Planetary Radio • Oct 12, 2022

Innovate! NASA’s leading-edge fellows share their amazing projects

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On This Episode

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David Brin

Science Fiction Author, Futurist, Astrophysicist, and Planetary Society Advisory Council member

John mather

John Mather

Senior Astrophysicist in the Observational Cosmology Lab at NASA’s Goddard Space Flight Center, and Senior Project Scientist for the JWST

Kaplan mat headshot 0114a print

Mat Kaplan

Senior Communications Adviser and former Host of Planetary Radio for The Planetary Society

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

Special guests include:

  • Bonnie Dunbar, former NASA astronaut and director of the Aerospace Human Systems Lab at Texas A&M University
  • Lynn Rothschild, senior research scientist at NASA Ames Research Center
  • Michael LaPointe, acting NIAC program executive
  • Joel Sercel, CEO and founder of TransAstra Corporation
  • Zac Manchester, Carnegie Mellon University, NIAC fellow for the Kilometer-Scale Space Structures from a Single Launch study
  • Jeff Lipton, University of Washington
  • Septarshi Bandyopadhyay, robotics technologist at NASA’s Jet Propulsion Laboratory
  • Kerry Nock, president, Global Aerospace Corporation
  • Amber Dubil, Johns Hopkins University Applied Physics Laboratory

Mat Kaplan once again hosted the live webcast from the annual NASA Innovative Advanced Concepts or NIAC symposium. He presents a speed dating sample of highlights. How about a Mars habitat grown from mushrooms? A lunar farside radio telescope built by robots? Or a kilometer-long space station launched by a single rocket? We’ll also join Planetary Society chief scientist Bruce Betts for another What’s Up scan of the night sky and more.

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Kilometer-scale space structures
Kilometer-scale space structures Illustration of a kilometer-scale space structure that could be constructed from a single rocket launch. These large structures could create artificial gravity near 1g when rotated at comfortable rotation rates of 1-2 RPM.Image: Zac Manchester

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Mat Kaplan: Dazzling innovations from NIAC this week on Planetary Radio.

Mat Kaplan: Welcome. I'm Mat Kaplan of The Planetary Society, with more of the human adventure across our solar system and beyond.

Mat Kaplan: NIAC is the NASA Innovative Advanced Concepts program. It was once again, my great pleasure to host the live webcast of the program's 2022 symposium in Tucson, Arizona. As you'll hear, there were new faces, familiar faces, and even a few famous faces among this year's NIAC presenters. We'll hear from a sizeable number of them in what I'm calling a speed dating introduction to their brilliant ideas that they hope to turn into realities. Then we'll try to get Bruce Betts to give you the shirt off his back.

Mat Kaplan: Have you heard? We didn't just nudge an asteroid. We gave it a great big shove. Congratulations to the Double Asteroid Redirection Test team and to NASA's Planetary Defense Coordination Office. We learned as this week's show was coming together that the DART spacecrafts impact caused a substantial change in the orbit of Dimorphos, the smallest moonlet space rock that orbits larger Didymos. The work is far from finish, but we now have good evidence that we can prevent asteroids from causing hell on Earth. If we find the dangerous ones soon enough.

Mat Kaplan: Check out our coverage at That's also where you'll find our free weekly newsletter at the downlink. The October 7 edition features a beautiful image of Jupiter's moon, Europa, captured just days ago by the Juno orbiter.

Mat Kaplan: Nearly all of the current NIAC Fellows, the men and women who lead the projects funded by the program came to the University of Arizona last month to share their progress. I've selected just eight of them from across a wide spectrum of projects that I'll share with you this week. The clips you'll hear are pulled from the live stand-up interviews I did across the three days of this year's symposium.

Mat Kaplan: Michael LaPointe would want you to know that you can read about all the studies on the NIAC website that we link to from this week's show page at slash radio. Michael is a longtime NASA veteran and the acting program executive for NIAC.

Mat Kaplan: Not your first horse race with NIAC because you are a two-time NIAC Fellow.

Michael LaPointe: I am. Actually, I had a award under the prior NASA Institute for Advanced Concepts, and one of the current NIAC program as well.

Mat Kaplan: What did receiving the NIAC support mean to the work that you were doing?

Michael LaPointe: So I'm at the Marshall Space Flight Center, which is known primarily for big rockets. And so, being able to do something as innovative as the NIAC visionary programs was a good chance to actually show that NASA personnel at different centers can do very innovative work beyond just the normal day-to-day routines. It was a quite an exciting opportunity for us.

Mat Kaplan: And I'm sure it is for the other 25 program Fellows that we'll be hearing from today. Could you go through the structure for us? Because we're going to be hearing from people who have received awards in each of three phases; I, II, and III.

Michael LaPointe: NIAC is a three-phase program. So phase I is basically a feasibility study. It's a nine-month project funded at about 175k for that nine-month study to basically look at the feasibility. Can we really do this? Or are there things that may be showstoppers along the way? If the phase I study is successful, they're eligible to compete for a phase II award.

Michael LaPointe: Phase II is a two-year, 600k study, where you put more meat on the bones of the concept, and actually flesh out the viability and such. Look for transition opportunities, really advanced to the point of a higher TRL, technology readiness level, that could be picked up by another NASA mission or a project or a program.

Michael LaPointe: Beyond phase II. We just recently instituted a phase III part of the program which is for those projects that really need an additional boost that look like they really have really high transition opportunities, but they need a little extra help to get over that valley of death for the TRL level. And what that does is it's a $2 million, two-year program where we really, really do a detailed analysis and evaluation, experimental activities, if possible, to really push that forward so that another institution or another government agency can pick it up.

Mat Kaplan: Those phase III awards are pretty rare though, right?

Michael LaPointe: They're extremely rare. We typically get 300 white paper submissions each year for the phase I awards, out of which we invite about 110 to 120 to submit full proposals. And of those, we fund basically 12 to 16. It's an incredibly competitive program.

Mat Kaplan: So the program Fellows who are here, who've received awards at any level, really have pretty good reason to be proud.

Michael LaPointe: They do. They are the cream of the crop. Absolutely.

Mat Kaplan: What does it take to become a NIAC Fellow? Who can apply?

Michael LaPointe: Actually, anyone in the United States can apply, any US organization. Individual inventors can apply as well, although you do have to get a CAGE code and a DUNS number, or what used to be a DUNS number to UEI, universal entity ID number from Because there's no way for us to pay you otherwise. But, actually, anyone in the United States can apply.

