Planetary Radio: Space Exploration, Astronomy and Science - Sailing on the Light of the Sun With Lou Friedman

Episode Date: September 6, 2017

The co-founder and Executive Director Emeritus of The Planetary Society returns for a conversation about the allure of sailing through space. Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

The Practical Romance of Solar Sailing, 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. Solar sailing is much more than light sail. Jason Davis is back with a review of projects that will send light-driven sails into space and possibly even to other stars. Then we'll visit with the founding executive director of the Planetary Society. Lou Friedman has

probably been our planet's most influential advocate and pioneer of solar sailing. And in an expanded visit with Bruce Betts, we'll hear the current status of the Planetary Society's LightSail 2, heading for orbit next year. We've also got a couple of space trivia contests to wrap up with Bruce. My colleague Jason Davis is the Society's digital editor. We talked a few days ago via Skype. Jason Davis, welcome back to the show. Hey, Matt. Thanks for having me. Always great to be here. Well, I appreciate that. We're glad to have you. A little bit different today. You've been our go-to guy. You and Bruce Betts, of course. Project manager, I think, is his title

for the LightSail project. He's bad at getting manager, director, and all those interchangeable terms straight. But yes, that sounds right. I'm glad somebody else suffers with that confusion. I don't know if that's a changeable term straight, but yes, that sounds right. I'm glad somebody else suffers with that confusion. You, of course, are our embedded reporter in the LightSail project. Great term. You're really in the trenches with that project. Yes.

But we're going to go to Bruce for a quick LightSail 2 update in a few minutes as part of this week's What's Up segment. You have written an article not about light sail for once, but about several other solar sailing projects, some of which are not far from launch, not far behind when we hope LightSail 2 will reach mid-Earth orbit. This is all in your August 23rd blog post titled, A Good Time for Solar Sailing. LightSail 2 finds itself among friends, which of course is at planetary.org. And we will put a direct link on this week's show page that you can reach from planetary.org slash radio. It appears that the magic, the romance, and the practical side of solar sailing is still very attractive to a lot of people.

Yeah, so when I first started looking into this article, I didn't know about all of the projects, and I started asking some people involved, and that led me from one thing to another. And I was really surprised at how many missions there are either close to launching or actually have launched recently. This is really still very much alive. And of course, I think we're going to talk a little bit about Breakthrough Initiatives. They have the ultimate goal of using these things for interstellar propulsion. So yeah, there's still a lot of solar sailing out there, and LightSail 2 is just kind of one project among these other projects. And of course, our former

executive director, Lou Friedman, who literally wrote the book on solar sailing, he's always said that solar sails, or sails anyway, perhaps driven by giant lasers, look like the only practical way to reach interstellar distances. But let's bring it much closer to home, quite literally first. Tell us about some of these projects that you learned so much about, beginning with one that may launch, well, not long after LightSail 2 launches on Falcon Heavy. We could start with NEA Scout. That is a NASA project. And the reason I start with that one is it's probably the most developed of all the other concepts that are going on right now. So NEA Scout is run out of NASA's Marshall Space Flight Center. It's very similar to LightSail in that it's a CubeSat. It's going to deploy a large square sail.

The only main difference between us and NEA Scout is that their sail area is about twice as big. And instead of a three-unit CubeSat, it's a six-unit CubeSat. So essentially, it's double the size for the core spacecraft. But that will be riding on the Space Launch System in 2019, or whenever the SLS ends up launching. Yes, right. Let's hope it's 2019 for that big Space Launch System rocket from NASA. Yes. So the first flight of SLS, as we know, is going out to the moon. It's sending the Orion spacecraft on a lap around the moon or near the moon on a test flight. There's going to be all these secondary payloads that get to hitch a free ride on that flight, and NEA Scout is one of them. It will pop off during the coast between

Earth and the moon, go into lunar orbit, and then it's going to deploy its solar sail, leave the moon system or the Earth-moon system entirely, and go visit a near-Earth asteroid. And something I didn't talk about in the article, but I think is really fascinating. So the original concept for this came from NASA wanting to find a way to do really cheap reconnaissance flights of near-Earth asteroids. And if you'll recall, why would we want to do that? It was back during the Obama administration when we were going to actually go visit an asteroid. So NASA said, hey, how can we, for cheap, go see these asteroids up close?

