Planetary Radio • May 11, 2022

Perseverance Perseveres: A Mars rover update from Ken Farley

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Kenneth Farley

W.M. Keck Foundation Professor of Geochemistry for California Institute of Technology

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Mat Kaplan

Senior Communications Adviser and former Host of Planetary Radio for The Planetary Society

Perseverance, the Mars 2020 rover, has begun an exciting new phase of its mission. Project scientist Ken Farley tells us why the ancient river delta it has entered is so enticing and intriguing. Ken also salutes Ingenuity, the Mars Helicopter, as we look forward to the day when samples of the Red Planet are sent to Earth. What did the Wright brothers, those pioneers of powered flight, contribute to the Apollo and space shuttle programs? Bruce Betts has the answer in What’s Up.

Jezero Crater on Mars
Jezero Crater on Mars Jezero Crater is the landing site of NASA's Perseverance rover. In the center of this image captured by the European Space Agency's Mars Express orbiter, the remains of an ancient river delta are visible. On Earth similar deltas preserve a record of past life.Image: ESA/DLR/FU-Berlin
Expanse of Jezero Crater's river delta
Expanse of Jezero Crater's river delta NASA's Perseverance Mars rover looks out at the expanse of Jezero Crater's river delta. The color bands of the image have been processed to improve visual contrast and accentuate color differences. The sky would not actually look blue to a human explorer on the Red Planet.Image: NASA/JPL-Caltech/ASU/MSSS
Perseverance Examines Ingenuity
Perseverance Examines Ingenuity NASA's Perseverance Rover examines the Ingenuity helicopter on 7 April 2021 prior to the helicopter's first controlled test flight.Image: NASA/JPL-Caltech/Kevin M. Gill
Perseverance's landing gear from above
Perseverance's landing gear from above Mission engineers for NASA’s Perseverance rover asked the Ingenuity Mars helicopter team to capture images of the landing gear that brought the rover and ’copter to the Martian surface in February 2021. The photo, which shows the parachute in the distance and the demolished backshell in the foreground, can help mission engineers understand the landing system’s performance and improve the design for future missions.Image: NASA/JPL-Caltech

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Why is there a depiction of a snake on the Perseverance rover?

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Complete the contest entry form at or write to us at [email protected] no later than Wednesday, May 25 at 8am Pacific Time. Be sure to include your name and mailing address.

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Name all asteroids that are bigger than Psyche and that have already been visited by a spacecraft. Exclude Ceres as it is now classified as a dwarf planet.


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Question from the April 27, 2022 space trivia contest:

What was the last spacecraft to do a Venus flyby? Venus orbiters do not qualify.


The last flyby of Venus by a spacecraft not going into orbit around that planet was the Parker Solar Probe in October of 2021.


Mat Kaplan: Perseverance perseveres with Rover Project Scientists, Ken Farley. This week on Planetary Radio.

Mat Kaplan: Welcome. I'm Mat Kaplan of The Planetary Society, with more of the human adventure across our solar system and beyond. Perseverance, the Mars 2020 rover, has entered an exciting new phase as it explores an ancient river delta on the red planet. If we're going to find evidence of past life, this could be the perfect place to look. That's according to the leader of the MissionScience effort. I'll explore this and other topics with Ken.

Mat Kaplan: Bruce Betts reminds us that a total lunar eclipse arrives soon for many of us on planet Earth. He'll have the details when we reach this week's What's Up. You'll also get the chance to win a great new book about all eclipses that includes solar eclipse viewing glasses, two pairs. I'm about to start an interesting couple of weeks. First up, will be my return to the Humans to Mars Summit from Explore Mars. You still have time to join some of the Mars community's biggest stars in Washington, DC, Tuesday through Thursday, May 17 to 19. I'll be co-hosting the webcast and moderating a couple of great sessions on the H2M stage. Check out the details at

Mat Kaplan: Then there's my upcoming return to London. We're now taking reservations to join us for Planetary Radio Live on the evening of Monday, May 23rd. I'll be at Imperial College London with Amanda Lee Falkenberg, composer of the Moons Symphony. On stage with Amanda and me will be artist and ISS astronaut, Nicole Stott. Cassini project scientist, Linda Spilker. You know her. Planetary scientist, volcanologist and author, Ashley Davies. And Imperial professor, Mark Sephton, a member of the Europa Clipper Science Team.

