Planetary Radio: Space Exploration, Astronomy and Science - Amy Mainzer: Asteroid Hunter

Episode Date: May 9, 2018

After taking over 10 million images of more than 30,000 solar system objects, the NEOWISE mission is finally in its last months.  Principal Investigator Amy Mainzer returns with an update on this phenomenal success and a look ahead toward a much more powerful asteroid and comet hunter called NEOCam.  It’s not just about defending our planet.  We are learning the origin story of Earth and other worlds.  Bruce Betts also shares a story or two, along with a new space trivia contest, in this week’s What’s Up segment.  Learn more about this week’s topic and see images here: http://www.planetary.org/multimedia/planetary-radio/show/2018/0509-amy-mainzer-neowise.htmlLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Amy Meinzer is back, 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. She's one of our perennial favorites. The principal investigator for both the NEOWISE and NEOCAM missions returns with an extended update on both of these and more, as the search for NEOs, the asteroids and comets that may threaten our world, continues. A simpler show this week as I once again host the live webcast from the Humans to Mars Summit

in Washington, D.C. But there's always time to visit with the Planetary Society's chief scientist, Bruce Betts. Bruce is back with an easier space trivia contest this time, since he stumped so many of you two weeks ago. NEOWISE is the Near-Earth Object Wide-Field Infrared Survey Explorer. But in this case, NEO stands for more than that. But in this case, NEO stands for more than that. The spacecraft started life as simply WISE and did a brilliant job of scanning the infrared skies for stars, galaxies, and more than a few asteroids. It completed that work and was reborn as a hunter and tracker of the rocks and comets that pepper our solar system with special attention to those that cross Earth's orbit. Why? Because, as Bill Nye says, the dinosaurs all died because they didn't have a

space program. With luck, that work will someday be amplified by NEOCAM, an infrared space telescope that is specifically designed to find, track, and characterize near-Earth objects. As PI, Amy Meinzer leads NEOCAM's development, even as she continues her direction of the NEOWISE mission. She joined me from her office at the Jet Propulsion Lab a few days ago. Amy, welcome back to Planetary Radio. Thank you for doing this again. No problem. Thanks so much for having me back, Matt. It was about three weeks ago that I got a press release from NASA and JPL about the latest release of data from NEOWISE, the spacecraft, one of the two, anyway, that you are a principal investigator for.

But this is the one that's been up there for a while. I was blown away by some of the numbers. So I went to the IPAC website, and we'll talk more about that in a moment. I can't get over these numbers. What does, first of all, the biggest one mean? And then we'll get back to some of the others. 76,889,141,513. What are we talking about here? Well, these are all of the objects detected by NEOWISE over the last four years. Basically, any star, galaxy, asteroid, comet, anything that we've seen by our telescope got archived and is captured at our public website, which is hosted at Caltech at IPAC. I have the acronym here somewhere, Infrared Processing and Analysis Center.

We'll still come back to that again, but these were derived from what? Over 10 million images taken by the spacecraft? That's right. I mean, this is a spacecraft that's been in orbit since late 2009. And we're just so lucky. It's continued to be the gift that keeps giving. This spacecraft is taking a picture every 11 seconds as it goes around the Earth of the sky. So that means it accumulates images really, really fast. And at this point, as you know, we have an awful lot of data that we've been calling through to, in our case, we're really interested in finding the nearest asteroids and comets.

But there's all kinds of other good stuff in there, too, that astronomers and folks all over the world are using. Out of these billions of images or billions of objects that you have captured in this over 10 million images, how many of those are among this group that you're really targeting? The ones that some of which may be targeting us someday. Right. Well, this is definitely a needle in a haystack kind of problem because you can see that there are literally billions of objects that we detect.

And the question is, which of these are actually objects in our solar system as opposed to stars and galaxies outside in our solar system, as opposed to stars and galaxies outside of our solar system, and which of those objects inside our solar system, which are the ones that get closest to the Earth. So as we sift all of those sources down, we're picking out the objects that really get the closest to us here. And in our case, there are about 1,300 what we call near-Earth objects, so asteroids and comets that get relatively close to the Earth, that we've observed and characterized with NEOWISE at our infrared wavelengths that we're using. There is a wonderful animation that was actually produced, I guess, after the third data release. Maybe it's been updated. You can tell me. That is looking down on the solar system from above. And we'll link to it from this week's show page.