And that's where the idea came out, well, you could use solar sails and send small spacecraft out and just do these kind of slow flybys of them. You're not going to stop and get into orbit of these things probably and do some reconnaissance. So this was the first technology demonstration of that concept. It did survive, you know, after we kind of pivoted back from the asteroid idea. There's this asteroid called 1991 VG, so eloquently named, rolls off the tongue, you know. Nia Scout will do a slow flyby of it and take some good images of it and send those back to Earth. So yeah, this is a really neat mission. And they're directly involved with the light sail team sharing information. Just recently, in fact, I think they were having a conference with the

light sail team about sail stickage. So when it's put in the storage for a long time, in fact, I think they were having a conference with the LightSail team about sail stickage. So when it's put in the storage for a long time, you know, you worry about your sails kind of smushing together, whether or not those would tear when you deployed them. So they were talking to our team about, you know, the same problem and seeing how we dealt with it. And yeah, so it's a cool project. Hope it gets off the ground in 2019. It's a cool project. I hope it gets off the ground in 2019. It is remarkable how similar it looks, at least in the illustrations in your blog, to the LightSail. I mean, you can't even tell, really, from the scale that it's a lot larger.

Yeah, it really does look a lot like ours. Let's move on to another one that's coming out of the University of Illinois Urbana-Champaign. Pretty ambitious. the University of Illinois Urbana-Champaign. Pretty ambitious. Interestingly, according to what you were told, inspired by a project that was championed once again by our founding executive director, Lou Friedman. Yeah, so this was the cool one that I did not know anything about going into this story until I just heard it mentioned in passing. And I said, CubeSail, what is CubeSail? I heard it mentioned in passing, and I said, CubeSail? What is CubeSail? CubeSail was a project started by the University of Illinois.

The PI of that project, her name is Victoria Coverstone, so I spoke with her about this. And she and her team were initially inspired by the giant heliogyro sail, the Halley's Comet solar sail that Lou Friedman was involved in, as you said. sail, the Halley's Comet solar sail that Lou Friedman was involved in, as you said, kind of looks like a giant ceiling fan, two ceiling fans stacked on top of one another with these miles long blades, really radical idea for the time. And of course, it never flew. They were trying to look at that and say, well, how could that actually become a reality? Their main concern when they looked at that original design was in the heliogyro concept, how do you turn the blades? How do you get a hold of these gigantic miles-long blades and turn them? And the heliogyro's original concept, you did that at the hub. Well, they were concerned that if you twist this giant blade near the hub, that might not actually twist out or turn the entire blade.

So they said, well, what if you put something on the end of the blade and twist it at the same time from both ends? And they did some models and simulations and found out that this might be a feasible way to do that. So NASA gave them a little money to study this concept back in the early 2000s. They didn't find any showstoppers for it. Essentially, the consensus was, yeah, this could actually work. Of course, just like the heliogyro, that would be a huge undertaking to actually fund and launch. So NASA said, why don't you start small, apply for a different grant, and we'll kind of keep working on this concept. So they went back to the CubeSail, just like we kind of did for LightSail, starting with the big sail and moving into something a little smaller as a technology demonstration.

CubeSail essentially is also a 3U CubeSat, and it's going to pop apart in Earth orbit into two one and a half U CubeSats. And it's going to unroll this long sheet of sail between the two satellites. And I believe it's 20 square meters of sail. Once it completely deploys, it will actually try to test out the technique of, hey, can you have two independently controlled CubeSats on both ends of this giant long sheet kind of twisting and turning it at the same time. So it's a pretty cool concept. And that's actually supposed to launch next year on the Electron. And that's a new rocket built by a company called Rocket Lab. And they launch out of New Zealand. And if they're successful, they will take it to the next step and try to do maybe multiple blades at a time or increase the size of the blades. Eventually, they're hoping to scale back up to this giant heliogyro concept.

And that really big one, that's the one that they call Ultrasail? Ultrasail, yeah. You go CubeSail to iSail, and the I stands for Illinois or IlliniSail. That's the next step. And then you'd go to Ultra SAIL, which is this, you know, theoretical giant heliogyro scale thing. A hundred thousand square meters, I learned from your piece. That is truly a titanic sail in space. Yeah. Hopefully it does not suffer the same fate as, you know, know sorry i stole that joke from you no no no i didn't want to jinx them so uh now it's on your shoulders but yeah yeah listen something else that

they have in common the first cube sail this one that may launch uh next year has in common with our light sail one right that it won't actually be able to sail on the light of the sun? Yeah, so they have this kind of same conundrum that LightSail 1 had. You're getting a free ride to orbit, so you can't always be choosy about the orbit you're going to get. So they will be in a low orbit where they're not quite high enough above Earth's atmospheric drag, to the point where the propulsion from solar sailing will be more than the amount the atmosphere slows you down. So it'll be a good test to actually demonstrate, you know, that they can pull this thing apart and angle it and turn it in different directions. But unfortunately, it won't truly demonstrate solar sailing. That would have to be for one of the