Mat Kaplan: You'll find a link on this week's show page at, but you can also go directly to Eventbrite. Plug in London as the location and search for Planetary Radio Live, we'll pop right up. I hope to see you for this first PlanRad Live since the pandemic began. We'll talk about the glorious intersection of art and science represented so well by the Moon Symphony. I can hardly wait.

Mat Kaplan: Did you catch last week's visit to the Jet Propulsion Lab and the Psyche spacecraft? This probe that will head for the metal asteroid of the same name has now arrived at the Kennedy Space Center for its launch in August. You can learn more when you read the May 6th edition of the Downlink, our free weekly newsletter. You'll also read about China's plans for its own asteroid deflection test, much like NASA's DART mission. I'm okay with another space power taking planetary defense seriously. And up at the top of the Downlink is the spectacular image of the parachute and backshell that helped get Perseverance safely down to the surface of Mars.

Mat Kaplan: Ken Farley and I will talk about this snapshot grabbed by Ingenuity, the Mars Helicopter. You'll always find the Downlink at, what else? Downlink. Ken Farley is the W.M. Keck Foundation Professor of Geochemistry at the California Institute of Technology in Pasadena, California. He directs the Noble Gas Lab at CalTech, where they use a lot of very cool equipment to investigate geochemistry and what the lab calls, Martian geochronology, figuring out the age and history of red planet rocks and soil.

Mat Kaplan: There's just one problem. They don't have any Martian rocks or soil to test directly. And that of course, is why Ken is one of the many Earthbound scientists who would give their right arm for even a few grams of Mars. It's that quest that keeps Ken at the nearby Jet Propulsion Lab and away from his own lab, more than he'd probably like. As project scientist for Perseverance, he leads the worldwide science team and works with the engineers.

Mat Kaplan: They get the rover to the most promising sites in Jezero Crater, where it collects samples of the material that will someday return to labs like, well, his own. It's a big job, which is one reason I was so grateful for the chance to talk a few days ago. Ken Farley, welcome to Planetary Radio. This is your first Planetary Radio interview. You've been heard on the show many times as part of bits and pieces of press briefings that we've covered. And a lot of your team has been on the show, including your deputy project scientist, but it is an honor to get you on. So thank you for joining us.

Ken Farley: Yeah, thank you for having me.

Mat Kaplan: Let's start with the health of the rover. How's it holding up?

Ken Farley: Very well. We have no serious issues with the rover itself, and the science instruments are performing very, very well.

Mat Kaplan: Thank goodness. That is the best possible news, of course, other than maybe the great science that you're doing. I read that what you call Campaign #2 began on April 18th, the 415th sol or Martian day since you landed. And you're calling this new campaign, the Delta Front. Tell us about it.

Ken Farley: We completed the first, about year on Mars exploring the crater floor. And then we began a long drive to get us to the main target that brought us to Jezero Crater, which was the delta. The geologic feature that tells us there was once a lake in this crater. We've now arrived at that feature and are starting to explore the sedimentary rocks that were once deposited in the lake or in rivers that were filling the lake.

Mat Kaplan: Absolutely fantastic. Well, how many samples have been collected to date?

Ken Farley: We've collected four samples, four different rocks. And we've taken pairs of each one of those, so we filled eight sample tubes with rocks.

Mat Kaplan: So that is impressive in itself, of course. I mean, is there greater excitement about this new region because of the characteristics that it has, this delta?