Could you describe this? Sure. What you're seeing is if you could imagine a sort of a bird's eye view or spacecraft eye view, I guess. If you could float above the inner part of our solar system and look at it, what you'd see are all of the small bodies, the asteroids and comets that NEOWISE has been detecting. And they're really just swimming around the sun. Most of them are in the main belt between Mars and Jupiter. Most asteroids there have been there for billions of years and are going to stay there for billions of years. But what you can also see in the animation is that there's a little pack of objects which are colored as green dots or yellow squares. And these are the near-Earth objects and comets.

And these objects are the ones that we really pay particular attention to. You know what is really fun or was for me about this? You have this massive gray, all these other objects. And the green ones, of course, you know, the ones that are a threat are circling as well. But then you've got those yellow squares, the comets that come in from outside the frame, make their circuit and then go away again. It's really fun. Right. Yeah. I mean, to be fair, most of these NEOs, they really don't get close enough to the earth to have any significant chance of impact at all whatsoever. So we pay attention to them

because we want to rule out the possibility of any threat. And in this case, we haven't found any objects that look like they're going to impact the Earth anytime soon. That said, we still keep our eyes peeled and we're always looking to discover more and new objects. But the cool thing about the comets is, yeah, as you know, they come in from the very distant outer parts of the solar system, some of them. Some of them are from way out there, about halfway to the nearest star even in some cases, and they come all the way in, make one pass by the sun, and then for our purposes, they're gone forever. Other classes of comets are closer in, and they are the so-called Jupiter family comets, and they go around the sun many more times from our perspective.

family comets. And they go around the sun many more times from our perspective. Thanks to spacecraft like NEOWISE and certainly lots of other good science has been done. Would you say that we know our solar system environment and these smaller objects a lot better than we did, say, 10, 15, 20 years ago? Well, that's been the fun thing about working on this project. I mean, this spacecraft was never intended to have as its primary objective looking at asteroids and comets, but it turned out to be pretty good at it. So we've really been trying to squeeze all the juice that we can out of it. And what we're learning is something about the sizes and the reflectivities of these objects. For most asteroids and comets, we know surprisingly little about them. When we find an object, the only thing we initially know about it is its apparent brightness and something about its orbit.

And that's it. We don't really know any other details, usually. So with this telescope, we've been able to say something about their sizes and about their reflectivities, how much sunlight bounces off the surface, and that gives us a clue as to the object's likely composition. What we've been learning specifically about them is that for example with the near-earth objects we find that there's a population of brighter any OHS and a population of much darker objects things that are dark like a printer toner if you ever get printer ink on your hands you know just how dark it is and and we know that there's a class of NEOs out there now that are like that.

The other thing we've learned is that that distribution of bright versus dark, how many are bright versus how many are dark, we know that that is more or less unchanged over a very wide range of sizes, all the way from things that are larger than a kilometer, all the way down to a couple hundred meters in size. So that's new and different for us. You have done this before on our program and many other places. But if you could talk for a moment about why being able to observe these in the infrared is so important and so useful. After all, that's the eye in NeoWISE is infrared. Right. Yeah. This is one of the fun things about being an astronomer is the more different ways you can look at an object, the more you can learn. With our eyes, we're sensitive to visible light,

of course. That's why it's called visible, because we can see it. But with infrared light, what we're actually sensing is the heat that's coming off of the asteroids and the comets. And that gives us a very different perspective on them than if we just had the visible light alone. So with the visible light alone. So with the infrared light, we are actually sensing the sunlight that is being absorbed and re-radiated from the objects. In a sense, that makes us much less sensitive to the variations in composition on the surface in the sense that if it's really, really dark, it's still going to absorb a lot of sunlight and re-radiate that energy as heat, which we can see in infrared wavelengths. So even if the object is, well, even a bright object is still going to glow

pretty brightly in the IR as well. So we can see both bright and dark objects. That's helpful. There is a great illustration of this. Do you remember, I think we'll link to this web page as well. It's you holding two coffee mugs. Yes. Yeah, that actually is a, it's a really fun experiment because it just sort of illustrates that, you know, what you see with your eyes is just the light that's bouncing off of the object. And if the object is, if it has the same reflectivity, the thing is going to look the same to you. So in other words, if I have two coffee mugs and one has hot water, but the other has cold water in it, your eye can't tell the difference unless there's some other clue, like steam coming out of one mug.