later concepts. It is a fascinating concept, though, and like you, I wish them the greatest of luck. It reminds me of the Planetary Society's Cosmos 1 solar sail, the one that we never got a chance to find out if it would work because it went into the drink on the malfunctioning former submarine-launched ICBM that we got on the cheap from the Russian Federation, unfortunately. But that also had sails that twisted to control the attitude, direction, obviously, of the sail. It is, in a sense, a return to that, but with this wonderful technological twist, if you'll pardon the expression. Well, yeah, and that, you know, it's interesting talking about this with you. That remains the hardest part of solar sailing. Essentially,

you've, in space, you know, you have no effect from gravity pulling, you know, the sail. It's kind of just free floating in all directions. And you've got to somehow get a hold of this giant sheet of mylar and maneuver it in certain ways. And that still remains from everything I've heard about the concept. That's the biggest challenge, and it will remain so for some time. So that's why you've got these. We started with these giant concepts, and then everybody said, okay, let's slow down and bring the technology back and try it on a small scale, and then we might be able to scale up to the big stuff one day. I honestly don't remember.

I know that the Japanese mission, the Icaros mission, generally acknowledged to be the first really successful dedicated solar sail. They also had an innovative system for controlling the attitude of the sail. They were using these really advanced LCD panels that would turn opaque or transparent. Do you know offhand how effective that was? I know they were able to demonstrate some kind of maneuvering, but I'm not familiar with it enough to know to what extent it worked. But I do believe you're right about the LCDs, and I think they were able to demonstrate that, yeah. Yeah, I'm pretty sure. And I'll mention in passing that, you know, I use the word dedicated. I applied that to Icarus on purpose because we know, it's been talked about on this

show, that there are other spacecraft that have had to take sort of solar sailing concepts into account. The Messenger spacecraft that, of course, was exploring Mercury had to deal with this as close to the sun as it was. And I just heard from the head of the NASA Heliophysics Division when we were talking about the solar eclipse, the Parker Solar Probe that will launch next year will also be doing a little bit of solar sailing with a giant shield that will be protecting that spacecraft as it enters the outer corona of the sun. So solar sailing is definitely out there and works. It's just harnessing it the way these projects we're talking about and LightSail hope to do it. I think that's the best way to put it. Yeah. Someone told me, and this was a couple of years ago, that the push from sunlight, it is a non-zero effect. And if you ignore that in your calculations, in your physics, when you're doing any space mission, if you ignore that effect, you ignore it at your own peril, was the quote that I heard. Because it will affect you whether you want it to or not. There's no stopping that push from sunlight.

affect you whether you want it to or not. There's no stopping that push from sunlight. Let's go on to the last and the tiniest of these exciting projects that are underway. Tell us about Starship. Starship came from this 2011 Kickstarter project from this guy at Cornell University called KickSat. And Kixat was advertised as like, hey, everybody can have their own spacecraft. We have these postage stamp size little chips called sprites, they were called at the time. And we'll load a bunch of them into a CubeSat,

you know, about the size of LightSail. We'll take you into Earth orbit and we'll just spit out all these chips. And it's a really, really cool idea, you know, to get a lot of people involved and say, hey, I could have my own spacecraft. These things, like I said, they're postage stamp size, but they actually have all the tiny components

that a spacecraft would have. They have a radio, a gyroscope, a little microcontroller, some antennas, and they can actually transmit and you can pick up the signals on Earth. This eventually became the basis for what Breakthrough Initiatives, and that's the group funded by the physicist entrepreneur, Mary Milner, that has all these advanced SETI-style projects in the works. So Breakthrough, when they announced a couple years ago this plan to send solar sails to Alpha Centauri, this Starship concept was kind of a key piece of that.

You need a really small spacecraft and a somewhat sizable sail, not huge by any means. You can zap those with a laser, accelerate them really fast. We're talking like 20% the speed of light, they would get to Alpha Centauri in maybe 20 years. And if you could perfect this technology enough, these little spacecraft would actually be able to take pictures, do all the things a big spacecraft would do, and relay that back to Earth. So how cool would that be to have an interstellar mission, a real interstellar mission?

Yeah, actually put within our reach. I mean, technology that exists today, although it's going to take a while to develop the lasers that would be needed for this, to reach the stars with these tiny, tiny spacecraft. This is something, of course, that we've talked about two, three times on this show with Philip Lubin of UC Santa Barbara, who's part of that Breakthrough Starshot project. We'll provide some links back to those previous shows on the show page, planetary.org slash radio. It really is fascinating. And they've had, what, at least one fairly successful launch of one of these little chip spacecraft? Yeah. So back in June, there was an Indian rocket. It had a

primary payload, this mapping satellite, threw out a bunch of CubeSats. By the way, we should acknowledge, if you've never seen the videos of these Indian spacecraft just deploying just tons of CubeSats in orbit, it is wild. They bolt like literally dozens of these things on their spacecraft and toss them out. Anyway, among those was these two smallsats named Max Vallier and Venta. They carried a couple of these starships. So it was kind of like a secondary payload of a secondary payload. Tertiary payloads. Yeah, tertiary.

