Planetary Radio: Space Exploration, Astronomy and Science - LightSail 2: A Year of Solar Sailing

Episode Date: June 17, 2020

The LightSail 2 team and 50,000 supporters around the world will celebrate the little spacecraft’s first anniversary on orbit in a few days. Planetary Society Chief Operating Officer Jennifer Vaughn remembers the long road to this accomplishment. LightSail Program Manager Bruce Betts and LightSail Project Manager Dave Spencer tell us what we’ve learned over the last year and look to the future of solar sailing. Dave also reveals his exciting new job at the Jet Propulsion Lab. Learn more at https://www.planetary.org/multimedia/planetary-radio/show/2020/0617-2020-light-sail-2-betts-spencer-vaughn.htmlSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

LightSail 2 reaches one year in space 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. That's right. The Earth has made one full revolution around the Sun since the Society's little CubeSat with 32 square meters of mylar sails rocketed into orbit aboard a roaring Falcon Heavy. We'll look back with Planetary Society Chief Operating Officer Jennifer Vaughn and then get the mission status and outlook from LightSail Program Manager Bruce Betts and LightSail 2 project manager Dave Spencer. Dave also has some very special news about his own work that he'll share. Bruce will stay with us for this week's What's Up Trek Across the Night Sky and a new space trivia contest. My favorite image in the latest edition of The Down Lake.

Might be hard to decipher without a caption. Bunny-suited technicians are reaching up to a matrix of brass-colored cylinders. Over their heads is a complex piece of technology that would be unrecognizable to many, at least from this angle. What we're watching is members of the Perseverance Mars rover team installing sample tubes in the belly of the rover. installing sample tubes in the belly of the rover. Someday, those very tubes, filled with Martian soil, will be returned to the great labs back here on Earth, and the dream of Mars sample return will have been realized.

NASA says Crew Dragon astronauts Bob Behnken and Doug Hurley are likely to make the International Space Station their home till at least August, and possibly longer. The extra hands are much appreciated by the other occupants. Bob and Doug might even get to help with some work outside the station. Suitable for framing, that's a huge mosaic image of asteroid Bennu's surface taken by NASA's OSIRIS-REx spacecraft last month. You can see the small crater called Osprey. It's a backup location for a collection of a sample later this year. I swear the picture is so sharp you feel like you could reach in and pick up a sample or two yourself.

And that's no more than a sample of what you'll find at planetary.org. where you can also subscribe to our great weekly newsletter for free. By the way, the June edition of my own monthly newsletter is now available at planetary.org slash radionews. We weren't the first to set sail on the light of the sun. That honor goes to Japan and its Icarus solar sail. But we tried to be first with our Cosmos One craft. solar sail, but we tried to be first with our Cosmos One craft. That episode was just one chapter in the Planetary Society's long-held dream, a dream that was finally realized last

year with LightSail 2. We'll get into the details with Bruce Betts and Dave Spencer. First, though, I wanted to get the bigger picture from Chief Operating Officer Jennifer Vaughn. She joined me just a couple of days ago. Jennifer, welcome back to the show. Nobody is going to be surprised to hear that you and I and our colleagues and all of our members are pretty proud right now to be reaching this milestone. I know you feel that way. I do. I do. And so proud. And I know above all, it's our members that they should be so proud that they came together and not only made this mission happen, but we have achieved our goals and we're still flying. We're still flying a year out. Hard to believe. Seriously, did you suspect I did not that we would be at this point be going into an extended mission. No, I certainly when we put out the estimates in the very beginning, we thought that it could easily stay up for a year. But that wasn't part of our primary goals.