Ken Farley: Definitely. As I said, this delta, it was produced about 3.5 billion years ago when Mars was very different to today, in a period when there was flowing liquid water on the surface. And because one of the central goals of the Mars 2020 mission is to look for the possibility of ancient life on Mars in this very distant time period, this is a very good place to look. A lake is of course, a very habitable place. The rocks that we found on the crater floor turned out to all be igneous rocks. They are not the kind of place where you go to look for life, but rocks that were deposited in the lake, very habitable.

Mat Kaplan: How long do you expect this campaign will last, and how much Martian territory do you think you'll cover in that time?

Ken Farley: This campaign will be very different from what we've been doing, which involved a fair bit of driving across long distances. Instead, here we will spend about the next, maybe six or eight months, in a quite restricted area. And that's because the delta has a very steep, almost a cliff, at the base which we call the Delta Front. And that's wonderful for exploration because the layers of the sedimentary rocks are exposed in this cliff. So we will spend this campaign exploring the layers that are outcropping in the Delta Front.

Mat Kaplan: Does this mean that it's a little bit more difficult for the rover to get around? I mean, what was involved in laying out your path through this part of the delta?

Ken Farley: Yeah, there were some interesting challenges that were new to us. In this area, the geologic targets are between sand ripples. Makes it a challenge for us to get to exactly where we want to go. The ripples are relatively small, and so far so good, we are able to navigate through them. One of the first things that we do is we lay out the route that the rover can go and decide where the best science can be done. Fortunately, this forms a cliff in most places along the Delta Front in the area we are right now, it's almost like a valley cuts down through it. And so we can drive up a relatively shallow grade allowing the rover to have access.

Mat Kaplan: Where is the rover right now? I mean, I know you give names to all the different areas you drive through and the features that surround the rover.

Ken Farley: We are in the middle of what we call the Cannery Passage loop, that is just at the base of the delta. So we are now taking images of the Delta Front, and we will, within the next few days be driving for the first time on the delta.

Mat Kaplan: I saw that term Cannery Passage. And I got to ask, is that a tribute to one of my favorite books, John Steinbeck's Cannery Row?

Ken Farley: Not exactly.

Mat Kaplan: Too bad.

Ken Farley: Yeah, it's a very interesting way that we assign names. We have decided beforehand, before we even landed, that specific areas on the crater floor, we would use target names that are taken from names that occur in national parks and preserves around the world. And the area that we're in right now from which Cannery Passage was drawn, is from the Katmai National Park. So Katmai is in Alaska. And I don't know what Cannery Passage is, but it must be a geographic feature in coastal Alaska.

Mat Kaplan: And I bet it looks somewhat different from where Perseverance is right now.

Ken Farley: Yeah.

Mat Kaplan: Are you and the other members of the science team, is there a lot of exciting stuff that you're driving through?

Ken Farley: Yeah. The rocks of the Delta Front, they have lots and lots of fascinating details. The layers are exposed so beautifully that we've just been acquiring an enormous number of images so far to figure out what the story is that the delta will tell us about how this lake filled. It might have expanded, it might have contracted, it might have had rivers flowing into it at one point. So far, we're just trying to figure out what the images are telling us. And then in the coming days and weeks, we'll start using our instruments that we need the rover to be up close with the rock to start seeing what the rocks will tell us. And I expect that we will acquire samples quite soon.

Mat Kaplan: Let's talk about that. You've been very judicious about where and when to collect samples. Can you say something about, what is the process for deciding to use one of those precious tubes?

Ken Farley: We started really going back years. As soon as we had selected the landing site, we started thinking about what is the proper diversity of rocks, the number of rocks, different kinds of rocks that we would want to collect in this area. We called that the notional cache. And now that we're on the surface, we are using that as a guide to figure out where we should be sampling. And to some extent, also where we're driving. The challenge is that it's easy to say in the abstract, "Yes, I want to collect a rock that was once a mud at the bottom of the lake." That sounds great. You got a rock in front of you. Is that a mud that was once on the bottom of the lake? And so this is why we have to use our instruments on the rover to actually look closely at these rocks and figure out if they fit the bill.