Each of these smallsats had one of these little star chips stuck on the side of it. The one satellite, Max Vallier, that was supposed to actually deploy some star chips. Unfortunately, it looks like there's a problem with the Max Vallier satellite. It's not transmitting. It hasn't turned on. And so that means it's not going to be able to spit out its little star chips. But the one on Venta, and that's actually Latvia's first satellite. Pete Worden was telling me this. He was the former NASA Ames Center Director who now heads up the Breakthrough project. Latvia's first satellite had this little star chip on it, and it turned on and was transmitting,

and they were able to receive the signal on Earth. And we're talking just fractions of a watt from this little postage stamp-sized spacecraft. It's healthy, and Breakthrough has declared this the smallest spacecraft ever flown by a technical margin, I guess, there, since it's attached to the other spacecraft. But still really cool, and a cool step forward for their hope of sending one of these things out to the stars.

And a sign of our times that having not the biggest, a cool step forward for their hope of sending one of these things out to the stars. And a sign of our times that having not the biggest, but the smallest spacecraft ever would become something to boast about. Yeah, exactly. Now I'm starting to think, what's the biggest spacecraft ever? Probably the International Space Station, I guess. Yeah, I would guess. In one piece, got to be the space shuttle. Yeah. You finished this blog post, this

August 23rd blog post, with a few words from Pete Worden, who you just talked about. He's the executive director of the Breakthrough Initiatives, working for Uri Milner on this tremendous project. It was a reminder that space is hard. Yeah, yeah. I ended with that quote because I just loved it. He was talking to me about this, and I said, how hard do you think this is going to be based on where are you now versus when you started? How has this come along? And he said, well, I think it's going to be a little easier than we thought it might have been two years ago when we started this. they've had some early successes, some promising technology. And then he kind of stopped and he said, well, I don't want to use the word easier. Let's say it's more feasible. None of this is easy. And I just love that quote because it, you know, it really does encompass space flight as a whole. You know, it, it might get easier in some respects, but at the end of the day, it's, it's, it's still hard. And all of this is still very difficult,

what they're trying to do. Difficult, but exciting, and a little romantic when you get to solar sailing. The whole concept seems that way to me. Jason, thank you very much for this update, this review of some of LightSail 2's, I'll use the word, competition. No, colleagues is probably much more accurate because we wish them all the greatest of success. And look forward to talking to you tomorrow as our own solar sail progresses toward launch on that big Falcon Heavy. Yeah, thanks, Matt. It was great talking about all this with you. That's Jason Davis, digital editor for the Planetary Society. And let me be the first to make it public. Internally, he's picked up a nickname, Scoop Davis, because that's exactly what he does

across not just solar sailing, but pretty much all of space exploration and the effort to reach humanity's destiny out there beyond the atmosphere of Earth. Much more to come, including that update on LightSail 2 from Bruce Betts when Planetary Radio continues. Hey, Planetary Radio listeners. The Planetary Society now has an official online store. We've teamed up with Chop Shop, known for their space mission posters, to bring you space-inspired art and merchandise.

You can find exclusive Planetary Society T-shirts, posters, and more. Visit planetly.com to learn more. That's planet.ly forward slash space shop. Our LightSail 2 solar sail mission is almost ready to fly, but we need your help in these last months before launch. I'm LightSail Program Manager Bruce Betts with an invitation to become part of our revolutionary CubeSat project. Your donation will help secure a $50,000 matching gift from a generous member of the Planetary Society. You can learn more at planetary.org slash lightsail. That's planetary.org slash lightsail. With your help, we'll soon be sailing on the light of the sun.

Welcome back to Planetary Radio. I'm Matt Kaplan. When we started this show 15 years ago, there could be only one choice for our first guest. Lou Friedman was still serving as executive director of the Planetary Society. He, Bruce Murray, and Carl Sagan founded the organization in 1980. Lou was fascinated by the potential of solar sails long before that. His book, Star Sailing, Solar Sails, and Interstellar Travel, published in 1988, remains a must-read for any team that hopes to sail on the light of the sun, or any other brilliant source. on the light of the sun, or any other brilliant source. As you'll hear in a conversation I had with Lou on Skype,

he is the first to admit that the concept has been around for many years. Its roots go back as far as Johannes Kepler, but it was the great Konstantin Tsiolkovsky who first proposed, nearly a hundred years ago, that spacecraft driven by the gentle pressure of sunlight could travel quickly and efficiently among the planets. Lou Friedman, it is always a pleasure to welcome my old boss back to Planetary Radio. Thanks for being part of this. It's a pleasure for me also, Matt. I'm glad to hear that. Are these good times for solar sailing? Well, yes and no. I mean, we've talked about solar sails for many, many years. You know that I started back in the mid-1970s when the solar sail,

we tried to come up with a mission to rendezvous with Halley's Comet. And there have been a whole number of attempted flights and everything like that. But there's only been one solar sail flight, and that's Icarus. And that's a remarkable and a great achievement that the Japanese did with that. They sent it on an interplanetary voyage, and it's been terrific. So yes and no. I think there have been many solar sail attempts. There's been attempts at races, private development, government development, and so forth.

