Planetary Radio: Space Exploration, Astronomy and Science - A Fond Farewell to Spirit and Opportunity

Episode Date: February 20, 2019

The Mars Exploration Rover mission was declared complete on February 13, 2019.  On the very next day, MER Project Manager John Callas and Deputy Project Scientist Abigail Fraeman came to Planetary Society headquarters for an extended and emotional conversation with Mat Kaplan and Emily Lakdawalla. They talked about the beloved rovers and the women and men of the team that has guided them for so many years. What’s Up offers another opportunity to win a coveted rubber asteroid as we learn about the night sky and more. Learn more about this week’s guest and topics at:  http://www.planetary.org/multimedia/planetary-radio/show/2019/0220-2019-mer-callas-fraeman-lakdawalla.htmlLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Saying goodbye to spirit and opportunity, this week on Planetary Radio. Welcome, I'm Matt Kaplan of the Planetary Society, with more of the human adventure across our solar system and beyond. It's Wednesday, February 13th, in the Jet Propulsion Lab's von Karman Auditorium. Here is NASA Associate Administrator Thomas Zurbuchen. I was there yesterday, and I was there with the team as these commands went out into the deep sky, and I learned this morning that we had not heard back, and our beloved Opportunity remained silent. It is therefore that I'm standing here with a sense of deep appreciation and gratitude

that I declare the Opportunity mission as complete, and with it, the Mars Exploration Rover mission as complete. And I have to tell you, this is an emotional time. I stand here surrounded by a team that I, before I even came to NASA, I got to know as I watched this amazing entry to Sand and Landing, the development, and of course at the center of that were two people. Pete Teisinger was right here ahead of me. He's a hero in the world that we live in.

And right next to me right here is Steve Squires. You're going to meet him later. Another hero for all of us. It's a team that makes success like this. It's a team that creates exploration, transformative exploration for science and engineering, and it's a team that is celebrating here today emotionally. I remember the emotions. I saw that Cornell professor jumping up and down like my four-year-old at his birthday when entry, descent, and landing was complete,

and the rower said, I'm here, and we're celebrating with emotion. Science is an emotional affair. It's a team sport, and that's what we're celebrating today. I will never forget the amazing work that happened here. It transformed our understanding of our planet. Everything we do and think about in our planetary neighborhood with Mars and elsewhere relates to the research that came from that and the engineering breakthroughs that came from that.

And it's really a great honor right now to introduce a champion for exploration and for science, the administrator, Bridenstine. Thank you so much, Thomas. It's an honor to be here. Almost two decades worth of work by so many extraordinarily impressive people in this room right now. And then last year, I became the administrator and opportunity quit communicating. Can you believe that so I take full responsibility? But this is a celebration of so many achievements, you know when this Little rover landed the objective was to have it be able to move 1,100 yards and survive for 90 days on Mars, 90 souls.

And instead, here we are 14 years later, after 28 miles of travel, and today we get to celebrate the end of this mission. So it's an honor for me as the NASA administrator to come out here to this amazing facility with so many amazingly talented people to say thank you for your great work, not just for our country, but for the science that people are going to be benefiting all over the world. They're going to be benefiting from this science

for years to come. That, of course, was NASA administrator Jim Bridenstine. It was the very next day that we welcomed two leaders of the Mars Exploration Rover mission to Planetary Society headquarters. John Callis has been with this magnificent effort since well before the launch of Spirit and Opportunity. He has served as project manager since 2006 when he took over from Pete Teisinger. Deputy Project Scientist Abigail, or Abby Freeman, became part of the mission much later, though, as you'll hear in our conversation, she first became deeply involved as a teenager

thanks to an opportunity led by my colleague, Planetary Society Senior Editor, Emily Lakdawalla. John and Abby, I almost cannot believe our good fortune. It was only yesterday you were in front of the entire world saying goodbye to this mission that so many of us have fallen in love with. And the next day, here you are with us in the Planetary Society studio, former bank vault, and that we are joined by my colleague, Emily, for this conversation, this little look back, this retrospective, this tribute to the Mars Exploration Rovers.

Thank you very much for making it over here. Oh, glad to be here. Thanks so much for having us. I was so glad that they didn't just line all of you up for the regular briefing format, that it was kind of done the way it was. But I don't know. Do you feel that way? But I don't know. Do you feel that way?

And we will put a link up to the video of that media briefing or event at JPL on the show page at planetary.org slash radio. But did you feel good about that? I did. But this mission has such a legacy that there's so much more to tell. And we only got a few minutes to tell a little bit. You know, I welcome the opportunity to tell more. And that's why I'm glad to be here. Maybe we can do that. I think it's a real shame that NASA TV didn't let you go for a second hour. Poor Gay, who obviously felt bad about the host, about having to get you out

of there. You knew this day was going to come. Was it more or less what you expected? Yeah, I think it was a combination of exactly what I expected and totally what I didn't expect. You know, it's something that you know is always going to happen. We knew the mission was always going to end, but to kind of actually be at that moment. And I don't know, when I heard John kind of read the final command saying, all right, this is it, telling the DSN, this is it. That's, I got really emotional. I wasn't expecting to feel that way because it's, it's a closing of a book. But it has been really fun to kind of look back over the last 15 years

and just think about how much 15 years is a long time, and we've done so much with this mission. So that's been fun taking trips down memory lane. You guys had such a long relationship with the Deep Space Network. Did they have any special messages for you at the end? relationship with the Deep Space Network. Did they have any special messages for you at the end? Well, they thanked us for a magnificent mission. And today, this morning, I got an email from one of the DSN controllers, again, expressing admiration and appreciation for a historic mission. And that was very nice to hear. I mean, I've been receiving in the last 48 hours,

numerous emails of congratulation and sympathy and acknowledgement from, you know, people all around the planet. And it's really heartening. Many from colleagues that, you know, really quite touching. So was the day more or less what you expected or had you avoided thinking about it? Well, I was very busy because we had a lot of orchestration to do with the decision that NASA made. I briefed NASA headquarters early Monday morning on the project status and the project's recommendation. morning on the project status and the project's recommendation. That set in motion the series events of then senior NASA management coming out to JPL the next day and meeting with the team. Abby did, you know, a magnificent job of coordinating and arranging for science team members to be present and to have a venue where we would meet with NASA headquarters and they

would tell us personally the decision. And yesterday was a very busy day with the press conference. The night before was a late night with the sending of the last commands. So I actually have to say that today is probably the hardest day for me because I come into work, and what do I do? There's no operations planning. There are no operational meetings. There are no operational meetings. There's no scheduling, no coordination that we have to do, no who's on shift. And it's all stopped just suddenly. You know, that's not an uncommon experience that people have when there's

significant loss in their life. If you lose a loved one or something like that, if you've been a caregiver for the last 15 years and suddenly that person isn't there anymore for you to care for, it's what do you do? For a lot of today, it's like, wow, what do I do? I mean, yes, there are a lot of things I have to do, but the normal routine is gone. And so it's a new routine. So I'm even more honored that you are here with us today as you are beginning this adjustment to a new phase in life.

