Citizen Science: Join the search for Martian clouds

Mat Kaplan: It's a nice day for cloudspotting on Mars. 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. Mars used to be so wet! We've learned it still has lots of water below the surface, but nothing like it had a few billion years ago. Where did it go? Scientists are still trying to solve that mystery. A new piece of the puzzle is being provided by a project that needs you. NASA Jet Propulsion Lab scientists Armin Kleinboehl and Marek Slipski will tell us about their new citizen science project called Cloudspotting on Mars. Later, on this somewhat abbreviated show, we'll check in with the chief scientist of The Planetary Society. Bruce Betts has good news and bad news about this year's Perseid meteor shower, but the new space trivia contest will keep us in the plus column.

Mat Kaplan: Mars is also at the top of the July 20 edition of The Downlink, The Planetary Society's free weekly newsletter. It's a false color image from the Mars Reconnaissance Orbiter, or MRO, the same spacecraft that supports the cloudspotting project. This pretty picture uses color to help us understand how wind has sculpted the Martian surface. It's very pretty. Here's a story I'm sure Casey and I will talk about in the August space policy edition show. The United States Senate has passed a bill that formally endorses full funding of the NEO Survey mission, that infrared telescope that is so badly needed to help us find near earth objects. We've also learned that Russia may not be in a hurry to leave the International Space Station. Casey is on this story, too. Also in The Downlink is mention of a great new article by my colleague, Jason Davis. It has the latest chapter in the effort to confirm phosphine in the atmosphere of Venus. We'll have to get researcher Jane Greaves back on the show soon. There's much more at planetary.org/downlink.

Mat Kaplan: Research scientist Armin Kleinboehl is the deputy principal investigator for the instrument on the venerable MRO called the Mars Climate Sounder. His JPL colleague, Marek Slipski, is a NASA post-doctoral program fellow. They both study Mars' thin but dynamic atmosphere. I invited them to join me when I read about their new project that is already attracted thousands of citizen scientists. Armin and Marek, welcome to Planetary Radio. Thank you for doing this today. Look forward to hearing about this great project. Citizen science project. If it wouldn't get The Planetary Society sued, I think I'd have opened this segment with Joni Mitchell saying she has looked at clouds from both sides now. Welcome to the show.

Armin Kleinboehl: Thanks for having us.

Marek Slipski: Yeah, thank you.

Mat Kaplan: I still run into people who are surprised and charmed to hear and even to see that Mars has clouds. How is this even possible with just one percent of the atmospheric pressure that we have here on Earth? Armin, you want to tackle that first?

Armin Kleinboehl: Sure. Yeah. I mean, Mars has clouds. They're actually quite interesting. And they're quite ubiquitous, actually, too. We find water-ice clouds on Mars pretty much in the same shape or what that we would expect from cirrus clouds here on Earth, but we also find clouds made of CO2 on Mars. CO2 is the main constituent of the atmosphere. Condensing out the main constituent of the atmosphere is something that's pretty weird and that's something that we don't experience here on Earth. They appear in different regions at different seasons. What we're interested in with the cloudspotting project is particularly the clouds on Mars that are high up in the atmosphere. Typically between 1580 kilometers, in the middle atmosphere as we call it, because they can tell us something about the structure and also about the ability of water vapor in that region of the atmosphere.

Mat Kaplan: Marek, before we go on talking about the science, I've seen a lot of pictures of these clouds. I bet a lot of our audience has too. They can be quite beautiful, can't they?

Marek Slipski: Indeed. Yeah. I know you had Mark Lemon on at one point-

Mat Kaplan: We did.

Marek Slipski: ... to talk about the mother of pearl clouds. We see some of those same clouds. Like Armin was saying. These middle atmosphere clouds that we're interested in are sort of like these noctilucent clouds that are seen on Earth.

Mat Kaplan: What is the idea here? Are we still trying to learn where that much thicker ancient Martian atmosphere has gone? Is that one of the reasons, at least, you've started this project?