We were out there to, one, get the first crowdfunded spacecraft up there and orbiting and actually achieve those goals of controlling our orbit. How long it stayed up in orbit was really just a bonus. And those early estimates of saying it could be up for a year sounded like a very long time at that point. But now it feels like yesterday that we were in Florida watching it launch. And how? Gosh, I was just talking with somebody about that, how it does not feel like it's been a year since we heard and felt that Falcon Heavy take LightSail 2 up into orbit. I mean, has anything surprised you about this mission and especially the reaction to it, how well it's been received? That's an interesting question. I don't know about surprise. It took us so long to get to this point that just the idea that we not only got off the ground, but that it was operational. I don't want

to call that a surprise, but it was such a wonderful welcome relief when that happened. Seeing those sales deploy, getting those images back, confirming. It was so exciting to see it actually coming to fruition after 10 years of preparation. Over time, though, the fact that I continue to meet people and they say, oh, yeah, I contributed to solar sailing when they find out what I do. I just love that connection point that all these people around the world are feeling such ownership over this spacecraft and they're very clear that they made this happen.

I hear the same from people all the time. You know, you talk about 10 years of developing LightSail, but I say, in fact, this is in my newsletter for this month that also comes out like this episode on the 17th of June. This really has been a long, hard road, and it stretches back to the beginning of the society, I guess, right? Because, I mean, at least two of our founders, maybe all three, this sailing on the light of the sun was a dream that they shared. Yes, and that was one of the things that they shared before the organization even existed. There was this connection with the concept of flying a solar sail

out to Halley's Comet. And Lou Friedman had an essential role in that mission design and concept. Bruce Murray was the head of the Jet Propulsion Laboratory at the time. And Carl Sagan was enamored with this idea of sailing on sunlight. So all three of them had this connection. And when the organization was formed in 1980, it was written into a lot of our very early documents that we as an organization were going to pursue the opportunity of solar

sailing. Right from the start and even before. What's next? Do you get the question that I still get from people, which is specifically, hey, when is light sail three? Oh, of course I get that question. It's an obvious question. That is the next line of thought. But I always say the same thing. We're not in the solar sail business. So while we, we're always looking for the next best opportunity for the public to make a real difference. So as we've mentioned a little bit before, we are developing a proposal opportunity, an open call for proposals that we will announce early in 21. And the idea behind that is that we can reach out to a very large community of people around the world. So it's not specific to any particular space agency

or university system. It's going to be an open call, letting the organization know how could the members of the Planetary Society help advance a new concept, a new way of exploring space, a new way of understanding the planets? We're excited to get that going. And it's really an extension of the way we've always done our work. We've always found great individuals who have compelling ideas and need the public support to get those things done.

So all we're doing with this proposal process is adding a schedule, adding an expected opportunity, adding some dollar figures of what we are hoping to support so that there's just clarity that this is what the organization is seeking. We want to hear from the community about where we can do the most good. And there does seem to be precedent for this. It's not a duplication in any way in the Shoemaker-Neo grants that the Planetary Society has been distributing and getting such good results with for a long time. We're enablers. We are.

And we use that model because that model has been so successful. And one of the things that makes it successful is that it's predictable. You know, every two years, we're going to offer this, and it's very clear what we're looking for. And that community of people who propose to the community grants has continued to grow over time. So we use that model and said we want to apply it to a much larger portfolio of project ideas. We are happy to share what we've learned. Very, very happy to share. It was really built into our initial goals that any work that we were doing on testing solar sailing in Earth orbit, we wanted to be able to share with the community. And we've already been quite successful. While it's been a whole year in orbit, it's only a year in orbit. And we've had a number of professional papers already in place, presentations. We do have these professional working relationships with NASA.

We are a big part of the international solar sailing community. So for all these reasons, it takes the organization's effort and it just multiplies it, amplifies it by bringing in whom have gone on to professions in aerospace. And they unanimously talk about the value of this project. Is that something you also think about? We do. Yes, I think about it. And a number of us in the organization are really looking at that as a success story for this particular project. But I think even more so looking at where can we build in student opportunities,

intern opportunities, and fellowship opportunities into the work of the Planetary Society. So we're looking at it beyond just our projects, but where else can we reach out as far as our communications efforts, our political advocacy efforts, and start developing real programming to bring young people very closely to these efforts? Jennifer, I look forward to raising a glass with you on June 25th when LightSail 2 graduates into the next phase of its existence. Thank you for this. And I'm delighted to be able to share your thoughts and share this experience with you.