But if you have an infrared camera, now you can actually see the different energy that's being radiated by the two mugs depending on their temperature. So if you have an infrared camera, it lets you sense the object's temperature. And if we know the orbit, in the case of an asteroid, if we can measure its temperature and know how far away it is, then we could say something about how big it is, its size. Are we able to learn anything about the composition of an object from the light that we see from it, both in the visible and the infrared and maybe elsewhere on the spectrum? Yeah, we can get some very important clues if we can say something about the reflectivity. That gives us some pretty good insights into what

the object is most likely made out of. That's for a combination of reasons. For one thing, we have meteorites on the ground. We get these amazing sort of free sample missions, if you will, from asteroids and comets all over the solar system. We get these little pieces of meteorites, and in some cases, big pieces that fall to the Earth. We know that the objects that are very dark, that tend to, you know, have the lowest reflectivities, those objects tend to be very carbon rich, they tend to be the lowest density. And they tend to be the most volatile rich, meaning that they contain the largest number of things like ices of different sorts of water. Of course, by the time they're meteorites on the surface of the Earth, they've had to pass through the Earth's atmosphere, and there have been changes as a result of being on

the Earth in our atmosphere and in weather. But nonetheless, we can still tell quite a bit about the composition from studying these objects and knowing what sort of reflectivity is typically associated with what sort of composition. That gives us a lot of clues that when we look at something in space and we see, oh, this one over here, this has a very dark surface, that tells us it is most likely that that object is one of these really carbon-rich, low-density objects. Neo-Wise, as you've said, has been doing this for a long time. And how much longer can we expect it to be making these discoveries?

Well, we've been so, so, so fortunate with this mission. This really is the little spacecraft that could. This has been a real privilege to get to operate the telescope for this long. But all good things will eventually come to an end. And what's going to happen to NEOWISE eventually is the orbit is starting to precess. It's actually starting to decay. It's a natural process. This orbit is actually, in my opinion, kind of a magic orbit because what it does, it's called a sun synchronous orbit. And that means it keeps the plane of the orbit always perpendicular to the line that connects the earth and the sun. So for

a telescope, it's great because it means you can always just point your telescope straight out away from the Earth and look right at the night sky and have a really direct view with the Sun on one side and the Earth below you. Problem is, over time, this orbit, it's starting to twist. So the plane of the orbit is now pulling a little bit so that it's no longer perfectly perpendicular to that Earth-Sun line. Eventually, it's going to get to a point where we won't be able to keep either the Sun or the Earth shine out of the telescope. And it's going to start to warm up. We don't know exactly how fast it's going to go. It depends actually on the solar activity, oddly enough.

Because what causes the orbit to precess more and more is atmospheric drag. If the sun is not very active, then the atmosphere is actually a little less puffy. And that means there's just a little bit less drag and the orbit precession is slower. On the other hand, if we're not lucky and there's more solar activity, the Earth's atmosphere is going to puff up a bit more, the drag will be worse, and that precession is going to happen faster. So it's a little hard to give a precise timetable because all of these things are very complex interacting phenomena. But I think we probably, if we're lucky, we'll keep going for another six months. If not, it could be sooner. And if we're very lucky, maybe beyond that. But at this point, we're definitely in bonus overtime at this point. So I'm really happy that we've gotten to come this far.

Clearly closing in on the end, let's switch to what I guess could be looked on as a follow-on to the NEOWISE mission. And this, of course, is NEO-CAM, another mission that you are leading and that we have talked about in the past on this show, which I was delighted, as were all of us at the Planetary Society, to see that back in January, you got another vote of confidence. First of all, tell us, what is NEO-CAM again? Remind us. Is it sort of, is it in the direct line of descendancy from NEO-WISE? Yeah. Is it in the direct line of descendancy from NEOWISE?