Mat Kaplan: About those instruments, you've got seven of them all told. One of them, that great demonstration of how we might make oxygen for people in rockets someday on Mars MOXIE. But it's obvious that the science that is coming from those while they're helping you to select sample sites, there is a great deal of science being done that's already has been delivered back to Earth in the form of data. Can you say something about what we're learning?

Ken Farley: The most surprising thing we've learned is that the rocks on the floor of the crater. So essentially downhill from the delta, we had expected, at least most of us had expected that those rocks would be rocks that were deposited in the lake. And they're not. They are igneous rocks. That took us quite a while to determine and then to really get our heads around. But what does this mean? It's quite puzzling. I have to say we still haven't quite figured out how all of that works. Undoubtedly, there were sedimentary rocks present, for example, where we landed that have eroded away. And this is one of the most interesting stories when you try to understand the way Mars works, you have to recognize that we are looking at billions of years of geologic history, such that that lake was present 3.5 billion years ago. And those rocks would've been deposited then, but they've had an enormous amount of time to erode away. It's very unearth like.

Mat Kaplan: It seems also that there... We're hearing, once again, a lesson we hear all the time on this show. And that is, even a planet that we are coming to know... Well, we know it's so much better now than we did 40, 50, even 20 years ago. Mars is still full of surprises.

Ken Farley: Yeah, absolutely. And we have very detailed orbital images that led us to believe a number of things about this landing site. And then when you get on down on the ground, some of those hypotheses are confirmed and others are refuted. And then there are things you just can't possibly have known from any data collected before. For example, these rocks on the crater floor, they're igneous, but they have also interacted with water. Maybe groundwater. Isn't really clear what the source of the water was. But those rocks were sitting in water for some significant amount of time. And that's really interesting from the point of view of looking for potentially habitable environments where each Martian microorganisms might have been able to live.

Mat Kaplan: You probably know that we at The Planetary Society have a special connection to Mastcam-Z and its principal investigator, Jim Bell. Are you as blown away by its performance as we are?

Ken Farley: Yeah. The images that Z cam is producing are really spectacular, I would say. Every month or so, I send an email to Jim and say, "Fantastic mosaic that you all just brought down." The Z cam images, they're science tools obviously. We use them all the time to do science. They're literally the first thing I look at when we start getting data down at the beginning of the day. First thing I look at because they just make me feel like I'm there. For me, that's the excitement of it like, "Wow, we are here." The human presence is up there on Mars.

Mat Kaplan: [inaudible 00:15:38]. I was at Arizona State University not too long ago and visiting with Jim and some other folks. But I also got to see the meeting that his group there leads, I guess every day or almost every day, deciding what to do with those mighty cameras on top of the Mastcam. And it said a lot to me about how this mission is spread not just across the United States among scientists here, but the international nature of this mission as well. And the hundreds, if not, thousands of people who are contributing to it.

Ken Farley: It's a huge team. And it's a fascinating human endeavor in the sense that many of us have never met each other. That would be different if it were not for the pandemic, but most of the operations among the science team they're done remotely, and I have not met the [inaudible 00:16:34] of these team members. It's kind of weird that you recognize people's voices better than you recognize their face.

Mat Kaplan: I also have to mention those microphones that are telling us what Mars sounds like for the very first time. Something that has been near and dear to The Planetary Society for decades, as you probably know. Is that sound, is it enabling real science as the rover rolls across the planet?

Ken Farley: Yes. It's doing a few things that are... I think partly they're just interesting to hear. The sounds of the rover crunching across the ground.

Mat Kaplan: Oh yeah.

