Planetary Radio: Space Exploration, Astronomy and Science - Crew Dragon Thrills While Mars Chills

Episode Date: June 3, 2020

This episode opens with a special message about The Planetary Society’s response to recent news, followed by a period of silence that marks the unjust loss of George Floyd and other black men and women. In our regular coverage, we celebrate the successful launch and arrival of the Crew Dragon spacecraft at the International Space Station. Then it’s off to Mars with planetary scientist Edgard Rivera-Valentin. Learn more at https://www.planetary.org/multimedia/planetary-radio/show/2020/0603-2020-edgard-rivera-valentin-mars-brines-crew-dragon.htmlSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Crew Dragon Thrills While Mars Chills, 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. That opening teaser line about thrills and chills would normally have been a very appropriate way to start this week's show, but events of the last few days have made it seem somewhat trite. and chills would normally have been a very appropriate way to start this week's show, but events of the last few days have made it seem somewhat trite. It has been a week of triumph and shame, of humanity at its best and very nearly its worst. Like many of you, all of us at the Society believed this would be a time to celebrate as humans return to space on a new ship. It is that, of course, and we will celebrate shortly, but the success of SpaceX and NASA with Crew Dragon has been overshadowed by other news.

We've struggled with this. Planetary radio and the Planetary Society generally look outward and upward, but we do this in concert with and on behalf of men and women around the world. Our mission statement begins with empowering the world's citizens. Yet there are too many of the world's citizens for whom empowerment is far beyond their reach, for whom even survival is not a reliable outcome. My colleagues and I have spent the last few days considering how we can do more to advance true empowerment, the kind that will create security, respect, honor, and opportunities that will give everyone space in their lives to look up in wonder.

We have some great ideas, but we're just getting started. I hope you'll also read the statement by our CEO, Bill Nye. Most of all, I hope you'll hold us to this commitment. It begins with a small gesture here on Planetary Radio. Like many other podcasts, broadcasters, and networks, we will now offer 8 minutes and 46 seconds of silence. That's how long it took for George Floyd's life to end in agony against the pavement. I'll be back immediately afterward with all of what would have been this

week's episode, including a conversation with planetary scientist Edgard Rivera-Valentin about surface water on Mars. And yes, a little of Robert Behnken and Douglas Hurley's trip to the International Space Station. This is Planetary Radio. you you you you you you you you you you you you you you you you you you you you you you you you you Thank you for staying with us. Chances are good you were watching on May 30th as a Falcon 9 lifted the Crew Dragon spaceship piloted by Bob Behnken and Doug Hurley. You may also have seen their arrival at the International Space Station.

If not, I've got a brief treat for you. Here are just over four minutes of heavily compressed highlights, beginning, where else, with the last seconds of the countdown. SpaceX Dragon, we're go for launch. Let's light this candle. 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0. Ignition, liftoff of the Falcon 9 and Crew Dragon. Go NASA, go SpaceX. Godspeed, bottom tug! America has launched. And so rises a new era of American space flight.

And with it the ambitions of a new generation continuing the dream. 20 seconds into flight, stage one propulsion is nominal. Seconds into flight stage one, propulsion is nominal. T-plus 30 seconds into this historic mission. Flying crew on board Dragon and Falcon 9, and look at them go. Falcon power, telemetry nominal. Confirmation of Seco's second engine cutoff. Now we are waiting for our first stage to make its way to our drone ship.

Of course, I still love you. Dragon SpaceX nominal orbital insertion. Confirmation of nominal orbital insertion. What you're seeing on your screen is a live view of our drone ship where our first stage will be coming down. Falcon 9 first stage will be coming down. Falcon 9 first stage successfully landed. And there you can see on your screen Falcon 9 has landed. This is the first Falcon 9 to carry humans to orbit so very exciting for us. And as you can see on your right screen Bob and Doug are still making their way to their targeted orbit.

