Planetary Radio: Space Exploration, Astronomy and Science - Return to Fiery Mercury With BepiColombo

Episode Date: September 19, 2018

Elsa Montagnon is Spacecraft Operations Manager for the European/Japanese mission leaving for our solar system’s innermost planet very soon. She joins us to talk about the long journey ahead. Elsa also has the cover article in the brand new edition of The Planetary Report, the Planetary Society’s once exclusive magazine that is now available to everyone online, according to its editor, Emily Lakdawalla.  Planetary Society CEO Bill Nye is happy for a very happy Elon Musk. The leader of SpaceX just introduced his paying customer for a trip around the moon in 2023. All this, and What’s Up! Learn and hear more at: http://www.planetary.org/multimedia/planetary-radio/show/2018/0919-2018-elsa-montagnon-bepicolombo.html Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

A return to fiery Mercury, 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. Engineer Elsa Montagnon is Spacecraft Operations Manager for the BepiColombo mission, launching in days on a long voyage toward the innermost planet in our solar system. She's my special guest on this episode. Did you watch the September 17 announcement from Elon Musk of SpaceX? If all goes well, in 2023, Japanese entrepreneur and billionaire Yusaka Maezawa and six to eight world-class artists will ride the

company's BFR or Big Falcon rocket around the moon. Elon himself might join them. Bill Nye will join me to discuss this news. Later, Bruce Betts and I will widen the definition of relativity for this week's What's Up. Planetary Society Senior Editor Emily Lakdawalla also has an announcement to make. Emily, as we speak, it has only been really a few minutes that something really wonderful has happened with the Planetary Report. That's right, Matt. The Planetary Report is the Planetary Society's flagship member magazine. It's been in print for 38 years. flagship member magazine. It's been in print for 38 years. This issue, the September Equinox issue just went out. It's my first issue as the editor of the Planetary Report. And with my first issue, I have made, and the Planetary Society has made the Planetary Report an open access magazine. So

anybody can read it. You may download it in PDF form or read it as HTML on our website. And I hope that it reaches a much broader audience than it used to. And I hope that people enjoy it. You may download it in PDF form or read it as HTML on our website. And I hope that it reaches a much broader audience than it used to. And I hope that people enjoy it. And as a member of the society, I am very proud and very excited to know that this is now going to be available to everybody around the world. How do people access it? You can access it on our website. Just go to planetary.org and go to the Explore tab, and the Planetary Report is one of your options there. Or actually, all of the articles are also now being fed out through our news feed, our blog feed, so you can read them there as well. One of the things that I love about this is that the magazine online, it's not just a PDF.

This is really adapted well for web reading. We did our best to make it as accessible as possible. And one of my big goals with it was also, you know, we have a lot of infographics that are specially designed and produced for the magazine. And I want those to live beyond the pages of the magazine. So I've made those available through Creative Commons licenses.

So anybody who wants to republish them may do so. So you can find all of those on the website at planetary.org. Your cover article by Elsa Montagnon, she is our featured guest that we'll be hearing from in just a few moments on this week's show. Yes, Elsa wrote an article about the BepiColombo mission. And then we have Long Xiao writing about the Chang'e 4 and 5 missions to the moon, as well as Sriram Biravarusu talking about the Chandrayaan-2 Indian mission to the moon. And all the other regular features of the magazine.

I hope everybody listening to this will go and check it out. Emily, you're in Portland, Oregon. Tell us why before we say goodbye. I had a great time last night talking to the Rose City astronomers and their guests at OMSI, the Museum of Science in Portland. It was a wonderful crowd, very enthusiastic, lots of kids, and I had a great time. Thank you, Emily. Thank you, Matt. That's our senior editor and now the editor-in-chief of the Planetary Report, the Planetary Society's planetary evangelist, Emily Lakdawalla. Let's talk with the CEO of the Planetary Society, Bill Nye the Science Guy,

