Planetary Radio: Space Exploration, Astronomy and Science - Happy Asteroid Day!

Episode Date: June 28, 2017

Asteroid Day, June 30th, marks the anniversary of the great Tunguska impact that leveled a Siberian forest. It reminds us that a Near Earth Object can destroy a city or even a civilization. Former Minor Planet Center Director Tim Spahr reviews our efforts to find and understand these bodies.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Hello again, podcast listeners. It's your friendly host, Matt. I thought of something earlier today that I wanted to put in one of these little special podcast messages to you. And don't worry, the show's coming right up. I get such a kick out of hearing from listeners who become members of the Planetary Society, which of course you can do at planetary.org slash membership. And I love to hear from them and then write back to them to thank them. So I just wanted to say, if you're considering becoming a member, and of course we hope every one of you is, and you go ahead and do it, let me know. Write to me at planetaryradio at planetary.org so that I can send you a personal thank you because I love to do that when that happens, but I don't get like an automatic notification of it. I do hear when someone donates to the show or designates a gift to Planetary Radio, but I do not hear about those

of you beloved listeners who become members, unless you tell me. Please consider doing a review as well. iTunes is a good spot to do that. Let's get on to talking about Asteroid Day and Asteroid Week. By the way, the Lindley Johnson who was mentioned, Lindley is the planetary defense officer who works for NASA. So I just want to clear up that mystery before it hits you. Happy Asteroid Day from Planetary Radio. Welcome. I'm Matt Kaplan of the Planetary Society

with more of the human adventure across our solar system and beyond. Asteroid Day falls on June 30th each year. We'll celebrate it with Tim Spahr, the former head of the Minor Planet Center, who has discovered many of these fascinating objects. Later, Bruce Betts will tell us how to apply for the Planetary Society's Shoemaker-Neo grants that enable amateur astronomers to help us avoid the fate of the dinosaurs. Bill Nye is worried about how we'll communicate with rovers on the Martian surface once aging orbiters finally fail. And digital editor Jason Davis is ready

right now to take us out to planets seven and eight, where only one robot has gone before. Jason, you posted this nice piece a few days ago, June 21st, about revisiting the ice giants. We're talking about Uranus and Neptune here, which we've really only seen up close, as we know, once by one of the Voyager spacecraft. Why are these worth going back to? They're not boring? They're not boring. No, they're super interesting. Yeah, we're trying to give the ice giants a little bit of love here. You know, when Voyager 2 flew past in the late 80s, we got these awesome pictures and glimpses of the atmospheres of the planets themselves. And then all of these crazy moons, you know, that's the thing we learned over time about these gas giants and the ice giants, that they have really interesting moons as well that you can take a

look at. But of course, Voyager 2 whizzed by, got a picture of just one side of the planet, similar to the way New Horizons did when it went past Pluto. And we haven't been back since, and we've had to look at it through telescopes. And there are still a lot of unanswered questions. Voyager, in many ways, gave us more questions about what's inside of these things. More recently, NASA's been finding a lot of exoplanets out there, and we think that planets with masses similar to Uranus and Neptune are far more common than Jupiter and Saturn. So it really behooves us to learn about Uranus and Neptune, because that is really going to tell us more about how our solar system formed and how other solar systems formed. So I want to assure Heidi Hamel, if she's listening today,

that I was kidding. I was really kidding, Heidi. You talked to Heidi, who is a board member of the Planetary Society, full disclosure. She has, for a very long time, had interest in visiting these worlds again. You recount a great story that she tells. Yeah, yeah. Heidi's kind of the resident Uranus and Neptune expert, so definitely wanted to talk to her on this. And she told me this great story about how in the very early days, and we're talking 1800s of astronomy, astronomers were looking at Uranus and Neptune through the telescope, especially Uranus. And, you know, they would hand draw what they were seeing back in the days before photography. Some of their drawings would actually have features on Uranus.

It's kind of similar to the way Percival Lowell was drawing canals on Mars back in the day. Right. And thought we had aliens on Mars. And when photography started changing the way we did astronomy, we got these first plates back, you know, of Uranus. And Neptune was so far away, we couldn't see much of anything. And Uranus was just featureless. And so we said, ah, these early astronomers must have been wrong. They must have been seeing things that weren't there.