Armin Kleinboehl: Yeah. This is one of the drivers. This is a big question. And it's a question that's got quite a bit of attention over the last couple of years because we found that, when water vapor is in the middle atmosphere of Mars, it can easily photolyze. It can be broken down by incoming solar light. Sunlight. It's split up into its constituents like hydrogen and oxygen. And the hydrogen, in turn, can be transported farther upward in the atmosphere and escape. That way, you have water loss. You can lose water from the Martian system to space. Water-ice clouds are a proxy for water vapor. If we have water-ice clouds, then there also has to be water vapor around. So, by looking at where these clouds are located in the middle atmosphere, we get an idea how high the water vapor can reach at a given season and that gives us an idea about how important that process of splitting up water in the middle atmosphere with subsequent hydrogen escape... How important this process really would be.

Mat Kaplan: Well, what are some of the specific questions that you're hoping to answer as we examine these clouds?

Marek Slipski: Just to maybe hit on a slightly different point... Just like we talk about global climate models for Earth and climate change, we work on these same sort of models for Mars in the present day and Mars in the past. Clouds can be a big source of uncertainty in these models. There's a lot of questions about how they form at the very small scales and they can impact the atmosphere in different ways. To map these clouds out, to determine their compositions, and to be able to iterate with the model air design where we do see them and where we have trouble forming them in models is important for understanding the whole climate of the planet, whether it be today or in the past.

Mat Kaplan: Armin, we talk about the Mars Reconnaissance Orbiter on this show all the time, but it's usually related to that amazing HiRise camera that gets most of the attention because it makes such undeniably gorgeous images. Tell us, though, about this instrument that you are working with, which is that the basis of the data that's coming into this citizen science project?

Armin Kleinboehl: We work with the Mars Climate Sounder instrument. MCS for short. It's an infrared radiometer. It has nine channels. Nine wavelength ranges where it can look at the surface or the atmosphere of Mars. And it predominantly looks at the Mars limb. That means it looks across a horizon. This is a way of looking at the atmosphere in much detail. If we have vertically resolved profiles of radiance that we can observe in the atmosphere, we can derive vertically resolved geophysical information from it like temperature profiles or the profiles of dust. Or clouds in our case. So, the MCS is really the primary atmospheric instrument on the MRO mission. It's been a fantastic investigation because we've been able to operate this instrument and the spacecraft since September 2006. We have about 16 years worth of data that corresponds to about eight Mars years. As we are climate scientists, these long time series are really valuable because we can find features and structures that might be repetitive in the atmosphere that you would not be able to find the futures had a year or two of data.

Mat Kaplan: Infrared observations have sure been in the news a lot lately thanks to the James Webb Space Telescope, of course. What is the particular advantage of having this instrument work in the infrared range as it scans the atmosphere of Mars?

Armin Kleinboehl: The infrared range... We work particularly in the thermal infrared. Everything essentially radiates in the thermal infrared. You, me, the Martian surface, and the Martian atmosphere. By picking up that radiation, we can basically do atmospheric measurements independent of the time of day. The instrument can do observations during daytime as well as during nighttime. And the intensity of the infrared radiation is converted pretty easily to a temperature because that connection is fairly direct. An infrared instrument is really the primary technique for doing these kinds of observations of atmospheric temperature in the atmosphere of Mars or in any planetary atmosphere.

Mat Kaplan: We've got so many spacecraft now orbiting Mars. Others that are also examining the atmosphere. I'm thinking of Maven and the UAE's Hope mission. Do you coordinate with the teams for these other orbiters and possibly for some of the spacecraft down on the ground? The rovers and landers.

Armin Kleinboehl: We do actually, yeah. We are in communication with the teams of these spacecraft that you mentioned. I actually did attend a team meeting of the Emirates Hope mission a couple of weeks ago. We do data comparisons and try to find synergies between these different kinds of measurements. They all have different measurement geometries and they have different strengths and weaknesses. By combining some of these measurements, we hope we'll be able to describe the atmosphere more comprehensively than any individual mission might be able to do.