about that big event that Elon Musk just hosted at SpaceX in Hawthorne, California. Bill, I don't know about you, but I had great fun watching Elon Musk seeming to have great fun announcing not just who's going to be going to the moon on his BFR, big Falcon rocket, but he just seemed to be thrilled about the whole concept. Well, this is the big stepping stone for to go to Mars. This has been Mr. Musk's thing from the get go. Everybody who works at SpaceX is on board with this idea that we're going to Mars, we're going to Mars, we're going to Mars. And that singular focus has, I believe, enabled SpaceX to accomplish all these remarkable technical things. And we were there in Adelaide at the Astronautical Congress in 2017 when he announced the existence

or the future, the plan rather, for the big Falcon rocket. And his argument is if you can make enough of them, enough of these rockets, and use them for domestic or rather terrestrial trips, you'll lower the cost of the whole thing. And so to actually build this actual rocket and actually get an actual astronaut actually on board the actual rocket is a huge step. And I'll just say, technically, as an aerospace engineer, a key idea is the fuel tank. The vision is to use methane, natural gas, in a visionary way, you'd produce it from carbon dioxide in the atmosphere, with the hypothetically limitless electricity from renewable sources like wind and solar energy, and then repurpose that carbon dioxide as methane and fly anywhere.

And a big idea is to densify, that's a verb now, to make the methane more dense by getting it really cold. So not only would the liquid oxygen be cold, but the methane would be cold in the same way that hydrogen, liquid hydrogen is used in rocket engines. So the whole thing is visionary. So no wonder he was happy. He was happy. And I just want to mention, do you remember the conversation I had with Mr. Musk nine years ago before a whole lot of people knew who he was and what he would accomplish. Well, I remember you describing that. This is the conversation. No, you go ahead. I remember you describing this.

We had this great conversation. We'll put up a link to that ancient show on this week's show page at planetary.org slash radio. And you can hear us, hear me talking to Elon. And we had a great conversation. The last question I asked him was, are you having fun? And it kind of threw him for a loop. Why would I have fun? What do you mean? Why is this fun? What is wrong with you people? Is that what you do with your time, pursuing fun? Exactly.

Aren't you in a hurry to get things done before you die? You can't have fun. But now. But now he seems to have caught on that this is actually a pretty, he's got the PB&J. The passion, beauty and joy of space exploration. No, but it really is visionary. So everybody, you know, Planetary Society has some experts. And we did an analysis of the Falcon Heavy and the reusable booster stages, Falcon 9 cores, as they're called, being repurposed and reused multiple times, extraordinary claims, several

dozen times, up to 100 times. But the BFR is sort of skipping that step. So to actually produce the fuel tank and actually plan to actually build the actual rocket, it's got to be cool. And I'm glad he's having fun. And for those of you who are Planetary Society members, thank you, thank you. The LightSail 2 spacecraft is on the manifest for the second Falcon Heavy launch. The launch period is still scheduled to open on the 30th of November or not before the 30th of November. The Falcon Heavy is an extraordinary, dramatic, amazing launch. I shudder to think or I'm excited to

think how the BFR launch would be like. And I'll say just not in closing, but let me add 2023 is pretty ambitious. Not saying it can't be done. It's just pretty ambitious. But of course, we sit by. We do. And I look forward to talking to you about LightSail 2 as we get closer to that launch. Oh, it's going to be cool. Everybody, LightSail 2 will be up for, it depends on atmospheric weather, but be up for about a year. Be able to see it in the sky for about a year. It's very exciting. And it's exciting and always fun to talk with you, Bill, about that PB&J of space exploration. Thanks again. Thank you.

That's the CEO of the Planetary Society, Bill Nye the Science Guy. BEPI-COLOMBO BEPI-COLOMBO will be only the second human-made robot to visit Mercury since Mariner 10's brief encounters 44 years ago. The joint European and Japanese mission is loaded with instruments that will help us learn much more about this small, unique world and about the equally unique region that surrounds it, one that is dominated by a strange magnetic field and the awesome, punishing radiation of the nearby star we call the sun. Elsa Montagnon will lead the team of engineers and others working over the next eight years