And maybe we'll come back to that. The conversation about opportunity, I've been reflecting, of course, as I'm sure you guys have as well, a lot about the end of this mission. In the last couple of years, I've witnessed the ends, directly witnessed the ends of several other missions, namely Cassini when it plunged into Saturn, Philae when it fell silent on the comet Triumfgeris and then Rosetta when it was shut off. And each of those ends was a little bit different. But this one opportunity was very different, because of course, the last we heard from it was in June. And since then, you guys have been fighting, fighting to keep to try to get back in touch. So it's, it's got to be a weird switch, modal switch rather than the expectation. It's, it's got to be very different.

Yeah, absolutely. I mean, the engineering team and you know, led by John have been just putting in heroic efforts these last eight months. As the science team, we've been doing off our own thing, but they have been combing through thousands of lines of code, trying to figure out, okay, what is the fault software going to do? How do we kind of kick it out of a fault mode once we get back? Figuring out this code that was written 20 years ago by people who are long gone from the mission. this code that was written 20 years ago by people who are long gone from the mission. They have been putting in long hours sending commands, trying to figure out what time to send the commands, trying to figure out, you know, if the rover's in this mode, what should

we do in that mode? What should we do? And it's been an enormous amount of work. Huge, huge gratitude from, I think, me and everyone else on the mission for what they've done. And it's hard because we didn't get the positive response we were hoping for. And it's interesting, you mentioned comparing this to the other missions. I think we've been talking a lot about the Cassini end of mission versus this, which is, you know, Cassini is very fresh in our mind, and it was a big deal at JPL. They had a huge media event and build up for a really long time

because they knew to the second when that mission was going to end. But for us, it was really kind of our decision. Okay, when do we really think that it's time we've done enough? And that's a harder call to make. Yeah, you're absolutely right, Abby. I guess I don't want to make too much of this analogy, but if you have a dear loved one who isn't going to recover and someone has to make the decision, when should the end come? That's really hard to make because you'd much rather something else decide it for you. And we had to make that decision. Now, it was based on engineering judgment.

It's the likelihood of recovery, the environment on Mars, you know, the absence of sunlight. But it's still a hard call because up until that point, we were trying to save its life. You know, we went from a healthy rover to a rover that has an unknown status. Is it still there and recoverable or is it gone? And that unknowing, that not knowing is really hard. And so that's why we push so hard to try to save it. If it was there, it was our obligation to try to do everything we could to try to save it. During the yesterday's event, now and then the camera panned the audience a little bit. I recognized a few people, looked like a whole bunch of people who were invested in this mission, had made it to von Karman Auditorium at JPL. I'm guessing that felt good because, John, it was your quote, I think.

I'm not sure I'll be able to quote you directly, but you said, it's the people. That's really the story. Well, a lot of us said that, both Thomas Rabuka and Administrator Bridenstine and Steve Squires. Yeah, I mean, it was people that brought this rover, these rovers into being, and it's people that operated them, and it's people that made the history with these rovers. And yeah, it was great having those people there, and all generations of members of the team, you know, because we've gone on so long, you know, as you know, and as Abby is living proof of this is that, you know, we have new

generations of people that came on board and participated and contributed and benefited from this mission and to have all those generations of people there to celebrate and to remember together. That was important, and I'm glad we did that. Twenty years, like you said, some passings as well. A lot of children born, a few weddings, I'm sure. I want to throw some names at you and just get reactions and then invite you to come up with some more of your own. And Emily, if you've got any, you can too. But I'll start with Pete Feisinger. Well, Pete's greatest mistake was hiring me to be on the MBR

project. We should note that you took over from him as project manager. Yes. It was remarkable to see Pete carry this project forward to success. You know, I remember telling Pete that I didn't always agree with his decisions, but at the end, I always felt he made the right decisions. Very early on, he stressed we have to produce a quality product, and we didn't cut any corners. I mean, we had to make tough decisions to stay within our available resource envelope. You know, a fancy way of saying, you know, make sure that we stayed in on budget. You know, and we didn't always do that. And there were a lot of challenges.

But it was remarkable to see how he carried us through a very difficult time because we had had two back-to-back failures prior to MER coming into being. And there was a lot of scrutiny and a lot of attention. And we were betting the farm on this mission. And he led us through that. He was very clear in his vision. And that made it really easy, relatively speaking, to achieve this objective is that we need to launch two spacecraft in the, you know, 2003 Opportunity that land safely on Mars that explore for 90 days. And, you know, that was it, essentially. And we all pulled in the same direction to deliver on that. And yet it became so much more, even. Abby, yesterday at the end of the event, when you guys were taking questions,

you were standing next to Matt Golombek, who back in 2003, he was the first person, the first guest I had on Planetary Radio that we devoted an entire main feature to the rovers. They weren't in space yet. This was only to talk about the landing sites, which maybe we'll come back to. When I think of you standing next to him and that the contrast there, generational contrast, if nothing else, your impressions. I mean, you work pretty closely with him. Yeah, I know. It's been so fun getting to know him over these past three years because I've joined as his deputy. Matt's the project scientist and I'm the deputy. It's been really fun hearing his stories and getting his perspective. You know, Matt has been through the system many times, obviously with the Pathfinder mission.

And in terms of landing site selection, he's the guy who's helped pick every single landing site on Mars for Pathfinder and beyond. So it's been really neat hearing his stories and hearing his perspective. And I think it's taught me a lot. And he's just a really great guy to work with. You know, he's got a good sense of humor and he's always willing to listen. And I really appreciate that and the time he's taken to explain, you know, how things work to me. Did you want to add anything, John? Oh, I agree with what Abby said. Matt's been a great person to work with. And, you know, how things work to me. Did you want to add anything, John? Oh, I agree with what Abby said. Matt's been a great person to work with. And, you know, and he's got this really spirited laugh.