Since then, we have started taking images with modern adaptive optics telescopes, which can actually filter out some of the atmospheric distortion. Uranus, it turns out, has lots of features going on, mainly because since Voyager has flown by, it's progressed in its orbit to be more sideways to the sun. And that's kind of activated its atmosphere and brought out all these interesting features. We can now see those through the telescope. And Heidi talked about this and said that perhaps some of these early photographic plates, they were getting distorted from atmospheric distortion and just turned the planets into these big orbs that didn't have any features. Maybe these early astronomers were actually right when they were drawing all this cool stuff on Uranus. Well, now we need to find those canals on Mars.

You have a great image of Uranus from the Keck 2 telescopes, still currently the biggest on this planet, I believe, with and without adaptive optics. It's worth reading this article, even if you don't read anything else. It's just fascinating to see the power of AO. What are the challenges? Why do these planets present such a challenge for sending spacecraft back? Well, the main reason is that they're just so darn far away. First, you have to wait until the planets are aligned correctly, so to speak. You want to typically get a boost from Jupiter to put you on the right trajectory and get you there a little quicker. And these planets, you know, they're just so far out that it's even with the right planetary alignments, it's going to take you at least 10 years to get there.

That's a big investment. You have to pretty much have a flagship mission that's going to last for a long time. Get there, slow down, get into orbit. It's no small task. That's why essentially we haven't been back since the Voyagers. People are going to think of New Horizons going to Pluto, but of course that's a flyby, not an orbiter. And it didn't carry a probe that descended to the planet, which I guess is something they're definitely looking for with exploration of these

two bigger worlds. Yeah, they would definitely bring a probe along kind of like Galileo or the Cassini mission that dropped a probe on Titan. So that would fly into the atmosphere and give them the first in-situ measurements of what the probe was actually seeing as it descended into the atmospheres. And then, of course, it would also slow down, get into orbit, and do multiple flybys of the moons and just bring back a lot of really cool science, providing we can wait for a long time for these missions to launch and then return data. Yeah, a really long time. But that's planetary science for you, right?

Yes. Jason, thank you. It's a great piece, as I said, a June 21st blog post from Jason Davis, digital editor at the Planetary Society. You can find it at planetary.org. I look forward to talking to you again soon. Thanks, Matt. We've got the CEO next. That's Bill Nye, Bill Nye the Science Guy.

Bill, there's a lot going on a lot ahead of us at Mars, including that 2020 rover. But if we're not careful, there may not be a way to communicate with it. That's right. The orbiting spacecraft at Mars are getting old, 10, 12 years old, and things wear out. They'll be there another three and a half, four years at least before the next spacecraft is really on the surface and working. So as these things age, there won't be a way for the spacecraft, the rover, to communicate with an orbiter to send data back

to Earth in an economical fashion. By economical, I mean quickly. And so this is a big deal. And these things cost hundreds of millions of dollars, but they don't cost billions. They don't cost trillions of dollars. But without a launch planned, we're just going to run out of communication. The phone's going to go dead. And then what are you going to do?

It's going to be frustrating. We need the right leadership to put the right spacecraft in the pipeline so that we can continue to explore Mars. Because as I say, Matt, if we were to discover life on another world, it would change this one. And this week, Jennifer Vaughn and I attended the Planetary Protection Conference. This week, Jennifer Vaughn and I attended the Planetary Protection Conference. This is about so-called forward contamination of Mars, violating the prime directive, where we bring Earth-bound or Earth-born microbes to this other planet, and then we can't tell which microbes are ours and which microbes are Martian, if that turns out to be an eventuality.

These are things that take organization, management. That's what we advocate for at the Planetary Society. We need Mars orbiters to stay in communication. We need an idea at the top that we're going to explore Mars and not contaminate it. We're going to look for life without contaminating it. This is, well, we don't have the right alloys. We don't have the right equipment. We don't have the right sterilization procedures. Well, let's invent them. That's what we did with Apollo.