to put the spacecraft, actually two spacecraft, into orbit. She joined me from her office at the European Space Agency in Germany to talk about what's about to begin. By the way, the audio quality improves as the conversation progresses. Elsa, thank you very much for joining us on Planetary Radio from there in Europe, where I'm sure you are excitedly looking forward to the launch of this next mission to Mercury. Yeah, indeed. It's only five weeks away, so we are counting down now already. I also want to congratulate you for a mission

already accomplished, a work well done. You and the entire Rosetta team, that wonderful, that glorious success, that visit to that comet, which we followed very carefully at the Planetary Society and here on Planetary Radio. Thank you very much. Rosetta was my first mission, and I remember it with great fondness. It's been a fantastic experience. Yeah, I wouldn't expect you to remember it any other way. So five weeks away as we speak. By the time people hear this, that will only be four weeks.

Are you, as we say, go for launch? Is everything looking good? Yeah, everything is looking very good. In fact, we've passed all the formal milestones confirming our readiness for launch. formal milestones confirming our readiness for launch. The spacecraft is now fully fueled and about to start its combined operations with the launchers in a matter of a few days or weeks, depending on when we start counting. So it's really happening now,

and we've been waiting for a long time for this. It means a lot to me, of course, personally, but also to the whole community. It's finally happening. And you really have been waiting a long time. You and, I guess, some people on the team who, I assume, may have been part of it since the mission got the go-ahead way back in the year 2000? Yes, indeed. I mean, we have colleagues who even started supporting the mission before that, when it was in its very early years, when the mission is being assessed. I think this started in the mid-90s. Myself, I joined the mission in the mid-2000s and got my current job in January

2007. So I've been here for more than a decade already working for this moment. You and the team are definitely in this for the long haul. I read that the spacecraft will not go into orbit around Mercury until 2026. That's a long time to spend in space before you reach your final orbit. Yeah, that's right. We have a very long cruise phase of seven years. This is very specific of a mission to Mercury, where we cannot go on a typical human transfer, a very short transfer. We have a very long cruise phase, which combines planetary swing-bys. We'll have nine of them with electric propulsion. And again, it's a typical trajectory for Mercury missions, but it's particularly complex. Can you remind us why it is so difficult to get into orbit

around Mercury? Yeah, Mercury is so close to its parent star that we have to avoid to fall into the sun, so to say. So we have to break the spacecraft. Also on this mission, we plan to use the gravity effects of Mercury and the sun to capture as naturally as possible. And this means we have to reach the sweet point where the attraction of Mercury is about the same as the one of the sun with respect to the spacecraft. And for this reason, this requires really a lot of energy. I mean, to illustrate this a little bit, maybe the spacecraft will travel during its seven-year cruise. It will travel 9 billion kilometers. For comparison, the Earth travels about 1 billion kilometers per year around the sun.

So we will travel more than we human beings on the Earth on our way around the sun. This will be a well-traveled spacecraft. I want you to know that we actually, we have a weekly space trivia contest for our listeners. And that number of flybys that you'll be making was actually the question that we asked. It won one of our listeners some prizes just recently. We noted that you'll be making two flybys of Venus. And I saw that after some

consideration, I guess there will be some science conducted during those flybys? Yes. The mission did not originally foresee to do much science during the cruise phase, but it's too tempting. We have about a dozen of instruments on the MPO and half a dozen on the MMOs, on the European and Japanese scientific orbiters we have. The most attractive of them for the general public are blocked by the transfer module during the transfer. So the cameras are not operable. But quite a few other sensors, in fact, most of the other instruments,

can do some science during the cruise phase. Maybe there will be some blockage of field of view. It's not going to be as ideal as when the spacecrafts are free flying, but there's still some opportunity, and the community is very excited about trying that out during the cruise phase. So we've decided to give it a go. Also, the second Venus flyby has a particularly favorable geometry for doing this. Our spacecraft is not very

maneuverable with respect to the sun. There's a lot of attitude constraints. Nevertheless, during this flyby, Venus will practically pass by the field of view on the backside of the satellite that some of our instruments have. And therefore, it's just too tempting. So we've decided to give it a try. Well, best of luck with that. This is such a complex mission in every respect. You already mentioned the two primary spacecraft that are being delivered to Mercury. But we'll post a picture of the spacecraft on the episode page for this week's show at planetary.org slash radio. at planetary.org slash radio.