Yeah. So NEOWISE, it's done great things for us. And we've learned a lot about, like I mentioned, the distribution of bright and dark near-Earth asteroids, bright and dark main-belt asteroids. We found the first known Earth Trojan that shares Earth's orbit. But this telescope was never originally designed to find and characterize near-Earth objects. And because of that, it has a lot of limitations. It's done a lot, but there are a lot of things it couldn't do. It can't see very, very large numbers compared to what we've already got now.

That's because of its field of view, the wavelengths that it has left, and the ability to keep the sun out and really survey a large volume around the Earth's orbit. So what we'd like to do is we'd like to design kind of a bigger and better cousin of this mission that really is optimized for finding near-Earth objects, asteroids and comets. And the way to do that, there's several things here. First of all, the wavelengths. In the case of NEOWISE, we lost the wavelengths that the asteroids are actually brightest at some time ago. It turns out that asteroids really glow brightly at wavelengths

of around 10 microns. So our eyes are sensitive to light at about sort of half a micron or so. Well, these are wavelengths that are about roughly 20 times that. That's where the asteroids are really putting out most of their energy, if they're near-Earth objects. In the case of WISE, our detectors that we were using at those wavelengths had to be kept extraordinarily cold, about, in our case, eight degrees Kelvin or eight degrees above absolute zero. To keep the detectors that cold required, in our case, solid hydrogen, a frozen ball of hydrogen that we kept around the detectors. Not just liquid hydrogen, but even colder, solid. Amazing in itself. Yeah, frozen hydrogen. And the thing of it is, is it doesn't last forever. It's kind of like a

popsicle. Eventually, it goes away. It lasted longer than it was supposed to, but it was never designed to last that long. And after about eight and some change months, the hydrogen was gone. And the two longest wavelength channels on WISE became inoperable at that point. So now we're using two shorter wavelength infrared channels. Those are the ones that are left. But with NeoCam, we have modified our detectors so that they can still operate at the 10 micron wavelengths, but they don't need to be nearly as cold. And what that means is if we park the telescope just a little bit away from the Earth to get away from the heat of the Earth, then we can keep the telescope and

its detectors at the right temperature so that we can operate at that 10 micron nice spot where the asteroids are really putting out a lot of their energy. Is this anything like what will happen with the James Webb Space Telescope, also largely an infrared instrument that has that big sunshade to help keep it cool? Yeah. So the JWST instrument is using some of the same principles that we would like to use on NEOCAM. The difference is it's way bigger. This is a much, much, much, much bigger telescope than NEOCAM needs to be. In our case, the primary mirror for NEOCAM needs to be about half a meter. So if you're sitting on a typical office chair, it's kind of about that size. That's the size of the primary mirror. James Webb is about a six and a half meter primary

mirror. So it's quite a bit larger. But the general idea, it's an observatory operating at infrared wavelengths. That's the same. We still want to be reasonably close to the Earth. So we chose as our target orbit, something called the Lagrange point. Sure. Yeah. These are these kind of magic places in space around the Earth and around the solar system, where if you park something there, it's going to tend to stay in that spot relative to the Earth. Which one of those are you hoping to hit? Well, with NEOCHEM, we would like to use the Sun-Earth L1 Lagrange point. So this is a place in space that's a few times, it's about five times the distance of the Moon. So we're just

outside the orbit of the Moon. And if you put a spacecraft there, it's going to tend to stay there as the earth goes around the sun. So we kind of get carried along. And the nice thing about that is if you're an observatory and you want to go say, look for asteroids, this is a great place to do it because you never get that far away from the earth. You're never close enough from the earth that the heat from the earth makes it impossible to keep cold, but you're close enough that you can get a nice high data rate, and it's a consistent, constant data rate too, meaning we can get all the images back. That's really important. We'll put up a link to the NEOCAM site as well, and you can see that it looks more like a traditional space telescope. I mean, you can kind of see a little bit of the Hubble heritage in this,

I guess, with that half meter mirror that you've been talking about. I mean, you can kind of see a little bit of the Hubble heritage in this, I guess, with that half meter mirror that you've been talking about. I was reading about your science objectives, which are not just about science. I mean, you're going to help us refine this ability to find those near earth objects and avoid them. Right. So this is a mission that would be run out of NASA's Planetary Defense Coordination Office, or PDCO. And the idea is its primary objective is really to go out and find some of the largest near-Earth objects. We really want to try to get as close as we can to finding at least 90% of the larger objects. But our requirements are that we will operate over about five years.

