Planetary Radio: Space Exploration, Astronomy and Science - Spiraling Closer to Ceres With the Dawn Mission’s Marc Rayman

Episode Date: May 19, 2015

It’s the biggest dwarf planet between here and Pluto, and it has a new permanent resident. The Dawn spacecraft is orbiting Ceres in the asteroid belt, revealing it as never before. What are those bright spots anyway? We spend time with Dawn’s Chief Engineer and Director, Marc Rayman.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Orbiting Series with Mark Raymond, this week on Planetary Radio. Welcome to the travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. This week we'll join the Dawn spacecraft at the biggest dwarf planet between here and Pluto. Our guide will once again be the mission's chief engineer and director, Mark Raymond. What the heck are those bright spots anyway? That's a question that will also come up as we talk with Emily Lakdawalla in moments. And we'll hear from Bill Nye, the very excited light sail guy, about the huge enthusiasm for that mission. Batting last in the lineup is our own Bruce

Betts offering another chance to win the coveted Planetary Radio t-shirt. Emily, probably needless to say to listeners of this program, it's a special week for everybody at the Planetary Society and many fans around the world. As we, well, as we record this, we look forward to the launch of LightSail, which, when many people hear this, it may have already happened. Or not, as is the way of space launches. You're not going to be with us in Florida, I know, but you will be monitoring other things. And believe it or not, there are other things going on in the solar system. What should we talk about? Yeah, the rest of the solar system sure doesn't stop when you get busy.

Right now, New Horizons is busy. Actually, New Horizons is wrapping up the last of a big segment of optical navigation images that it's shooting of the Pluto system. That's where the spacecraft actually uses its science camera to figure out exactly where in the sky its eventual targets will be. You know, for a long time, New Horizons, its camera is not as good as our Earth-based telescopes. So for a long time, Earth-based telescopes have been better at telling us where exactly Pluto and Charon and all its moons are. But now New Horizons is close enough that the images it is taking of Pluto, Charon, Nix, Hydra, Kerberos, and Styx will tell us more about their positions and their orbits and their motions than what we can learn from Earth. And that's very important if you're planning to shoot

pictures of them at a close flyby. So I've got a blog entry this week on the first sighting of Kerberos and Styx by New Horizons. There's a fun collection of images at the end where you've taken moons of Saturn and used them to give us an idea of the relationship, what, between the sizes between these objects in the Plutonian system? Yeah, and I was also trying to get a sense of what we might expect their shapes to be. You know, Pluto and Charon are both large enough to be round. There's absolutely no question that both of those objects are going to look roughly spherical. But I was wondering about the shapes of the smaller moons. And so I looked up their sizes and compared them to sizes of various of Saturn's moons. And my guess is that Nix, Hydra, Kerberos, and Styx are going to be quite lumpy looking, although we could be very surprised when we pass them by. But it was an interesting exercise. In a moment or two, we're going to be talking with Mark Raymond, of course, of the Dawn mission. I spoke to him at the IC Series event that you moderated a panel for.

Give us just a little bit of an update on what's going on out there at the solar system's biggest asteroid. Sure. Well, Dawn is now spiraling down from its first orbit, what they call the RC3, or Rotation Characterization 3 orbit, down to its first major science orbit. In RC3, they captured these global images of Ceres. And, of course, everybody wants to know what those white dots are. And they're separating into more white dots, but we still don't know what they are yet.

It's going to be pretty fun to try to solve this problem as dawn spirals closer. Closer and closer as we are about to hear from Mark Raymond. Emily, thanks again very much. We will talk to you again next week and hopefully have good news about light sail as well. I hope so too, Matt. Emily is our senior editor at the Planetary Society. We also call her our planetary evangelist, and she's a contributing editor to Sky and Telescope magazine. Well, before we talk to Mark, we've got the CEO of the Planetary Society, and they don't come much more excited this week than Bill Nye. Bill, I don't think

anybody will be surprised that our topic this week, once again, is light sail. Oh, yes, yes. What an amazing international reaction we have received for this project. Oh, yes. Yes. What an amazing international reaction we have received for this project. Oh, it's true. Yeah. We had so many people go visit the Planetary Society website and agree to support the LightSail program.

It really is gratifying. And it goes back all the way back. We have that video on the website showing Carl Sagan talking to Johnny Carson of the Tonight Show about the project. It was 39 years ago, Matt. And we are finally going to launch, at least in aspect, that is to say we're going to launch a square sail with a diamond or cross-shaped support system. It's amazing. It truly is.