Mat Kaplan: What are we up to here over the next two and a half days? Why is it important to bring all these Fellows together?

Michael LaPointe: So the last couple of years have been virtual which has been great to hear about the Fellows' research status and updates and such. It's great to bring them together in person because a big part of NIAC is the fellowship. In fact, they're called NIAC Fellows versus Principal Investigators because of the collaboration opportunities that we see here. Everyone in this room is incredibly innovative and have incredibly great ideas and being able to bring them together into a symposium like this. Someone will give a talk, and some will say, "Hey, I have an idea that could been a lot of that." And so, it's a great opportunity for us to bring the Fellows together, as well as the folks online, to understand how NIAC works, and to actually build on the opportunities to propose new concepts.

Mat Kaplan: You're a nuclear engineer, an expert in electric propulsion, pretty innovative advanced stuff in itself. Is it personally exciting for you to be here to hear these presentations?

Michael LaPointe: Oh, incredibly exciting. I mean, this is the most forward-looking program that NASA has. And the folks in this room are the ones that are going to really transform how we do future missions. And so, it is just an awesome privilege to be able to be associated with the program.

Mat Kaplan: I feel the same way myself. It is. I'm thrilled to be back for another NIAC symposium, and I'm very much looking forward to hearing the presentations, and also talking to some of the presenters right here where you're standing across the next two and a half days. Thank you, Mike.

Michael LaPointe: Thank you, Mat. We appreciate you being here, sir.

Mat Kaplan: The NIAC external council is a key part of the program support structure. Several of its members have been heard on planetary radio more than once, including David Brin, physicist, engineer, entrepreneur, consultant, and winner of every known science fiction prize in the known universe. Welcome, David.

David Brin: I could imagine a couple that I haven't gotten, but it's wonderful to be back at NIAC. I've had 10 years on the external council, it's been so much fun. The blurb for NIAC is, "It's not science fiction." Well, you know what, it's no insult to say that you have one leg in the science fiction. These are amazing projects. And the role of NIAC in fertilizing things that are just on the edge of plausible is something to be really proud of. I don't know that many nations or civilizations would, as joyfully and successfully, invest in what if?

Mat Kaplan: You have a distinguished bunch of colleagues on the external council. It's chaired by John Cramer, University of Washington. Includes my first boss, who's standing over there, Louis Friedman, co-founder of The Planetary Society. Mae Jemison, 100 Year Starship, astronaut, MD. It's quite a group.

David Brin: Oh yes. And until recently we had The Great Frank Drake, a wonderful inspiration to us all.

David Brin: I urge viewers to go to the NIAC site. Look at some of the presentations, see how well these folks, we call them Fellows, are now expressing amazing ideas about atmospheric flyers in Venus and new types of telescopes and even new kinds of optical systems using scientific things that boggled me. I mean, I may have a PhD in physics, but I'm a Franciscan. These are guys are Jesuits.

Mat Kaplan: Want to live in a mushroom house on Mars or maybe a similar structure on our own world? Lynn Rothschild and partners in her NIAC study are working on fungi-based building materials that are starting to demonstrate the advantages of what they call mycotecture.

Mat Kaplan: Mycotecture. I mean, just starting there, what a great term.

Lynn Rothschild: We start with the Greeks. Myco meaning all things fungal, tecture from the word architecture, so it's a portmanteau, fungal architecture.

Mat Kaplan: Congratulations on the publication of the paper, that you said on stage happened, like what, two hours ago?

Lynn Rothschild: Yes.

Mat Kaplan: Maybe, two and a half now.

Lynn Rothschild: Yes, yes. And we're very excited to finally have our first publication out on this. I think one of the reasons that people become interested in this is that it's not some exotic physics principle. Everyone knows what a mushroom is. And you think mushroom and space, you put those together, that seems weird and exotic, but it's something that's tangible. And in fact, speaking of tangible, I brought you some things.

Mat Kaplan: Look at these wonderful props which are more than props.

Lynn Rothschild: These are actually pieces of mycotecture. These are fungal composites. So the fungal mycelia, these hair-like structures that are beneath the ground, all mushrooms have plus many other fungi, binding together things like wood chips. Of course, we wouldn't have wood chips on Mars. You might bind together the lunar regolith or the martian regolith, or maybe drop stitches inflatable or something like that. But I really want you to take a look at these and smell them. And you tell me right [inaudible 00:10:30]-

Mat Kaplan: I did, and if this was Smell-O-Vision, it would be wonderful because, well, this one which you said looks like plywood, doesn't smell like plywood. It smells like what it's made of.

Lynn Rothschild: It smells vaguely mushroomy, doesn't it? And here, you can tell once it's baked, and it's good and hard. You can hear it, this is a nice heavy brick. We've been joking about throwing into people. We will not do that. But it clearly, you could build a house out of this without any trouble. This, you don't have to worry about joints, you just fill mold to conform to whatever shape you want.

Mat Kaplan: You're testing these materials on the ISS?

Lynn Rothschild: Exactly. We had the opportunity to test some of these on ISS, and it was great. They actually survived very nicely. They lost very little mass. They were up there for about five months.

Lynn Rothschild: You notice that these are pretty dark. There are no invisible mushrooms that I know of. And you're not an albino, and I'm not an albino. All of us on planet Earth, virtually, every organism has this compound called melanin of some sort. And so that's giving the color to our skin, keeping us from being dead white or our hair, and also with mushrooms. And it turns out the melanin can provide protection from radiation. Sort of weird there, but you think, "Aha! Radiation, space." And so that was one of the things that they were testing on ISS, is particularly, these melanized mushrooms, the ones that are pretty much black. And I know this is disgusting, but you've probably seen black fungi when you go open your dishwasher, if you haven't cleaned it in a while, you see this blackish gunk around the edge.

Mat Kaplan: Black mold.

Lynn Rothschild: Those are exactly what that, and those are highly resistant to radiation, bad news. So go clean your dishwasher.

Mat Kaplan: Fascinating. And it's planet Earth that I want to finish up with, because it also looks like-

Lynn Rothschild: My favorite planet.

Mat Kaplan: That's where everybody I know lives here. The work that you are doing, not intending it for the Moon or Mars, but to benefit society, civilizations, in many cases, people who are underserved right here on Earth, in the United States, in Africa. Say something else about that.