And what our listeners will immediately see is that it really looks like three different spacecraft, not just JAXA's MMO, the Mercury Magnetospheric Orbiter, and ESA's MPO, the Mercury Planetary Orbiter, but that transfer module that you mentioned. Is that how you look at it as well, three different spacecraft, each with its own work to do? That's one way to look at it, well, three different spacecraft, each with its own work to do? That's one way to look at it. Even so, for us operators, actually, when they are stacked together, they will do for seven years of the interplanetary transfer, it would be maybe a

little bit dangerous to consider them too much as separate modules. We really have to see the attached modules as a single machine. So for us, it's basically not so much three modules independent from each other as four different configurations that are each of it a spacecraft with its own identity. I mean, in all cases, the MPO is a brain. So the MPO has the control, it has the computers, it has the mass memories and so on. It drives the whole show. But between the phase where the MTM is attached and the phase where the MTM is gone, it's radically different for the entire composite. So we use a different chemical propulsion system.

We have completely different access to solar power through our solar arrays. So for us operators, it's more the difference between the MTM attached or not attached, rather than the three spacecraft, each one individually. The MTM, that Mercury Transfer Module, is going to be somewhat history-making for ESA. I read about the comparisons to the Dawn spacecraft now completing its mission and the other successful electric thruster or ion engine missions around the solar system. But this is a first for ESA, isn't it? Yeah.

Okay. We've flown that technology already, but with much more reduced thrust levels. We've had a moon mission a few years ago called Smart One that demonstrated the technology in ESA. And then the technology that we're using, those thrusters, they flew in a less powerful version on our mission Goche around the Earth. These thrusters were designed to thrust up to 145 millinewton each, which is significantly larger than what we had achieved on Goche. It was less, it was not needed to go that high for that mission. And in that form, the package is quite new. It's also been quite entertaining to develop and to validate.

In fact, one of the tests is still going on as we speak. We're still validating the thrusters with respect to the required lifetime, because each one of them needs to be able to thrust for above 10,000 hours. And we want to verify that. So this test is still ongoing now. I find ion engines, electric thrusters, to be really very charming. And not that there'll be anybody there to see it, but to watch this spacecraft over those seven years

as it makes its way to Mercury with its 30-meter-wide, almost 100-foot-wide solar panels or solar wings, it really sounds like it'll be spectacular. Yeah, the spacecraft is really beautiful. I mean, it's not just the futuristic shape. It's very unusual. It looks a bit like a bus. But for me, what's also very particular is the thermal coating. The thermal coating is white, so iridescent white. It's ceramic fibers. It was developed specifically for the high temperature of the Mercury environment, and it gives the spacecraft a particularly beautiful dress, in my personal view. So it's quite a special machine,

yeah. Speaking of how close you will be to the Sun, spacecraft usually have to work hard to keep their solar panels oriented toward the sun. You'll sometimes be working just as hard to keep them pointed away. Yeah. In fact, this is one of the greatest challenges for operations during the mission. It would have been great to qualify the solar panels to be able to point to the sun at all times. It would have made our lives significantly easier. But this would have required the panel to sustain temperatures of the order of 350 degrees Celsius. We reached 200 through our qualifications,

so something's got to give. So we need to keep the panels really off-pointed. And we're not talking about an off-pointing of a few degrees. We're talking of an off-pointing of up to 70, 80 degrees in some phases of the mission. Wow. So, of course, the power production is significantly reduced through this. This has been one aspect of the design and the development that has given us also some headaches. But, okay.

Yeah. Now we have this concept in place, and it's also very specific to BepiColombo, I think, yes. At the Planetary Society, we have a special fondness for solar sails or any spacecraft that behave like them. I remember talking to members of the messenger team and how they had to take the pressure of sunlight into account. I assume you are having to do the same as the spacecraft navigates across the solar system. Yes, that's correct. The modeling of the solar radiation pressure is one of the aspects that we take into account for the planning of the attitude of the satellites. And in fact, with a satellite with the shape of BepiColombo that doesn't have many symmetries and is very largely exposed to the solar wind, the effects are going to be very visible.