And we have a few going on right now. The interest is still there, but the reality is not yet. Well, we just talked to Jason Davis, my colleague, about three different efforts. Two of them really involve solar sails. It's interesting how often your name comes up when you talk to people around the world about solar sailing. And as I tell people, you did write the book. I did write the book, and I also am given a lot of credit,

sometimes a little undeservedly. I didn't either come up with the idea. Of course, that goes back many more decades before me. I wasn't the first to introduce it to NASA. Others did that. There was a number of efforts before I got involved. What I did, however, was try to do what I always do, which is to make something happen, to make it into a real project. We did that with the Halley Comet effort, and of course, tried it also with the Planetary

Society and our effort with Cosmos One and the starting of LightSail. Pete Warden mentions he's now the head of the Breakthrough Foundation. I'm on their advisory group, because the thing that makes solar sailing so special, in fact, the only thing that makes solar sailing so special is that it is the only known technology, and I assert this somewhat stronger than other people do, the only known technology that leads us to interstellar flight. Now, it's still a long way from interstellar flight, and we can't do it today. And when you ultimately do solar sailing, or when you ultimately do interstellar flight, I mean, it won't be done with solar sails.

It'll be done with laser sails, which is slightly different technology and has different requirements. But solar sails are on the critical pathway. For any other application, whether it's an Earth orbit or interplanetary space or even one that I'm working on right now about going to the solar gravity lens focus out at 500 to 600 AU from the sun, there's always some other alternative that can be done differently. But for interstellar flight, the only way we know how to do it is with a laser sail. So what do you think of the breakthrough Starshot effort that is trying to lay the foundation for exactly what you're talking about, using these fairly small sails and

knocking them with big lasers up to like 20% of light speed? Well, I'm skeptical about the big laser. That's a development somewhat like nuclear fusion. You know, it's always, we talk about it and talk about it for years, but the political difficulty in getting something like that committed to and paid for and overcoming all the issues of environment and arms control and everything else that goes into that is huge. And so, therefore, I'm skeptical that the laser will ever be used in that way. The other thing about Breakthrough's project, which is very interesting, I think very exciting,

I say it's the only new interstellar propulsion technology, and that's small spacecraft. Because in solar sails or laser sails, the important thing is the area you have on the sail divided by the mass of what you're trying to propel. That's how you get velocity. What they're trying to propel is one gram. They're trying to develop a one-gram spacecraft. trying to develop a one-gram spacecraft. Well, Matt, the smallest spacecraft we've ever talked about for interplanetary flight is on the order of tens of kilograms. I'm trying to determine whether a one-kilogram spacecraft is possible, and I'm not sure about that answer. So the one-gram spacecraft in many ways is about as big a challenge as the huge laser that they want to use.

Let me see if I still have the advantages of any sort of solar sailing correct. It's constant acceleration with no propellant that you have to carry along. That's right. It's the no propellant aspect which is truly, because to do interstellar flight or to get anything up to those speeds, you have to have an external energy source. If you carry your energy on board, even if you carried an unknown technology of energy like matter, antimatter, and tried to bottle that up in some tank and carry it along, interstellar flight would be nearly impossible.

So it's that external energy source that we can use and the ability of being able to make the spacecraft very light that makes it sort of hopeful that this is the direction to pursue. We'll take that, Captain Kirk. Take us back to that period when you were a part of this grand project to build a truly magnificent solar sail craft that would have taken us to Halley's Comet. We'll put an image of that, an artist concept of what was planned. It really was magnificent. If it had gotten the support required, do you think it could have been accomplished? Well, I asked that question actually of one of my old bosses, a man who, of course, is retired from JPL now and led many of the aspects of the Halley Comet Rendezvous Project.

Because I keep wondering, what were we thinking of? If we proposed that project today, I think NASA would throw us out of the room because it was truly ambitious. The sail area that we were thinking of was 800 by 800 meters. That is a half mile by a half mile on the side. Or in the heliogyro concept, which people are interested in again, the heliogyro would have covered the entire surface area of, say, Brooklyn in New York. It would have been seven and a half kilometer blades extending for a diameter of 15 kilometers in sailing out there in space. It was very audacious.