Let's go. Let's get this done, peoples. Oh, Matt, Matt, one more thing. Happy Asteroid Week. It's the anniversary of the Tunguska impact, June 30th, 1908. Wow. It could happen again. Speaking of planetary protection, we've got to be ready for planetary defense. Back to you, Matt. Thank you very much, and happy asteroid week to you as well, Bill. We're going to help celebrate it in a conversation with Tim Spahr, formerly of the Minor Planet Center, right now. June 30th, Asteroid Day. It's a day to remember the terrible destructive power of falling space rocks. It's also a day for science and learning about the origin of our solar system. Tim Spahr

has discovered quite a herd of asteroids and a lot of other objects, as you're about to hear. He's the former head of the Minor Planet Center. After decades of working in this field for others, Tim now heads his own consulting firm, Neo Sciences. That's Neo as in near-Earth objects, the asteroids and comets that cross the orbit of our fragile planet, and every now and then make a deep impact on it. Tim Spahr, it is a pleasure to welcome you back to Planetary Radio.

It's been too long, but the timing is great, even though a lot of people will be hearing this after Asteroid Day. I don't know, it seems to me every day should be Asteroid Day. What do you think? Oh, I agree, and certainly every day has been asteroid day for me for years. If you get Lindley Johnson on the air, he'll say every day is asteroid day at NASA headquarters. Yes, he will. And he has come pretty close to doing exactly that on this show. Do you have any idea how many objects, asteroids and otherwise you've discovered? I sort of lost track somewhere in there. I found several dozen on film. And then once the CCD survey got started, it was sort of hard to decide how to take credit. You know, I wrote software that discovered asteroids. Did I really discover them that the software found it?

I don't know. So it's lots. If you wrote the software, I think it's fair for you to claim credit. And there is a long list in your Wikipedia entry if you've ever seen it or even if you haven't. And it is not just asteroids. You've picked up at least a couple of moons, right? Yeah. And I have to say those were very exciting. One of the satellites of Jupiter and one of the satellites of Saturn, they were found by completely different means. The satellite of Saturn, I discovered as part of a program with Matt Holman, where I just used telescope time and took images. I just ran a script, and the next morning, he came to my office and said, we just discovered a satellite of Saturn last night. And I just thought that was great.

The satellite of Jupiter was found actually from data. So I wasn't taking any images. I was looking at astrometric positions, and I was having trouble tying a couple of objects together. I went across the hall to Gareth Williams and he said, hey, try putting them around Jupiter and everything fit together. And that was how we discovered that satellite. He's a co-discoverer of that one. So you are the practitioner of this art of finding small bodies moving against the starfield. It's something that goes way back in the history of astronomy, doesn't it? Oh, gosh, yeah. This is, well, you know, the definition of planet is wanderer. So somebody discovered the first moving object that was the moon followed by the planets. And so it's an ancient science, really. You know, just on last week's show, we were talking with the author of a book about the eclipse of 1878.

And some of the characters who were in that book were acclaimed worldwide because they had discovered minor planets. And there's a segue to the job that you had, that you still had the last time we talked, the Minor Planet Center. You've moved on from there. What is it that you're up to now? I think technically I'm a mercenary now. I run, yeah, such a thing, an astronomical mercenary, yeah.

I run a limited liability corporation. I'm available for hire to do various consulting work. I have worked for the Jet Propulsion Laboratory. I've worked for NASA. I've worked for a couple of private organizations. I really enjoy it. I like to not have a boss or to be my own boss, because then it's up to me what I do every day. And if I don't like what I did, it's kind of my

fault. So I can change that easily. The Minor Planet Center, that place that you spent, what, about 14 years at, remind us of what that center does and why it exists. The Minor Planet Center is the world's data collection center for all positional measurements for asteroids and comets. And they're really the, they're sort of the judge. They're the arbiter of discovery for every small body in the solar system. It's really essential to have an international clearinghouse for that because you don't want the Australians and the Czechs and the Spaniards all to claim discovery for something that they found independently. You want to have one place that says, here's who found this and when they found it, and here's the orbit.

And it's been that way for 70 or 80 years that one place has handled that. For that long. It started in the 1940s, I think I read. Yeah. Is it kind of first come, first served? I mean, it's whoever gets their report into the MPC first is declared the discoverer of that object? Yeah, that's the shortest version. There's a couple of other complications. It's best if the object is observed a few times around the discovery, but the key is reporting the object first. When I worked at the Minor Planet Center, Gareth Williams and I spent a lot of time

on defining discovery that way because we wanted to encourage rapid transmission of information. This is, you know, the internet age of all things. So the faster you can get your information, the faster we could make decisions about it. You know, there were some time critical objects. We did have an object that hit the Earth 19 hours after it was reported to us. So sometimes it is very important to report things as fast as possible. Which object was that? Was that the one that came down in Sudan or was that it wasn't Chelyabinsk, was it? No, no. This was a 2008 TC3 discovered by my good buddy,