M1D to recovery one. So exciting today. M1D. It doesn't stop. It does not stop. So we're closing in at less than a tenth of a meter per second at this point. You can see the surface section Draco is just doing all these very small minor attitude corrections. Really the the autonomous docking system at work making sure

that the the vestibule and the soft capture system is lined up with IDA2. It's the international docking adapter. And we are just five meters away. Again, we're racing that sunset. Dragon continues to close. Four meters to go. Those shadows of the space station on the vehicle. Two meters. We are inside the hands-off point, the chop, the crew hands-off point. One meter to go. Soft capture complete. Soft capture confirmed. Standby for retraction and docking. And we just heard it. Soft capture. We have docking.

That coming at 7.16 a.m. Pacific time with the station and Dragon flying 262 statute miles right over the border between northern China and Mongolia. We have Bob Behnken from SpaceX Demo-2 mission entering the International Space Station. Followed by Doug Hurley. And Station Houston, we see you, and it's a great-looking photograph. So thanks for that. Stand by one. We'll call you when we're ready for the event in the next few seconds. Station, this is the NASA Administrator.

Can you hear me? We hear you loud and clear, sir. Welcome to the space station. Thank you, Chris. It's good to see you. And welcome to Bob and Doug. I will tell you, the whole world saw this mission, and we are so, so proud of everything you have done for our country and, in fact, to inspire the world. We sure appreciate that, sir.

It's obviously been our honor to be just a small part of this. We have to give credit to SpaceX, the Commercial Crew Program, and of course NASA. It's great to get the United States back in the crewed launch business, and we're just really glad to be on board this magnificent complex. Highlights of the launch, docking, and welcoming of Bob Behnken and Doug Hurley on the ISS. We congratulate NASA and SpaceX on this historic achievement, and we look forward to it becoming commonplace. We can thank Emily Lakdawalla for suggesting the return of Edgard Rivera-Valentin to our show. Emily pointed me to great research led by Ed that may mean that Mars is a much safer place

for robots and humans to visit. Not safer for the robots and humans, but for any native Martian life that could still exist on or just below the surface of the red planet. It was last January that Ed joined five other planetary scientists here. Each of them talked about great science goals for a world in our solar system. Ed took Mercury back then. This time our conversation was inspired by his team's paper titled Distribution and Habitability of Metastable Brines on Present-Day Mars. Don't let that intimidate you. I think you'll enjoy this new session with Ed, who is a

scientist for the university's Space Research Association at the Lunar and Planetary Institute. Ed, welcome back to Planetary Radio. I did not know that we'd be talking again so soon, but then I didn't know that you had this great bit of research that was about to be published in Nature Astronomy. Congratulations on this to you and your whole team. Thank you. Thank you very much. Thank you for inviting me back. It's a pleasure, and this is fascinating work. In fact, there's something about this research

that is nearly as fascinating as your conclusions that we'll get to in a moment. I read in your great Nature Astronomy blog post that the team actually set out to investigate something else altogether. Correct. So when we started in this project, our goal was to actually look at where, when, and for how long could there be a stable brine on Mars? Because we were trying to answer the question, what is the role of these type of liquids in making some of these, what we call

slope failure events that we're seeing on Mars. And a good example of one would be these reoccurring slope lineae. At the time when we started doing this research, reoccurring slope lineae were very indicative that there was liquid water active on Mars today because they were forming always in spring and summer. They were forming on crater walls that were facing the equator. Those are the crater walls that get the more intensely heated by the sun. And they grew over time, they darkened, and then they faded back to the background color. So when we saw these, we were like, oh my gosh, there's liquid water on Mars. But in order for it to be liquid water, it has to be brine.

That's how you're going to have something stable under Martian conditions today. But as time has gone on and we've gotten more data on these features, we're going, well, maybe they're not made by liquid water. There might be something else involved with making these. But by then we had all of this data. So we had to answer another question with it. And that is, are these liquids habitable? And that was what led us to this conversation today. You weren't alone in that excitement about those RSLs. There were a lot of us at

the Planetary Society and among our membership and outside our membership who were pretty thrilled by this possibility. And I guess the possibility, it is still possible, right, that this is a liquid that we see appear and disappear on these slopes? So the best data we have right now is more suggestive that the flow itself is not made of liquid, but rather maybe it is instigated or triggered by a liquid forming. So one of the things that I guess is my soapbox to stand on whenever we talk about flows on Mars is that although Earth is a great analog when we're looking at Earth geology and try to look out in the solar system and do these comparisons with other solar