At some price, could we have made it work? I don't know. To me now, I think we were a little too confident of our abilities, and we certainly haven't proposed anything of that size or of that scope since then. Now, it'll be interesting because in just a few decades, Halley's Comet will once again come into the inner solar system. And again, people will wonder, how can we rendezvous with this comet? It's very hard. It comes in backwards through the solar system. So to match

its orbital velocity, we have to basically stop the world and get off and turn ourselves around and go the other way. That's why the energy requirement is so large. Maybe we can do it with a solar sail by the year 2061. I don't know. I'd love to see that happen. Of course, I don't think either of us will be here to see it happen. But it does sound like the allure of solar sailing hasn't been diminished in your mind. Well, solar sailing is an incredibly inspiring concept, using the free energy from the sun. Actually, that's what inspired Andrea, Carl Sagan's widow, when she provided the initial funding support for a solar sail project of the

Planetary Society. The romance of sailing in space has been a allure. And then the idea of accomplishing the kinds of missions that can't otherwise be accomplished, like leading on the path to interstellar flight, is very important. That said, NASA has not put it in their plans for future missions yet. They said there's always an alternative, whether it's ion propulsion or chemical rockets or doing missions in different ways. The Japanese have told me just recently, a couple of weeks ago, I heard that they are planning on a follow-on to the Icarus mission.

But even in their concept, they're doing hybrid solar sails, some mix of using solar electric and solar propulsion, light propulsion, that is. So I think that it'll continue to drive us forward. And of course, if the Breakthrough Project can pick up steam, we certainly will be developing a roadmap for how sails can lead to interstellar flight. So we're going to try all these things. But I think we have to take the lessons that we've already learned in the last couple of decades and be sure that we realize that it's still an audacious idea. Lou, thank you for helping to get the ball rolling. I will always regret that we didn't get a chance to find out if Cosmos 1 might have been the first successful solar sail all those years ago.

But I am so proud to have been a part of that project that you led. Thanks, Matt. I, too, regret that we didn't ever find out. We still call it the world's first solar sail spacecraft because it was built and launched to be a solar sail spacecraft. But like you say, it failed on launch. But as you know, in the space business, we keep trying, and each time we keep trying, we learn a little more, and I think we'll have success. I certainly hope so in the case of LightSail. Thanks again, Lou, and Ad Astra.

Okay, thank you. Good to talk to you. That's Lou Friedman, the founding executive director of the Planetary Society, my former boss. Executive Director of the Planetary Society, my former boss. Time for a special edition of What's Up with the Director of Science and Technology for the Planetary Society, Bruce Betts, who also happens to be, have I got it right, Program Manager for LightSail? Yes, that is correct. Excellent. Good. I'd have had to correct Jason, too.

He gave me some reassurance. We saved this little update on our own project, the Planetary Societies Project, for you because of that title that you have. How's that little sail doing? What's the status? It's doing well. We've been working for months doing testing and then tweaking things because of the testing and then doing more testing, trying to make sure we find any problems here on Earth rather than in space. And now we're basically done with the hardware testing. We're just getting ready to button up the spacecraft and tie everything off, literally and figuratively, in terms of the spacecraft itself. And it'll be

shipped it's currently in Pasadena at ecliptic enterprises it'll be shipped up to Cal Poly San Luis Obispo and then at some point in the next several weeks it'll be integrated into the deployment mechanism the so-called peapod that ejects it kind of like a jack-in-the-box once it's in space. And then it will be delivered to Air Force Research Laboratory in Albuquerque, New Mexico, and integrated with PROX-1 spacecraft. And then meanwhile, we'll continue to do work on software and making sure we understand operations and work on operational readiness tests as we get closer to launch. So still a lot of effort working to get it to the launch pad.

And what is the outlook for launch on that? Will it be the second or the third Falcon Heavy from SpaceX? We don't know. We fly with the STP-2 payload, it's called, of the U.S. Air Force. BP2 payload, it's called, of the U.S. Air Force. And we fly as part of PROX-1. The George Tech spacecraft selected by the university's NANOSAT program. It will depend on SpaceX, I guess, and their launch order and manifest. We presumed it would be the second, but we now have some indication it could be second or third,

depending on where things fall. But right now we're looking at a launch no earlier than April 30th of 2018. It certainly could be beyond that because, of course, we're definitely not on the first launch of the new Falcon Heavy, and they'll have a test launch sometime in the coming months, and then that'll start giving a better idea of when our actual launch is, but still we're delivering the spacecraft whenever Air Force Research Lab wants it. I've heard that patience is a virtue.