Well, thank you. We are so excited. Once again, this is just testament to the power of people coming together, rallying around a very big, audacious idea and making it happen. Everyone should be very proud. Empowering the world's citizens.

You got it. That's Jennifer Vaugh proud. Empowering the world's citizens. You got it. That's Jennifer Vaughn. She is the Chief Operating Officer of the Planetary Society. We'll hopefully, Jen, be talking to you again on this program before too long. Thanks again. Thank you, Matt. You know Bruce Betts as Chief Scientist for the Planetary Society and as my partner for the What's Up segment. You may also have heard his occasional updates on the LightSail mission. He delivers those as the longtime LightSail program manager. You may not know Dave Spencer as well. Up until just days ago, Dave was an associate professor of aeronautics and astronautics

in the Purdue University College of Engineering. He's also the founder and director of the Spaceflight Projects Lab at Purdue. Then there were the 17 years he spent at JPL, including his service as Mission Manager for Mars Odyssey and Deep Impact, and as Deputy Project Manager for the Phoenix Mars Lander. He even helped Pathfinder make it to the surface of the Red Planet back in 1997. Now he is about to return to the Jet Propulsion Lab in a new and exciting position, one that we'll ask him about in a few minutes. But Dave has primarily joined Bruce and me to help us mark the first anniversary of LightSail 2 on orbit. Gentlemen, congratulations.

I did not think, as I said to Jennifer Vaughn, that we would a year later be talking about this transition into an extended mission for LightSail 2. And we have you and the rest of the team to thank, and obviously a great spacecraft and a lot of members of the Planetary Society. So again, congratulations and welcome to the show. Thank you. Good to be here, Matt. Thank you, Matt.

As we speak, where's that light sail? Bruce? It's flying somewhere between 24 degrees north and 24 degrees south. I'll check, Matt. I'll get you an answer in just a moment. Why, you must be going to that handy dashboard at planetary.org. Oh, yeah. I could have done that. I went to my more detailed program I use to plan imaging and things like that. Yeah, I'm not surprised that you guys have something a great deal more detailed to tell you about where LightSail is, but also what it's up to. Dave, what is it up to? What is the current status of the spacecraft?

We're solar sailing just about every day. We turn the spacecraft twice in orbit so that we get a little boost from solar photons. And we're actively controlling the spacecraft on a daily basis. Every day, it takes a few hours to basically damp attitude rates and manage the momentum on the momentum wheel, which is used to reorient the spacecraft. We take a couple hours to de-spin the spacecraft, get the wheel speeds down, and then go back into solar sailing. And so that's been pretty much the routine for quite a while. And we've been addressing a number of different challenges and trying also to improve the solar sailing performance. Things are going well, and we're pretty much in the routine of solar sailing at this point.

Is this reorientation of the spacecraft of Lightsail 2, is it automatic? Or is somebody saying, okay, we're coming back into the sun. It's time to turn X degrees. No, it's automatic. We have onboard software that was developed before launch. And we have made some updates to it. But basically, it's autonomously controlled onboard the spacecraft. And we have several different attitude control modes of which solar sailing is just one. I've also mentioned the de-tumble mode

where we damp rates. We've also got a no-torque mode where we don't have any actuation that would change the orientation of the spacecraft. We've also uploaded recently a mode where we point the sail directly at the sun, which is useful for recharging the batteries. Other than these sort of gross adjustments to catch those rays, whether it's to propel you or to charge the batteries, are there other kind of minor attitude adjustments being made perhaps more often? Other than the ones I've already mentioned, no. And with the control that we have with the spacecraft, we're not able to do really fine pointing.