Lynn Rothschild: Absolutely. So one of the parts of the NIAC program is that, let's be honest, not everything that were funded for will ever fly. And so, it's really important to show that they have spin-offs for planet Earth. And this one has such obvious spin-offs. One of the things that we've thought about all along is the potential for building refugee shelters. And my colleague Chris Maurer, who's a principal architect at Red House Studios, has moved forward, in a way that I can't, in civil servant. Actually, starting to build refugee shelters in Namibia. Using exactly the technology that we're developing for NASA as well as actually building some houses in Cleveland, Ohio for underserved communities.

Lynn Rothschild: We also, interestingly enough on the other side, have thought a bit about building parts of sustainable restaurants using this approach. And so, we've been very fortunate to have a connection with a restaurant in the Basque region of Spain called Azurmendi, which is one of the top restaurants in the world. I have not eaten there yet, but I certainly plan to, and it has been rated the top sustainability restaurant in the world. And their chef, Chef Eneko has gotten very excited about our technology. And so, he's allowing us to have a NASA corner outside. So there will be a whole booth and structure and tables made out of this mycotecture. And my vision is ultimately, we had the food, we had the clothing, we have the tablecloth all made out of fungal mycelia.

Mat Kaplan: And no doubt, some new mushroom-based dish that you'll be served at that meal.

Lynn Rothschild: We have had sake before, and there are many soy sauce... There are many mushroom-based products. Of course, penicillin and so on. But maybe we'll come up with some new ones too. We are working with the Basque Culinary Institute on that very project.

Mat Kaplan: It's the wrong language, but bon appetit Lynn, thank you so much. It's always really fun to talk with you. I didn't get to ask my trucky question about the mycelial network that emanates across the galaxy. That is a way to go faster than warp drive.

Lynn Rothschild: I'm afraid if I told you, I'd have to kill you.

Mat Kaplan: When I talked with Joel Sercel of TransAstra, it was in front of an impressively large structure, supporting four telescopes that are even more than they appeared.

Mat Kaplan: Tell us about this new project which is why we have this wonderful and very heavy prop sitting right behind us.

Joel Sercel: This is not just a prop, this is an actual functioning Sutter telescope. So the Sutter telescopes were invented by the TransAstra team as a way to find dark moving objects in space. Sutter's named after Sutter's Mill where gold was discovered in California. We've actually invented this technology to find thousands of asteroids that are at lower-delta-v's, that's the amount of rocket propelling it takes to get places in space, that are actually easier in terms of rocket propellant than the Moon. And we think that when we find those thousands of asteroids, it will usher in a gold rush to the solar system. But what's really cool about it, in the near term, is that the same technology can be used to track spacecraft in orbital debris all the way out, way beyond the orbit of the Moon. And that's a really urgent need right now with commercial industry flourishing in Earth orbit with a hundred thousand satellites planned to be launched into Earth orbit in the next 10 years, we've got to maintain awareness of traffic and debris for astronaut safety and spacecraft safety. So it's one of these serendipitous discoveries.

Mat Kaplan: Sutter Ultra, obviously, this is a prototype, the ultimate would be what, three spacecraft? Each of them with a hundred telescopes roughly this size.

Joel Sercel: Yeah, these are actually telescopes made by the Celestron company.

Mat Kaplan: I own one myself.

Joel Sercel: And these telescopes can be purchased for about four or $5,000 at your local camera shop. With our software tied to these telescopes, it makes them a hundred or a thousand times more powerful for tracking moving objects in space. So as effective as a million dollar or half million dollar telescope. So we can actually, with this telescope, track an object the size of a washing machine out beyond the orbit of the Moon.

Mat Kaplan: Did I also read correctly that the brains, the software that will be built into these, each of these 109 or so telescopes will have its own smarts?

Joel Sercel: Yes. Now, we use a method for finding these moving objects which is referred to in the literature as shift-and-add methods. Shift-and-add methods have been used for decades to find asteroids and deep space. But it's very computationally intensive. Typically, a postdoc in Hawaii might be processing thousands of images from big telescopes using a super computer to find moving objects in the deep solar system.

Joel Sercel: What our breakthrough is a new patent pending technology that we have called optimized match filter tracking, which reduces the computational requirements. The amount of computer power that you need by factors of thousands. So that an ordinary processor that can fly in space and not consume very much power could be tied to each one of these telescopes and that it becomes completely feasible from a computational perspective to implement that on a spacecraft.

Mat Kaplan: And I assume that also means you have an amazing level of redundancy.

Joel Sercel: Yeah, that's true. I mean, it's an inherently redundant system.

Mat Kaplan: How important to this project and the previous ones that you've done has been the support of NIAC?

Joel Sercel: Oh my gosh. We are so grateful to NIAC. NIAC is a genius program, designed to change the art of the possible, and it has been a fantastic boom to TransAstra. What's really cool is it's a classic example of public-private partnership where the taxpayers' money is highly leveraged by private sector investments.

Joel Sercel: I'm really honored to be a seven-time NIAC Fellow. I think I might be the only one. And that funding from NIAC seeded the TransAstra Corporation, and with that we've been able to attract more than $7 million of private sector investment based on the promise of these breakthrough technologies. Including the Sutter telescope technology. Including optical mining, which is our patented and more patents pending method of extracting valuable resources from asteroids. And our omnivore solar thermal rocket engine, which is the only rocket engine in the world that uses clean, safe, renewable sunlight, and the same engine can actually be used to run on water or virtually any fluid as propellant. So these are very practical breakthroughs that have the potential to completely change humanity's future in space. And we're developing them and commercializing them in the lab every day.

Joel Sercel: Our goal is to create a trillion dollar new space industry, harnessing the resources of the asteroids so that people can live and work in space, and humanity can expand with a positive vision for the future into the indefinite horizon without straining the biosphere.

Mat Kaplan: The biggest structure currently in space is the International Space Station of course. It took many space shuttle and other launches to put the pieces in place. Zac Manchester and Jeff Lipton are thinking much bigger. They envision a kilometer-wide space station. One who's intricate expanding framework might be put in orbit with a single rocket launch.

Mat Kaplan: I don't know if you're fans of The Expanse TV show. They're the best demonstration of Coriolis force I've ever seen, was in an episode of The Expanse. Where somebody was pouring some booze from a bottle into a glass on a spinning space station and the liquid, obviously CGI, didn't go where you would've expected to on Earth. That's what you want to minimize, right?