system bodies, Earth has more gravity than Mars. Gravity is a very important factor in fluid mechanics. So something will flow differently under a different gravity regime. On Mars, because the gravity is about a third compared to Earth, things don't need a fluid. Things don't need a lot of liquid inside of it to make it look as if it's a flow, as if it would have been a flow on Earth. So the same thing on Earth does not need the same amount of liquid

to look like it on Mars. So the type of research that people have been doing, doing a lot more, going through all these images, it's showing that, yeah, they're probably very dry. You're looking at the dark stuff that you're seeing is actually the regolith that's under the surface. We know that regolith is much darker than the surface stuff, but that type of flow still needs an instigation, still needs a trigger to start it off. One of the ideas that we have is that you might still form a liquid. And as that liquid quickly evaporates away, that energy is what

could be used to instigate the flow. That's very interesting. Well, at least a little liquid is better than none at all, I suppose. Exactly. Let's talk about these brines. I'm a native of Southern California where we don't have much need to put salt on our roads. But that's a bit of what we're talking about, aren't we? I mean, what are you referring to when you say a brine? Right. So in pantry science, when we're talking about brines, we're talking about very salty liquids. I'm a chef. I like cooking.

I'm not literally a chef because it's not my professional, but I like cooking a lot. And people for Thanksgiving like to sometimes take their turkeys and put them in a brine, and that is water with a truckload of salt inside of it. That's what we're talking about when we say brines. It's a liquid with a lot of salt in it. So I note that you frequently refer to stable liquids. So I guess a brine doesn't need to be water-based. It's a good catch. I try to be a little bit precise when I say stable liquids for Mars, just because there might be something else that allows liquid water to exist besides salt. The cool thing about salt is that it changes the freezing temperature of the liquid. So when you have a brine, despite the fact that, you know, you need zero degrees

Celsius to freeze something, well, a brine could reduce that to maybe minus 10 degrees Celsius. Those people who are in the north, they're used to having to throw salt into the street when it snows. And the reason they do that is so that the snow goes back into the liquid state. And that's because the salts change that freezing temperature of that mixture. And now you can have liquid again, whereas you would have had ice under the temperatures that there exists there. Very much like those roads that I didn't grow up with. I don't think you did either, actually. But I noted, and this was an image I'd never seen before, an image that was connected to some of this work was looking under the Phoenix Lander, may it rest in peace. I'd looked under the Phoenix Lander before with others to see the ice that it found just below the surface. But this was something I hadn't seen. What looked

like little drops of condensation. Yes. That picture when they came back, super excited me. Because at that time, I was a graduate student and doing brine research. I was like, yes, we have evidence. My work here is done or just started. But the cool thing, so it's that picture is neat to let us know that you could have liquid water stable on Mars. It's going to be a brine. But we also have to remember that those droplets formed very shortly after the spacecraft had landed. So that area was very warm.

The idea we have is the Phoenix landed, it kicked up some of the ice, the ice fell onto the struts, and it started forming those droplets. And a great paper by Renault back in 2008, if I remember correctly, they actually have a sequence of images showing those drops kind of coming together. So we were seeing them flow and then evaporate away. And it looked like very strong evidence that they should be liquid water. And in positive science, we're a little bit, we try to be slightly skeptical when we talk about liquids on Mars. So you'll hear me say things like, we think these were liquid droplets. There are people that don't

think they are. And unless we have some sort of spectrometer taking data of that droplet as it was forming and it said H2O, we'll just keep saying it looks like, it behaves like a brine. Extraordinary claims require extraordinary evidence, right? Exactly. More of my conversation with Edgard Rivera-Valentin about liquids on the surface of Mars is coming up after a break. Hi, this is Kate from the Planetary Society. How does space spark your creativity? We want to hear from you. Whether you make cosmic art, take photos through a telescope, write haikus about the

planets, or invent space games for your family, really any creative activity that's space-related, we invite you to share it with us. You can add your work to our collection by emailing it to us at connect at planetary dot org. That's connect at planetary dot org. Thanks. Tell me about the model that was developed out of this work that has revealed these interesting predictions about regions of Mars. What we did here is we put together a climate model that is used to figure out, you know,