Mat Kaplan: Marek, let me turn back now specifically to the Cloudspotting on Mars project and something that I think maybe you've been asked because it's actually addressed on the project website. By the way, we'll put up links. The link to the project website, where I took your nice tutorial, gentleman. It looks like it would not only be fairly easy, but kind of fun to participate in this project. We'll put up that link and some other relevant stuff on this week's show page at planetary.org/radio. But here's a question that occurred to me even before I saw a reference to it in some of the material I read. Why do you need human eyes for this work? Isn't this kind of thing well-suited for some dedicated AI with a nice algorithm running inside it?

Marek Slipski: That's a great question and it's sort of how this started. I was working to build an algorithm to pick these out, especially these high altitude clouds. We can do this. Once you get going with it and you look at, say, one channel... Armin described we have these nine different spectral channels that we look in... you start to see these clouds all over the place. At all different seasons, different latitudes, longitudes, day and night. And then you want to apply that to each channel and you want to do this in different Mars years. We know that Mars can be very different... the atmosphere can be very different year to year with dust and dust storms. That affects how these show up.

Marek Slipski: As I was looking at the results or the output of this automated algorithm, you still have to go back and verify that it's spitting something out that's meaningful. And so I started to build up my own database of looking at these and put together a tool where I could visualize these arches and zoom in and out and change the color contrast to pick up the faint ones and then be able to pull the exact location out and save that to a file. As I started to do this, I realized that sampling all the different channels and all the different locations and different seasons and years was going to be quite a time sink for one person. That was kind of the basis for reaching out to some citizen scientists and saying we eed help to track all these and make sure we're doing this correctly.

Mat Kaplan: You mentioned the arches, which... Now, I've been to the site. I did the tutorial, as I said, so I kind of know what you're talking about. But other people must be wondering. Because you're presented with an image. In some of these, at least in the samples that were displayed, there is this thing which reminded me a little bit of the great St. Louis Arch. That big architectural structure that is next to the river in St. Louis, Missouri. I hope that's a decent comparison. It looks like a parabola.

Marek Slipski: Yeah, I think that's a great comparison. It can be quite striking in some of the images. In some, there'll be several right next to each other or, in some images, there might be 20 of these scattered throughout. You get those arches because the observing geometry that Armin was talking about. We look at the horizon. The spacecraft is going to move through its orbit. It's going to be looking at different slice of horizon at each point. And so, originally, there might be a cloud behind the slice of atmosphere you're looking through, but as that spacecraft moves, as MRO moves, and we look at a slightly different view, it seems like the cloud is at a higher altitude. It kind of keeps moving up until we actually see it at its true altitude and then that kind of comes back down. So if you're looking at these measurements as a function of time and altitude, you see these nice arches pop up.

Mat Kaplan: If I was doing the cloudspotting project, I'd be looking for the very peak of those arches and I'd just drop a little marker there, right?

Marek Slipski: That's right. It's a fairly simple project on Zooniverse. Some Zooniverse projects will have all sorts of questions about the image you're looking at, but here, we're just trying to pick out the peak of those arches, which is the altitude of the cloud.

Mat Kaplan: I'm glad you mentioned Zooniverse. We have talked about that citizen science platform before, which is so powerful and so popular. What led you to choosing Zooniverse? Was it particularly well-suited for what you had in mind?

Marek Slipski: Yeah. Like I was describing, this tool, we tried to hand that off to some citizen scientists that Armin was working with at the time. We got it working for a couple people, but we also ran into some technical difficulties. That was about the same time that we were realizing that citizen scientists might be interested in this and that it might make for a good project. So, we thought about extending this and Zooniverse is sort of the central hub for these projects. They have a huge user base. You were describing the tool that you used to find these. They have those ready out of the box. They have this nice infrastructure set that we can format our data a certain way, upload it, and they're going to take care of the rest in terms of recording all of the user input and handing it to us on the backside to look at that output.