Speaker 6: Yeah, yeah. 100%. Yeah, that's great. I need to catch up on The Expanse. I only got in two seasons, but yeah, totally. So it turns out humans are really surprisingly sensitive to this. There've been a ton of human study experiments where they put people in centrifuges and things like this to see what people can tolerate. And it's not much. Surprisingly, people are only able to tolerate about one to two RPM, any faster than that and you feel sick. [inaudible 00:21:20] sick and yeah, and in order to do any artificial gravity with spin, that just necessitates a very, very long structure and the kind of stuff we're talking about.

Mat Kaplan: Just big enough so that even just spinning at one or two rpm, you could simulate what? One g?

Speaker 6: One g. Yeah. Turns out one g at a kilometer long is like one in a third RPM. Right in the range where it's just under where you start to feel it.

Mat Kaplan: You talked about some of the other possible applications, a kilometer wide telescope, whether it's optical or radio, but another one occurred to me is something that some people have been talking about for decades at least since Gerard K. O'Neill, solar power satellites. Is there potential there?

Speaker 6: Yeah. On that particular topic, there's fantastic work being done at Caltech right now. A group of people working on space-based solar power, and it all comes down to very large, very lightweight deployable structures. And I mean, certainly, the sort of thing we're working on has potential there, but there's other ways to do it.

Mat Kaplan: Where are we with this? I mean it sounds like these will have to be fabricated to exquisite tolerances.

Speaker 7: That's actually what we're trying to get around. So our biggest problem right now is really jamming. And so, what we're trying to do right now is find ways of making joints that can be selectively compliant. How can we make it so that they're compliant during deployment and then when they're there we can lock them into place. We've really started with this initial structure.

Mat Kaplan: And here for the radio audience, here's another toy.

Speaker 7: Another toy. So our initial structure is if you look at just the joints is they move, we can lock the rotational joints, and now we have these joints between sections that are the next ones. We need to figure out how to have these multiple degrees of freedoms that we can suppress on demand.

Speaker 6: It's super hard to model and understand, and I think it's a very deep question actually.

Mat Kaplan: Anybody who looks at just the list of titles of these projects that are being presented today might not realize the depth of research of work that has gone into these that makes them much more than the flights of fancy that people might say, "Oh yeah, that's crazy stuff." But your project is one of those, among all the ones we've heard about, you've done a tremendous amount of work. Backing this up.

Speaker 6: We're trying. Almost anything like this, if you actually take rigorous engineering and scientific approach to these things, there's just so much depth there right below the surface that's vaguely science-fictiony. So, if you take it seriously, there's just a lot there. And I think that's true of just about everything here.

Speaker 7: Occasionally, when you're doing these types of projects, you're going to find a giant gaping hole in either your knowledge base or humanities knowledge base that you have to fill in order to push the envelope.

Mat Kaplan: Just one of question guys. The value of being selected as a NIAC Fellow to support this work, what has it been to you?

Speaker 6: Oh, it's amazing. I mean, this is absolutely one of my favorite things that NASA does. I think it's a phenomenal to be here and to see all these blue sky crazy things that everyone's working on. Being taken seriously and supported in this way, it's amazing.

Mat Kaplan: I'll introduce you to several more leaders of fascinating NIAC studies in a minute, including a five-time astronaut developing a better space suit, and a Nobel Prize winner.

Sarah Al-Ahmed: There's so much going on in the world of space science and exploration. And we're here to share it with you. Hi, I'm Sarah, Digital Community manager for The Planetary Society. Want more space? We've got the latest news, pretty planetary pictures, and planetary society publications on our social media channels. You can find The Planetary Society on Instagram, Twitter, YouTube, and Facebook. I hope you'll like and subscribe so you never miss the next exciting update from the world of planetary science.

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Mat Kaplan: Some of you will remember my delightful conversation earlier this year with our next NIAC Fellow. John Mather, senior astrophysicist, NASA Goddard Space Flight Center Fellow, senior project scientist for the James Webb Space telescope, and incidentally, shared the Nobel Prize for physics in 2006.

John Mather: Yes, it's a great adventure to be having, and here I am at NIAC because I have another idea.

Mat Kaplan: And we're going to talk about that idea primarily. It is great to see you again. You were a guest on Planetary Radio early February. The JWST was just beginning its deployment. I think it's safe to say that went well.

John Mather: Yeah, it worked out.

Mat Kaplan: Well, we could spend the next hour or two talking about the JWST and hopefully, looking at some of those beautiful images. But this new proposal which you have called The Hybrid Observatory for Earth-like exoplanets, you're not sitting on your laurels, are you?

John Mather: No. This is an idea that actually is not new. Other people thought about it, but I think the time could be now for doing it. So the idea is once put an orbiting Starshade, a hundred meters across out in outer space orbiting around the Earth. And put it where it can cast a shadow of a star onto a telescope on the ground. So we're building really big telescopes on the ground. They're going to be a lot bigger than we can build in space anytime soon. So the biggest one is 39 meters across, which is six times as big as the Webb, and it's a lot bigger than the biggest one NASA plans to do in the future in space. So let's see if we can do this. So how does it work? Well, cast a shadow that blocks the starlight and then you can see the little planets that are next to it, that's pretty hard, but it's not impossible.

Mat Kaplan: What's that figure that on average the stars outshine the planet, circling them by how much?

John Mather: Well, the sun is 10 billion times brighter than the Earth. Well, you're trying to find a firefly next to a search light. Well, you just got to not look at the search light.

Mat Kaplan: The star shade itself. Quite a beautiful object, very interesting shape. And you made the point that a good part of the design that you guys are looking at is based on prior NIAC work.

John Mather: Absolutely. Webster Cash proposed this back many years ago, maybe more than 20, and they found the solution. The mathematical shape that was required, to make the pointed star shade keep the light away from the telescope. There's a thing called diffraction. Light bends around corners, bends around edges. So if you don't want that to happen, you have to have a special shape so the light will still bend, but send it away from the telescope. So that's what those sharp points do.

Mat Kaplan: It's easy to slew a telescope on the ground, but the star shade is going to have to move really far, won't it? If you want to move to a star system in another part of the galaxy.

John Mather: Oh absolutely. The orbit we've found, we're calling this an astrostationary orbit, so it's not geostationary. We wanted the star shade to hover on the line between the telescope and the star. That's astrostationary. So first, you got to put it there and then you got to keep it there for a while. We can do that for maybe an hour with rocket engines. So you got to match the acceleration of the observatory as the Earth rotates. Then you say, "Well I'm done with that star, let me try another one." So now you have to reorient that orbit completely. That's hard to do. So needs propulsion again.