We've come to the realization or recognition, which is not too far from what we predicted, that we can orient the sail within about 15 degrees of the desired orientation. So that's about as good as we can do. And we don't do a lot of fine tuning. We do have one more attitude mode where we can basically align the orientation of the CubeSat with the Earth's magnetic field. But we haven't used that too much since we actually started solar sailing. Bruce, I mean, maybe not optimal attitude adjustment, but obviously adequate. Does this meet the expectations that you had before the launch and the deployment of the sails? Yes. First, let me give you that important answer,

Matt. We're over the South Pacific in the middle of the ocean right at the moment we're recording. It'll, of course, be different when people are listening. I'll keep you updated. We should hit South America in a few minutes. Well, aloha. We're kind of far south, but we do pass near and over Hawaii at times. Yeah, this definitely has met the expectations. I mean, we set the fundamental goal for the mission was to demonstrate controlled solar sailing in a small spacecraft, a CubeSat in this case, size of a loaf of bread. it for the first time as a way to spur interest in solar sailing, but also demonstrate that you can use these CubeSats that have been used in Earth orbit, that you could use solar sails as a propulsion technique in interplanetary space. Our opportunity for launch was to Earth orbit,

so that's what we're doing. But yes, even with the errors and pointing, et cetera, we definitely see that we're able to control the spacecraft. And it does, usually, does what we want it to be doing. And we can adjust the orbit therein. So we achieve the desired big goal early on. And the rest is a whole lot of icing that we're putting on the cake to learn more about solar sailing and share that with the world. Bruce Betts and Dave Spencer have much more to share about LightSail after a break. Stay with us. Greetings. Bill Nye here, CEO of the Planetary Society.

Even with everything going on in our world right now, I know that a positive future is ahead of us. Space exploration is an inherently optimistic enterprise. An active space program raises expectations and fosters collective hope. As part of the Planetary Society team, you can help kickstart the most exciting time for U.S. space exploration since the moon landings. With the upcoming election only months away, our time to act is now. You can make a gift to support our work. Visit planetary.org slash advocacy. Your financial contribution will help us tell the next administration and every member of Congress

how the U.S. space program benefits their constituents and the world. Then you can sign the petitions to President Trump and presumptive nominee Biden and let them know that you vote for space exploration. Go to planetary.org slash advocacy today. Thank you. Let's change the world. So it's worked. Bruce, you've told us many times it did exactly what it was supposed to, raising its orbit.

But it is also losing altitude, right? I mean, how much longer before light sail just starts picking up too many molecules of air and not enough photons? Well, it'll be at least many months. I don't know if Dave has more he wants to say about it. But the fundamental thing, as you note, Matt, is that even though we're in space and we're some 700 kilometers up in altitude, there's still molecules of air. And when you've got a little tiny low-mass spacecraft and a big sail area, you're getting atmospheric drag. And so we are gradually going down.

And although we make adjustments to the orbit, and when we're solar sailing efficiently, we decrease how quickly we're going down. And although we make adjustments to the orbit and when we're solar sailing efficiently, we decrease how quickly we're going down and even a few days have increased altitude. Generally, we're fighting a losing battle with the atmosphere and atmospheric drag. So it's a matter of time, but we've got time. And so we're trying to keep things going, learn more, take pretty pictures and understand things. And just about a year into operations, we've lost only 10 or 15 kilometers worth of altitude. And so the orbit's decaying very slowly. We do expect that decay rate to accelerate, but it's really difficult to tell because the atmosphere responds to solar events when the

sun gets more active and throws off energetic particles, the atmosphere expands and atmospheric densities up where we're solar sailing get higher, and that increases the atmospheric drag. And so we can't really give a precise prediction about when we're going to deorbit, but we do expect the decay rate to pick up here in the next year. What about the technology? You've got batteries. They don't last forever. You've got that spinning wheel that has to spin up and You mentioned a couple of the life-limiting technologies. The batteries are lithium polymer batteries. They have a limit to the number of cycles they can go through before they start losing charge. And I would expect that we're getting fairly close to that limit. So it wouldn't be surprising to see some degradation in the