Richard Kowalski at the Catalina Sky Survey, another place I used to work. Yeah, Richard picked up that object with their 1.5 meter telescope and it hit the earth about 19 hours after he found it. So that was the one in Sudan or in the Sudan? Yes, that landed in the Sudan. And of course, you know, there were pieces recovered, which just makes an absolutely fantastic story. Yeah. How does the MPC fit into what is now a worldwide structure? I mean, you know, we talk sometimes with Paul Chodas at JPL, and he keeps track of a lot of objects as well. How does it all work?

In my mind, it's a beautiful system, really. So you have this international team of asteroid surveys, and I mean truly international. Dozens of countries report positional measurements every day. Certainly the US leads the effort in discovery, but there's a lot of work being done around the world. Everyone in that network sends their positional measurements to the Minor Planet Center. So they're literally the first line of defense. If there's an impact coming immediately, an imminent impact, they will know before anyone else.

So they process the data, they quality check it, and distribute it very rapidly to the community. And this is where other orbit computers come in. So now we have the Minor Planet Center publishing data. Paul Chodas and his team at CENIOS, the Center for NEO Studies, they perform extremely high-precision calculations looking for impacts far out into the future. And that's a time consuming thing to do. So the MPC doesn't worry about that. The MPC is about the quickest announcements and the short term impacts, and then CENIOS takes over and looks for the impacts out into the future. Key to a lot of this is something you already mentioned, which is that it's often not just one observation of an object, because really that's not enough to tell whether it's moving against the star field, but multiple

observations are extremely important. Yeah. And in fact, without enough observations, we don't have enough to compute an orbit that is certain enough to tell if there's an impact. So the Minor Planet Center maintains a near-Earth object confirmation page that's certain enough to tell if there's an impact. So the Minor Planet Center maintains a near-Earth object confirmation page that's viewable to anyone in the world, and that has candidate near-Earth objects. And so anyone around the world can go, ooh, hey, look, I could find, you know, observe that object and report data to the MPC, and then that enables the MPC to make more precise calculations immediately. I've been told that nowadays, most of the asteroids being discovered are being discovered by these big, well-funded,

well, I don't know if they're well-funded, but these major surveys that are scanning the sky robotically. Yes, that's certainly the case. And a decade ago, there was a lot of room for amateur astronomers with smaller equipment, but it's very hard to compete with million-dollar systems like are being operated now. I will tip my hat to one of the

teams in the Southern Hemisphere. There's a group in Brazil that is concentrating on the southern sky, which that area can't be observed from Pan-STARRS or from Catalina because they're Northern Hemisphere telescopes. They find their share of new comets and asteroids. But still a role for these so-called amateur astronomers, some of whom we've talked to on this show. And now we're kind of edging into your role with this program the Planetary Society has sponsored for so many years, the Shoemaker-Neo program, where amateurs may not always, some of them do discover objects, but apparently they still have

a pretty important role doing the follow-up? Yeah, certainly the role has changed. And again, hats off to people who have been involved in a field and altered what they've been doing as the field has sort of changed out from under them. It's really fantastic. The big work that's being done now by a lot of these grant recipients, they're doing light curves. They're getting physical observations. A light curve tells you about the rotation rate of an object, which, you know, you say, oh, well, what does that tell me? Hey, if you want to land on an asteroid, you want to know how fast it's spinning. That is the first question every astronaut is going to ask if you send in there, hey, how fast is this thing going if I'm going to land on it?

Every astronaut is going to ask if you send in there, hey, how fast is this thing going if I'm going to land on it? Shoemaker NEO program, you have a major role in that. How does that work and how do you contribute to this program from the society? My role is in chairing the group of people who read the proposals. So we have a panel. There'll be an international panel of experts read the proposals from anyone that has submitted, and we rank them, and we help make the decision on who will be funded by the society. We'll have Bruce Betts on for the regular What's Up segment in a few moments, and he's going to talk about how people can get into this.