Oh, yes. All over the place. And it's great. And it's great. I have a Matt Golombek story for reasons that we'll get into a little bit later. I think in this podcast, I was in with the scientists at the landing of Opportunity. And when they got the first images down that showed the outcrop in the wall of the crater that Opportunity had landed in, Matt was just jumping up and down with his arms in the air yelling, running in circles around the science assessment room, because he knew what was in front of him. It was bedrock. and that's what he was there to explore. And so that's always stuck with me.

I think he was also yelling, can I help you guys pick a landing site or what? You're right. Well, looking back now, Gusev Crater, Meridiani Planum, we know a lot more about Mars now than we did when those sites were chosen. Do you ever find yourself wishing, gee, yeah, those were great, but if only we had gone to... Well, I think actually it's a really interesting example that shows us the limitations of what we can learn about these sites from orbit. If we had to choose a landing site today without any rover

data, Gusev wouldn't be on the table. I think, you know, the morphology was interesting, but we didn't see any of the minerals that we'd see that we think are water. It's not this beautiful delta. But what we found with Spirit was the evidence that the site could actually be really important for astrobiology. We found these little silicon nodules that a team member, Steve Ruff, has gotten really interested in studying and actually found that they could be an ancient hot spring. And it's because of this finding that Gusev was actually really highly ranked on the list for a return for 2020. And this kind of finding, we would have had no idea with just the orbital data alone. So yeah, there's other places on Mars we'd love to go, but it was pretty good that we went to Gusev, I think. I got another name for you. She was a participant in yesterday's briefing,

Jennifer Trosper. Jennifer has been there from the beginning. She was on Pathfinder and project system engineer for MER and is now project system engineer for Mars 2020. So she has the entire rover corporate history in her head, and she brings that to all subsequent missions. You know, I have one fond memory of when we landed, and I meant to share this, but remind Jennifer of this. During development, it was actually pretty contentious between some aspects of the science team and the engineering team. That never happens. Well, we have a phenomenal record of cooperative work.

But one of the things that was frustrating was schedules always moved around. During development, the engineering team would just move a meeting schedule at the drop of a hat. But many of these meetings involved the science team, which were traveling from other locations. And so they'd have a meeting for, you know, Thursday afternoon at 4 o'clock. Well, suddenly the meeting has now moved to next Tuesday at 8 o'clock. And I said, you can't do that. I said, I have 50 people with nonrefundable airplane tickets coming in. And, you know, so Jennifer and I would arm wrestle over this all the time.

would arm wrestle over this all the time. But when Opportunity rolled off the lander onto the surface of Mars, she was in the sequencing surface mission support area, you know, directing that and confirming that we now have six more wheels on Mars. I came up and I presented her with 12 roses for 12 wheels on Mars. And for me, that was a touching moment. Rob Manning, perennial favorite on this show and a lot of other places. Well, I can speak to my interactions with Rob. I mean, obviously, I was much younger, and I saw his face all over everything. On all of the documentaries and the movies, Rob was one of the figures. So when I came to JPL, I'd see him in the

hallways in the cafeteria. But you know, this guy, he's big wig, he doesn't know me, he doesn't want to talk to me. But no, Rob actually took the time to get to know me. He's popped into my office once or twice, much to my surprise. And he's just been so friendly and perpetually enthusiastic about the future of space exploration. And we need more people like him, I think, on lab and in the world. He's just wonderful. More people who know as much as him about how to get stuff down onto the red planet in one piece. Indeed. I have fond memory of Rob Manning in the, I think it was spirit operations early in the mission when I had a bunch of students hanging around waiting for image data to come down.

And he came and spent, I think, 45 minutes explaining the landing. And I have all these pictures of him with his arms in all different directions gesticulating all the parts of the rover and the lander. Just, you know, as ebullient as he always is. And he's just always a fun guy to talk to. Last one on my list, Steve Squires. Steve is part of the reason why I'm here. He recommended to Pete Tysinger that I come on as a science manager. I worked with Steve on the gamma-ray spectrometer for Mars Observer.

So I've known Steve since 1989, and I've always been incredibly impressed with him. I've learned so much from Steve. I've learned how to be a better communicator and a better teacher, and I try to emulate him whenever I can. The best technical presentations I have ever seen have been given by Steve Squires. He's really exceptional in that ability. He's a great communicator. Yeah, I mean, Steve has the amazing ability to be, on the one hand, an excellent scientist. And you can go back and read his papers that he's written through his scientific career, and they're really good. But as you said, he also has this really unique ability to bring that science to life, to tell the story of the rover in a way that captivates everyone. And I think that's part of the reason

that the mission is so successful and embraced by the public is because it was communicated so well. I was always impressed with Steve's ability to lead scientists, which required a combination of listening and achieving consensus, and also sometimes just deciding to be a dictator. And he was able to balance the requirements as needed, which on a rover mission, you're limited in time. You have so little time to plan each day. You do have to make decisions, and you've got to herd the cats to make the scientists come to some kind of decision.

And I always had the impression that he was able to balance that a lot better than a lot of other PIs I've seen on other missions. I don't want to put you on the spot because I'm sure you could go for a half hour talking about other brothers and sisters on the Mars Exploration Rover team. But is there anybody else that you would want to give honorable mention to? Well, absolutely. For me, the name that immediately comes to mind is Ray Arvidson, who's the deputy PI of the mission.

But, you know, there's two rovers. So when Spirit and Opportunity landed, I think Steve went off with the Opportunity and Ray stuck with Spirit. And, you know, since then, he's really been on ops every day for the last 15 years, helping to lead the science team. You know, personally, he was my graduate school advisor. So I worked very closely with him. And he's a remarkable teacher. Students are so important to him. And it's neat to see the number of students he's had who he exposed to planetary science by allowing them to participate in the mission. You know, starting with the undergrad, he brought Bethany Ellman, who's now a professor at Caltech. And the reason she's in planetary science is because Ray brought her along to help do operations as an undergraduate because he trusted students and he understands how important it is to include students in events like this.

So major shout out to Ray for all the work he's done keeping this mission running for so long. Full disclosure, too, Bethany is the newest member of the Planetary Society Board. John, did you want to add anything or anybody else? I guess I want to be careful because there are so many people that have contributed to this project. And, you know, it would be shameful if we can't mention them all. It really is a team effort. And the team is huge. And the team is dedicated and skilled.

And it's really all about them. I'll have to mention two names. One of them should be no surprise to you. It's Jim Bell, who's the team leader of the Pan-Came Instrument and also the president of our board. I have to mention Jim for his leadership in deciding to release all of the rover images to the public. in deciding to release all of the rover images to the public. I mean, I'm sure that that decision was made by a group of people together, but it made such a huge difference to the public impact of this mission, not only the Mars Exploration Rover mission, but all the missions that followed it that also released their raw images to the web like Cassini and all the other Mars missions.