batteries here in the next several months. Also, as a CubeSat, there's no radiation hardening on the electronics. We do get periodic, spontaneous reboots of the flight computer that are likely caused by energetic particle interactions, radiation. But at some point, we could have a catastrophic failure of the spacecraft due to radiation. We hope that doesn't happen. It's kind of uplifting to think of our little CubeSat suffering from the same cosmic ray hits that have at least temporarily taken out so many other spacecraft that have gone far deeper into the solar system. Speaking of other spacecraft, Dave, you've been a part of, in fact, you've led several other missions with slightly larger budgets than LightSail 2. How does it compare?

I mean, doing a project like this on almost a literal shoestring and pulling it off. Well, I tell you, there are same amount of excitement and enthusiasm and just get as charged up about LightSail as I have any of the other missions that I've worked on, including the Phoenix Mars Lander and Mars Pathfinder, Odyssey, Deep Impact. The excitement and enjoyment I get from operating LightSail is just in family with those other missions. One of the key differences is that the team's a lot smaller. We've got six people that basically operate the LightSail 2 spacecraft

on a day-to-day basis. Everybody's got a lot of responsibility, and it's just a very close-knit team, but that's a much smaller flight team than what I'm used to, so that's a big difference. Bruce, I'm going to give you a chance to talk a little bit about Dave. You've been part of this program from the start. Dave is not. You've worked with a lot of people. How has Dave been as somebody to work with on this team? And what has he brought to the project?

He's terrible. He's obnoxious. Wait. Oh, wait. Are we recording? Yeah, I'm afraid obnoxious. Wait. Oh, wait. Are we recording? Yeah, I'm afraid we did start. Okay. I mean, Dave's great. Sorry, I couldn't resist.

Now, Dave's brought a great sense of experience, organization. He's easy to work with and has everything you want in a project and mission manager, He has everything you want in a project and mission manager, which is the roles he's filled very well and has dealt with the fact that we do have a shoestring budget. We do have a small team. We have the breadth of the team, but we necessarily don't have the depth. So he's been great at adapting to the situations as they occur. Because you've been with it for so long, Bruce, you've weathered all of the many challenges of getting the spacecraft built, launched, deployed.

What would you point to? What were the biggest challenges outside of the things that I know you had to deal with as well, but at least you had help with finding the money to make all this happen and pulling the team together? What were some of the expected and unexpected challenges? I think the expected broad challenge is you're flying in a hostile environment with little forgiveness on a comparatively small budget,

trying to do something that no one's done with such a small spacecraft. The Japanese with a much larger spacecraft and larger budget flew Icarus, and there was a solar sail. But trying to shove a boxing ring-sized Mylar sail into a loaf-of-bread-sized spacecraft and operate it has been challenging, to say the least. Now, the good news and bad news, we had the challenge of the launch of the Falcon Heavy kept slipping and slipping and slipping, but it was never clear when it was slipping to. So we had a lot of early just schedule trying to figure out what to do, but it did give us

chance to do a lot more testing on the ground. So that has helped us considerably. In orbit, we've had different challenges that come up as we go along, things that are unexpected. One of the solar panels didn't deploy fully, and it took us a while and an image of shadows to figure that out. But once we did, it made a lot more things make sense, and we adapted to it. It isn't a major effect on the mission. effect on the mission. Various glitches here and there, but all of them, thanks to Dave and the team at Cal Poly San Luis Obispo and Boreal Space and Ecliptic Enterprises. Thanks to the team, we've come through all of those. So that's a long and unwieldy explanation, but you like to get me into those, don't you? I liked it. I liked it.