And, of course, we want to know as much as we can about some of the smaller near-Earth objects as well. We want to compile very good statistics on how often asteroid and comet impacts happen on a sort of human timescale of about 100 years. That asteroids and comets impact the Earth on giant timescales, but we care about them on human timescales. So planetary defense first, thank you. But there is more to this because asteroids have this potential of telling us something about how all of us got our start, how the solar system began, right? Yeah, that's one of the things that's really fascinating about these little objects is that, and some not so little, is that they really reflect conditions in the solar nebula from long ago. Everything

that's here on the Earth is subject to geological weathering processes. Of course, the atmosphere, the rain, plate tectonics has the effect of turning things over and breaking rocks and minerals down. And so what we have on the surface of the Earth at this point is now heavily processed by all of that. When we get material from space, you know, if we get a meteorite, we can tell something if we look at that meteorite about what the solar system was made of when it was first formed, without that weathering having broken it down and changed and altered it. So that's one of the reasons why we love to study asteroids and comets, because they really are these time capsules. They're a window to what

things were like back in time at the beginning of the solar system. With NEOCAM, we're going to find a huge number of these objects. And one of the benefits of looking for things that get especially close to the Earth is that these are the asteroids that are the easiest to get to. They'll require the least amount of propulsion to reach. So by looking for the ones that are the most likely to have orbits that get close to the Earth, we're also finding the population that's easiest to go to and visit directly. And you would like to see that happen? I'd love to. I think asteroids are just fascinating. I mean, there's an incredible diversity in all kinds of the compositions, the sizes, the shapes.

It's just like rocks here on Earth. You can pick up all kinds of different rocks, and they look completely different, and they have different origins. The same thing is true with the asteroids. It's pretty clear, as I said, that there are people at NASA as well as at the Planetary Society and elsewhere who have high hopes for this mission because you are now in this extended Phase A funding period. What does that mean, and what is the outlook for the mission? Because you are now in this extended phase A funding period. What does that

mean? And what is the outlook for the mission? We're really lucky. I mean, we've gone through the Discovery Program, which is one of NASA's competed line of missions where basically, if you get an idea and you're a scientist or an investigator and you want to see if NASA's possibly interested in making that mission happen, you can apply to the Discovery Program. In our case, that's what I did. We submitted to the Discovery Rounds, and we were given technology development funding to work on maturing the infrared detectors that we need.

That was a very successful development, and it went really well. So in this most recent round, NASA said that they really liked the project, and they gave us what is called extended phase A funding, which means we're working hard on maturing the design. We're working on risk reduction. So right now, specifically, we're concentrating on refining the design of the payload, which is the telescope, the camera assembly, some of the thermal shields. We've been working hard on that. We're also working on the science data processing pipeline. So this is the science data system. This is the set of algorithms that allows us to go through that giant, giant number of detections that we expect to have and really pull out the most interesting objects and then connect all

the dots together to find new asteroids and comets. So it's kind of an impossible question to answer, but if all went well, when might we see NEOCAM see first light, start to take a look around the solar system to find more of these objects? Right. Well, it really depends on the funding profile that we're given from NASA, but it's certainly feasible to think of this mission being finished and put together inside of five years from the technical perspective. Obviously, this is all subject to the budget and the constraints that NASA has to work with, but we are raring to go.