That was just huge. That brought the public into this mission in a way that we had not been invited to participate in the past. The other person that I want to give a shout out to is Scott Maxwell at Mars Rover Driver on Twitter. And the reason that I wanted to mention him is because five years after the landing, he started publishing his notes, his journal entries from five years before. And I got a window into the operations of the mission in a way that I had never seen before. And just being able to see the kind of day-to-day decisions, which you also see through the images on the mission, gave me, I think, a more intimate appreciation for what it takes to make a mission like this work.

There's at least one more team member who we need to talk about here. And I want either Emily, you, or Abby, or the two of you, to talk about how you, Abby, got involved with this mission. Ah, yes. So as has been alluded to, I was actually quite young when the mission landed. I was 16 and in high school. I love science. I love space. And I was actually quite young when the mission landed. I was 16 and in high school. I love science. I love space.

And I was, you know, Googling one day, and I found the Planetary Society website, and I found they were sponsoring a contest called Red Rover Goes to Mars. They were looking for student astronauts to come and be at JPL for a couple days during operations of Spirit and Opportunity. And Emily was the leader of this program. I went ahead and I applied because who wouldn't want to apply to something like that? That kind of set the ball rolling, you know, for the few months leading up to the landing. Emily had us all on telecons, you know, as high school kids, teaching us, okay, here's what

basalt is, here's what olivine is. Let me introduce you to some very basic image processing. Let me tell you all about the rovers. Let's talk about the different parts on them and the instruments. And so we'd learned all that and then came out to JPL and Emily shepherded us around and introduced us to the science team, the engineering team, and we got to be in the room with them for operations and landing during that really special time in the mission. This was actually why I was hired at the Planetary Society, was to work on Red Rover Goes to Mars. I'd had a master's degree in planetary science. I'd been a middle school science teacher for two years. Then I followed my husband out to Los

Angeles and had been working for a year as an environmental consultant, not very happily in a corporate environment. And I just stumbled across this job listing for the Planetary Society was looking for somebody who could run an education program involved in this space mission. I said, I think my resume fits that. That's how I got here. So these students are why I'm at the Planetary Society. I got to select 16 amazing kids from all over the world. The two Americans, I'm proud to say, are now doing planetary science or space science in America. The other one is Courtney Dressing, who's an exoplanet astronomer now. But there were kids all over the

world. We got to bring them together. They got to witness mission operations. They started blogging on our website before blogging was even a thing. And it was just a wonderful introduction and to have the opportunity to be inside the actual operations of a mission is something I had never been involved in before. And it was just such a privilege. And I'm so grateful for it. Pretty successful program. Not a bad result. We got to talk about some of the stuff that I know you must be dying to talk about, about this mission. Oh, yeah. Science accomplishments, engineering accomplishments. It could go on and on. Well, these rovers, I've had the opportunity to write a lot about the place of these rovers and other Mars missions in Mars exploration. And it really is, having gone back

to research how this mission came to be and how the Curiosity mission came to be. It's really quite amazing to remember that before Spirit and Opportunity landed, we weren't sure that Mars had sedimentary rocks. We weren't sure that it had had a water cycle where there was precipitation that washed down hills and brought sediment deposit turned to rock. down hills and brought sediment deposit turned to rock. And Opportunity especially almost immediately proved the existence of a sedimentary rock cycle on Mars, proved that it was habitable really before Curiosity got there, that it was a habitable environment. And so that I think just looking, that was just amazing. And it was also a triumph for seeing mineralogy from space. We saw the hematite using what now seem like fairly primitive instruments on Mars Global Surveyor, but hematite was the one mineral.

Hematite is an iron oxide. It's sometimes sold as Apache tears. It's got a gray metallic appearance. It requires water to form. And sure enough, Opportunity found it on the surface. You know how rare it is for one mission to actually confirm as correct the conclusion of a previous mission? It doesn't happen that often in planetary science. It's happening more often now. And so I think those are the two most amazing things. But then, of course, Opportunity continued to roll across the surface, as did Spirit. So I'm actually wondering, what do you guys, Abby and John, what do you feel are your most proud scientific accomplishments of the mission? Well, I think for Opportunity, it was getting to the rim of Endeavor Crater. From orbit, we had new instruments that came into orbit after Opportunity landed, in particular,

the Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM, which is another instrument designed to look at mineralogy slightly different way than the one that had originally detected the hematite. And with CRISM, we saw that there were clays in the rim of Endeavor Crater. We see clays all over Mars with CRISM, but this was going to be our first opportunity to look at them with the vehicle on the ground. So to interject there, to explain to the audience, why do we care about clay? Well, clay is what happens when you take a lava mineral or a lava rock, basalt, and you attack it with water.

So it has the same kinds of atoms in it, except that in between the atoms that came from the basalt, there's sort of a layered mineral that has a bunch of water molecules stuffed inside the layers like a big sandwich. So that's what clay is, and that's why we're excited to see it on Mars, because it requires water. And I'll throw in excited now, because Curiosity, as you have pointed out, Emily, online, has just reached clays. It has just reached clays, but Opportunity got there first. Well, Api got first where we see clay signatures from orbit. But yeah, we picked out a spot on the rim of Endeavor Crater in a region called Cape York. And we drove right towards where the pixels were telling us to go.

And we discovered this remarkable alteration area called Esperance. We could see it on the ground. It was kind of a different color. called Esperance. We could see it on the ground. It was kind of a different color. And what we found when we looked at it was actually it was really enriched with certain elements that told us that there had been a lot of water moving through it that had carried away some of the elements that were more soluble. And it was kind of a confirmation that there had been a lot of water here. And we could think about what was the chemistry of the water. And what we realized, it was probably a lot more neutral pH. It was a lot more drinkable water than the kind of water that formed with the hematite,

which is more like battery acid, which is a little bit more difficult for life. So on the rim of Endeavor Crater, we found conditions that we think would have been even more habitable than those first findings. And it also demonstrated that there had not only been liquid water in this area, but it had been there probably for a lot of different periods of time, probably many different chemistries. And I think that's a really interesting result. Yeah, I think that's one of the most striking things about both the opportunity and curiosity results is the way that, you know, water had to be involved in creating the sediments. Water had to be involved in transporting them and laying them down and turning them into rocks. And then there's evidence from veins and other stuff, cross-cutting the rocks and alterations of

different minerals that water has coursed through the rocks once, twice, perhaps multiple times in the past. So that's multiple episodes of different types of habitable environments that have moved through these rocks over a very long period of Mars's past. So it seems that if it's relatively easy to initiate life, and that is admittedly a big if, but there's no reason to think that it couldn't have hung around on Mars for a long time. There seems to be an opportunity to say this in virtually every conversation we have about this planet, but it is a wonderfully diverse place and a wonderfully dynamic place, right? It's certainly true of Mars. I think that we have that impression of Mars because we've had so many missions there. I studied as a graduate student, I studied Venus,

and so I always had a little chip on my shoulder about how many Mars missions there were, because where are the Venus missions? Where's the return mission to Uranus and Neptune? Why aren't we at Mercury yet? But I think that I recognized seeing what we've accomplished at Mars, how much more you get when you send more than one mission. You send two missions, you don't just get double, you get quadruple because by overlaying one mission's results on another mission's data, you actually multiply what you can see. It's like exponential. I shouldn't feel jealous about Mars.