But my understanding is that we're open for proposals right now. Yes, and hi to Bruce. I love Bruce. And I saw him in Japan at the Planetary Defense Conference. I'm looking forward to seeing him again soon. More from asteroid discoverer and explorer Tim Spahr is just ahead. This is Planetary Radio. Hey, Planetary Radio listeners. The Planetary Society now has an official online store.

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Our mission is to give you the power to advance space science and exploration. With your support, we sponsor innovative space technologies, inspire curious minds, and advocate for our future in space. We are the Planetary Society. Join us. Welcome back to Planetary Radio. I'm Matt Kaplan welcoming back ace asteroid finder Tim Spahr. Tim has more or less gotten out of the discovery business and no longer runs the Minor Planet Center,

but he's still deeply involved in our quest to find, characterize, track, and understand the millions of asteroids and comets we share the solar system with, especially the ones known as near-Earth objects, or NEOs. Are you satisfied with the attention that near-Earth objects are now getting in the United States and worldwide? I'm going to answer the question honestly. I always like to be honest. There's plenty of attention, and I always want more good attention. Whatever I'm interested in, I want more international attention focusing on this problem. And I'm sort of asking, you know, hey, let's spend the money for the next generation surveys to find the smaller and smaller objects.

Chelyabinsk, for me, I was at the United Nations talking about asteroids when that impact happened. I was with Lindley Johnson and Don Yeomans and Jose Luis Galache, another minor planet center staffer. And it was exciting, but it was also, you know, hey, we're all here talking about this problem and something hit the earth. And could we stop all 20 meter objects? That would take billions of dollars a year to do that. But it brought attention to that problem. And it certainly said, Hey, there's more we can do. So maybe we don't stop all the 20 meter objects, but we probably ought to be working on stopping the 50 and a hundred meter ones, right? Yeah. There will be a NASA report published shortly that's going to say,

it's going to endorse the recommendations of the 2003 report that says we need to get 90% of the 140 meter objects to reduce the hazard by the next decadal step. So, you know, reduce the hazard by 90% if we can get the 140 meter objects. So it reduces the hazard by 90% if we can get the 140-meter objects. Tell us about this organization, which I had only barely heard about. But Bruce said, be sure to ask Tim about this, the International Asteroid Warning Network, or IAWN, or what do you guys call it? We call it IWAN. Astronomers are really big about having something they can sound out like NEOs. So I-1 it is.

And why not? So the International Asteroid Warning Network is a United Nations endorsed organization. This was a recommendation after, you know, about a decade of work in a group that was associated with the Committee on the Peaceful Uses of Outer Space Science and Technical Subcommittee. There were some recommendations to assemble an international team for surveying, reporting of hazards, reporting of possible impacts, and really general communication on the subject, communication and education. I won. It's growing in membership now. NASA is a member. ESA, the European Space Agency, European Southern Observatory. There's some amateur astronomers, Peter Burt Whistle, who I don't know if you've had on. As there's more IWAN membership, there's better communication distribution of information worldwide. to the Committee on the Peaceful Uses of Outer Space once or twice a year. This is the very beginning of a sort of focused international effort that reports to the UN. There's also a Space Mission Planning Advisory Group. We're kind of sister organizations. So if there's

anything that actually is going to impact and we have a lead time, we report it to the Space Mission Planning Advisory Group and they will start studying mission options for deflection. Look into the future. You said you'd like to see the surveys that are underway expanded, or maybe there was a reference to entire new surveys. What other steps do you think we Earthlings should be taking, not just to make sure that the rock with our name on it is deflected, but also because there's such great science out of studying these objects. Oh gosh, the science is why I got into the field in the first place. The idea that you can study something that is a solar system object that isn't the earth. And in the case of Richard Kowalski, he has held in his hand something he

discovered. The idea that you can tie all that together from the discovery where all you get is just a little reflected light from the object. And you can see something moving to knowing the composition of the object, knowing the mass, knowing the density. You can even tell where that thing formed if you get enough information. That to me is there's a romantic quality to the whole field based on that. How do you feel about the missions that are either underway or will be soon that are going to try to bring back some material from an asteroid? Of course, we've already had a little bit. A few grains came back with Hayabusa. I'm so supportive of any mission that's going to study anything about asteroids.