We really want to get this thing put together, get it on the sky, and start getting data back. So, the sooner the better from my perspective. Yeah. Before we wrap up, you're the PI, the principal investigator for both of these projects, one that's up there, one that we hope will be up there before too long. You've got other science that you're involved with. I don't know where you find the time to also do all of the public outreach work that you do, but I'm very grateful that you do it. We were talking before we started recording, I know you were with our boss, Bill Nye the Science Guy, for the big solar eclipse last fall. Yeah, that was just, oh my goodness, what a blast. I mean, this is one of the fun things about getting to do science is that it's really great to get to work on projects that

we think are important, that are in the public interest. And a part of that is, you know, really sharing what we do with everybody else, because we have a lot of obligation to do that. I think as scientists, it's really important that we tell everybody about what we're learning. In a lot of cases, we're publicly funded, we absolutely depend on the support of the public. And as a result, we're obligated to tell the world about all the great stuff, in my opinion, that we're doing. Plus, if you love your subject, it's really fun to get to talk about it. I'm glad you feel that way. And you're very good at it. I'm not going to let you go until you mention one other outreach project that you have in your way, which I can't wait to introduce my grandson to. He's still a bit young for it, but do you know

the one I'm talking about? Certain cartoon show. Oh, yes. So this is Ready, Jet, Go. And this is for the very littlest of explorers. This is a show that we've been working on with PBS Kids, and it's intended to be a kid's first space show. So it's about space and earth science, and it really is intended for little, little ones. This is for the sort of three to eight-year-olds, although kids who are older than that will hopefully enjoy it too. Maybe some grown-ups. But the idea is, you know, we want to try to use fun and humor and songs and music to teach about science. It's been a blast to work on that. Well, my grandson is about to become a very precocious two-year-old.

to work on that. Well, my grandson is about to become a very precocious two-year-old. I think he'll be ready. And especially if I'm sitting there with him, because I'm one of those older kids who also enjoys watching the show. Amy, I look forward to any other opportunity to talk. It has been a pleasure to have you on this time and all the previous appearances that you've made on Planetary Radio. And I trust that this is not the last time. Maybe we can talk again when the NEOWISE mission comes to an end. Hopefully that won't be for much longer than the six months that you were projecting. But also to continue to follow the progress of NEOCAM. Well, thanks so much, Matt. It is always a pleasure to get to talk to you.

And I hope everybody out there enjoys the show. That's Amy Meinzer. She is, as we've said, the principal investigator for NEOWISE and for the NEOCAM project that hopes to put that much more advanced infrared space telescope up there searching for asteroids and comets, including those that pose a threat to Mother Earth and us, she was awarded the Exceptional Scientific Achievement Medal in 2012. That's just one of the many recognitions that she has received for the great work that she does there at JPL on behalf of all of us who are enthusiastic about space exploration. We'll talk to another space enthusiast in a moment. That's Bruce Betts with this week's edition of What's Up. Time again for What's Up on Planetary Radio. Bruce Betts is the chief scientist for the Planetary Society. And he's here again to this lesser part of his duties as a chief scientist

to talk to me every week about all this. This is never lesser. Thank you for that. I do appreciate it. Yeah, I certainly have fun taking up a few minutes of your time. Tell us, what's up? Just thinking if you're a constellation, you'd be the matter Major, the greater Matt. The greater Matt. What is the lesser Matt? Everyone else? Maybe it's the greater show.

You were just saying, never mind. This seemed like it would be a funny avenue to walk, but apparently it's not. So let's move on to what's in the night sky. We've got, hey, go check out Jupiter. Jupiter has just passed opposition on May 8th, where it is on the opposite side of the Earth from the sun. And so that also means it's rising around sunset in the east and setting around sunrise in the west.

And it's closest it gets to Earth. It's always bright, but it's even a little brighter right now. So check that out in the eastern sky in the early evening. It's the super bright thing. The super bright thing over in the western sky in the early evening is Venus. And then we've got Mars and Saturn coming up in the middle of the night. We move on to this week in space history. on to This Week in Space History. It was 45 years ago this week, 1973, that Skylab launched the first American space station. And what a great space station it was. By the way, I've decided Matt Golombek, he would be the greater Matt constellation. I'd be the lesser Matt. You've been thinking about it, haven't you? I have. During that whole time, you were telling me about the night sky.

But I'll listen to it later. All right, Matt and Minor. We move on to Random Space Fact. Oh, that was cheery. I'm trying. So by volume, you could fit about six and two thirds Marses inside earth. Whoa, that's, that's many more than I thought, but yeah, that, I guess that is how it works, right? By the cube.