Ken Farley: That's another aspect of... Yeah, it's like you're being there. You can hear those sounds. And you can hear the sound of the wind is kind of a lonesome sound to me. But there's also really interesting information content that's coming out of that, that I at least had not been anticipating. For example, there have been studies done to determine speed of sound in the Martian environment using Ingenuity, the helicopter, as a sound source. So that's pretty interesting. And the other thing which is really fascinating is you can get high frequency information on the wind from the microphone. It's at frequencies that are too high to be measured with the wind sensors on the weather instrument called MEDA. So it's very interesting to see all that play out.

Mat Kaplan: I am very glad that you mentioned Ingenuity, that cute little whirly bird that Perseverance carried to the red planet. And the rover still support, still enables it to communicate with us. I'm especially thinking of those images that were released yesterday, as you and I speak, of the backshell and the parachute that helped get you down to the surface. I wrote to your colleague JPL Chief Engineer, Rob Manning about them yesterday. He said to say hi, and he added, "Yes, it's very cool and weird to see our once pristine white backshell now toasted, squished, and dusty sitting on another planet, awaiting future archeologists." I mean, were you surprised to see Ingenuity become not just a little test of technology, but a real contributor to your overall mission?

Ken Farley: Yes, this was completely unexpected. And just to remind everybody that the Ingenuity was a technology demonstration. It was meant to do five or six flights and declare victory. It did that. And then we realized, "Hey, this helicopter is showing no indication of not being able to survive for the long term." And so now, essentially a year later, we continue to have Ingenuity with us. It was an interesting challenge to have Ingenuity keep up with us when we drove. We just completed a five kilometer drive in just about one month. It was hard for Ingenuity to keep up with us, but Ingenuity was able to take a shortcut across an area that the rover could not drive. And now, as you saw from those images, Ingenuity is doing work for us, characterizing the landscape and also the entry, descent, and landing hardware.

Mat Kaplan: Absolutely amazing. There's one more tribute just to the engineering of the rover that I have to make, and it's also something we've talked about in the past. I've had people describe Perseverance to me as a robot with another robot inside it. I'm talking about that absolutely amazing mechanical system inside for handling your samples. And of course, it takes up a lot of the room that, on Curiosity is filled up with robotic laboratories. I mean, you've been with this for so long now, I wonder, do you still sometimes just marvel at what this machine is capable of doing?

Ken Farley: Yeah, absolutely. And I have to say, as I live through the development phase... It's one thing to see it on paper or hear the engineers talk about it. And then I saw the first video taken in the test bed several years ago, and I thought, "Wow, what have we done? This thing is so complicated and it must work." It is mission critical. Our central objective of collecting samples demands that this thing work. We've had some interesting challenges. We got some pebbles jammed in the mechanism about three, four months ago. We got them out. Hopefully, we will continue to be successful in keeping it going.

Mat Kaplan: So what comes after this current Delta Front campaign?

Ken Farley: We will complete the prime mission in a little over year and a half. And then, presuming we get extended, the idea is we will continue towards the rim of the crater where we will cross an area that we call the marginal units. It is possible those are lakeshore deposits, or even rocks that were deposited directly in the lake. Carbonate rocks deposited in the lake. And then the current plan is we will then drive up the crater rim, it's almost a kilometer high, but we'll drive up the rim and explore the area surrounding the crater called Nili Planum, geologically completely different than where we've been.

Mat Kaplan: Lot of excitement to come. I was looking at your CalTech website not long ago, your personal site. And I recommend listeners, take a look. We'll put the link on this week's show page How do you find time to lead the Perseverance science team and continue your own research?

Ken Farley: Well, I ask that myself. Seriously, it is all about working with the right people, both on the rover mission and in my own laboratory. One of the things that is really interesting as a professor who has spent, until recently, my entire career working with a small number of people joining the Perseverance team which at its peak, probably had more than a thousand people working on it, is to just trust everybody to do their job. And that's been really rewarding to me to play a part in these really big teams with people you can trust. So that's my way of coping with too much to do, work with the people that make it happen.