what are the conditions of Mars when we're about to send a spacecraft, better understand the type of atmospheric conditions that entry is going to encounter. We took that type of model and we also meshed it with experimental data that we've done at the University of Arkansas that has a Mars simulation chamber and has been looking at the stability of these brines and trying to understand it from a thermodynamics perspective. So I took all of the actual experimental data, put it together with the climate model, and then meshed everything together to try to figure out, okay, given this temperature, given this relative humidity at the surface, compared to the experimental data where we saw liquid stable, would a liquid be stable? Yes or no. And then we

tracked that liquid over time to try to figure out what its chemistry is and what its temperature is. That allowed us to see that at most, the stable brines that can form on Mars will only ever reach a temperature of about 225 Kelvin. We think that, well, okay, life as we know it. There's that phrase again. Yeah, it's a very important phrase. So there's that phrase again. Yeah, it's a very important phrase.

But typically life, as we know, it needs a temperature a bit higher than 250 Kelvin for it to be able to replicate and metabolize. So they'll actually be alive. Anything lower than that and it starts getting a little fuzzy, whether it's just metabolizing very slowly or if it just completely stopped repl, or if it went into a spore phase. But that temperature is used by international policy when we're trying to consider planetary protection. And when we're trying to consider, okay, if we're going to send a spacecraft there, do we have to be extra careful? Because the conditions might allow for life as we know it to exist there. How has this been received in the planetary protection community? Because, I mean, this indicates, as you've said in the research, that putting robots and maybe humans on Mars,

as long as they don't dig down too deep, or they're careful when they dig down deep, that this might be safer for anything that may still be on Mars than we thought. So I actually haven't heard back from people. I don't know if I should be scared or not. But I know when we're thinking about sending any type of spacecraft into these type of environments, we are very cautious and rightfully so, right? Because if we send a spacecraft that is contaminated in any way, and it goes into an environment, even if the best models we have,

even if the best experiments we have go and show us, okay, we only expect a liquid there that isn't habitable. So it's okay. But some random happenstance happens and you just took a bug to Mars and that bug suddenly was okay living in that environment. And you send another spacecraft and you go, oh, I found life on Mars. Oh, but no, it's actually Earth contamination. You just ruined one of the most important questions that we have in astronomy and planetary science. And that is, are we alone in the universe? So we are rightfully cautious when we send spacecraft out there. And I would say that

this work isn't to say that we shouldn't be cautious at all, but rather that we don't have to be extraordinarily, extremely cautious to the point where if we see an RSL or if we're in an area where there might be a liquid, we need to be kilometers upon kilometers away just to be safe. We maybe can get a little bit closer. Maybe we could send a helicopter to take a picture of it. And I'm hoping there's maybe newer avenues that will allow us to explore these regions. Gee, if only somebody was sending a helicopter to Mars. Wait a minute, we are. It's not just a hypothetical. This had to be taken into consideration for Curiosity, the Mars science laboratory, because it was supposed to go through an area with some RSLs, wasn't it? Correct. So Curiosity, as it was roving along, it took some very interesting pictures of these dark streets

emanating from bedrock. When those pictures ended up going all the way up to the Pontiac Protection Office, it was my, I'm not involved with MSL, but from what I read on the news, it caused a lot of stir because when you see those type of features, you immediately think, oh, they might be liquid. So it would have meant that MSL would have had to completely change its trajectory. Instead of going up where it was going, it would have had to go somewhere else or worst case scenario, just completely stop. More data came in, more orbital data came in. There was a lot more research done and we saw, okay, that's probably not liquid what you're seeing, most definitely not. So it might be safer, but just be cautious.

And then, of course, there's Perseverance leaving for Mars this summer, followed, we hope, in a couple of years by the Rosalind Franklin rover from the European Space Agency. Perseverance is designed to go to these areas, and Rosalind Franklin has got a drill to go meters down. Do we need more data? Or are you fairly confident now, partly based on your model, that they can do the work they need to do, assuming we've sterilized them as well as we can back here on Earth? So I would say that the work that we've done definitely says that we don't have to be extraordinarily cautious to the level of do not send a spacecraft here because it seems as if the type of liquids shouldn't allow for what we call for contamination. Do we need more data to be 100% sure? Of course. The one type of feedback I have gotten from this type of work is from the biology community, who brings up a lot of these micro environments where they have been seeing life exist, even though its surroundings and the bulk environmental conditions would say life shouldn't.