You're choked up, Matt. I am. The Kickstarter campaign, I believe it was well under 24 hours before it made its goal of $200,000. First goal of $200,000. And there are something like 5,000 people who've joined in.

It's really gratifying. So this is what we say. If you want to participate in space exploration, if you want to do something about 5,000 people who've joined in. It's really gratifying. So this is what we say. If you want to participate in space exploration, if you want to do something about space, then the Planetary Society is for you. So this is not where you've given money, you pay taxes and money goes to the National Air and Space Administration, and you really don't have control over how it's spent.

This is where you are a citizen and a member of the planetary side. You can direct us and we'll do what you want. And overwhelmingly, people have wanted to fly light sail for years. You may recall, we tried Cosmos 1 in 2005. And it is now in the Barents Sea, part of the Arctic Ocean, a region of the Arctic Ocean. It never got sailing. So this is exciting. We're on a real Atlas V rocket, and we're going to get on orbit, as we like to say. As people hear this, at least as people hear the online version of this, you and I are probably in Florida getting ready for the launch. What do you expect to be up to there?

I'll meet with members of Planetary Society. I hope to get my feet wet in the Atlantic Ocean. And then the excitement of a launch is just amazing. You get up in the morning and you just can't help it. You're looking at your watch, you're looking at the sky, you wonder if it's going to go, is there going to be a thunderstorm, is some fisherman going to drive his motorboat into the downrange area and delay everything. It really is, for me, decades and decades of chipping away at this problem. And this is an enormous step, getting on orbit.

I mean, I can describe the excitement. You're tense. You're wound up. But you're also, you just want to see if it's going to work. Like, circumspect is the word I'm looking for. You're sitting back. Is it really going to work. Like, circumspect is the word I'm looking for. You're sitting back. Is it really going to go? This time next week, hopefully we will be telling people on this program that LightSail is in orbit, though probably not yet deployed.

Probably not. Probably not. But still, getting in orbit is a huge step, an enormous step for the Planetary Society. We're pretty sure it'll work. We're pretty sure it'll work. We're pretty confident it'll work, but we've got to run this test. One test is worth a thousand expert opinions, Matt. Sometime we'll have you talk about that quote because I know you love it. Thank you, Bill.

Hopefully by this time next week we'll have even more reason to celebrate. It will be fabulous. Thank you, sir. Carry on. He's the CEO of the Planetary Society. I look forward to joining him next week at Cape Canaveral, the Air Force Base, where that Atlas 5 will incidentally be carrying light sail into low Earth orbit. Up next is a guy who's got a spacecraft orbiting, but not here. It's orbiting Ceres, the largest asteroid in our solar system.

Mark Raymond coming up in a moment. Riding on the brilliant blue glow of the ion streaming from its engine, Dawn departed Vesta, the second biggest asteroid, more than two and a half years ago, becoming the first spacecraft to orbit one object and then leave for another. Dawn departed Vesta, the second biggest asteroid, more than two and a half years ago, becoming the first spacecraft to orbit one object and then leave for another. Now, as we heard from Emily, it has arrived at a very different and even bigger world. Ceres is a true dwarf planet and the largest of the asteroids. There was a celebration of this and other exploration milestones at Caltech on May 9th. More than a thousand space fans of all ages came to the Pasadena campus

to learn about spacecraft throughout our solar system from some of the scientists and engineers who keep them on course and delivering great science. The Planetary Society was there, and it was in the Society's booth on that cool Southern California day that I sat down with an old friend of the show, Dawn Mission Director Mark Raymond. Mark, great to welcome you back to Planetary Radio, and what a terrific setting to do this in. Thanks, Matt. This is a fun place, and I'm always happy to talk to you. So here we are surrounded by fans of space exploration, and there are booths here, representatives of every mission, many that haven't flown yet.

But it does seem to kind of be centered on one mission. I mean, after all, it's called IC Series. You must be proud. I'm very proud and even more important, I'm very happy with how successful the mission is. It's really going beautifully. We're having a fantastic time exploring this mysterious alien world. Last time we talked was another icy event. It was that Icy Worlds Day at JPL. That's right. And you were still on your way.

In orbit now. In fact, you told me just a moment ago, not just in orbit, but moving down to one of the closer orbits that you have planned. That's right. So Dawn just completed a little more than two weeks of its first mapping orbit. It was very successful. We got spectacular views. I'll say.