John Mather: So we have in mind a solar electric propulsion, which of course we know how to do it. We're just trying to minimize the amount that we need. So that leads us to why are we here for NIAC? Because we said, well, we know how to design one of these things, but it's too heavy and too expensive. So let's look for a lighter weight one that we could maybe cut the mass by a factor of five or 10. Well that would cut the cost by a factor of five or 10 maybe. So it's worth trying. So we now need an ingenious way to unfold this thing as a hundred meters across as big as two football fields side by side and put it out there in space and then push it around with a rocket.

Mat Kaplan: Have you heard any presentations today that have some promise for helping you to achieve this in terms of reducing mass or anything else?

John Mather: Well, the one that I heard about actually was a while ago. NIAC supported a concept from Tethers Unlimited, and it was called a trusselator. So they had in mind a little device that would produce a truss starting with spools of material. And so, I would like to have that. So I actually already wrote to the company and they say they're interested.

Mat Kaplan: That was a fascinating presentation here yesterday, that kilometer-wide structure out of one launch.

John Mather: Anyway, it makes my problem sound easy.

Mat Kaplan: I wouldn't go that far. Maybe easier. Anyway, that 39-Meter telescope, I also think of the giant Magellan telescope, a little bit smaller. The mirrors are being made for that telescope right across this campus at the University of Arizona in the mirror lab. Is that also in the scale of telescopes that might... At what range, how many light-years be able to reveal an Earthlike planet?

John Mather: Yeah, absolutely. The distance you can see is proportional to the size of the telescope. So 24 meters is good too. You can see awfully far with that. So it just takes you a little bit longer to see those planets, but absolutely they're good enough.

Mat Kaplan: One more major point because it was how I think you closed your presentation. I think we can call it citizen science, although we were reaching out to schools and students. And how you've brought them into the research, the questions that you want to answer?

John Mather: Well, we have two steps. We discovered that NASA has a community challenge process, an office, and we said, "Okay. Can we play?" And they said, "Yes, we can do this." There's an organization called Amateur designers, professional designers they contribute their computerated designs to this place. So we say, "Okay, you send us a design." And we got at least 50 interesting designs came in and we gave prizes for the best.

John Mather: The next step is going to go through the society physics students, and send out a challenge to colleges and universities around the country and around the world. And set it up as a fairly formal thing. Say, "Show us your mechanical concept. Show us why's could be good enough, strong enough, stiff enough, light enough. And then if we like it, we'll send you some resources so you can actually go onto the next step and end up with a scale model, one meter, two meters, three meters that shows us the principle you have in mind, and why it should really be the right thing."

Mat Kaplan: I want to congratulate the winner of that first round competition. You had Abner Gomez, who happens to be at an institution in Mexico. How can others learn about this and maybe come up with a submission?

John Mather: You just get a login, and you can go look and see what people have posted as challenges. It's not just NASA that offers challenges to this community and be watching when we announce the one through the students. So we plan to send it out to all the colleges and universities that have physics and aerospace engineering departments.

Mat Kaplan: John, delightful to talk to you once again. Thank you for this, and let's go find those worlds that look like ours.

John Mather: Yes, thank you Mat. They're out there,

Mat Kaplan: A radio telescope on the far side of the Moon where it would be shielded from much interference, that's the old dream adopted by NIAC Fellow Saptarshi Bandyopadhyay with an interesting robotic twist.

Mat Kaplan: This is a concept that people have been talking about for many, many decades.

Septarshi Bandyopadhyay: The first workshop on this idea was held in 1960s when man was going to the Moon. And this idea has been around, and we should do this.

Mat Kaplan: And talk about the advantages. Maybe it's obvious to most people, but there might be a few out there. Why build a radio telescope on the backside of the Moon?

Septarshi Bandyopadhyay: Okay, so the first big reason why we want to build something on the far side of the Moon is there is this region of the universe that we can't observe. It's the region where the radio wavelengths are longer than 10 meters. And that region is very important because it is the region of the universe right after Big Bang to the stage where JWST is currently observing the first stars and the first galaxies. That entire region is unobservable. And this is 2022, we still don't know what the universe looks like in those regions. So that's what we are trying to observe.

Septarshi Bandyopadhyay: So the next question is why can't we observe it from Earth? That reason is because there's ionosphere around Earth. The ionosphere is both strong absorber and a strong reflector in these wavelengths. So if you are on Earth's surface, the ionosphere is essentially taken out all the signal and you can't get anything on Earth's surface. If you put a telescope around Earth, then the ionosphere is a strong noise source and that makes the telescope have no signal to noise ratio.

Mat Kaplan: So it's a great thing for those of us who live down here that thank goodness we have a magnetic field, not so great for astronomy.

Septarshi Bandyopadhyay: Yeah, I mean, I, any day want the ionosphere over doing that science, like life might not exist if we didn't have the protection of the ionosphere, but because of that we can't put something around Earth. So now we have to go to some place where we are shielded from the Earth's noise and the far side of the Moon because it Moon is ideally locked to Earth, never sees the Earth's noise. So the far side of Moon is a great place.

Mat Kaplan: So these designs and renderings have been done, like we said for decades. You had examples of at least one or two in your presentation and they looked like the dear departed Arecibo dish. Big, heavy structure, huge, suspended dish. Yours is much simpler, and it's deployed without the need for any humans.

Septarshi Bandyopadhyay: Yeah. So that's been one of the major focus of this NIAC. Proving the feasibility of building this entire telescope on the far side of the Moon using, essentially, a robotic concept. Although, we need this huge reflector, a 350-meter diameter reflector. The entire telescope actually weighs less than two tons with all the spacecraft hardware, the thermals, the power systems, everything included. So it's very much possible to build something like this on the Moon with present day technology.

Mat Kaplan: And there is a terrific animation which I hope people can find. I don't know that it's on the NIAC website. Although, of course, people can read about your award, this project on the NIAC website along with all the other projects from the other NIAC Fellows. But the animation is terrific. I mean, you see these projectiles all fired at the same time radially out across this crater. And you've even picked the crater that would be ideal on the far side and then the dish is deployed. I'm going to be a little self-serving here. It reminded me of the deployment of our LightSail from The Planetary Society.