This itty bitty environment in this itty bitty other place is suddenly just right. So that is still something that we need to consider because again, if we accidentally contaminate that we're doing a lot, but the more data we have from experiments, the more data we have in situ, in situ environmental data on Mars will definitely help improve these types of models and give us better insights as to how cautious we need to be where we go. And, you know, if we're actually trying to answer the question, is there active liquids on Mars, then it also is informing our observation strategies. Where do I need to look? And when do I need to look to make sure, yes, liquids are

forming there? And according to your model, we're not talking about everywhere on Mars, right? That we might find even these brines, which appear to be so, that may be so unfriendly to life as we know it. Correct. So there's only certain places on Mars where the environmental conditions are just right to allow for brines to actually be stable. And not only that, when they're stable, it's not, you know, they're stable for hours upon hours on end. They're only stable for maybe about a percent or two throughout the year. And at most, they're stable for six consecutive hours. That only happens in the very special regions up in the northern hemispheres of Mars. But more typically, wherever they can exist and are stable,

they'll only be stable for maybe an hour or two. That's the more typical value that we're seeing. So it's very short-lived liquids because Mars is so, so, so dry that once it gets a little bit too hot, you will evaporate that brine very, very quickly. Does your research have anything to say about what may be going on a couple of meters, three meters down below the surface? Since I think you're only talking about the surface and maybe a handful of centimeters down, right? Right. So what I talk about is surface and what we call the shallow subsurface. The shallow subsurface is the part of the soil that actually can talk to the atmosphere

and is actively exchanging water with the atmosphere. Once you get something about below 10 centimeters or so, that activist change slows down very, very quickly. It's no longer seeing the day. It might be seeing something on the order of the season. And once you go below a meter or more, you're really not exchanging water vapor too much with the atmosphere at all, even throughout the year. Down there, that ends up being a whole new world, to quote Aladdin, where other people

are doing research to figure out if there could be larger bodies of water down there. So if Mark Watney, the Martian, comes to you or calls you on the radio and says, hey, can I start planting and fertilizing potatoes on Mars? Or maybe the asparagus that NASA chief scientist Jim Green said might grow better there, according to the most recent research. I mean, what would be your advice? I wouldn't grow anything. I wouldn't grow anything on Mars and try to eat it, but I'm extra cautious. The type of salts that I'm looking at that forms these brines, calcium perchlorate, that's the same type of ingredient that is in a lot of toilet bowl cleaners. And I wouldn't drink my toilet bowl cleaner, so I wouldn't even touch that. I don't know. It could turn out that it works against COVID-19 too soon.

Oh, true. There you go. So we've talked about Mercury with you. Now Mars. You've possibly made it a safer place for us to visit. What else is happening and what's ahead for you in your research? On Twitter, you can find me at at Planet Trekkie. And I use that handle because I love to track the planets.

Fundamentally, I do what's called system science. At the base of everything, I like to do math. But I specifically like to understand how these different things can come together to make that which you are observing. So instead of doing just the geochemistry or just the atmospheric science, I'll put everything together into this paper where I can look at the chemistry of the brines based on the atmospheric science that we have. I talked about Mercury because I was doing planetary radar and I was zapping Mercury with radar to figure out how these ices might be stable at the poles of Mercury. Is that changing over time? How deep are they and where could they have come from? Putting all of that picture together with this

added data. Other type of work I also do, I'll observe icy moons. So I have a project using Cassini data, may it rest in peace, of the Saturnian satellites. I use that data, I'll count the craters. I'll also use another spectrometer that Cassini has that looks like at the ice phase distribution on the moon. That lets you know something about how old a crater could be, because when a crater forms, it changes the ice that is around it. And over time, the ice will come back to its amorphous phase. So I have basically a clock and I have craters there. So I can start putting together what the impact cratering rate is for the Saturn system that lets me know how old certain ages are. And then I could put everything together and go back to the bigger question we have out there.