I've heard it is too, and certainly in the space game, it is a requirement. All right, well, thank you for that quick update, and we'll check back again. I'm still hoping to pay one last visit to LightSail 2 up at Cal Poly before they send it off to the Air Force. I hope I can see you up there. You're not allowed to touch it. Just to be clear, I'm not allowed to touch it either. These are my rules. He is the LightSail project manager. Program manager. Program manager. Better get on to WhatsApp before I... Doctor program manager to you. To you. What's up, Bruce? Oh, what's up is we got the pre-dawn sky just hopping right now.

We got Venus dominating over in the east shortly after, or sorry, shortly before sunrise. But coming up below it, we've got Mars and Mercury. Mars looking kind of orangish reddish mercury looking bright both of them much dimmer than venus both lower and they mars and mercury will move past each other they will be particularly close as we see see them in the sky on september 16th the morning of september 16th so check that out. We still have bright Jupiter low in the west after sunset and somewhat bright Saturn up in the south and west after sunset as well. We move on to this week in space history.

Always, every year, I try to mention, for your benefit, Matt, 1966, what premiered? Oh, for what else? Star Trek. Exactly. This week, 1966. Then 20 years ago, Mars Global Surveyor launched, which started a continuous presence of humanity at Mars with robotic spacecraft starting in 1997 and launched in the same opportunity as Mars Pathfinder. Mars Global Surveyor, of course, worked for many, many, many, many years and revolutionized our understanding of the red planet. We move on

to Random Space Effect. I don't know why. Cassini, big deal, coming up. You've talked about it. You'll keep talking about it. After launch, the propellant mass of Cassini-Huygens spacecraft was more than the mass

of Voyager and Galileo spacecraft combined. The total mass of those other spacecraft? The total mass of those. Just the propellant mass of Cassini-Huygens. It was a big spacecraft for a deep space spacecraft. Almost out of gas too. It's true, but it lasted 20 years, which is more than my tank of gas lasts. Excellent mileage. All right, we move on to the trivia contest. And we've got two previous trivia contests for you due to the timing weirdnesses that happened with the solar eclipse. So you wanted to start with the more recent one, correct, Matt? I do. And even before we do that, we had so many lovely messages from people who were sending us good wishes regarding the eclipse or giving us reports on their experience of the eclipse, mostly from Totality. Thank you to all of you. Great stuff.

Some people sent their pictures. It was really fun to read. We got this from Neil Ashelman in Davenport, Iowa. He had an extra special activity to enhance the partial eclipse that he saw. It was fun to listen to the latest episode of Planetary Radio while safely viewing 90%-ish totality up here in Iowa. So I hope, Neil, that Bruce and I and others provided the extra 10% to boost you up to totality. And then this, how do you say where you were in Oregon? Madras. I believe that's how they pronounce it there. Yeah. Well, here's what we got from Jeff Sosby in Sacramento, California.

He says, Bruce, you were probably told this on your visit to Madras. That is how the Oregonians pronounce it, Madras. Say it like Madras, and they will give you the side eye because they know you're Shudder from California. Well, first of all, yeah, I'm from California. But second of all, I didn't realize I mispronounced it. I apologize. That's quite all right. I think it was you. I think it was realize I mispronounced it. I apologize. That's quite all right. I think it was you. I think it was you that mispronounced it. I think I did it yet another way.

I think I did it a third way. We asked you, to within a minute, what is the longest possible time of totality for a total solar eclipse as seen from the surface of Earth? How'd we do, Matt? This got a terrific response. How'd we do, Matt? This got a terrific response. I think the eclipse really excited people, and so did the chance to win a 2017 Great American Eclipse commemorative shot glass. That shot glass is going to Nathan Hunter in Portland, Oregon, where he probably says Madras. He said the maximum length of totality is about seven and a half minutes.

But I wonder if Bruce should have specified a time frame. It occurs to me that the moon used to orbit much closer to Earth. So presumably dinosaurs saw considerably longer eclipses. Actually, they were smart enough not to look at the sun. Not without their protective glasses. Exactly. No, that's a good point. The moon keeps moving farther and farther from the earth.

So total eclipses lasted longer long ago and will get shorter going forward. I was inferring and implying the present time frame approximately, but I should have specified you were correct. And our revenge on the AIs who will replace us will be that in, what, several hundred million years, they won't get a total solar eclipse at all. Ha ha. Ha! In their faces or whatever they have. Nathan, you have won the brand new Chop Shop designed Planetary Radio T-shirt

right out of the Planetary Radio store there at chopshopstore.com. You also got a 200-point itelescope.net astronomy account, the non-profit Worldwide Network of Telescopes, and that wonderful shot glass that has a little spot on it where Carbondale, Illinois is, displays the path of totality on the 21st of last month. Craig Balog of Woodbridge, New Jersey, who we hear from pretty frequently, he says that the next longest eclipse, the one that will basically reach that time limit, will be on July 16th, 2186, which we got from a lot of people. The eclipse that day will last 7 minutes and 29 seconds, which he points out, rather fitting fittingly will be on a Sunday.