And we have to carefully manage the usage of our chemical fuel during the cruise phase. And this is going to be an interesting aspect as well. You have a very busy period immediately after launch when, you know, I might have thought that you'd be able to relax a little bit, but it sounds like there will be a lot of work to undertake. Can you talk a little bit about that? What will you be doing? Yeah, the launch phase itself, we call it launch and early orbit phase in ESA. It's basically lasting only two and a half days. So we split the team into shifts of 12 hours each and it's very dense, but it should be very quickly over.

But for my team and myself, as soon as we're out of the layup, as we call it, we go into the commissioning phase, which is the checkout and testing of the spacecraft. We go subsystem by subsystem, verifying the functionalities. And then once we're happy with that, we move on to the instruments and the MMO, of course. This phase will last two months. It's largely dominated by the checkout of the electric propulsion subsystems that we've already mentioned. It's so complex that the checkout of this subsystem alone will take about three weeks. Now, because what we want to do after launch is our first rendezvous, if you like, is with the Earth for a flyby about one and a half years after launch. We need electric propulsion to meet this rendezvous point. And

therefore, it's really important that we start using nominally the electric propulsion thrusters as soon as possible. In fact, from a trajectory point of view, the earlier the better. And for this reason, we've decided to plan the commissioning operations every day of the week, including weekends, in order not to waste time. So this means we have a relatively dense plan of operations lasting two months. So it's going to be quite intense for the team. So we'll have to wait a bit before we can relax. So we'll have to wait a bit before we can relax.

And then, eight years from now, another very intense period as you prepare, beginning many days ahead of time, to achieve orbit. Yeah. The MOI, I would say that the first challenge of the mission is to get the electric propulsion going and keep it going because we really needed to make it to Mercury. Once we reach Mercury, the next big challenge is the Mercury orbit insertion phase. It's of tremendous complexity. We plan to have as natural as possible a capture, but then the orbit itself, of course, that we would end up with a natural capture is not the one we want to be in for science. So we have a series of 15 maneuvers that will bring us from this insertion orbit, if you like, first to the MMO orbit and then to the NPO orbit. On the way, as part of this process, we also split the stack. So first, before we capture

around Mercury and enter, going to insertion, we will jettison the MTM because it will have done its job by then. We cannot afford to take it with us down to Mercury. And then once we reach the MMO orbit, we'll deliver the MMO into its scientific orbit from which they fly then on their own. And then we go further down with the MPO. I think I want to close by asking you to sort of represent your colleagues who are the scientists on the BepiColombo team.

Would you say that it's more or less accurate to say that you have one spacecraft that will be looking downward at the planet and another that will be looking at the region surrounding the planet Mercury? Yeah, I think that's pretty accurate. We indeed have two scientific satellites on this mission, the MPO built by the European Space Agency and the MMO built by the Japanese Space Agency. And MMO will indeed concentrate more on the magnetosphere surrounded Mercury in a quite elliptical orbit of nine hours, while MPO will concentrate more on the surface itself

and the composition, of course. It has all the classical instruments for such a planet investigation. So in this sense, it's quite a unique opportunity, actually, because it's not very often that we get the chance to fly two spacecraft at the same time around another object in the solar system. This gives a great opportunity to combine measurements, to take, for example, on the magnetic system. This gives a great opportunity to combine measurements, to take, for example, on the magnetic field. We have magnetometers on both satellites, and of course, then they will

be taking simultaneous measurements at various places in orbit. And this, apparently, for the scientists is a golden opportunity for doing their science. So I think they are very much looking forward to this very specific configuration. I've talked to some scientists who were very excited to see this mission picking up where others, particularly the MESSENGER mission, left off. And it really seems to be a very ambitious suite of instruments. Yes, the MPO carries a dozen of instruments of various kinds.

We have a laser altimeter, we have spectrometers, we have cameras, of course, and various bands. Magnetometer, I've mentioned. It's a classical equipment of such an ESA cornerstone. You could compare it to Rosetta. It's very finely tailored to its scientific objective. I'm also aware that specific instruments have not flown around Mercury before, so we look forward to very unique measurements that have not been acquired so far.