It's a mini of Mars. Lesser earth. That's what we should have called Mars. Really mess with the Martians. Yeah. We don't want to make them mad. All right, speaking of Mars, I asked you in the trivia contest, what country does the mound, called now

Mount Sharp or Aeolus Mons, the mound that Curiosity is exploring look like from orbit, at least according to a NASA press kit. And I guess I just stumped people on average. Is that true, Matt? And how?

We had like a third the size of the usual response we got. And even some of the people who managed to find this said, wow, you really, Bruce really made us work for this this time. Let's start with the person who I believe is our winner, because this was the preponderance of responses. Joshua Guarino, far as I know, a first-time winner in Plainfield, Illinois. He says that according to that NASA reporter or a publication, at least, Mount Sharp looks like Australia from orbit. That is indeed correct. I just added the NASA press kit part to make sure there was a definitive

answer. I would have been happy if people just stared at the crater and thought, Hey, the Mount looks like kind of, kind of looks like Australia. It's particularly evident if you look at the false color topography data and the image, but did we hear from anyone else? We did. Christopher Beck and Claude Plymaid, a pretty good astronomer in his own right, they both gave us some of the history.

It says Gale Crater was named in 1991 for an Australian astronomer and banker, Walter F. Gale. He had discovered several comets through maps of Mars and Jupiter. What's interesting especially is that not only does it look like Australia, but it's named for an Australian. So I don't know, maybe they had that in mind when they named it, I guess, right? That would make sense, wouldn't it? I really don't know. I know all craters of that size are supposed to be named for banker astronomers, though.

We got this from Mel Powell in Sherman Oaks. He came up with Australia, but he doesn't like it. He's fighting this one. He says that Mount Sharp in the crater just looks like a mountain to him. He says, clearly, I'm not as sharp as Mount Sharp. He does say, though, if it is Australia, we can all hope that somehow deep in the Martian soil, we find evidence of past life down under. Finally, from Mark Dunning, who said the interwebs failed me, he was not able to find it. He took a look at it and gave us this photographic analysis. He says Mount Sharp looks like a kitten.

gave us this photographic analysis. He says Mount Sharp looks like a kitten. If there were a country named kitten, I'd give it to him. All right. Well, we're going to send Joshua Guarino, who is our winner this time around, a Planetary Radio t-shirt and a 200-point itelescope.net astronomy account. And we're going to do the same for whoever comes up with the right answer and is chosen by random.org for this next contest that Bruce is about to lay on us. I think the interwebs will be kinder to you this time.

Who was the only person to discover a planet or moons in the 18th century? So in the 1700s, I was amazed to find only one person discovered any planets or moons in the 18th century. So in the 1700s, I was amazed to find only one person discovered any planets or moons. Who was that? Go to planetary.org slash radio contest. What a terribly strange dry spell. I mean, there were so, you had the Enlightenment and everybody was looking at the sky.

That's very surprising. Thank you. Would have made a great random space fact, wouldn't it? Well, I'll just, I'll recycle it as a random space fact. Maybe no one will notice. Wait a few years. We'll have a whole new audience. You've got this time until the 16th. That'd be May 16 at 8 a.m. Pacific time to get us the answer and win yourself that Planetary Radio t-shirt. You can see it at chopshopstore.com in the Planetary Society store there. And a 200-point itelescope.net account.

Worldwide nonprofit network of telescopes that anybody can get on and take pictures of Mars. Why not? We're done. All right, everybody. Go out there, look up at the night sky, and think about editing a radio show. Thank you, and good night. Did you enjoy your little behind-the-scenes look at how we get this done? Bruce was actually online when I was doing some editing.

Man, making sausage is prettier. No, I'm kidding. It's amazing. You clean us all up for the good of the world. it's amazing. You clean us all up for the good of the world. He's Bruce Betts, all natural, no nitrites, the chief scientist of the Planetary Society, who comes to us every week here in What's Up. I don't know if I have nitrites or not. I'll be at the International Space Development Conference in Los Angeles, May 24 to 27, with Jeff Bezos, Freeman Dyson, Linda Spilker, Catherine Sullivan, and many

other leaders of the quest for the final frontier. You can learn more at nss.org. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its Near Earth Objective 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.