Septarshi Bandyopadhyay: I completely agree. This idea of firing out these anchors from a single lander is something that is not that difficult because there is a lot of existing technology that is used. The army has a bunch of ideas where they do that for making bridges across rivers. And so, we were able to use a lot of existing know-how on how to deploy anchors with long wires coming out of them. And that's one of the reasons we went with this approach as opposed to having a rover going around and putting those anchors in place. It looks very scary at the beginning, but once you start going through the details, you realize this is a lot of technology that we understand.

Mat Kaplan: The brilliant New Horizons mission revealed a wondrous Pluto as it zip passed at enormous speed. Kerry Nock has been thinking about how we might manage to slow down and land on that beautiful, still mysterious, and distant world.

Kerry Nock: We wanted to have a mission that would be somewhat the same cost as New Horizons. That would enable a mission in about 10 or 11 years. A relatively small launch vehicle. The problem is that spacecraft flew by Pluto at 14 kilometers per second.

Mat Kaplan: And you want to land.

Kerry Nock: And we want to land. In order to land. If you had a Falcon 9 with your lander on it, you might have enough propulsion system to be able to land, but how do you get the Falcon 9, the entire launch vehicle off Earth at that kind of a speed and you can't. And so, we wanted to have a way to do that. And it turns out Pluto has an atmosphere, not much only about 1:100,000 of the Earth's atmosphere. But that's enough because it's a lot high atmosphere. It goes out to maybe 1600 kilometers or more from the surface. We go through that atmosphere and slow down to about couple hundred miles an hour and use propulsion to land about 11 kilograms of fuel.

Mat Kaplan: But it's that slow down, as you described it, which is really pretty miraculous here using this giant inflated sphere. I don't know if you directly remember it, but I'm sure you know about the old Echo communication satellites from the early 1960s.

Kerry Nock: Oh yeah. We're very familiar with that because there were a lot of lessons that we've learned based on their work. Interesting, the Echo 2 was about 40 meters in diameter, smaller than ours, but a much thinner envelope, and it was able to deploy itself and inflate in less than a minute.

Mat Kaplan: You did generate a lot of enthusiasm from other attendees here at the symposium. I think it was David Brin who said, "Hey, you blew right past something that was pretty amazing." But it was on one of your slides. And that was one of the other possible applications for this approach. As a sort of emergency escape vehicle for people in lower Earth orbit.

Kerry Nock: Yes, we've been looking at that as a spin-off for this work from NIAC. You have a problem on a space station, could be the ISS, it could be a new one, Axiom or one of these other companies have developed. If you don't have a way home with a dragon vehicle or some other return vehicle, this would be a way to leave a space station that was in trouble, maybe fire, gas, vacuum leaks, whatever. It would enable you to get home safely. Alternatively, you can leave your spacecraft there docked all the time, but there's a cost to that and that cost for private companies may be too much to bear when you want to make a profit.

Mat Kaplan: I was delighted to welcome NIAC Fellow Bonnie Dunbar for one of my brief interviews at the 2022 NIAC symposium.

Mat Kaplan: And if her name or face looked familiar, it's probably because she rode the space shuttle into low Earth orbit five times between 1985 and 1998. So not too surprising to learn that you might be someone who wants to see astronauts in the best possible space suits. Welcome, Bonnie.

Bonnie Dunbar: Thank you very much. And you're right. I think my father used to say that necessity is the mother of invention, and I learned where necessity needed to be applied.

Mat Kaplan: I mean, you didn't do any extra vehicular activity right across your five, but you still had to, I'm sure, wear the suits.

Bonnie Dunbar: Well, I was assigned to Contingency EVA for my first two flights. So I went through all of the water training with another crew member on my flights, the suit fits and so forth. And we practiced to do things like emergency door closures for the contingency environment. So for all intents and purposes, I was trained for two flights to do space walks.

Mat Kaplan: And you certainly had lots of colleagues who were doing EVAs and learned pretty quickly. I guess most of you did. One size does not fit all.

Bonnie Dunbar: Well, that's true. We actually, during Apollo had custom suits. They were very much customized to the individual for not just fit but also performance because we're going to the Moon. There was a different strategy implied applied for the shuttle. And they started out with five of these chest sizes called hard upper torsos to fit fifth percentile females to 95th percentile males. And for budgetary reasons and engineering reasons by the way, that was reduced at one point to two and then back up to three. But the smallest size ended up being medium and then went large and extra large, and unfortunately, those original HUTs also were sized for shoulder widths that were more male oriented. And so, it made it very problematic for most of the women to train in them.

Mat Kaplan: Why am I not surprised that women got the short end of the stick in deciding what sizes to keep? I wanted to make reference. In fact, I might've mentioned it to you, and you'd heard of the book that I'd talked about Spacesuit: Fashioning Apollo by Nicholas de Monchaux. Absolutely, fascinating story about what it took to make those Apollo suits. And during your presentation, I mean, you had slides, one in particular that really demonstrated once again. Basically, a space suit, especially one that is designed to for walking on the Moon or Mars or being out there in space. These are human shaped spaceships.

Bonnie Dunbar: Well, absolutely, and that actually makes it more complex and difficult to design because you have to have mobility in them. Altogether, if you count the liquid cooling garment on it, you've got about 17 layers of fabric all bunch together that you've got to move. When it's pressurized, you're like a balloon. And the delta pressure is about 4.3 psi. So as soon as you do that, you rigidize these soft fabrics. Now, you still have to bend your elbows, you have to be able to work your gloves. And if you're on a planet, you have to be able to bend over, and you have to be able to bend your knees because you're now a planetary geologist. So it's a complicated problem, but one that we want to take on.

Mat Kaplan: I'm also thinking, you got to get back up if you happen to fall down while you're on the Moon or Mars. What is digital thread, which is the catchy term that you've come up with?

Bonnie Dunbar: Well, I didn't invent the term, I'm applying it. Digital thread is actually relatively new in the literature, but it's the whole process started at that, I think out, in aviation where now we can design airplanes digitally, we can apply computational fluid dynamics, we can design wings and look at the flight all in modeling and sign the airplane, then go build it. So I thought, well why can't I do that with a space suit? Because we haven't actually designed a new space suit in 45 years, so there are no digital CADs of this, the suits we're wearing. But if we start at the very beginning, and we can build the models, and we can scan the human to go into the suit and then we can look at performance. We're calling it the virtual thread first and then start to follow the steps of a digital thread that's used in manufacturing in airplanes for example.