Mat Kaplan: Great platform. So, what has the response been? I didn't get the announcement of this project very long ago. How long has it been open for people to work on?

Marek Slipski: A little over two weeks at this point. It hasn't been long. We have over 2000 registered users who have interacted with the project, which is fantastic. It's definitely exceeded our expectations. They've classified over 100000 images. We haven't uploaded that many, but we've had at least 20 people look at every image that we've uploaded. Yeah. It's been fantastic and we're thrilled with the engagement we've had.

Mat Kaplan: Man, the power of citizen science and putting that kind of motivated team to work. I hope that one of you can say something about the NASA effort that has funded this project. I had not heard of the Citizen Science Seed Funding Program before, which I guess enabled you to pull this off.

Armin Kleinboehl: Yeah, that was... I think that was kind of lucky. That this is a fairly new program. I think we were the first year... When we applied for funding from this program, we were the first... It was the first year when this program was actually established. And it's a program that tries to fund citizen science projects or at least the initial development of citizen science projects in the fields of planetary science, heliophysics, and astrophysics. In earth science, there's a longer tradition with citizen science activities, but I believe NASA wanted to have a dedicated vehicle to foster citizen science in these three other branches of NASA research. So, I guess the timing was just about right. That this announcement was made that there might be funding available. Marek and I wrote a proposal and it was actually selected as the only planetary science proposal at the time. The timing was just right. I'm really glad that we wrote a winning proposal and had the opportunity to do this project and develop a tool that now can be used by citizen scientists all over the planet.

Mat Kaplan: I was on the website for the citizen science program at NASA, which we will put up the link to also on this week's show page. I counted nearly 30 NASA sponsored projects. Apparently, they just funded the second round of these. I will say... Don't tell anybody that I said this, but I think you guys had the best project logo. I might be biased.

Marek Slipski: Thank you. Yeah, we really appreciate that. Shout out to the JPL people who put that together for us.

Mat Kaplan: I think we may have already answered this question, but if people want to get involved, they just go to the website, right? Really, it's kind of self-explanatory once you're there.

Marek Slipski: That's right. We have a couple of pages that describe the science and the motivation. Some of the things we've been talking about here. The main page itself will walk you through sort of what you need to know to pick these out and what's going on and how to use it. This is another thing that Zooniverse has set up super well to make these nice tutorials and get people introduced quickly so that they can start exploring and interacting with the data.

Mat Kaplan: I hesitate to call them rewards for your participants, but don't you have some gatherings, some webinars, that you offer for people who work on the project?

Marek Slipski: Yeah. Just about to have our first webinar where we've invited all the citizen scientists to come hear more about the science and the research and about MRO and Mars. We want to meet and hear how they got involved and what they're interested in. We've had talks with people from other NASA citizen science projects in the past and they really encouraged us to do this. To not just keep everything on the website. There's lots of room for discussion on the talk boards of Zooniverse, but it's also good to see faces and hear voices and really try to build a community out of this.

Armin Kleinboehl: There is actually also an opportunity for participation past the website. The dataset that will be created through this project will be publicly available. Anybody, essentially, who's interested in this kind of science can download data and look at some of these cloud distributions that we find through the project themselves. Also, we are always open for ideas and suggestions and ways on how to analyze the data or how to look for certain features. There's a broad community out there with people with very different skills and very different interests, so we would like to hear about these people and talk and talk to those people and maybe new ways of doing analysis and new ways of looking at the data will emerge.

Mat Kaplan: Well, I have to tell you that, as pioneers in the field of citizen science, all of us at the Planetary Society love these projects. I like to tell people that we provided some of the startup funding for [inaudible 00:20:18] to the folks up at UC Berkeley and look what that has turned into over the years. You guys have certainly provided a terrific example of what can be done by we citizen scientists who don't have letters after our names that would immediately qualify us for this kind of work. I wonder, as you talk about how people are coming to this, how the two of you got into this line of work. Armin?