Mat Kaplan: You know, I love that photo of hundreds of rover team members that was taken outside at JPL not too long ago, I guess. And it sure gives you a feel for what it takes to pull off something like this.

Ken Farley: I think it's really easy to forget that. What that drives home for me is how exclusively complicated this piece of hardware is. It's just a marvel. And people, individuals built this marvel bit by bit. It's just incredible.

Mat Kaplan: I got just one more for you. Are you still running those ultra distance foot races?

Ken Farley: I have had to put that aside. That's one of the things that when I got fully engaged in this mission, I just did not have time. If you want to run a hundred miles, you need to train a lot. And I was just not able to keep up with that.

Mat Kaplan: So here's where I'm going with this, a hundred miles. Do you think we'll ever have robots with that kind of ability on Mars or elsewhere, to find their way as quickly as a human can down here on Earth?

Ken Farley: I don't know about as quickly, but I have no doubt we will be able to cover on Mars long distances. And part of the reason for that is the computer revolution is coming. On Perseverance, we're using a very old processor because it's flight qualified. But when the revolution that allowed autonomous driving on Earth to happen, when that comes to space exploration, that's going to be huge.

Mat Kaplan: And isn't Perseverance doing some autonomous driving now? I mean, you say, "We need you to go over there." And it kind of finds its way.

Ken Farley: Well, more than kind of. It really does find its way. We put on board, specifically for this purpose, a dedicated processor for doing image processing. And that has allowed us to drive up to about 300 meters in a single sol. It is still necessary for us to have ground in the loop to do a lot of the things that we do, but the autonomy that's facilitated by a really fast processor. If you can start taking ground out of the loop, meaning that meeting all the people back at JPL and around the world that are making this mission happen. When you can let the rover, or whatever the spacecraft is, make its own decisions, that'll really speed everything up.

Mat Kaplan: We sure have come a long way from little [inaudible 00:25:24], or haven't we?

Ken Farley: Yeah, absolutely.

Mat Kaplan: Ken, you have a lot of us out here. Certainly everybody listening to this show who will be following along, as you, your team, and that rover continued to explore and pick up bits of Mars for later return to Earth. Cannot wait to get those samples back into big labs down here on our home planet. Best of continued success as the exploration continues. We'll be following.

Ken Farley: Yeah, thank you very much. And thanks for having me on.

Mat Kaplan: A quick break now for a message from someone my brother and sister Star Trek fans know well. I'll be right back for more fun with Bruce Betts, including the new space trivia contest. Ladies and gentlemen, here is John de Lancie also known to many of us as Q.

John de Lancie: Star Trek has always represented the hope for a better future. I don't think you can have that without pushing boundaries. And in the case of space, that is all that we're doing, is pushing those boundaries and finding out more. Always finding out more. And I think it's really important as a human being, as a society, to be able to do something like that. And this is where we do it. 200, 300 years ago, we did it on sailing ships across the ocean.

John de Lancie: Space is important to me because it's kind of a metaphor for risk-taking tremendous rewards, possible rewards, being more expansive in one's thinking, and opening one's self up to the infinite possibilities. Probably the biggest thing that differentiates Star Trek from almost everything else is the community in which you enter. Well, The Planetary Society is that type of a community. If you share like me, the need to expand into infinite possibilities as my character does in Star Trek. And as I have said to Picard on more than one occasion, then certainly, joining The Planetary Society is a good way to go. Join The Planetary Society.

Mat Kaplan: It's time for What's Up on Planetary Radio. Bruce Betts is the Chief Scientist of The Planetary Society. He is with us yet again.