I love it. And one of my best friends in the world, Carl Hergenrother, is working for OSIRIS-REx. I sort of held my breath on the launch, thinking of the field, but also thinking of my bud. Okay, Carl, hope this thing goes for you. We're going to learn things from that. The best part about science is that you have a picture in your head, going to go do this experiment, and something will happen that nobody thought of. We will get those pieces back and somebody will say, my gosh, look at that. We didn't think of that at all. And that's one of the really beautiful parts of it. Well, I'll tell you, if there is a recurring theme on this show that comes up on almost every episode, it is no matter where we go, no matter what new tools we use, there will

be surprises. Yeah, it's to me the nature of science is discovery. You know, of course, about the NEOWISE mission, and now the proposal's trying to get the one called NEOCAM up there from Amy Meinzer at JPL. How important is this effort to find these from a platform in space using infrared? As will come out in this NASA report I referenced earlier, there's already been a presentation, a public presentation by Grant Stokes on this. In order to complete the inventory of smaller objects, it is essential we go to space. We need to do that. Infrared has really unbelievable power for this. Think of it, a half meter infrared telescope is more

effective than an eight meter telescope on the ground. And it has to do with when you're not dealing with reflected light, rather dealing with what's emitted from the object, you get a lot more photons that way. And infrared is, you know, it was a novel technique a few years ago. Now it's the staple, it's the bread and butter, it's what we need to do. So I know it's more your job to find and track and characterize these things, but have you given much thought to what's going to happen when we find that big one that's out there right now that's going to impact us and try to do, or it will if we don't do something about it, and will try to do to us what one a long time ago did to the dinosaurs. Are we making decent progress learning how we're going to deflect one of these?

Yes, I would say we've made amazing progress on that. I was much more skeptical a decade ago about that and now I have a lot of confidence. If we had 20 years of warning for a couple hundred meter object. I think we could prevent the impact. Tim, I am grateful, and frankly, I think maybe the whole human race should be grateful to people like you and others of the kind that we've been talking about, because you might just save civilization. And even if that's not necessary in the next thousand or a million years, the science alone is pretty exciting. I totally agree. And it's exciting enough for me to stay in the field, even if I'm not discovering anything anymore. I'm going to stick around. Thank you, Tim. I look forward to talking to you again. Best of luck with

those applicants for the latest Shoemaker-Neo round. And we will probably be talking to some of those winners after you and your colleagues select them. Definitely. I'm looking forward to the proposals again this year. We've been talking with Tim Spahr. He was, for many years, the director of the Minor Planet Center, has been involved in this business of finding minor planets, asteroids, comets, even a moon or two, for a very long time. Now he has this operation called Neo Sciences. Neo, as in near-Earth objects.

And he is also the chair of the group that will be deciding who will get the next Shoemaker-Neo grants from the Planetary Society. A guy who's very much involved with that program, somebody we talk to every week, is up next. Tim, it's your friend Bruce Betts. Time for What's Up on Planetary Radio. Bruce Betts, the Director of Science and Technology for the Planetary Society, is here with us to give us another report on the night sky and also to accept my best wishes for a happy asteroid week. Thank you.

Happy asteroid week to you as well, man. Thank you. There's a lot of that going around on today's show. In our conversation with Tim Spahr, I said that you would tell anybody who's interested how they can get in on this Shoemaker-Neo grant process. If you're interested in learning about what's involved in a proposal or submitting a proposal, you can go to planetary.org slash neogrants, N-E-O grants, one word, and you can find all the information you need.

Deadline is July 31st. I also want to congratulate you on an excellent new series of Random Space Facts. Why, thank you. I'm excited about it. We made six short videos in the Random space effect format all about the asteroid threat. So one introduction and background and then one each for each of the five steps of the Planetary Society five-step plan to prevent asteroid impact. Video creator Mark Boyan has introduced a whole cast of dinosaurs to the video series. And they're very cute. It's a very entertaining way to present a fairly comprehensive plan on how we ought to be dealing with these objects.

And people can find it at planetary.org, correct? Yes, you can find it there through the links or at planetary.org slash defense or always planetary.org slash RSF. All right, then. The night sky. The night sky has Jupiter high and bright in the southwest during the evening. It's got a blue star Spica hanging out to the left of it a little ways. We've also got Saturn up in the evening over in the east looking yellowish and not as bright, but still like a bright star. And Venus dominating the predawn sky over in the east.