Bonnie Dunbar: And that's when you pull everything together. So you've got everything on a file that's digitally about that suit. And why is that important? Well, if you're going to Mars for three years, you're not going to have a Home Depot down the street. You may not always have the ready access to mission control. You might have to repair there. You might have to repurpose materials. Do you need a 3D printer? Do you need a 3D knitter? What do you need to help keep that suit operational? Because without the suit you're not exploring and that's the vision. But also, the vision is to take that digital environment, scan you and in a very short period of time, have a suit that fits you. That's the science fiction part of it.

Mat Kaplan: I couldn't end this sampling of NASA Innovative Advanced Concepts studies without at least one solar or light sail. There were several, but only one had been elevated to a coveted phase 3 effort. It is led by Amber Dubill.

Mat Kaplan: I'm a little biased. I think that our reflective LightSail 2 is kind of pretty, but I have to admit the Diffractive Sail might win a beauty contest. The comparison that I've heard in talking about a Diffractive Sail is like, if people remember CDs and DVDs, kind of the same principle, and you get a nice rainbow.

Amber Dubil: Well, I will say, I heard that there was a very nice viewing of LightSail 2 from the ground as people saw it pass. So, of course, we're very excited to see that. But you can imagine that with the rainbow effect on top of it and that might be what you would see.

Mat Kaplan: Yeah, you might just went out. Talk about the difference between a reflective sail, just a shiny mirror like LightSail 2, and most other light sails are solar sails so far, and a Diffractive Sail which allows light to pass through but bends it or redirects it.

Amber Dubil: Yes. So it's based off of the law of diffraction, which you might have held up a prism in the sun and seen that the colors come out the other way instead of just bouncing off the reflective surface. And this allows you to do this at specific angles that are different from the reflective sail, traditional type of control.

Mat Kaplan: Is that key to potential advantage of a Diffractive Sail?

Amber Dubil: Yes, so the Diffractive Sail can allow you to do creative maneuvers that are more effective and more efficient. Most definitely, you are able to be entirely sun facing. If you were sailing into the wind and you could face your sail directly at the wind and still go in the right direction toward the wind.

Mat Kaplan: Very cool. And that's not just my opinion, the program manager for our LightSail program, Bruce Betts, our chief scientist, he was very excited to hear that I would be talking with you because, really, I guess, this has generated a lot of interest across the fairly small but very enthusiastic sail community.

Amber Dubil: Oh, of course. We start as solar sailing enthusiasts, first and foremost. So obviously, we're huge fans of The Planetary Society, and I have talked to your chief engineer before. So this is just a new modern take on that, and it really generates the excitement to develop solar sailing as a whole further.

Mat Kaplan: With the material that you have so far which is more responsive, if that's the right word to a particular wavelength or particular color of light. Would that mean it would also be useful and maybe better for being driven by a laser?

Amber Dubil: My Co-I, Dr. Swartzlander, he does have his hands in that breakthrough starshot laser-driven sail community. He does have some support from there as well.

Mat Kaplan: Something that Phil Lubin, who's right behind us here, something that he's been working on quite a bit. It sounded like the project is as much about your targeted mission as it is developing the sail which is this Solar Polar Orbiter Constellation. And that you've given, obviously, quite a bit of thought to. Why is it so important to be able to get these observations, more or less continuous observations of the poles of our star?

Amber Dubil: We have all these models and these thoughts about how certain environments around celestial objects are, especially in our solar system and of course, our own Sun, our closest star that we are pretty much in its own mercy. And so, if we don't know much about that environment, we have predictions, we have thoughts about what that solar environment or the heliosphere looks like. But how do you know that you're right? Unless you verify that. And then you get into the space weather monitoring. So now, you can have full coverage, real-time coverage of what is happening on the other side of the sun. Or as certain parts of the solar environment are interacting because you have that full view at the same time.

Mat Kaplan: And space weather which you just mentioned there, obviously of increasing importance that's being called out by a lot of agencies around the world as being really critical to avoiding potential disaster on Earth as well as great danger to spacecraft and astronauts that might be in them.

Amber Dubil: Of course. And if you have that consolation, first of all, you can better understand the environment so you can better predict those types of disasters or those types of solar weather that could be detrimental to our planet. But also, now you have almost an alert system or the potential to be part of a larger alert system.

Mat Kaplan: Why is constellation made up of these sails better than traditional spacecraft? Something like Parker Solar Probe?

Amber Dubil: Of course, that's going very, very close to the sun within 30 solar radii. The missions we talk about are a little bit further out, but it's really getting out of the ecliptic that is the issue. A Parker Solar Probe is in the ecliptic. Being able to do a mission or having that capability to go out of the ecliptic is what enables the constellation. You can't get four pi coverage unless you're out above, let's say 60 degrees out of the ecliptic plane and that's really where the sails impact the mission.

Mat Kaplan: Because getting out of the ecliptic, the plane that we all live on, basically, is really hard. I mean, you talked about it took seven years for another of these solar observing spacecraft.

Amber Dubil: It takes years because they have to go out to use Jupiter as a gravity assist, or you have to go inward, outward to use a combination of Venus, Earth, to Jupiter. To be able to do that in your own propulsion. That is infinite massless type of propellant. That's where the advantages of solar sails and then now in particular Diffractive Solar Sails comes into play with getting out of that ecliptic. Everything's in the ecliptic for a reason. It is hard to get out as like you said.

Mat Kaplan: Remember. You can learn more about these and all the other current and past NIAC studies on the program website. I'm very grateful to acting program executive Michael LaPointe and his outstanding staff for allowing me to once again meet so many of the outstanding NIAC Fellows. I also thank the great crew from the National Institute of Aerospace that produced this year's symposium webcast. I hope to see them all again next year.

Mat Kaplan: Time, once again for What's Up on Planetary Radio. So here's the chief scientist of The Planetary Society. Bruce Betts is with us once again. Tell us about the night sky and oh, so much more. Welcome back.

Bruce Betts: Hi, Mat.

Mat Kaplan: Listen, I didn't warn you, but I thought, maybe I would give you a chance to congratulate the DART team on, really, a brilliant success.

Bruce Betts: I am rendered nearly speechless. It's quite impressively awesome what they did in changing the orbital period so significantly using kinetic impactor, it bodes well for the future of planetary defense and congratulations.

Mat Kaplan: Hey, what's going on up there?