Okay. Are the Saturn's rings young or old? That's the type of question I like to look at. Put all of these little bits together to figure out how all of the system pumps and gets you what you observe. Sounds like you're at home all over the solar system. Yes, it's fun. All right, Ed, thank you. I'm very glad that I was able to get you back for this. And again, congratulations to you and the team that put together this model and has come out with this new data and conclusions.

And we'll have lots of great links to this work on this week's show page at planetary.org slash radio. Ed, live long and keep trekking. Thank you so much. You have a good day. You too. Planetary scientist Edgard Rivera-Valentin works for the university's Space Research Association at the Lunar and Planetary Institute. Great links to his work and other topics we cover on this week's show are at planetary.org slash radio. Time for What's Up on Planetary Radio. Bruce Betts is the chief scientist of the Planetary Society. He is here one more time. Well, one more time. Many more times, I hope. What? What do you know that I don't know? Nothing, nothing at all. Nothing, no secrets here.

Anyway, he's here to tell us about the night sky, and we're going to give away a copy of his new book for kids, My First Book of Planets. Welcome. Thank you. Good to be here, Matt. It's especially good to have you here this week. It's good to be with old friends.

So what's up there? You know what's not in the evening sky? Venus. It's gone. It's good to be with old friends. So what's up there? You know, it's not in the evening sky, Venus. It's gone. It's gone, man. It's out of there. It was a heck of a show. It was, but it'll be coming to the morning sky shortly because it's between us and the sun right now and it'll be popping out on the other side, which puts it in the morning sky, but not quite yet. But in the middle of the night, taking over are Jupiter and Saturn, rising around 11 midnight, depending on where you are. They will be near the moon on June 7th and 8th. It'll make a lovely triplet, Jupiter being the much brighter of the Jupiter-Saturn pair.

And a couple hours later, so quite middle of the night, Mars rises in the east and it's getting bright. So it's now in negative magnitudes for those who play the astronomical apparent magnitude game, meaning it's brighter than the star Vega and it'll keep brightening through its opposition in October. So Vega is magnitude zero, right? Yep. Invisible equivalent to what we see. Yes. On to this week in space history. It was 55 years ago in 1965 that Ed White took the first American spacewalk. And 45 years ago, the Venera 9 launched.

The Soviet Venera 9 that would become the first spacecraft to return pictures from the surface of another planet, in this case, Venus. Still such an amazing feat that they actually put something on the surface of that living or dead hell, and it survived to take some pictures. I mean, my goodness. Yeah, impressive. Speaking of impressive, we're going to move on to

Random Space Fact. Feel like we're flying, Matt? The friendly skies. The space station. The International Space Station has an internal pressurized volume. In other words, where the astronauts and cosmonauts hang out

equal to that of a Boeing 747. internal pressurized volume, in other words, where the astronauts and cosmonauts hang out, equal to that of a Boeing 747. Does that include, you remember, I don't know if you do remember when the 747 first came out, there was a piano bar upstairs. Does the ISS, it doesn't, no, it doesn't have a piano, does it? No, it just has the bar. Okay. So anyway, we move on to the trivia contest. And I asked you approximately how many days did LightSail 1, the LightSail test mission, LightSail 1 spend in orbit?

How'd we do, Matt? A very nice response to this one. And here is the answer delivered by our poet laureate, Dave Fairchild. response to this one, and here is the answer delivered by our poet laureate, Dave Fairchild. LightSail A, later LightSail 1, was launched into space nice and clean. It flew as a payload on ULA's rocket in May back in 2015. Despite having problems in keeping Earth contact, the sail still blossomed in June, and 25 days after launch, it re-entered our atmosphere and was consumed. Nice. I mean, not that it was consumed, but that was the plan. We knew as soon as we put the sail out, it would be dragged down.

Unlike LightSail 2, that we'll probably come up here in just a moment because of some reaction we got from some other folks. Here's our winner, first time winner, John Georges in Silver Spring, Maryland, who responded correctly with the 25 days. A few people were off a little bit. A few people thought maybe that was after deployment when it didn't last very long, I assume because the drag was so much increased. Yeah, because LightSail 1 went to a much lower orbit. And that's why we knew it was just going to be a test mission, not able to solar sail.