And just a wonderful wealth of data. It was really terrific. But starting just earlier this morning, May 9th, we fired up the ion propulsion system again, and now we're spiraling down to a lower altitude to get an even better view. So those blue lights are on in the control room. They are. That's right. You got to see them. I did. I did, and so did a lot of people who saw that really cool video that we did as well, which people can find at planetary.org, a little plug there.

Once you get into this lower orbit, and how much closer is it? Well, so the orbit that we just finished up yesterday was at an altitude of 8,400 miles or 13,600 kilometers. And now we're spiraling down to the second orbit, which will be at an altitude of about 4,400 kilometers or 2,700 miles. So it's three times closer, which means our pictures will be three times sharper. But the science has been underway. I mean, it was underway even before you got into orbit, right? That's right. Even when we were approaching Ceres, starting in January, we began taking pictures.

By the end of January, our pictures were just a little bit better than the best that we had previously had from Hubble, and they've only been getting better since then. You're going to get much closer, aren't you, eventually? Yes. By the end of the year, we'll be down at an altitude of 375 kilometers or 230 miles, so we'll be closer to the surface of Ceres than the space station is to the surface of Earth. That's amazing. It is. We're going to have really fabulous views.

But actually, I think we already have fabulous views. Well, the best ever. Does that, getting that close, does that present additional challenges for the spacecraft? I mean, just because the world, I almost said the planet, this world, this round world is just whizzing by under you. It is, but we did something very similar at Vesta. Dawn orbited Vesta in 2011, 2012,

and we got down to low altitude there and then, in fact, climbed back up and even escaped from Vesta, of course, so we could get to Ceres. So it's challenging, but I think the spacecraft and the flight team are both up to it. So I'm looking forward to a very productive mission here. I imagine the scientists are kind of maybe happy?

Maybe ecstatic would be another way to put it. People have been studying Ceres for more than two centuries. This was the first dwarf planet discovered, and it used to be called a planet. And there's a great deal of interest in this place. It's the most massive body between the sun and Pluto that's not previously been visited by a spacecraft. And there are a lot of things we want to learn about it and it's fabulous to see the data now finally coming in.

Wouldn't you agree, I mean, for those people who still think of Pluto as a planet, if Pluto's a planet, then Ceres probably deserves to be as well. I think it does. It satisfies all the attributes of a dwarf planet that Pluto does. There are a lot of emotions on this topic, and we could spend this whole interview and perhaps the rest of our lives discussing this. And we could pull Alan Stern over as well, and he would tell us in no uncertain terms how he feels. He probably has his opinions on the topic. To me, actually, just as an aside, I think there was a big missed opportunity would tell us in no uncertain terms how he feels. He probably has his opinions on the topic.

To me, actually, just as an aside, I think the whole, there was a big missed opportunity in education in 2006 with the reclassification of Pluto and Ceres at the same time as dwarf planets. In my view, people don't appreciate that sometimes you have to change vocabulary to reflect changes in scientific understanding. But there are so many strong emotions on this topic. I think it's more fun to talk not about what we call it, but about what it is. And to me, it's actually pretty clear what we call it. We call it Ceres. Dawn calls it home.

That's what counts. All right, let's talk more about the science. But beginning with those images, we've got to talk about those two bright spots. Anybody got any more ideas? Oh, everybody has ideas, ranging from the frankly ridiculous to the pretty intriguing because of the ideas being realistic. pretty intriguing because of the ideas being realistic. The most ridiculous, of course, is that they're lights from a Syrian city, alien civilization there, which, of course, is preposterous because how do we know the Syrians live in cities?

That's true. Maybe they live in rural communities. Maybe they have large states. We don't know. Maybe they are dark sky believers and they don't put out that kind of light pollution. Right, so I think those theories are all, those ideas are all ridiculous. We don't know. Maybe they are dark sky believers and they don't put out that kind of light pollution. Right. So I think those theories are all, those ideas are all ridiculous. But, you know, there's a lot of interest in the possibility of there being water at Ceres, mostly in the form of ice, hence the name of the event where you and I are right now, Icy Ceres.

And, of course, one of the very compelling questions is whether these bright features are an indication of ice on the surface. They're clearly very reflective, whether they are indeed ice or they're remnants from ice. For example, there could have been ice on the surface that sublimated, that is, transformed from a solid into a gas, and the water molecules then departed into space. As we see happening on Mars and elsewhere. That's right, and perhaps leaving behind some bright deposit, so maybe that's what we're seeing, maybe it's not ice, but the bright deposit left behind from ice.