On the MMO, we are dealing with half a dozen of instruments as well, the multiple sensors, again, finally tailored to the study of the magnetic field and the interaction with the solar wind. So I think we're blessed with a very rich scientific complement, and we should look forward to get extremely interesting measurements picking up indeed from where MESSENGER left off. As we know, every new mission brings answers, but opens also new questions. So it will be very complementary and adding material for the knowledge we have. Absolutely. Will you be attempting to do some science during the earlier flybys, before you go into orbit, just as you explained that you hope to do at Venus? For sure, we're going to give it a try. It's going to be difficult, as I've mentioned before.

We have these very severe constraints that we need to get used to. We'll have to see what the attitude and the trajectory will be and whether we manage to capture a glimpse. I would expect that for some instruments like the magnetometer, for instance, we have a number that we should be able to activate in the surrounding of Mercury when we fly by. For the remote sensing, it might be more difficult. Okay, some of them cannot be used at all, but even the ones that can be used for those, we need a very specific attitude profile that we can only influence very little. So we'll have to see exactly what the trajectory will be. But for sure, if we can do it, we will do it.

Elsa, I hope you will allow us to make an appointment to repeat this conversation. Certainly in eight years, when you go into orbit around the planet Mercury, maybe sooner than that, perhaps after one or more of those flybys that BepiColombo will be making, if you wouldn't mind coming back on Planetary Radio to give us a progress report? Yes, that would be a great pleasure. I think it makes a lot of sense for this very long lasting mission. There are always interesting things to report. And I shall look forward to that. Wonderful. Thank you so much for this conversation. I should say merci beaucoup and bonne chance. We all are hoping, of course, for great success as BepiColombo heads inward and looking forward to an exciting launch that is now just a few weeks away.

Thank you. We have been talking with Elsa Montagnon. Space Agency and JAXA, the Japanese space agency that is about to begin its long journey falling inward toward our sun and the planet Mercury. Time for What's Up on Planetary Radio. Bruce Betts is the chief scientist of the Planetary Society, and he's here every week to talk to us about the night sky and all the other stuff we do in this little segment. We're ready to try that again right now. Give it another shot.

I'm going to be boring, but just a little bit longer and point you to Venus low in the west shortly after sunset. Still looking beautifully bright, but getting lower and lower. And Jupiter getting closer to it, up to its upper left. Also looking very bright, but not as bright. Then less bright even than those, Saturn, as you go farther towards the east across the southern sky. And then you reach Mars, which is still bright. It's about the brightest, it's about as bright as the brightest star in the sky, Sirius, right now. And looking reddish-orangish as usual.

We move on to this week in space history. It was 15 years ago that the Galileo mission, after successfully exploring the Jupiter system, came to an end as they intentionally crashed it into Jupiter. I apparently cannot speak well today. I apologize. You're forgiven. Thank you. I apparently cannot speak well today. I apologize.

You're forgiven. Thank you. Also, 2014, both the MAVEN spacecraft and MOM, Mars Orbiter Mission from India, went into orbit around Mars. Why is time speeding up? I don't know, but I think it's relativity. I blame Einstein. Why not? He's responsible for pretty much everything.

As we head into Random Space Fact, I've got a celebrity, a science celebrity intro for you. Here she is. Hi, this is Dr. Michelle Thaller. I'm an astronomer at NASA. And Bruce, would you give me a Random Space Fact? Yeah, Michelle Thaller, who is involved with science communication at the Goddard Space Flight Center. Yeah, Michelle Fowler, who is involved with science communication at the Goddard Space Flight Center. Our associate producer, Mary Liz Bender, ran into her at the launch of ICESat, the very last Delta II launch. That was last weekend, as you and I speak. Well, that's fun. Thank you. And here's your random space fact. Going back to Ceres, where Don is still hanging out, Ceres had two elements named after it, two chemical elements. Cerium, discovered in 1803, was named after Ceres. But in the same year, another element

was also initially named after Ceres. But when Cerium was named, the discoverer changed the name of the second one to Palladium after the second discovered asteroid to Pallas. That is terrific. I had no idea. I was just thinking what a great trivia question this would have been. Oh, darn it. Too late now. You gave it away.