I should just advocate for there to be more missions to all these other places. Hear, hear. Yeah, so here's the problem, I think. The more we learn about Mars, the more we see how diverse it is, and we can say, oh, man, we should go there. We should land here. We should land here. And we learn how much more we learn when we land.

So it's like the more missions we send, it makes us need to send even more. John? Well, I don't think I can add anything more than they've already said on this subject. I mean, I agree with it. But what else stands out for you? Apart from the science, I've been talking about this a lot the last couple of days, is that there is this great intangible that opportunity and spirit have given us, and that they've made Mars a familiar place.

It's our neighborhood. And I've had a team that has gone to work on Mars every day for the past 14 and a half years. It's their workplace. They have become Martians. So we have Martians here on Earth because they work on Mars. They show up and they do their work in this strange place we call the Red Planet. So our world is now larger. It's no longer confined just to the planet Earth.

It now has to include the surface of Mars. Because we know it. We know parts of it. There are familiar sites. We can look at the images and we can say, I know that place. We've been there. And I think that's significant. I think that's important because it's more than just a scientific mission, which is of itself tremendously important. But I think it expands our thinking about ourselves as human beings, and that we are explorers, and that we are no longer confined to the old world. There's a new world that is now part of our domain of exploration, and it's a place that we should continue to explore. And we have, because we've had this sustained surface exploration of Mars since January of 2004.

And my hope and my expectation is that we'll continue for as long as humanity explores. And sustained orbital exploration since 1997. I mean, our presence there has been long. We haven't started a new mission since 1997. I mean, our presence there has been long. We haven't started a new mission since 2012. It's been a gap. Not to take issue with that, but the surface mission gives a human scale to the exploration. You feel like you are standing there and you're seeing it for yourself. there and you're seeing it for yourself. And you progress along with a roving vehicle as if you are walking or traveling yourself. And I think that is a very important aspect of this mission. Ray Bradbury would be so proud. We are the Martians. Anything from on the engineering side where this was also such an amazingly successful effort?

There are many things now that we take for granted. Safely landing on the surface of Mars. The entry, descent, and landing system is a remarkable way to land in a hostile, unknown environment. The airbags have their limitations, so, you know, Curiosity had to use a sky crane, which is even a more phenomenal accomplishment. There are several things. One is, you know, learning how to do geology through a robotic system. Because all these field geologists, they're all accustomed to walking around with their boots and their backpack and their rock hammer and their hand lens and, lens, and working a site in a matter of

minutes. And it's different with a rover. Relay communications. Actually, this is one of the unsung heroes. When we landed on Mars, a prime method of data return were going to be multiple X-band communication sessions with a rover each day. But that's very expensive in terms of energy because you're talking about transmitting from the surface of Mars all the way back to Earth. That's a distance that's measured in hundreds of millions of kilometers. It takes a lot of transmit power to do that. Whereas with an orbiting relay asset where the orbiter is less than a thousand kilometers away, you know, and I'm sure Emily has talked about one over r squared in terms of uh signal strength for distant objects uh it was much more energy efficient to do relay

but we never tested that end to end each component the relay system on mars odyssey which was built and designed years ahead of wherever mer was going to, was never fully integrated with the test systems at JPL. So we did some testing, but it wasn't considered prime communication. And even on landing day, it was a gamble whether the UHF system would work because that was the system that returned the first images. When you see this picture of people in the control room and the images flash up on the screen and Matt Golombek is doing cartwheels, that came through the Mars Odyssey UHF relay system. And we didn't know if it was going to work because it had never been tested. And it worked beautifully from day one.

We returned well over 95% of all data from the surface of Mars for Spirit and Opportunity through the relay system. It was a phenomenal workhorse, one of the many technologies. And then you can go down the list, autonomous robotics, there are autonomous navigations, visual odometry, stereo imaging, all those things now are standard parts of our toolkit, but they were all experimental with MER, and they really enabled us to explore and to do what we did. Without them, we couldn't have gone the distance. We couldn't have been as

productive in our science observations without all those capabilities. The radio relay, the telecom, I think is actually a remarkable legacy of the Mars Exploration Rovers because, you know, Odyssey took an early model of the relay radio and now JPL is outfitting all their Mars spacecraft with this Electra radio relay system. on ExoMars, Trace Gas Orbiter, the European mission. And I know that NASA is in talks with the Indian Space Research Organization about putting an electric radio on their orbiter. So it's actually become an international standard for telecom on Mars. I think that's just wonderful. So when you hear about the orbit of MAVEN being adjusted so that it can be a better relay,

even though you won't be able to take advantage of it with your rovers, do you think about that legacy? Well, what came about with MER is the integrated Mars exploration program. This combination of orbiters, landers, and rovers that all work together as a family. And that's been the real value, the real productivity enhancement for Mars exploration. Because you know you had Mars Global Surveyor first doing

the initial surface imaging with the mock camera to find the landing sites for MER. Later on it was a Mars Reconnaissance Orbiter with a high-rise camera. Eyes in the sky that allowed us to get to Endeavor Crater. It observed the path that we needed to follow to get there as quickly as possible. And then the relay communication. And then the weather monitoring. You know, unfortunately, the weather took opportunity. But there was a time many years ago, we got a late phone call from Bruce Cantor at Malin Space Sciences on a Friday

saying there is a regional dust storm that had just erupted, and I think it was near Spirit, but I'm not sure on that. I'd have to go back and look. And I called in a team to come in on Saturday and change the commands that were going to the rover to configure it for a reduced energy situation. It was a smart move to make because we found that we needed to hunker down while the storm passed over us. And so we got a heads up from the eyes in the sky that this hazard was coming. A weather satellite. Yeah. And that just is one illustration of how this Mars program, and as Emily said, having these relays now on every orbiter that goes to Mars now really returns the data from the surface.