But whatever it is, there's certainly the intriguing possibility that this is some indication of ice in the present or recent past. So that's very exciting. That's Mark Raymond of the Dawn Mission, now orbiting Dwarf Planet Ceres. He'll be back in a minute when Planetary Radio continues. Greetings, Planetary Radio listeners. Bill Nye here, inviting you to become part of our citizen-funded LightSail project. LightSail is at the center of our very first Kickstarter campaign.

Help us realize the fantastic potential of this innovative spacecraft for as little as $1. We've got terrific rewards for those who can afford even a little bit more. How about a square centimeter of the sail? Or lunch with me? Learn more at planetary.org slash kickstarter. Together, we will change the world. Random Space Fact! Together, we will change the world. is, and hilarious. See, Matt would never lie to you, would he? I really wouldn't. A new Random Space Fact video is released each Friday at youtube.com slash Planetary Society. You can subscribe to join our growing community and you'll never miss a fact. Can I go back to my radio now?

Welcome back to Planetary Radio. I'm Matt Kaplan. Mark Raymond has returned to our show with an update on the amazing Dawn mission planned and managed by the Jet Propulsion Lab for NASA. Mark is Dawn's chief engineer and mission director. The spacecraft is now orbiting Ceres, the dwarf planet that is the largest object in the asteroid belt, out there between Mars and Jupiter. Even before entering orbit, Dawn was revealing Ceres in far, far greater detail than we had ever seen before. Those views are improving further as the probe draws even closer. And so there are some indications, and I don't know how much can really be said about the science at this very early stage,

but that this is like so many of the other places in the solar system that people might have thought were simply dead cinders. This may be a dynamic living place. That's right. It may be active. And, in fact, last year it was reported that the Herschel Space Observatory, a European Space Agency telescope, observed water vapor around Ceres. It was extremely, extremely thin. Very, very tenuous. In fact, the density of the water vapor was lower than the density of air even above the International Space Station. So it's not as if the spacecraft is going to need windshield wipers.

But still, it means there is some source of water there and we're going to scour the surface and use our sophisticated sensors to see if we can find what's going on. Any thinking that this could be yet another one of our neighbors in the solar system that has maybe a lot of water maybe even an ocean? Yes indeed there is such thinking. It's believed that perhaps 25% or maybe even more of the mass of Ceres is indeed ice. And it is possible, we don't know of course, but it's possible that

there's subsurface liquid water. So there could be ponds or lakes or maybe an ocean. And even if there isn't now, there may have been at some time in the past. So absolutely, that's something of great interest. Does Dawn have the capability, might may have been at some time in the past. So absolutely, that's something of great interest. Does Dawn have the capability, might it have the capability, to answer that question for us? We certainly will provide evidence that will bear on it. We do not have the instruments to directly detect a subsurface ocean. But if there is a subsurface ocean, or if there was, there may be evidence on the surface of the interaction between that subsurface water and the surface.

For example, perhaps through cracks that allowed water to make its way to the surface and leave its chemical signatures or structural or mechanical indications of interactions with water. With all of the different kinds of data we will collect, I'm sure we'll be able to say something pretty strong about the present or past presence of liquid water at Ceres. What are some of the other science questions about this dwarf planet that you're hoping Don and your team members, teammates, will be able to answer? Well, there are many. One of them is about the nature of life in the rough and tumble asteroid belt. I mean, Ceres, as Vesta, retains a record

of the impacts from many bodies over the lifetime of the solar system. As the scientists call it, the dynamics, that is the motions and the activity in the asteroid belt may be revealed by studying Ceres, as well also as the early movement of objects in the solar system. Maybe many of the listeners know about current ideas that the planets, the giant planets moved around early in the lifetime of the solar system. It's possible that Ceres formed somewhere else and was transported to its current location. And so investigating what its present properties are

may give us some indication of where it formed. This is a very exciting time, isn't it, to have a spacecraft out there with a whole bunch of sister, sister craft, exploring our solar system. It is. I mean, I think we're really fortunate, and this, of course, isn't an original idea, but we're wonderfully fortunate to live in a time when we're learning, we're discovering so much. And this year in particular, with the first two dwarf planets, Ceres and Pluto, both being explored, I think is really, really exciting. I've got to throw you a curve because there's something I just discovered,

and I'm dying to ask you about this. I read that you are an advisor to the folks at Deep Space Industries. It's one of the two companies with planetary resources that has this dream of someday harvesting asteroids and mining asteroids. More generally, using resources in space for commercial purposes. But go ahead. And that's great. I didn't know that. But what I was even more excited about was being able to ask you,