We move on to this week in space history. We remember the cosmonauts who died in 1971 this week when Soyuz 11 had a major catastrophic failure during reentry. major catastrophic failure during re-entry. And then we, of course, as you've probably discussed, 1908 this week, Tunguska event impact in Siberia, leveling 2,000 square kilometers of forest or about the equivalent area of one and a half Los Angeleses, the city that is. Yeah. I didn't so much discuss it as Bill and I did, but yeah, it's quite an anniversary. I hear you've got something for me. Yeah, we've got a little guest intro for what's coming next. Hey, Bruce, it's Tim. It's time for this week's Random Space Fact.

Thank you, Tim. Thank you, Tim. The Tunguska event in Siberia produced air pressure variations that were detected in Great Britain. Wow. Impressive, isn't it? I'll say. We should make sure that doesn't happen again. What a wonderful idea if only someone had a plan.

We have a plan. Head for the choppa. No, that's not the plan. Head for the dragon capsule, I think. Go ahead. We can find them. We can track them, characterize them. We can deflect them. And we always relies on international coordination and education. Hey, that's the plan. All right,

we move on to the trivia contest. I asked you, what fuel do the Cassini spacecraft 16 thrusters, not the main engines, what fuel do they use? How do we do? I said last week that that was maybe the last Planetary Radio t-shirt, the older style that we would hand out. I was wrong. It's actually this week. So that shirt might be going to this week's winner, James Hutchison. He said that the fuel used by those thrusters is our old friend hydrazine, our old toxic friend. Our old toxic friend. Yes, that is correct. Everybody's got a toxic friend or two, right? James, you're right. You got it. And because random.org chose you, you will be receiving a Planetary Radio t-shirt, a 200-point itelescope.net astronomy account,

that worldwide network, a non-profit network of telescopes, and a Planetary Radio sticker. And guess where James wrote to us from? I don't know. You never would. Beijing. He lives in Beijing, China. That shirt and sticker will be making its way over there. We got a few others, as always.

Craig Balog, he says it's the same fuel that Mark Watney uses in the movie The Martian to make water, and that almost kills him. We got the same response from Andres Espina in Bogota, Colombia, and Bradley Chassie in exotic Berwick, Maine. Mel Powell, hydrazine, or N2H4. He said he believes that's a lesser-known third cousin once removed from R2D2. He was hoping it would be something more interesting, like, say, prune juice. Along those lines, Nicole Martinez in Wausau.

There's something along those lines? There is, actually. Oh, my gosh. Okay, go ahead. Nicole Martinez in Wisconsin. She says, is that what powers my cats? I don't think so. It reminds me of a joke my mother told me a long

time ago that I won't tell. Finally, Dave Fairchild, our poet laureate, he says, sure, highly toxic chemical was used to power the W W2, World War II German rocket-powered fighter that didn't really see much action during the war. It's apparently used here and there elsewhere, and it's found in tobacco smoke. And so here's his poetic contribution with apologies to, I think it was a 50s acapella group or rock group, The Cress.

You've only got 16, but you're my Cassini queen. You're the prettiest spacecraft that I've ever seen. 16 thrusters in your heart will glow burning hydrazine, and it makes you go. Thank you, Dave. Wow. I'm sorry I couldn't sing it, but you're probably not. No, not really. All right, we're ready for next time.

In what year was the supernova observed that formed the Crab Nebula? Go to planetary.org slash radio contest. You've got this time until Wednesday, July 5th at 8 a.m. Pacific time. That's the 5th of July, the day after we defeated the invading aliens. We'll have waiting for you if you're chosen by random.org, one of the brand new, really nice Planetary Radio t-shirts that you can also find in the Chop Shop store, along with the new Planetary Society shirts.

First time you can buy a Planetary Radio t-shirt, but you can get one for free if you win out. Also a 200-point itelescope.net account. All right, everybody, go out there, look up the night sky, and think about how much nicer it would be if we broke the day into 10 segments instead of 24. The hour into 100, the minute into 100. Wouldn't it just be easier for everyone? I have 10 fingers. For God's sake, go out there and think about this. I am going to think about it. I think that's brilliant.

A metric day. Why not? Thank you, sir. You're welcome. Thank you. Bruce Batts is the Director of Science and Technology for the Planetary Society, who joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena,

California, and is made possible by its impactful members. Danielle Gunn is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser. I'm Matt Kaplan. Clear skies.