken out because that’s where Valley is more of this place. Yeah. I’m just going to keep saying that. 

Fraser Cain [00:19:26] And there are so many these other objects out there. There’s Eris, there’s Sedna, there’s car, there’s Gong, Gong, there’s like all of these objects out there. 

Pamela Gay [00:19:34] I mayar with its moons and its rapid rotation. 

Fraser Cain [00:19:38] Yeah, yeah. And and like, we need to go back. And there was some recent study with Webb where they looked at them and they look different from each other. Like, they’re not like none of these things are the same. And each one needs to be fixed. Each one is its own special butterfly that we need to go back to. But, one of the cool things you talk about doing heliospheric science, like one of the really cool projects that they recently had New Horizons do, was look into the universe from this unique perspective. Out beyond. Were you following the story? 

Pamela Gay [00:20:09] Not as much as you. So go ahead. 

Fraser Cain [00:20:11] Yeah. So one of the big questions that astronomers have always had is how much light pollution are we getting in the inner solar system because we are trapped inside the inner solar system. There’s all that zodiacal dust. There’s a lot of stuff that’s leftover from the solar system. But once you get out into the outer solar system, then you are beyond this light pollution, and now you’re getting the most pristine view of the universe, and the only telescope in the, you know, capable of making these observations is the instrument on board New Horizons. And so they were able to image just the universe itself, and then compare the amount of sky glow that they were getting from those images, compared to what astronomers see farther into the solar system, and then use that to then make better estimates about the amount of galaxies and dust and all of that that’s out there in the universe. And so without new horizons like this, would be worth sending a telescope out to do all on its own to get these kinds of observations and give us this baseline for the darkness. And so now we know how dark the universe truly is. And I don’t know if you get this question, people always ask me this question like, oh, should we put a telescope? Would it make sense to put a telescope out at, say, Neptune? And my answer had always been no, no. Like there’s no value to go. Like once you’re in space, you’re in space. It’s fine. But I’m wrong. I was wrong that that it is darker out at Neptune and that you will get darker clear skies. You’ll get a better view of the universe. And for certain kinds of observations, that’s what you need. All right. Let’s talk about. The villagers. Give me your memory. Your memories of the voyagers. 

Pamela Gay [00:21:48] So I was like. Early early elementary school when they went through the Jupiter system. And I think you really have to see Jupiter system, given those moons are worlds in their own right, with Ganymede being bigger than Mercury. And one of my earliest memories is getting into a fight over whether or not I had to take a nap because. We were going to stay up and watch the images come back and be on TV. And I was in Louisville and and from that point on, it was like I was going to stubbornly watch every image that ever came back from that mission and throughout my life. Event after event was just bookmarked, and the one that makes me sad is the Uranus encounter was just a couple of days before the challenger disaster. And so it just, like, completely got lost in the news. And I mean, admittedly, Uranus is basically a really nice teal ball, but but still, this is this is the entirety of my life, in a way. World after world, getting encountered by these outward traveling missions. 

Fraser Cain [00:23:18] Yeah, the Neptune one was more meaningful for me. That was in 1989. Uranus was in 86, Voyager two reached Neptune 99, and I was in my final year of high school, and it was in the newspaper, and we were sitting on the bus coming back from school, and a bunch of my friends were big narrating. So we were geeking out about about Neptune and the images. And I just remember this so vividly about being so excited because I remember those, those original flybys of Saturn and Jupiter. You know, 1977, I was like six years old. So I even remember the launch. And then just grew up with those spacecraft. And I’m sure people are listening to this now, like, you have your version of that, but I think for for me and Pamela, it’s the Voyagers. And they have been there side by side with us through our entire lives. You know, we’re I’m 52 now, and. 

Pamela Gay [00:24:19] It’s this wild metaphor. 

Fraser Cain [00:24:22] They’re still going. 

Pamela Gay [00:24:23] They’re still going, but they’re starting to fall apart. And like. 

Fraser Cain [00:24:28] So are we. 

Pamela Gay [00:24:29] Me two. Voyager. 

Fraser Cain [00:24:31] Yeah. Mood. 

Pamela Gay [00:24:35] And so? So earlier this year we got news that that with Voyager two they were figuring out okay. So we want to keep them going as long as possible. We want to keep doing as much science as possible. And and so they’re just like one by one turning off different instruments, trying to keep the heat going, the warmth going, the antennas powered so they can keep sending us back data. They they have managed to I don’t know how many times recover these two little missions from safe mode. I. I just love that. They’re like, okay, so we don’t need your cameras anymore off, right? I was going to other things. Okay? We don’t need this thing anymore. You have definitely passed the heliopause off. It’s kind of merciless. But for the purpose of just keeping it going and going. And there was this wild time that you probably remember as well, where it felt like every other year we were like. And now the Voyagers have actually left the solar system. And the problem was that they were doing this when our sun was being erratic and when the sun got really active, the magnetic field expanded out and protected a larger volume of space and rim compassed the voyagers. Sun calmed itself down a little bit. Solar system got a little bit smaller and the Voyagers were no longer within that protective shell. Well, at this point, I mean, we’re admittedly going into solar maximum, so we could be proven wrong, but as far as we know, they’re out there seeing particle fluxes. They’re seeing magnetic field behaviors that are not what was measured within that magnetic safety net. They’re out there in interstellar space. 