were you a student of Gerard K. O'Neill? I wasn't a student of him, but I was in the, all of my degrees are in physics, and I was an undergraduate at Princeton in the physics department when O'Neill was there. I was already passionate about space. I mean, you and I know each other. You know I've been very enthusiastic about space since I was four years old. I've devoted most of my life to it, and so when I was at Princeton... And a big room at your house as well, actually several. As you so nicely highlighted in a fun video tour that you made. So when I was at Princeton, I was very interested in O'Neill's work. I talked to him a number of

times and some of his colleagues. I even thought about doing my senior thesis under him. I was more interested, as I even still am, in fundamental physics. My principal scientific interests are elsewhere. But I was certainly inspired and remain inspired by his work. Okay, I'll ask you to go even further now, because here I threw this name out there, and I'm sure there are people, even in the Planetary Radio audience, who don't know who Gerard K. O'Neill was. Give people a thumbnail description. Sure. I'm sorry. I should have done that right off the bat. So he, of course, as I just indicated, was a physicist at Princeton. But he was one of the early visionaries of having large-scale

human settlements in space. This came out of an introductory physics course he taught before I was there, where, if I recall correctly, he had his students consider questions about what it would take to get humans to live in large communities in orbit. And he ended up developing these ideas in much greater detail for cities of many thousands of people that would be in orbit and would use resources in space. And for a while, they were thinking of putting this at a location that we probably don't have time to discuss here, but it's called L5.

And so this transformed into the L5 Society and really inspired a great many people with the idea of space isn't just the domain of astronauts and it isn't just the domain of explorers in science fiction. This is a place that people like you, Matt, and I, and everybody who's listening can go and live, live rich, rewarding, productive, realistic lives. And we don't have to be an exclusively earthbound species i mean i mean in the sense

of bound to earth we can truly be an extraterrestrial species o'neill's transforming this into realistic ideas sure not something that could be implemented today or tomorrow but you know maybe the day after that especially if you're pulling all night or tonight. But investigating what it really would take to do this. And that really inspired many, many people. And I think it's wonderful. And the Planetary Society continues with many of those same themes. And that's one of the things that I think is so wonderful about that. It certainly inspired me.

I have that book that was the result of the O'Neill studies. The High Frontier. That's right. I do, too. In fact, I have an autographed copy. Oh, my God. Now I'm incredibly envious. Next time you come over, I'll show it to you.

Thank you, sir. It is incredibly inspiring. And in the meantime, until we start building those cities and solar power satellites in space, I think there's still a lot of very exciting stuff for us. And your mission, Don, is certainly a terrific example of that. Well, I appreciate that. And even though we can't all go out there physically, I think we get transported through our spacecraft. I mean, this is, you know, although they're robotic spacecraft,

in my view, this is human exploration. We're operating the spacecraft. They provide our eyes and our other sense organs. And I think we get transported there in a really in a virtual sense. That's a little oxymoronic. We get transported there in a virtual sense, and I feel we can all gain a feeling of what it would be like to be out there. What are the views like? And I think through the work of you and your colleagues at the Planetary Society, everybody can really get the sense of what's going on out there and what would it be like if we were really physically there.

I love thinking about that sort of thing. Me too. And thank you. It's nice to play a small part in this, but even nicer... I think it's a big part. Well, thank you. But it's especially fun for me to have the opportunity to welcome folks like you back periodically. And you know, of course, this won't be the last time that we talk about this mission. I hope it isn't. No, we're going to be talking again as the Dawn spacecraft closes in, gets even closer to that dwarf planet, the biggest of the asteroids series.

Thank you, Mark, so much. It's always my pleasure, Matt. Thank you. And now I will throw in, although I'll probably do it after the fact, Mark Raymond has been our guest once again on the show. He is both chief engineer and mission director on the mission that we've been talking about, the DAWN mission. It's not an acronym. It's just called DAWN. That is the first in so many ways, including the first human emissary to visit a body, orbit it, leave, and head for someplace else. And that someplace

else is the one that it's revealing to us right now, Ceres, the biggest object in the asteroid belt. We'll be back to talk about all kinds of objects that are up in the night sky right now with Bruce Batts for this the skypline. He is the director of science and technology for the Planetary Society, one of the people who will be holding down the fort, ready to take media questions about light sail while the rest of us are gallivanting through Cape Canaveral for the

launch. Hi there. Thank you for taking care of that, by the way. My pleasure. For you personally, though, realize I will disavow any knowledge of behavior in Florida. Okay, well, then I guess you won't be my one phone call. I wouldn't suggest it, although please let me record it if you do. Instead of recording that, help us record what's up this week. What's up in the night sky? We've still got Venus and Jupiter super bright. Low in the west. Well, not even that low.