Armin Kleinboehl: I've been interested in space my whole life. Maybe part of it was an excursion that I did maybe in elementary school to a private observatory not too far away from where I grew up in Germany. They always would have an open house over Easter. My parents took me there once. I was so fascinated. I insisted on going there every Easter for several years. I'm still very interested in this. I studied physics and did a PhD in earth atmospheric science originally, actually. But after couple years of postdoc at Jet Propulsion Laboratory, there was the opportunity to join the Mars program and work on Mars Climate Sounder and Mars Reconnaissance Orbiter. I took that and I think it was a very good decision. It's been a great mission and it's been a great, great experience to work on this topic.

Mat Kaplan: Sounds like it. I have said before on this show that I kind of grew up... I'm an LA kid. I kind of grew up at the Griffith Observation up there above Hollywood here in California. Marek, how'd you end up in this business?

Marek Slipski: I've always been interested in space and physics. Yeah, that bug got me early. Studied physics and astronomy in undergrad and spent a ton of time at the local observatory doing observing nights and learning how to use the CCD camera mounted to the telescope. Decided to go after a PhD. Around that point, I realized that planetary, the solar system planets, is what I wanted to focus on. Got lucky enough to get involved with the Maven mission at the University of Colorado Boulder. That really got me hooked on planetary missions as a way to answer these questions. They're designed to answer specific big picture questions and they have a variety of instruments where you get a diverse group of people who are interested in really different physics associated with the different instruments, but they all have to come together to answer these big questions. It's just awesome to see this continue.

Mat Kaplan: One of the best things about planetary science... makes my job more fun too... is how multidisciplinary it is. How it has to be to be able to get this work done. Gentlemen, thank you so much. This is fascinating. I hope that this conversation leads you to picking up a few more cloudspotters out there. If you were just straight astronomers, I would wish you clear skies, but I guess that would be counterproductive in this case.

Marek Slipski: That's correct.

Armin Kleinboehl: Thanks, Mat. Thanks for having us.

Marek Slipski: Yeah, thanks so much for having us. It's been a pleasure.

Mat Kaplan: My pleasure. Thank you very much. JPL researchers Armin Kleinboehl and Marek Slipski manage the Cloudspotting on Mars citizen science project. I'll be back with Bruce and What's Up in about a minute.

George Takei: Hello. I'm George Takei. As you know, I'm very proud of my association with Star Trek. Star Trek was a show that looked to the future with optimism, boldly going where no one had gone before. I want you to know about a very special organization called The Planetary Society. They are working to make the future that Star Trek represents a reality. When you become a member of The Planetary Society, you join their mission to increase discoveries in our solar system, to elevate the search for life outside our planet, and decrease the risk of earth being hit by an asteroid. Co-founded by Carl Sagan and led today by CEO Bill Nye, The Planetary Society exists for those who believe in space exploration to take action together. So join The Planetary Society and boldly go together to build our future.

Mat Kaplan: Time for What's Up on Planetary Radio, so here's the chief scientist of The Planetary Society. It's Bruce Betts. Welcome once again!

Bruce Betts: Thank you, man. Always great to be with you here in this formal setting.

Mat Kaplan: If this is a formal setting, I'd like to join you in an informal one someday.

Bruce Betts: You can't handle the truth!

Mat Kaplan: I can barely handle the formality. What's up?

Bruce Betts: We got all sorts of good stuff. We're going to clip through this. We've got four planets. We got Saturn coming up in the early evening. In the east, of course. And then Jupiter looking bright a couple hours later. Mars kind of middle of the night. And Venus low in the east in the pre-dawn. But wait! It's not over yet. We'll also throw in Uranus if you have some binoculars, which we'll also be happy to sell you... No. Uranus. If you're picking this up right after we come out on the third or fourth of August, you can check out Uranus through binoculars as a blue dot near the much brighter Mars coming up in the middle of the night. What do we got? We've got so much coming up after that. We've got the Moon near Saturn on the night of August 11th into the 12th. By the way, there's a meteor shower. Hey, Mat, I've got good news and bad news for you.