Dave, anything to add? And it's your chance to get back at Bruce. Well, yeah. Likewise, Bruce is really tough to work with. He's just not a very likable guy if you get right down to it. No, I'm just kidding. Bruce is great. And the team that we've got, you know, we talk on a daily basis. We've, I think, developed a very close working relationship. And so it's really a great team. But we're all distributed and we've got a lot of university involvement as well as industry partners involvement. So it's a really neat makeup for the team. I think in terms of challenges that we've overcome that maybe were

unexpected, the one that we've really been wrestling with since we initially deployed the sail back in July of last year is momentum management, managing the angular momentum of the solar sail craft. We've got one small momentum wheel on board that's used for doing these turns along with some torque rods, basically running a charge through a coil of copper wire and having that electric field generate a magnetic field that interacts with the Earth's magnetic field. With those actuators, we try to turn the sailcraft twice every orbit, and the momentum wheel tends to rapidly reach its maximum wheel speed. And so just being able to come up with an approach to manage that and get the wheel speeds down to

where we're not saturating the wheel, that's been one of the key challenges that we've dealt with really since the beginning of the mission. And we've continued to try to automate that process. And I think we've gotten better and better at it as the mission's proceeded. I failed to mention Dave's host institution that he's been at, which is Purdue. And one of Dave's grad students has been critical to the team in figuring things out like that, Justin Mansell. Yeah, that's one thing that's been really neat is, you know, Justin has had a key role throughout operations. There have also been a couple of Cal Poly students, and I'll mention Michael Fernandez specifically, that have really been key in operations as well as just communicating with the spacecraft.

The students have carried a lot of weight in terms of making sure that they're on console for those shifts where we need to do manual commanding of the spacecraft. No, it's been great. The student involvement and John Bilardo, who manages everything in the software and the ground stations at Cal Poly, has been working with undergrads there. So it's been a great experience for us and for the students. I brought this up with Jennifer when we talked as well about how rewarding it has been to watch these students, to watch these students, some of whom are now off in aerospace careers, and point to this experience with great fondness, but also talk about the tremendous experience that it gave them. I don't know. Dave or Bruce, did you have an opportunity, anything like this when you were at that age?

This is Dave, and I certainly didn't. I basically came out of college having done a master's degree that was purely based on analysis. No real hands-on experience, no real flight project experience. I think that that is a key selling point for students. I tell students when they go into an interview position, they need to be able to explain to the interviewer how they can fit into the organization, how they can contribute, and hopefully point back to relevant experience where they've actually done that sort of thing. Hands-on experience on light sail is really key for these young students' careers. So I'm happy that we could provide some of that opportunity. I did not have flight operations experience per se, but I did do image planning and had it accepted by the Soviet Phobos 88 mission and then had a mission failure before anything I planned got done. So I learned the early lessons of the challenges of spaceflight.

But no, this has been a great opportunity with these students and ones who have worked on everything from the hardware to flight operations to modeling the spacecraft and what's going on. Bruce, I had forgotten about that early imaging or image planning experience that you had. That must make it even sweeter to now see these gorgeous images coming back from LightSail 2 in a program that you manage. Oh, it is. I got into planetary science originally because I love the pictures going back to childhood. So to have a spacecraft and we're taking pictures that we are taking, you know, the primary reason is for engineering to look for variations in the spacecraft originally to confirm the deployment of the sail. But we're also, you know, we're the Planetary Society. We're about

public interest and exciting the public about space and seeing that big shiny sail with pictures of the Nile River in the background or, you know, Central Australia or the Himalayas. It just makes for exciting, exciting stuff. So yeah, I'm having fun. From LightSail 1, we got one image down and we were ecstatic to get that one image down and we got lucky in having the sun centered in the field of view. But for LightSail 2, you know, we've gotten dozens of really beautiful images down that have the earth in the background. Bruce mentioned my favorite, which is one that shows the Nile River and the Red Sea. But it's really tough to pick a favorite because there are so many stunning images. So I encourage your members to go to the LightSail website and take a look at those images. And Hal, yeah, if you haven't, folks, do it today.