Bruce Betts: And we've got the lunar eclipse. Total lunar eclipse turns out once in a while. That crazy moon passes through the Earth's shadow. It's gone right through the middle of the Earth's shadow this time, so it'll be a nice long period of totality. That'll be the night of May 15th or 16th. It is visible from North America, yay. And portions of Western Europe and Western Africa. You can check out it beginning at 2:27 UTC on May 16th. That's Pacific Time 7:27 PM on May 15th.

Mat Kaplan: Does the moon ever say, (singing). Probably not.

Bruce Betts: Thinking. I've not personally heard it say that.

Mat Kaplan: In space, no one can hear you sing bad renditions of Cat Stevens.

Bruce Betts: That was my second favorite thing about space. All right. By the way, totality starts at 3:29 UTC on the 16th, 8:29 PM on the 15th for Pacific Time. And totality lasts about an hour and a half, and should get nice and dark as it goes through the middle of the Earth's shadow (singing). If you're up in pre-dawn check out super bright Venus, low in the east, and above it, bright Jupiter. And above that, reddish Mars and yellowish Saturn. This weekend's space history. 1973, Skylab was launched starting the series of Skylab. First US space station missions. Onto space fact.

Mat Kaplan: You can't place that. I don't know what Cat Steven song that was, but go ahead.

Bruce Betts: Oh my God. The Wright Flyer, you may have heard of it. First powered flight, 1903. I don't know where they're getting all the pieces from it, but pieces have flown and on various missions. So it's intriguing. The missions that pieces of the Wright Flyer have flown on. Neil Armstrong took some on Apollo 11 to the surface of moon and back. And I didn't realize this one that in 1986, it was on the unfortunate Challenger that blew up. They were taking it to space. What's more amazing is they recovered it. They recovered the wood and fabric and a note from Orville, right? And those are on display at a North Carolina Museum of History.

Mat Kaplan: Oh my, that just floors me. Wow.

Bruce Betts: In happier, happier, happier news, a small piece of the wing fabric is attached to a cable underneath the solar panel of the helicopter, Ingenuity, flying around on Mars. First powered flight on Mars is flying part of the first powered flight on Earth.

Mat Kaplan: I didn't know that either. How cool. I hope they listen. I hope they can find little bits and pieces that they can take along with them right up until the point we reach Proximus Centauri. So that's fantastic, thank you.

Bruce Betts: The Wright Flyer at the Smithsonian will just be like a framework, because they will have taken all the pieces and flown them elsewhere. I asked you, what was the last spacecraft to do a Venus fly by, orbiters don't count. How'd we do Mat?

Mat Kaplan: Oh man. Did you throw people off here? And I think it's just because so many references online probably haven't been updated. We got BepiColombo from a lot of people. BepiColombo that ESA probe headed to mercury. It passed by Venus last, in August of 2021, apparently. But that's not the most recent, was it?

Bruce Betts: No, it wasn't. It was the Mat Kaplan. No, what did we find out Matt?

Mat Kaplan: You're close. You're close. Here's the answer from Dave Fairchild, our poet laureate in Kansas. "If you are a solar craft, then Venus is your gravity helping you improve the way you reach the sun more agilely. Parker is a solar probe, and that's how NASA gets it done passing by our neighbor in October 2021."

Mat Kaplan: Hey, sorry, everybody. There were the huge number of you who came up with BepiColombo, but I think even more who got it right with Parker Solar Probe. And one of those was Keith Landa. Keith, congratulations. You were chosen by Keith in Connecticut. Actually a part of Connecticut that I know very, very well. He indeed said, "Parker Solo Probe on the 3rd of October 2020." I'm sorry. I think that date's wrong, but it was in October of 2021. Good enough. So Keith, we are going to send you a copy of The End of Astronauts, Why Robots are the Future of Exploration by Don Goldsmith and Martin Rees, UK's Astronomer Royal, who of course we talked to just a couple of weeks ago on the show. The book is from Belknap Press, which is an imprint of the Harvard University Press.