Because we can always collect more data on the surface than we can get back to Earth. And so if you really want to enhance data return from Mars or enhance the science you get back, just improve the communication link because the science collection is being done. And we should say Malin Space Systems, a lot of our audience will know, but they happen to be the people who build a lot of the cameras at Mars and elsewhere around the solar system. You mentioned something that made me remember something else that I think is quite remarkable about the Mars Exploration Rovers as compared to Curiosity, which is that Curiosity landed with the benefit of reconnaissance from Mars Reconnaissance Orbiter to plan out all of its future paths. The Mars Exploration Rovers had only their own eyes to figure out what was safe.

You had to take images every day and say, OK, I think that this direction is going to be a safe direction to go. But once I get there, I don't know if I'm going to be able to go on any further, especially with Spirit. The mountain climb that you guys did was just amazing. Yeah, we do so much root planning now using those high-rise 25-centimeter-per-pixel images for both opportunity and for curiosity. You know, we had paths laid out. We had hazards identified to go around. And I can't imagine doing ops without

the HiRISE. You know, Matt, one of the things that I think is so true of the set of missions is that so many things work so well that I think a lot of people have the impression they've always been there. Just like, you know, didn't the ancient Egyptians have hand calculators? You know, Didn't the ancient Egyptians have hand calculators? You know, Abby was talking about high-rise. I mean, we now treat it as if it's always been there. But, yeah, there was a time we didn't have that, and it made navigation challenging. But it worked so well.

You know, relay now works so well. You know, everyone thinks, didn't we always have relay at Mars? But when we landed, we weren't planning on using it as our baseline. When Curiosity was first conceived, they weren't sure that Mars Reconnaissance Orbiter was going to succeed, so they couldn't depend on relay. So that rover was designed with like a practically one meter dish sitting on its back. I've seen those pictures. Communicate with Earth. That was quite, I'm glad they didn't have to do that. Going back to Jennifer Trosper, because she said something along these lines at the briefing yesterday, that because she's had this tenure and is now working to put together the next rover, the 2020 rover, she talked about its heritage.

When you look at Curiosity, when you see the 2020 rover coming together, do you think about this genealogy that comes directly from you folks? And to a degree, I suppose, Sojourner, but not as much. Well, actually, I think a lot of it comes from Sojourner because we're talking about a six-wheel rocker-bogey suspension system with Ackerman steering. They all have it, and it started with Sojourner. People ask, well, why aren't you using eight wheels instead of six?

Or why aren't you using just a four-wheel drive? And it started with Sojourner and found that this six-wheel rocker bogey suspension system is the best suited for irregular terrain and making good rolling progress. If it ain't broke. It's working. You know, no one's come up with anything better than that. Yeah, and certainly in terms of the ops process, which is what I'm most familiar with and what I spend my time doing, I think the way that the day is structured in terms of here's when we need our inputs, here's how we're going to put together a plan. Certainly, each rover has built on the previous one.

But as you get more and more complicated rovers with more and more intense requirements for how far they need to go and how much they need to do in a day, your operational plan changes. But its genesis is always from what you've done previously and what you learned worked and what didn't work. Imitation is the highest form of flattery. And so it's interesting to see the European designs for rovers and the Chinese designs for rovers, and they look awfully familiar. Should have gotten that patent. What scared you the most? Something that you recovered from? I mean, there are scary moments. The 2007 dust storm was one. The embedding of spirit was scary. And that, unfortunately, was realized for what it was. You know, this dust storm that took opportunity was scary.

But maybe I'll take an opportunity to talk about situations where I wasn't scared. And that was the Sol 18 anomaly for spirit when we had the flash memory. And, you know, Jennifer Trosper talked about that and how they were scared. I wasn't. I wasn't because I knew we had the finest people in the solar system to solve this problem. I knew they knew the system intimately, and I knew they were talented and innovative

and that they would find the solution, and they did. And so I was calm, cool, and collected during that whole hysterical moment where Jennifer and her team were running around trying to fix this thing. I just said, they're going to fix it. I hope that they were more reassured than irritated by your confidence. What was a scary time for you? I think the one that most recently happened was the left front actuator getting stuck, towed 30 degrees. We were in the middle of a turn and it

just stopped turning. This was just a year or so ago. It's not a great thing to have your steering wheel stuck, turned out. And the right front steering actuator had also been stuck. It would have made it really hard to drive the rover. We sent commands, straighten, straighten, straighten, nothing happened. We convened a bunch of what we call tiger teams to figure out, okay, can we do anything that would make this worse? Decided no. So, you know, said, okay, well, let's just try to straighten again, see what happens. And, you know, miraculously on the last sequenced command, the thing straightened. And we got that wheel out at zero degrees pointed straight out, at which point we said, okay, we're not going to steer with these wheels anymore. We're going to steer with the back wheels, kind of like driving a car.

But it would have made things a lot more difficult if we couldn't have straightened that wheel, I think. Yeah, I agree with you on that one. That was scary. But it was miraculous because we had tried straightening it and we were unsuccessful. And we had a series of commands to do it. Well, OK, we'll try it one more time. And we tried it several times. And it was the last command on the last day.

And it straightened. And it's like, all right. And we were trying to figure it out. You brought in, we found models of the motors and we were taking them apart and you were looking, okay, what in this mechanism could have broken it? You know, we were trying to figure out why would it jam. The interesting thing about the steering actuators

is that they are identical to the drive actuators. But the drive actuators have hundreds of times more actuations on them because they're spinning all the time and you rarely, infrequently steer relative to the amount of times the wheels spin. So we've thought if something's going to break, it would be the drive actuators that would break first. And so why did the steering actuators break? And so why did the steering actuators break? Our best theory on that is that we have these little detent magnets on the shafts on all the actuators. And they may have actually have broken on all of them.

But because the drive actuators are horizontal, the fragments of the magnets would just fall away from the drive mechanism. Where the steering actuators are more vertically oriented along their axes. And so the fragments would fall into the gear train. And so we think that might be the source of a potential debris that could periodically jam the steering actuator. What a great example of the kind of detective work that you'd had to do to keep these rovers going as long as you did. Emily, what scared you? I mean, what made you anxious? Well, you know, I didn't work mission operations, so I didn't actually have to worry about a lot of these things. I could just remain confident that people could handle them. But I'll have to tell you, as a backseat driver on these missions, the driving on the steep slopes where the rover would

like slide downhill more than it moved forward as it was just watching this. I was like, oh my God, I can't believe the engineers are letting you do that. But I think it was, it showed the close cooperation and the trust between the scientists and the engineers that the scientists were always like, can you get me to that outcrop? Can you get me to that spot? And the engineers were like, that the scientists were always like, can you get me to that outcrop? Can you get me to that spot? And the engineers were like, okay, we'll try. And they set the safety limits as needed on everything, and they tried.