Fraser Cain [00:26:50] Yeah. Yeah. I mean, they’re I mean, to anthropomorphize them at this point, as you said, you know, because their energy system uses this decaying chunk of plutonium that is down to just a fraction of the heat output that it began with. They don’t have a lot of watts to work with. And so, as you said, they’ve been shutting down the instruments one after the other, taking away their senses. You know, maybe they had ten instruments in the beginning. I don’t know the exact number. And then they shut off this, they shut off the camera, they shut off this other thing, and they’re left with now just feeling the wind. Yeah. Feeling the wind of space and feeling whether they’re in the solar system and feeling the, the, the particles streaming from the solar wind. And now they’re out of that, and now they’re just feeling the collective interstellar winds from all of the stars around us. 

Pamela Gay [00:27:39] And then we’re able to keep doing that in the most ridiculous of ways. They they were like, okay, how do we keep powering this science instrument? And so they powered off a variable voltage safety filter. And so now they’re going to have some variable voltage. But it’s preferable to have variable voltage and data than no data. 

Fraser Cain [00:28:04] Yeah. And again just enough to power their transmitter, send it home, receive new commands and continue to, you know, deaf blind, sort of pushing their way through interstellar wind. 

Pamela Gay [00:28:18] And shouty in the radio. It’s still shouting home. 

Fraser Cain [00:28:22] Right? Yeah. Well it’s I mean, they’re still able to yell back what it’s hearing, what it’s what it’s seeing out there. And I love it. So, you know, it won’t be too much longer. They’ll probably another couple of years and then they will in the end have to shut down either Voyager one or Voyager two, and then the other one will be shut down. And then we will lose those our companions through in our in our science communication lives and our lives, our entire lives. And, yeah, sucks. But there you are. Well, that wraps up our journey through the solar system, the active spacecraft that occurred there. I know we missed a bunch. Like, did we talk about tests? Like ones that are weird orbits that are in strange places? And so I apologize to all of the spacecraft that we missed. We love you, too. 

Pamela Gay [00:29:08] It’s true. 

Fraser Cain [00:29:09] Yeah, but that was a lot of fun. All right. Thanks, panel. 

Pamela Gay [00:29:13] Thank you. And thank you so much to all of our patrons who are out there supporting us week after week, month after month. I wish I could read all of your names every episode, but I can’t. We do, however, have a special Patreon tier where if you give enough each month and the same is true with Cosmic Quest, I will attempt to pronounce your name in our podcast this weeks. People whose names I shall attempt to pronounce are Jeff Collins, Simon Parton, Stuart Mills, Jeremy Kerwin, Kellyanne and David Parker. Herald, bargain Hagan, Greg Davis, Alex Cohen, Ken Siya, pencil. Yanko, Claudia mastroianni. A 1961 super symmetrical Matt Rucker share some mark Steven Rusnak and Esau Abraham Cantrell, Paul L Hayden, Steven Coffey, Alex Rain, Andrew Stephenson, Benjamin Carrier, Frank Tippin, Bart Flaherty, the lonely sand person, Jim schooler, Tim McMeekin, Gregory. Singleton, Kenneth Ryan, Michael Regan and Ninja Neck. You allow us to do what we do. Thank you so much and thank you for giving, for forgiving my lack of phonics week after week. 

Fraser Cain [00:30:36] Thanks everyone, and we’ll see you next week. 

Pamela Gay [00:30:38] Buh bye. Astronomy cast is a joint product of Universe Today and the Planetary Science Institute. Astronomy cast is released under a Creative Commons Attribution license. So love it, share it, and remix it, but please credit it to our hosts, Fraser Cain and Doctor Pamela Gay. You can get more information on today’s show topic on our website. Astronomy. Cars.com. This episode was brought to you. Thanks to our generous patrons on Patreon. If you want to help keep the show going, please consider joining our community at Patreon.com Slash Astronomy Cast. Not only do you help us pay our producers a fair wage, you will also get special access to content right in your inbox and invites to online events. We are so grateful to all of you who have joined our Patreon community already. Anyways, keep looking up. This has been Astronomy Cast. 

Show Notes

ESA’s Mission navigator (ESA)

Jupiter: Exploration (NASA Science)

Saturn: Exploration (NASA Science)

Voyager (JPL, NASA)

OSIRIS-APEX | OSIRIS-REx (University of Arizona)

Lucy Mission Resources (NASA Science)

New Horizons to Continue Exploring Outer Solar System (NASA)

Jupiter Icy Moons Explorer (Juice) (ESA)