Oh, I get it. Sunday. Yeah. And finally, with this contest anyway, Keith White, Ottawa, Ontario. Another shout-out to Bruce for giving me an entertaining few minutes reading the Journal of the British Astronomical Association, Volume 113, Number 6, pages 343 to 348. For all the parameters that affect this time, ouch, he adds. It wasn't required reading, but I'm glad you went for it and just dove right in. Now we're ready for the second contest.

This is actually the one that preceded the one that we just handled. All right, I asked you, what is the funny word used when three celestial bodies are lined up like in an eclipse? Great word. Everybody's favorite Scrabble word. Random.org chose Richard Egge. Richard Egge of Wyoming, Minnesota. Did you know there was a town called Wyoming in Minnesota? It's a little northwest of Minneapolis. He says the answer, he thinks the word you're looking for is Syzygy. That is correct.

S-Y-Z-Y G-Y. Richard, congratulations. It's been over two years since he last got the quiz question right. You are going to get a Chop Shop Design Planetary Radio t-shirt, a 200-point itelescope.net astronomy account, and what the heck, we'll throw in a shot glass. Just throwing those things around everywhere, aren't you? I bought too many. I brought back too

many. And, you know, maybe he'll drink to our health. Well, I hope so. I have some other good ones here, too. From Stephen Coulter in Woodville, Australia. He says, a good illustration of syzygy is the very beginning of the movie 2001, A Space Odyssey. And if I remember correctly, in 2001, it was more than three bodies. It was a really cosmic moment for the solar system. I bet you know this one. Steve Wienel, another guy we hear from a lot in Antelope, California, which I don't think is far from this place. He says he wants to see a syzygy from Zizek's Road, Z-Z-Y-Z-X. I've been to the end of Zizek's Road. Have you?

Not that I recall, but I remember Zizek's Road. Yeah, you pass it. It's just outside of Baker, which is distinguished by the presence of the Mad Greek. And since I don't want to do a commercial for them, but Zizek's Road, there's something very interesting at the end of Zizek's Road, which I won't describe. It's true. We drove all over the Mojave Desert, you know, doing geology field trips and such. So that's where I met it. But you're not going to describe it, huh? No, I don't know. Is it like a Pikes Peak-shaped pile of mashed potatoes? That's just a guess.

Na, na, na, na, na. Jenny King, Bailey, Colorado. What happens when Bruce, Matt, and the black hole at the center of our galaxy all find themselves in Syzygy? Hopefully it stays far away from us and nothing in particular happens. But I definitely hope Matt's the one that's closer because of the beautiful view. I think it's the dawning of the age of Aquarius myself. Finally, from our poet laureate, Dave Fairchild in Shawnee, Kansas.

Now, with deep apologies to Gilbert and Sullivan. When I have learned alignments that occur when you have bodies three, when I know that eclipses always happen due to syzygy, in short, in matters in the skies you check with a spectrometer, I am the very model of a modern-day astronomer. Thank you. You used to be in musicals, didn't you? Oh, a long, long time ago.

But mostly just in the chorus. That's it for these. What do you got for next time? Back to Cassini. How long is the longest dimension of the Cassini spacecraft? This is not counting booms like the magnetometer boom, but the main spacecraft's structure before deployments.

How long is Cassini in its longest dimension? Go to planetary.org slash radio contest. I am so glad that you clarified not including the booms. That should be very helpful to people who will be attempting to get us their answers by the 13th. That'll be September 13th at 8 a.m. Pacific time. And you've got a chance of winning that Chop Shop designed Planetary Radio t-shirt. It's cool. 200-point itelescope.net account.

And you know what? We have some artwork we're going to start giving away. I think I'll do that next week and give away one more Great American Eclipse commemorative shot glass. How's that? That's glorious. You're very generous. And you're done. All right, everybody, go out there, look up the night sky and think about what Saturn, which is less dense than water if saturn were in a big giant bathtub would it leave rings around the bathtub think about that thank you and good night okay only hurts when i broke you he's bruce betts he runs circles and rings around all of us

when he does what's up here on Planetary Radio. We've had to move our live celebration of the Cassini mission to Caltech's biggest venue, Beckman Auditorium. Even that space may be at capacity by the time you hear this. If you don't have a reservation, I hope you'll still join us for the live stream beginning at 7.30 p.m. Pacific time this. If you don't have a reservation, I hope you'll still join us for the live stream beginning at 7.30 p.m. Pacific time on the evening of Monday, September 18th. The link is on our show page at

planetary.org slash radio. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its Light Sailing members. Daniel Gunn is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser. I'm Matt Kaplan. Clear skies.