And they got out on these outcrops that were tilted at an angle. The spirit was climbing ridiculous slopes, and it was just really impressive. Well, opportunity at the end. We were in this area called Perseverance Valley, which was pretty steep. And the engineers were thrilled with the science team when we kept finding interesting targets we wanted to visit that were back uphill. The plan was to kind of toboggan down a one-way trip this valley. But we kept saying, oh, you know that thing that we passed that's back there? Can we go there? That looked cool. And yeah, they got real good with figuring out how to drive on a slope that we knew we were going to slip in,

estimating how much we would kind of skid downhill to get the rover exactly where we needed it to do the science. Can you just imagine having a camera on that rover doing stuff? We did have a camera on the rover. We have these images. You've been very generous with your time. There are just a couple other things that I would love to ask you about. You already mentioned John. Jim Bridenstine, NASA administrator, was there with you.

Spoke a couple of times at the briefing yesterday. And he looked like he was as thrilled as anybody could have been to be amongst all of you. Did you like what you heard from him as he saluted you? But he also looked to the future. He said, this is not the end. He said, eventually, we're going to put boots on Mars. And those boots are going to be there with robotic boots or wheels. First of all, I think it meant a tremendous amount to the team that he took the time to come out in person and be here. You know, he's got an incredibly busy schedule, and it just shows a tremendous amount of respect from him to the team. And it really was a gesture that we sincerely appreciated.

You know, it was interesting to hear the comments about the future of exploration. And there's a long way to go between the rovers we have on Mars and boots on the ground. And so I'll be interested to see what the plans are between, you know, what comes after 2020. We've been talking about the importance of a sustained program of Mars exploration and early career scientists like myself, we're asking, okay, we're trained up, we know how to run these rovers. What's next? And so I really do hope that that is a focus in considering the importance of what needs to be completed before we get boots on the ground.

He did also mention sample return. We should be going there, right? Yes. You know, if we want to definitively establish whether there was or is life on Mars, we need to do sample return. We need to bring back carefully selected, curated samples from the surface of Mars and examine them in the expert laboratories here on the Earth to determine that definitively. So, yeah. Have we graduated from follow the water to find the life? So we've absolutely graduated from follow the water. I think that there are two kind of emerging

questions that are equally interesting in terms of life. There's of course the find the life question. Can we find evidence for present or past day life on Mars? But I think what is also becoming extremely interesting is the idea of thinking about Mars in a system way as a terrestrial planet. You know, how did the climate of Mars evolve over time? What were the factors that made Mars habitable in the past? And why is it uninhabitable? How does that compare to Venus? Why is Venus not habitable? is it uninhabitable? How does that compare to Venus? Why is Venus not habitable? I think Mars is an amazing place to study these questions because so much of the rock record is so old.

We don't have those rocks that are that old on Earth anymore because plate tectonics have recycled it, but Mars doesn't have plate tectonics. That's another interesting question. Why not? What gives a planet plate tectonics? How does that make it habitable or not? And all of these wonderful questions, I think, can be answered by going to Mars, by going to Venus, by going to these planets in our own solar system. And then we can extrapolate what we learn to exoplanets around other stars. You know, we talk about the habitable zone. We see a planet a certain distance from the sun. Well, how do we know that that's habitable? How can we make a guess? Does it have plate tectonics? That's probably a huge driver. So Mars is a fascinating place. I think let's look for life there, sure, but let's also use it as a laboratory to learn

how planets work. John, I wish our audience could have been watching your expressions as Abby spoke, as I was. Obviously, you agree. I do. Mars can answer many big questions. And, you know, the question of are we alone, but also what is our future? I mean, we're struggling with the challenges of climate change and the need to be good stewards of our planet. So by studying other worlds, we can learn more about our own world and be informed about making those decisions. What's next for the two of you? So for me, I've been pretty involved with Curiosity rover operations. So I think I'm going to continue to do that and probably start spending more time on that because I'll have the time available and hopefully also taking the time to write some of the papers about what Opportunity was finding.

You know, we have a whole story about Perseverance Valley that we need to tell. Abby's being modest here. She actually led the scientific campaign on the Vera Rubin Ridge on Curiosity. So she's been quite involved in science operations on Curiosity. I have those papers to write, too. John, 20 years of your life. Well, I'm going to be the new host of Planet Radio. You didn't get the memo.

I guess not. I have to go talk to the boss. Excuse me. Well, you know, there is so much to explore out there, and there are so many exciting opportunities. And I've been, for some time now, been helping out in exoplanet exploration. And so we'll be helping to advance that field because there are now an incountable number of worlds out there for us to explore as we've been exploring Mars.

I'm going to close pretty much where we started by talking about the emotional attachment that the two of you have, I think that Emily and I have, to these rovers. Your team has. But it is a worldwide phenomenon. I saw it in the coverage yesterday. I was watching the PBS NewsHour and Judy Woodruff, I would be willing to bet, was almost tearing up a little bit as she talked about the end of this mission. And I think we all share this sense of sadness, but also a good deal of warmth and pride. We sure do here at the Planetary Society. Congratulations and thank you to both of you and to the entire team.

Great to be with you and to share this story. Yes, thank you so much. Mars Exploration Rover Project Manager John Callis, Deputy Project Scientist Abigail Freeman, and Planetary Society Senior Editor Emily Lakdawalla joining me in the Society studio on Thursday, February 14th, Valentine's Day, and the day after the Mars Exploration Rover mission was declared complete. May all our explorations end so triumphantly.

Time for What's Up on Planetary Radio. Bruce Betts is the chief scientist for the Planetary Society, and he is back with all of the great little features of this segment of our show that has been going on for 16 and almost 16 and a half years. Welcome back. Thank you. Good to be back, Matt. I've got lots of planet stuff in the sky to spew at you today. In the evening, we've got Mars in the southwest getting,

still looking like a bright star, but not that bright, looking reddish. But if you use Mars, you can then go a few degrees below Mars with some binoculars and see Uranus. Or a telescope. You'll probably want to get a finder chart online if you're going to go hunting Uranus. Or if you're in an amazingly dark site with really good eyes, you might just see it. But otherwise, probably not. And Mercury, speaking of things that are tough to see, Mercury plenty bright, but very low in the horizon in the evening west. Be getting a little bit higher over the next week or so. In the pre-dawn, we've still got the beautiful sky show from upper right to lower left. Bright Jupiter, medium bright, yellowish Saturn, and then Venus just shaming them both below that.