Mat Kaplan: Which do I want first?

Bruce Betts: You want the good news first. No? You want the bad news first. No, you want the good news. Good news. Definitely good news. Perseid meteor show. Traditionally, the second best of the year. 60 to 100 meteors from a dark site.

Mat Kaplan: An hour.

Bruce Betts: Yeah. And now you ask me.

Mat Kaplan: Oh. So, Perseid. That's all good news. You have another side of the coin?

Bruce Betts: I do. At least if you're looking at meteors. There's a full moon that night of the peak. August 12th, the 13th. It'll wash out many of the fainter meteors. But you still can go and check them out and check out the part of the sky that's not right at the full moon. Look after midnight and you'll get more meteors. And the peak is several days in existence. It's a broad peak and so you can look a few days before, a few days afterwards. Should still get some meteors [inaudible 00:27:00] Go outside, stare at the sky, and chill until you fall asleep and then imagine meteors without a full moon.

Mat Kaplan: That's terrible planning. Just terrible planning. Why'd they do this during a full moon?

Bruce Betts: I don't know. I'll talk to the powers that be.

Mat Kaplan: Thank you.

Bruce Betts: On to this weekend's space history. It was this week in 2004 that Messenger launched to Mercury and would become the first Mercury orbiter. In 2007, that Phoenix launched to Mars and gave us the first successful near polar region lander on Mars. And you may have heard of it. Curiosity rover landed 10 years ago this week and it's still going strong.

Mat Kaplan: That is a heck of a week for planetary science.

Bruce Betts: It really is. You know what else was a heck of a thing.

Mat Kaplan: No! What?

Bruce Betts: Random space fact. Random space fact! The Moon... our moon, the Moon... has a surface gravity more than two and a half times the surface gravity of Pluto.

Mat Kaplan: Wow!

Bruce Betts: You'd have the same mass, of course, but your weight would be two and a half times on the Moon and we already think of the Moon as not having a whole lot of gravity. It's 16 percent of Earth. We should go on to the trivia contest. What was the first published scientific work to include telescopic observations to the Moon including drawings? We'll see if anyone can rhyme with the Latin name of the word.

Mat Kaplan: You know where people are going to excuse you of being tricky here? It's that word published. Here is why. It comes directly from this week's winner, Jerry Robinette, who has been listening for a very long time. I believe this is his first win. Congratulations, Jerry. In the great state of Ohio. Here's his answer. The winner is Sidereus Nuncius, usually translated as starry messenger, by Galileo Galilee in 1610. Only because Thomas Harriett never published drawings from observations a few months earlier. The moral of the story? Publish or perish.

Bruce Betts: This was like 400 years ago. I'm pretty sure everyone perished. That's kind of a bummer.

Mat Kaplan: Oh god.

Bruce Betts: This time, I wasn't trying to be tricky, but I was trying to be very specific. That is why I went with published. We've got Sidereus Nuncius, which means sidereal nonsense.

Mat Kaplan: No.

Bruce Betts: Wait, no.

Mat Kaplan: It does not.

Bruce Betts: You said it.

Mat Kaplan: In fact, here it is from Edwin King in the UK. Galileo called the book, after Mat, Starry Messenger.

Bruce Betts: Aww. I didn't know that.

Mat Kaplan: Can we get Edwin on the payroll, too?

Bruce Betts: No.

Mat Kaplan: Right. Hey, Jerry. You're going to get... oh my goodness... a Planetary Society Kick Asteroid rubber asteroid. Congratulations. I've got other good stuff or is there more you wanted to add?

Bruce Betts: Oh, no. Please share.