Bruce Betts: Well, in other news in the sky, we've got planets, but we've got other stuff going on too. So in the evening sky, it's great planet viewing right now, except when it's cloudy. We've got bright Jupiter up in the evening in the east and then we've got Saturn looking yellowish up above it. Coming up a couple hours later in the mid to late evening is reddish Mars. Mars getting brighter and brighter over the next couple months. Look for it, watch for it. It'll be cool. And the Moon is hanging out near Mars on the 14th. But wait, don't order yet. We've also got average mediocre meteor shower which if you're in a dark side... I just don't like to build people up [inaudible 00:53:38] -

Mat Kaplan: Yeah, don't over sell.

Bruce Betts: No, there's a meteor shower tonight. I don't like to. This is easy things seeing the night sky. This is good if you're in a dark side and if you're patient. This is debris left over by Comet Halley. So it's got famous debris. I mean, you can get up to 20 meteors per hour from a really dark side. You'll want to look late in the evening approaching midnight, and after midnight. The Moon will come up at two or three in the morning and interfere some, but not too badly. But wait, if you're in the right part of the world, we've also got a partial solar eclipse. This will be visible on-

Mat Kaplan: Oh.

Bruce Betts: Not for you. On October 25th, visible from most of Europe, Southwestern Asia, and Northeastern Africa. This is a partial solar eclipse. So hey, direct viewing without proper eye protection can hurt kids. Don't do it. Find a safe way to watch.

Mat Kaplan: So how do you know I'm not in Northeastern Africa? Since you do know and maybe people can tell I'm not in my normal studio.

Bruce Betts: Wow, that is a pretty generic room you're in. Well, if you're there, enjoy on October 25th, we'll get more details next week for you. We move on to this week in space history. Amazingly, it is 25 years since the launch of the Cassini spacecraft, eventually getting to Saturn and doing all sorts of awesome things. It's with Saturn, its moons, its environment. And that good stuff launched 25 years ago this week onto Random Space Fact.

Mat Kaplan: (singing)

Bruce Betts: (singing) As we've discussed before, in terms of average densities of planets in our solar system, Earth is the highest and Saturn is the lowest. How do they compare the average density of Earth compared to the average density of Saturn is like the density of iron compared to the density of water. Saturn looks at us and says, "You're really dense."

Mat Kaplan: You have done it again. That is another outstanding Random Space... That is a Hall of Fame Random Space Fact.

Bruce Betts: Really? Okay, cool. I knew it was random. Now, I know it's Hall of Fame. Whew. This is exciting. I'm exhilarated. Appropriately when I'm exhilarated, let's go onto the trivia contest. I asked you in the ESA, European Space Agency, studied mission Don Quixote which never went beyond a study, but was one part of what led to DART, which we talked about, and Hera the follow-on mission from ESA. What were the two spacecraft going to be named that were part of Don Quixote? How'd we do, Mat?

Mat Kaplan: Just a quick response this time from our Poet Laureate, Dave Fairchild in Kansas. Don Quixote was a mission ESA had in mind, deflecting of an asteroid, Hidalgo's main design. Sancho hung around to watch to film Ejecta Stream and DART just showed us why it's not impossible to dream, get it? Impossible dream.

Bruce Betts: Oh my gosh, I didn't get it. Wow. Wow. Impressive.

Mat Kaplan: Yeah, I agree. But Sancho and Hidalgo?

Bruce Betts: Si, si, si.

Mat Kaplan: I'm fine with Sancho, but Hidalgo? No Dulcinea, no Rocinante. Although, we did hear from several people, Rocinante has been taken by The Expanse, but still, I just wonder.

Bruce Betts: I can't tell you why not Dulcinea, but I can tell you why Hidalgo. Hidalgo was a minor noble at the time, and it was the rank of Don Quixote. And in the original Spanish title it was actually referred to him as the Hidalgo instead of the Man of La Mancha or Don Quixote de La Mancha. It actually involved Hidalgo in the title.

Mat Kaplan: That's very illuminating actually.

Bruce Betts: You know. It sound unconvinced.

Mat Kaplan: It makes sense to me. Because as someone else pointed out, Hidalgo just charges into things, and Sancho was thoughtful and hangs back and watches. And that's what Sancho was going to do for this mission.

Bruce Betts: Perfect. And do you realize how hard it was that they actually ended up canceling the mission, they didn't make this mission because they couldn't find a windmill-shaped asteroid.

Mat Kaplan: You just thought of that, didn't you? We have a winner. It's-

Bruce Betts: Yeah, I do.

Mat Kaplan: I got it. I got it. Stephen Whitehead in the United Kingdom. Congratulations, Stephen. He's been entering off and on for a long time, but this is a first time win for Stephen. And of course, what do we have for him? I'm afraid it's not a windmill-shaped asteroid. It's just a good old Planetary Society KickAsteroid r-r-r-rubber asteroid. So congratulations, Stephen. We'll put that in the mail to you.

Bruce Betts: Congratulations. We move on to next time. As of now, October 2022. What spacecraft at Mars has been operating the second longest? Operating at Mars the second longest. Go to currently at Mars and operating, second longest one doing that.

Mat Kaplan: It's clear. Thank you. Yes, you have until the 19th. That'll be Wednesday, October 19, 2022, to get us this answer by 8:00 AM Pacific time. I know what I want to give them. I want to give him your really cool shirt.

Bruce Betts: No, no, no, no, no.

Mat Kaplan: Bruce has this great shirt. It is, I swear, a T-Rex being ridden by a sloth. And the T-Rex has what happening?

Bruce Betts: I think you're tripping pretty hard, buddy. You should-

Mat Kaplan: No, no, no. I'm looking right at it. He has laser beams.

Bruce Betts: I'm wearing a blue polo shirt.

Mat Kaplan: He's lying everyone. He is absolutely lying. It is against a wonderful star field as well. And the T-Rex has lasers shooting out of his eyes. Ok, we're done. No, we're not. We're not going to give you Bruce's shirt off his back. We're going to give you a Planetary Society KickAsteroid r-r-r-rubber asteroid, because there's so many of you out there who still want to win one. Now we're done.

Bruce Betts: All right. Everybody go out there, look up the night sky and think about what Mat just described in his fever dream, without a fever, but add in a windmill-shaped asteroid. Thank you. And good night.

Mat Kaplan: You know there's got to be one out there right among all those hundreds of thousands. He's Bruce Betts. No one would know better than him. He's the chief scientist of 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 innovative members. Help us advance by visiting Mark Hilverda and Rae Paoletta are our associate producers. Josh Doyle composed our theme, which is arranged and performed by Pieter Schlosser. Ad astra.