And the trivia question is... But that is a really good RSF. We can go on into this week's contest. All righty. I asked you, what is the diameter of the Voyager 1 or Voyager 2 high gain antennae? How'd we do, man? Very nice response and a lot of clever stuff from our listeners. I'm going to open this week with Dave Fairchild, our poet laureate out there in Shawnee, Kansas.

When Voyager was talking to the Earth in time of need, it used a dual polarized, that's casagrain, for feed, a circular reflector with a parabolic side that measured quite exactly 3.66 meters wide. Very nice. And correct? Yes, yes. Yeah, I rounded off to 3.7, but yes, that is correct. Thank you, Dave. But congratulations, Scott. Scott Schlieper,

who's in Colorado Springs, Colorado, and he indeed said 3.66 meters. He is our winner this week. This is a little creepy. He seems to win almost exactly every two years. He is a three-time winner with this one. He last won in something like October or November of 2016, and then previously in November of 2014. Now, does he only enter every two years? That would really be strange. We'd have to look to Einstein again, I'm sure. I think he's in much more frequently. But anyway, congratulations, Scott. You've gotten yourself a Planetary Radio t-shirt that you can find at chopshopstore.com,

in the Planetary Society store there, of course, and a 200-point itelescope.net astronomy account, the worldwide network of telescopes, and a 200-point itelescope.net astronomy account, the worldwide network of telescopes operated on a non-profit basis and all kinds of great tools to help you do that astronomy. And you can also donate it. And we can take care of that donation if you choose, Scott, by working with Astronomers Without Borders. They'll send it someplace great. I have some other good stuff. Wojtek Nawylek. You know, we love to get these wonderful custom units of measure.

Indeed. 370 million beard seconds, which is the average distance grown by an average beard in one second. Wow. Mel Powell in Sherman Oaks, California. He said if you stood cosmonaut Alexei Leonov on top of NBA star LeBron James, you would have the right diameter. Or if you prefer, two Leonard Nimoy's of six feet each would come to 12 feet or 3.7 meters. Live long and transmit. meters, live long and transmit. A different sort of measure from David Fisher, who gave us the wattage as it is being received on Earth. I gave up after trying to figure out all the zeros. It's something less than one quadrillionth of a watt that is now reaching the Deep Space Network from Voyagers 1 and 2.

Wow. That's not a lot. No. And finally, Bruce Cordell, almost in reaction to that, he's up in Covington, Washington, he said, yeah, at least until Voyager gets that V'ger upgrade. Yeah, until then. Then it gets all sorts of more impressive, scary things. Captain Kirk, help us. We're ready to move on.

All right. I got a question for you this time. And that question is, what is the tallest mountain on Ceres? Go to planetary.org slash radio contest. Can I just say that Mark Raymond is not eligible to enter this contest? I don't know. Mark's worked really hard on a really good mission. I think he should be eligible. All right. Okay, Mark, you're okay. We'll just, well, we'll give you a t-shirt if you win for sure. Anyway, you have until the 26th, that's September 26th at 8 a.m. Pacific time to get your answer in. And I'm sure you're wondering what you're going to win if you win this one. Well, a Planetary Radio t-shirt, Natch, a 200-point itelescope.net account, and the great people at Distant Suns VR, Distant Suns Virtual Reality, they gave us a couple of more codes to download that app.

Remember, it's for Apple devices, iOS devices only, iOS. You can win yourself that terrific app and explore the universe with it. And I think that's a pretty good prize package, which means we're done. All right, everybody, go out there, look up the night sky and think about age relativity, things that move at different rates, things that gain mass at different rates with age. Thank you and good night. So it's still mid-afternoon here and I'm ready for dinner. Is that relativity?

Yes. That is another amazing example of Betz's age relativity. Special or general? Never mind. He's Bruce Betz, the chief scientist of the Planetary Society, who joins us every week here for a very relative version of What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its appropriately mercurial members, Mary Liz Bender is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser.

I'm Matt Kaplan at Astro.