Up medium height in the early evening in the west. Two brightest objects there. Venus is the brighter and lower one. They'll keep getting closer. The crescent moon will be hanging out near Jupiter on May 24th. That'll be quite lovely. And then Saturn is at opposition on May 23rd. So it is on the opposite side of the Earth from the sun, meaning it's rising right around sunset in the east and then setting around sunrise in the west.

We move on to this week in space history. 1969, Apollo 10 launched and went down within 17 or so kilometers of the surface of the moon in a test run for Apollo 11. Five years ago to the day from the planned launch of light sail was the launch of the Japanese Icarus solar sailing spacecraft, the first solar sail designed spacecraft to fly successfully in space. Precursor to ours, which will try to demonstrate solar sailing with little tiny spacecraft. Yeah, little tiny, very inexpensive spacecraft, too. Yeah. Now, I know what you're getting ready for here.

It's the random space fact. But we got email from Austin Hinkle. You know, our contest entry form has a field that says how to pronounce your name. And Austin said the way Bruce says random space fact. So, take it, Bruce. Austin Hinkle! Be careful what you ask for. What's the random space fact?

I'll light sail all the time. The force from a flight pushing on the 32 square meter sail of the light sail spacecraft is equivalent to the force of a housefly sitting on your hand. And I knew this because I watched a random space fact video. Did you meet Dr. Housefly? I did, yeah. He's very cute. I was afraid you were going to crush him when he landed on your hand. That was an option, but Merck encouraged me not to.

Merck, the ace video producer and partner in the random space fact videos with Bruce. If you haven't seen him, check it out at Planetary TV. All right, let's go on to the contest. We asked you, in microns or micrometers, how thick are the light-sail spacecraft's solar sails? How'd we do? Wow, some very entertaining entries for this one. Our winner, I believe, is Victor Underwood from the United Kingdom,

where I will be soon. And I'll have an announcement about that before too long. Sort of an informal little get together we might be putting together there while I'm in London. Victor said light sails thickness is 4.5 microns. That is correct. Excellent. Victor, congratulations. You have won yourself a fabulous Planetary Radio t-shirt. You know, you pointed out last week that it's about a fourth the thickness of the average trash bag. We got this from Joe Murray in Hoboken, New Jersey. He said, luckily, therefore, light sail will not be sailing near Ursa Major or Minor as bears have been known to rip apart trash bags.

Phew. Can I give you some more of these? So four and a half microns, about the size of an average human red blood cell. I assume the diameter, that we got from Joseph Endres in Reeford, North Carolina. Mark Schindler in Honolulu, he said, how about 4.8 times 10 to the minus 22nd light years? Well, that makes it easy to comprehend. Now, here's just about my favorite. It's a measure of related to what you were just telling us about with that housefly. He said he figured out that the solar sail would get about five and a half billion times

higher thrust if we used it as a regular sail on a boat. I haven't checked the math. Tougher to fly those boats in space, though. That, by the way, from Davy Van Ness, Davy in Rotterdam in the Netherlands. So thank you, everybody, as always. What do you got for next time? Well, that's great because people are already working along the lines that I'm going to ask them explicitly,

which is what's an analogy for the surface area of the light sail sails? So there are 32 square meters. I've been working unsuccessfully to come up with some meaningful analogy to make it simple to envision. Now, you can watch the random space fact video. We've got a simulated one. Someone came up with a boxing ring, and that's cool, but they turn out to be pretty non-standardized. So what's an analogy? And we'll give winners for either a good analogy that makes you really sense how big it is or just funny analogies.

Go to planetary.org slash radio contest. Love it. And you've got until the 26th. That would be May 26th, Tuesday at 8 a.m. Pacific time to get us this clever answer. All right, everybody, go out there. Look up in the night sky and think about sailing through space. Thank you, and good night. That's Bruce Betts, the Director of Science and Technology for the Planetary Society. He will join us again next week for What's Up. Back next week with special light sail coverage, Planetary Radio is produced by the Planetary Society in Pasadena,

California, and is made possible by the members of the Society. Danielle Gunn is our associate producer. The theme music comes from Josh Doyle. I'm Matt Kaplan. Clear skies.