And, and, don't order yet, the crescent moon joins the party being near Jupiter on the 27th and Venus on the second should be quite lovely. Go see it, Matt. I will. And we've had some beautiful skies down my way. And so I will do my best to check these out. Of course, I'm still stuck back on your intro line, which sounds like you stole it from my bio, a bright star, but not very bright. No, Matt, you're the Venus of our lives. Okay. Hey, Venus. Go on. All right. This week in space history, 1962, John Glenn became the first American to orbit the

Earth. And 25 years ago, 1994, the Clementine mission went into orbit around the moon, did some nice moon studies, checked out a bunch of technology, and was an interesting partnership between the Strategic Defense Initiative Office and NASA. And a relatively small spacecraft, which reminds me of a little CubeSat. I meant to warn you about this, that I might ask you about it before we started recording, but didn't. What's going on with LightSail? LightSail 2 is snug in storage at Cal Poly San Luis Obispo. We pull it out every month or two and charge its batteries. And we may be getting close to launch, but I've heard that before. We are now on the next launch of the Falcon Heavy, which we thought was going to be ours, is actually going to be a communications satellite called Arabsat, and that may be coming up in a month or so. And then we're

sometime after that on the next launch of the Falcon Heavy. Thank you for that somewhat out of context, I suppose, update. We move on then to random space fact. As of February 2019, there are five objects that are called dwarf planets, Ceres, Pluto, Eris, Makemake, and Haumea. If you add the masses of all the dwarf planets together, the total is less than half the mass of the Earth's moon. That is just great. I'm letting it sink.

They're just not that big. No, they're really not. Or our moon is really huge. Well, it is one of the largest in the solar system, but it's still a heck of a lot smaller than Earth. All right, you ready to move on to the trivia contest? Why not? I don't know.

No, it's a rhetorical question. You can go on. Oh, sorry. Okay. All right. I asked you, how long was the longest Skylab mission? How'd we do, Matt? Very well. A lot of people must be interested in this book that we're giving away, and it looks like we're going to be giving it to a first-time winner, Kevin Cowder, or Cow-ger, he didn't give me a pronunciation guide, of Cremora, Virginia, who says that the longest of the Skylab missions, the longest that any of those crews stayed on board Skylab, any of those crews stayed on board Skylab was the so-called Skylab 4 mission, which went for 84 days. Not bad. Indeed, that is the correct answer. The third mission with humans on Skylab known as Skylab 4. All right, Kevin, congratulations to you. You will be getting the full set of Kik asteroid stickers from Chop Shop via the Planetary Society and the

oversight of our friend, the chief scientist, and a 200-point itelescope.net astronomy account, along with, and this is the biggie for this time, I guess, the Universe Today Ultimate Guide to Viewing the Cosmos. You might think of it as the adult version of Astronomy for Kids from the chief scientist there. This is by David Dickinson with Fraser Cain. Fraser, of course, the publisher of Universe Today. It has a forward by our friend Dr. Pamela Gay. It's from Page Street Publishing.

It's a beautifully done book, and we will put it in the mail to Kevin. Got some other stuff. Galen Drinnen in Toronto, reading through some articles about the Skylab missions, he was amazed to learn how many glitches, failures, and unexpected challenges they face, but also how they were ingeniously repaired by NASA and the astronauts on board. Riveting stuff, Galen says. That's true, man. Right from the start, man. They had terrible problems with Skylab, right? Yeah. They had all sorts of struggles with it. Also,

it sounds like you were describing me glitchy and failures. Now I'm sad. Don't be sad. Norman Kassoon in the UK. The crew photographed the Earth from orbit. Despite instructions not to do so, the crew perhaps inadvertently photographed Area 51, causing a minor dispute between various government agencies as to whether the photograph showing the secret facility should be released. In the end, the picture was published along with all the others in NASA's Skylab image archive, but remained unnoticed for years. I wonder if they caught the aliens waving up to them. Martin, Martin Hujoski, their splashdown, that is the splashdown of the three members of the crew, Gerald Carr, Edward Gibson, Hoot Gibson, and William Pogue. It was 353 kilometers south-southwest of Los Angeles. The closest any landing of a NASA-involved space mission came to the headquarters of the Planetary Society,

at least since, he adds, Bill Dana in the X-15 in 1968 at Edwards Air Force Base. Wow. Is this obscure? That is an awesome random space fact. That's beautiful. Air Force Base. Wow. Is this obscure? That is an awesome random space fact.

That's beautiful. 160 kilometers away is Edwards, as we know, because we've driven out there several times. Finally, this from Andrew Zimmerman in Tokyo. Skylab, despite the Apollo veterans among the crews, these missions never received their due recognition. He says, as a young boy of the 70s, however, I was enthralled. He's pretty much right about that. These were real pioneers doing stuff that nobody had ever done before, and they deserve great kudos even today. That is so true. Speaking of anti-kudos, I need to correct something you said, Matt. What'd I say? You referred to Edward Gibson as Hoot Gibson. Oh, I said Hoot, didn't I? Yeah. Sorry about that. Hoot Gibson is Robert

L. Gibson, an astronaut in a later time period, veteran of many shuttle missions. Edward Gibson, the veteran of Skylab 4. Thank you for that. I'm glad you know your astronauts. Yeah. They just deny that they know me. All right. What do you got for next time?

For next time, we return to the magnificent land of dwarf planets. Of the five dwarf planets as of, you know, now, which is the only one that does not have at least one moon? Go to planetary.org slash radio contest. All the others, they got moons. You know, you got your list to work from, from Bruce earlier in the segment. Which one doesn't have a moon? Let us know by the 27th, February 27th at 8 a.m. Pacific time.

And we will award you a kick asteroid, rubber asteroid. I was able to do it this time, along with a 200-point itelescope.net account. And you can use those remote telescopes that are all over the world to try and catch one of those dwarf planets. Good luck with that.

I think we're done. All right, everybody, go out there, look up at the night sky, and think about your favorite spacecraft that's no longer communicating with us. Which one would it be? Thank you and good night. Ah, there's so many to choose from, sadly. He's Bruce Betts, the chief scientist for the Planetary Society, who joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California,

and is made possible by its Martian members. Mary Liz Bender is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser. I'm Matt Kaplan, Ad Astra.