Don't do it right now unless you want you want to think it'll enhance this conversation. My favorite, I think, has to be the one of looking up from Baja, California toward my home, actually, in the San Diego area. And I'm sure I was out there waving at the time. As we celebrate this year, and as you share what we've learned, this is something I also talked with Jennifer about, and the collaboration that is underway with the NASA folks behind the Near Earth Asteroid Scout Mission, NEA Scout. What kinds of things are you telling folks like that? What are you putting in the papers that you're presenting? The kind of thing that would be like, if you're going to build LightSail 3, because we're not, whatever you do, don't do this. Bruce? Don't let Matt near the hardware.

I don't know if you heard, Dave, but John Berardo at Cal Poly insisted that I pull the spacecraft out of the P-Pod, its little ejector. And I said, I really should not be touching this because if anything goes wrong, I'm never going to hear the end of it from Bruce. It's true. I would have been harassing you week after week on planetary radio. No, I think the, you know, the lessons are similar to, first of all, what's always there, which is test as much as you can, but that it's challenging. As Dave mentioned, the momentum management, I think, is something that we have helped contribute to, which is just an understanding of how hard it is to spin down your momentum wheel and get the momentum out of it, or whatever you're using. They're using multiple momentum

wheels, I believe, on NEA Scout. But it's similar just thinking through those things as much as you can beforehand. Dave may have some other insight here. Well, I think one thing, and Bruce alluded to this, we found in imaging months into the mission that apparently one of the four booms that pulled the sail material out from their storage compartment and that keep the sail in its fully deployed configuration, one of those booms apparently has partially buckled. It's not real obvious from the imaging, but we see a boom in a location where it just shouldn't be. That's a key finding because solar sails and drag sails, you know, are going to be dependent on structures like booms. In fact, Neoscout has

similar booms, although made out of a different material, that they're going to be flying. And so, you know, anytime you get experience with these sort of mechanisms in flight, it's, you know, very useful to characterize the performance. So that's a key takeaway as well. But I think from my perspective, one of the things that the LightSail did, which sets it apart from other missions, is the fact that it was member funded, funded by donors, not funded by a national space agency. And it's such an ambitious mission. That really sets it apart from previous missions. We're just crossing the coast of South America now. Dave, I'm glad you mentioned drag sails because that takes me into the future. What is the contribution of LightSail 2 for the future? Is this a technology that beyond Neoscout

seems to have promise? Perhaps even, as I know you've talked about at times, Bruce, getting us to the stars someday? Yeah, I mean, I think we've helped demonstrate that you can do solar sailing. And the far-reaching one is getting us to the stars because you can conceptually accelerate this with high-powered lasers. But there are a lot of near-term ones like NEOScout using it to go to an asteroid. You can also, because you're not dependent on fuel, you can visit multiple asteroids. you can visit multiple asteroids. We can have missions that are in what would otherwise be unstable orbits, for example, solar monitoring missions that are closer to the sun than the stable L1 point of gravity balance. And so you get more warning for solar storms coming. I think that we're really at the infancy of this technology and we've played a role in it, but it'll be great to see what happens going forward. You mentioned drag sail technology. So drag sails are used to deorbit spacecraft or space objects at the end of their useful lifetime. Think about the satellite mega constellations that SpaceX and others are planning for global

internet service. At the end of mission, they're going to have to deorbit in order to keep that orbital region usable. Otherwise, if you have defunct satellites flying around, they pose a major hazard for collision. Drag sails are a technology that can be used to basically deploy at the end of mission and get those space objects out of orbit much more quickly than they would otherwise be able to de-orbit. They can be used for launch vehicle upper stage de-orbit as well as spacecraft. So at Purdue, we've got a couple of drag sail technologies that we're planning on flying, demonstration missions. And conceptually, they're very similar to light sail. They use the same sort of sail deployment technique, can use similar sail material.