It had a periaps, a low point in the orbit that I forgot exactly, orbit, and that's why we knew it was just going to be a test mission, not able to solar sail. It had a periaps, a low point in the orbit that I forgot exactly, but it was between 300 and 400 kilometers. So with that little tiny mass and that big giant sail, the atmosphere drags you down in a hurry, whereas LightSail 2 started out around 720 kilometers, where there's still some atmosphere, but a lot less. John, congratulations. You have won a copy of Bruce's brand new book that we mentioned from Rockridge Press, My First Book of Planets, all about the solar system for kids. It's a great first book introduction to the solar system and astronomy, for that matter. It's available now, I think, right, As an ebook? It is.

It just came out available as an ebook, at least on Amazon. And in two weeks, it'll be out as a paperback. Okay. Well, it's going out to you, John. And you should read it before you give it to some young person. I think you'll enjoy it as well. So 25 days. Burton Caldwell in New York said,

that's four more days than Sputnik 1 lasted. Did you know that? There's a random space fact. That's very nice. Yeah, I had never connected those two. Nicely done. Zippy Olson in Wisconsin. I track the satellite every day,

and I'm currently tracking LightSail 2. Thanks, Zippy, and love your comics, Zippy. Mel Powell. You'll answer this in the 939th all-time episode of Planetary Radio. For ease of math, average length of episode, 60 minutes. That's a bit long, but we'll let it slide. LightSail 1 would have had to remain on orbit for an additional 14 days and three hours to hear all of our episodes end to end. Oh, my gosh. Wow. That's a lot of episodes, man.

Mel, you made it in again with that. How could we pass it up? Martin Hajoski, perhaps somewhat prophetic, the number one song on the Billboard Hot 100, both on launch day, May 20, 2015, and the day the orbit finally decayed, June 14, was To You Again by Wiz Khalifa and Charlie, is it Puth? Puth? I know Wiz Khalifa and Charlie, is it Puth? Puth? I know Wiz Khalifa but I don't know Charlie P-U-T-H.

Anyway, Martin says, how about that? I didn't know that. Finally, another poem from Gene Luan up at Fairchild Air Force Base in Washington. Light Sail 1 accompanied by X-37B, a test of the new CubeSat and the OTV, assisted by a rocket that

bears the Atlas name with 40,000 donors and a Kickstarter campaign. 25 days it orbited around the pale blue dot, proving solar sailing, demonstrating what was sought. Nice. Okay, thank you everybody. Try again next time and you might just win something great. But Bruce, first set it up for us. All right. We, of course, just had the very successful Crew Dragon Demo 2 launch. Before Crew Dragon Demo 2, what was the last two-person orbital spaceflight launched from the United States? Go to planetary.org slash radio contest.

This time you have until the 10th, Wednesday, June 10th at 8 a.m. Pacific time to get us your answer. We opened the show with this, highlights of the Crew Dragon launch and arrival at the International Space Station. And maybe some of you saw the astronauts holding a little celestial buddy. Little Earth is what it's called, or Earthy, little plush toy. I have the Mars version of it sitting up above my head here. We have one to give to you. No, it's not signed by the astronauts or anything like that, but it is exactly the kind that was brought up

on the demo mission number one on crewed and will be brought back to Earth by Bob Behnken and Doug Hurley when they return in, we don't know yet, some number of weeks or months, could be up to four months.

But we've got a picture of the astronauts with this little celestial buddy, Little Earth, on the International Space Station. So there'll be three passengers on the way home. How's that? That's really cool. And next week, ice cream. Nice. Oh man, now I want ice cream. Of course you do. We're done though. You can go get some.

All right, everybody, at the risk of being thematic, everybody go out there, look up at the night sky and think about how fun space is. Thank you and good night. It's very fun. More fun than a piano bar on a 747. Maybe they'll put one on Starship. Note to Elon. He's Bruce Betts, the chief scientist of 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 members. Join them to help empower the world's citizens to advance space science and exploration. Mark Hilverda is our associate producer. Josh Doyle composed our theme, which is arranged and performed

by Peter Schlosser. Per aspera ad astra, or through struggle to the stars.