Mat Kaplan: Elijah Marshall in Australia. He says, "I should stop entering the trivia contest. The rabbit holes are getting out of hand. Seriously interesting, but way too deep." They're just right, Elijah. Just keep it up. Or Eli. Sorry, I think he prefers to go by Eli. Alan Mosley was a little bit off. He said, "Most recent Venus fly by, was it the Tesla Roadster? The electric car?" I'm sorry, Alan. No, no, the Tesla's last fly by was it as it happens at Proximus Centauri. So I'm sorry. Not eligible in this particular contest. Mel Powell, our funny guy in California, "Venus has got to be getting annoyed by now. Parker Solar Probe has made five fly bys so far and it's not done yet. If something buzzes my head five times, I go for the swatter."

Bruce Betts: That would be unfortunate.

Mat Kaplan: Joe Calaputray in New Jersey, "Getting so close to the sun, will the Parker get baked like a roll?" Get it, Parker House roll.

Bruce Betts: Nah, I don't get it.

Mat Kaplan: Parker House rolls. Those delicious, slight fluffy, white bread. Nevermind. All right. Finally, one other poem from a poet we've never heard from before. Gregory Vanderslice in Quebec, Canada, "Leaving our globe doesn't sound like much fun, unless you were a probe set to visit the sun. Then you would surely not protest, being the answer to this week contest."

Bruce Betts: Nice.

Mat Kaplan: We can move on.

Bruce Betts: I like this one. Why is there a depiction of a snake on the Perseverance rover? Go to

Mat Kaplan: I certainly do not know this one. Maybe you do or maybe you can find out if so. End of the contest, and guess what? You have extra time because I'm going to be out of town first at that Human to Mars Summit that I mentioned upfront, and then in London, as I also mentioned upfront. So I've got that Planetary Radio Live show, so that if you're going to be in the area of London...

Bruce Betts: Don't abandon me.

Mat Kaplan: I know. I'm sorry. I'll be back, I promise. May 23rd is that show in London at Imperial College London where we'll celebrate the Moon Symphony. And we have that link because reservations are necessary. We've got the link on this week show page of Love to see you. But because of that, we're going to delay the contest deadline to May 25. And I know a lot of you don't get to hear the show in the first week after we publish it, so you got a shot this time. That's May 25, Wednesday at 8:00 AM Pacific Time.

Mat Kaplan: And if you get it in correctly and are chosen by, we have a copy of a brand new book from our friend, Jeff Bennett. Jeffrey Bennett of the Big Kid Science. He has a beautiful new hardcover book that includes solar glasses, because the book is called Totality, An Eclipse Guide in Rhyme and Science. So I guess it's an honor of the lunar eclipse, Bruce, that you told us about. But you can get ready for the next big total solar eclipse, if you have a chance to reach it like that one that's a little less than two years away now in North America. It's a great book, and this is a signed copy from Jeff Bennett. So that can be yours. Two pairs of eclipse glasses, actually.

Bruce Betts: [inaudible 00:36:33].

Mat Kaplan: Nice. Yeah, it's a cool book. It's really well done. Anyway, once again, Totality, An Eclipse Guide in Rhyme and Science from Big Kid Science.

Bruce Betts: All right everybody, go out there, look up in the night sky and think about, if Mat had a British accent, what type of British accent would he have? From what region? Go to No. Thank you and goodnight.

Mat Kaplan: (singing).

Bruce Betts: Stop with the Cat Stevens. Don't you ever like a Dog Stevens, at least?

Mat Kaplan: That irritated person is the Chief Scientist of The Planetary Society, Bruce Betts, who joins us every week here on What's Up.

Mat Kaplan: Planetary Radio is produced by The Planetary Society in Pasadena, California, and is made possible by its persevering members. Help them and us out at Mark Hilverda and Rae Paoletta are our associate producers. Josh Doyle composed our theme which is arranged and performed by Pieter Schlosser. Ad astra.