Mat Kaplan: Well, from Dave Fairchild, the poet laureate in Kansas. In March of 1610, we know that Galileo thought, I'll publish me a treatise that is more than just a shot. These people say I do not know what's in the brilliant skies. That everything I talk about is nothing more than lies. I'll write a book and show them clear that I know what I'm doing. And fill it with astronomy and other things I'm doing. With telescope discoveries and also with my sketching. And call it Starry Messenger. So, stop with the [inaudible 00:30:33]. Hey, Dave. You get the Dr. Seuss award of the year, I think, for that one. That's well-done. Mel Powell in California. The e-book version that came out in 1611 really helped it take off in popularity. He then added in parentheses, "You actually can get a Kindle version of Starry Messenger." Mel says Bruce's new book is better, though.

Bruce Betts: Wow. I'm on the one hand extremely honored except that I worry it's only because Starry Messenger was written in a form of Latin.

Mat Kaplan: [inaudible 00:31:09] in Belarus. He looks back to when we had that conversation with Jim Green. Jim talked about that first UNIVAC computer he used that used paper tape for input. And output, I think. Progress is moving so fast that both Galileo's drawings and UNIVAC's paper tape seem to be on the same technological level. [inaudible 00:31:28]. Too true. Jean Lewin, finally, in the state of Washington. Predating selenography, quintessence it was thought to be, those sketches pinned by Galilee directly challenged Ptolemy. Not smooth at all. In fact, diverse. The published drawings were the first. A treatise detailing what he'd seen viewed by telescopic means, his starry message did contradict, helping label him a heretic. Sidereus Nuncius, its Latin name, now resides in astronomic fame.

Bruce Betts: Wow.

Mat Kaplan: Pretty impressive.

Bruce Betts: There were some big words in there.

Mat Kaplan: I got a few more words to add from Jerry Robinette because, once again, I want to thank all the people who have been sending me lovely, lovely notes about my moving out of the host chair for this show come late November. I can go back to our winner because this is what he said. Mat, say it ain't so! Okay, you've definitely earned the chance to pursue other adventures. But your combination of professionalism and sincere enthusiasm will be very hard to replace. Thank you, Jerry. We'll see about that because we're going to find the perfect host. Don't worry. No worries. Don't worry, Bruce. You know what? You need a distraction. Tell us what's happening next time.

Bruce Betts: All right. Here's a question to distract yourselves with. What solar system moon has the highest surface gravity? Go to planetary.org/radiocontest.

Mat Kaplan: You have until the 10th of August. That would be Wednesday, August 10 at 8:00 AM Pacific time to get us this one. Bruce, do you remember when we gave away a book called Carbon? This beautifully illustrated book that traces the life story of a carbon molecule?

Bruce Betts: Yes. The surprise ending was shocking.

Mat Kaplan: Well, it wasn't shocking, but it did... what's the word I want... combine with a lot of stuff. You know, carbon.

Bruce Betts: Amalgamated.

Mat Kaplan: Oh, that's perfect.

Bruce Betts: That might be it.

Mat Kaplan: This is from John Barnett. We've given it away before. It's been a while. We found an extra copy. You will love this book. It is just gorgeously illustrated. Each page reveals another chapter in the life of this very busy little carbon molecule.

Bruce Betts: I don't remember. Does it have a name?

Mat Kaplan: Carbon. Oh, you mean the molecule. I don't know. I guess we could name it. Why don't we do that maybe as part of the contest? Give us the best name for this carbon molecule. That won't necessarily help you win, but it might help you get you mentioned on the show in two weeks.

Bruce Betts: Nice.

Mat Kaplan: We're done.

Bruce Betts: All right, everybody. Go out there, look at the night sky, and think about this. You can record and then you can re-record. You can do. You can redo. But do you do first when you repeat. Do you peat? Thank you and goodnight.

Mat Kaplan: Oh, for Pete's sake. He's the chief scientist of the Planetary Society. Bruce Betts. And he repeats it 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 cloudspotting members. Cloudy or clear, you can always find your way to planetary.org/join. Mark Hilverda and Rae Paoletta are our associate producers. Josh Doyle composed our theme, which is arranged and performed by Pieter Schloser. Ad astra.