The difference is generally they're passive. Once you deploy the sail, you don't control them, unlike what we're doing on light sail 2, where we are actively controlling the attitude. What about just the basic science? I mean, the amount of acceleration that we've been able to get from those photons flying out of the sun. Has LightSail 2 also helped to refine any of that science, Bruce? It's once again verified that it works as physics tells us it would. But because of the uncertainties we've got with things like pointing, at least I would say, no, we haven't made any revisions to the basic understanding of the amount of momentum delivered.

It's certainly consistent with what we'd expect. So Newton and Einstein are safe. Well, I don't know about that. Guys, this is just the beginning of a celebration. Guys, this is just the beginning of a celebration. I look forward to joining the two of you and others, including our CEO, Bill Nye, the science guy, and even more folks, including Jennifer Vaughn, on the 25th of June when we're going to have a little online video celebration on the actual anniversary of that launch of LightSail 2 on the SpaceX Falcon Heavy. So I look forward to joining you there. It's a celebration. I think we've already opened it up, I think, to our members and supporters of the LightSail project. Hopefully we'll have lots of space

left over for other members of the public who are excited about this project, where they can join in too. All the details should be at planetary.org by the time anybody can hear this show. Thank you for this. Just one more thing, Dave, congratulations. You've got a new job. Tell us about what it means to be headed back to JPL. Well, thank you, Matt. Yeah, I'm extremely excited about this. I've just recently accepted a position as the mission system manager for the Mars sample return campaign. The sample return campaign is actually just about to get going with the launch of the Mars 2020 rover next month. It's going to go out to Mars and land and cache samples, store samples and sample tubes for future return to Earth. And then in 2026, there'll be a lander and an orbiter,

a European orbiter that go out and retrieve those samples, bring them back into Mars orbit, and then that European orbiter is going to return it to Earth for a landing in Utah in 2031. So it's probably, in my opinion, it's the most ambitious planetary science undertaking that NASA or anyone has ever attempted. And I'm really excited to be a part of it. So as the mission system manager, I'm going to be working on mission design and navigation, mission operations, those sorts of things. Similar in many ways to what I've been doing on LightSail, but on a much larger scale with many more people involved. And so can't wait to get into it. And I've just recently started that position. I have often called this on planetary

radio, the holy grail of robotic space exploration. There are, I don't know how many thousands of planetary scientists and others and just members of the public like me, who are going to be hoping and praying that you're able to successfully pull this off. But I know it's a big challenge. Exciting, though. Yeah, thank you. And from a planetary science standpoint, this has been the number one priority for the last couple of decades. And so, you know, from a science standpoint, the community is really looking forward to actually achieving this mission. Bruce, before we go, anything else that you would want to add? Although you will be back with us in seconds for this week's What's Up? I think it's appropriate to return back. As Dave mentioned, this is completely funded by individuals. So thank you.

Thank you to the 50,000 people from pretty much all over the world who contributed to make this mission a success. We appreciate it. All right, guys. Thanks again very much. We'll continue to follow the mission and I will see both of you on the 25th for that celebration on the one-year anniversary of Lightsail 2's launch. Thanks, Matt. That was Dave Spencer, Associate Professor of Aeronautics and Astronautics in the Purdue University College of Engineering. But moving from that position to the one you just heard about, mission system manager for the Mars sample return campaign at the Jet Propulsion Lab,

not far from the headquarters of the Planetary Society. And, of course, he has been the project manager for LightSail, working with the program manager for LightSail. That's Bruce Betts, who's also the chief scientist for the Planetary Society, who joins us for What's Up. Indeed, it is time for What's Up with Bruce Betts, who I bet you know is the chief scientist for the Planetary Society, in addition to being the program manager for LightSail. Welcome back. I missed you so much, Matt. It's been so long. I know, I know. And I bet the stars have shifted in the sky since we last spoke. Well, certainly LightSail moved. It's over

Africa now. Is it really? Wow. Boy, time flies and so does LightSail. So what is up? What's up there above light sail? All sorts of things. But we're going to talk about the ones that are easy to see in the night sky. So that would be in the late evening. So now 10, 11 p.m. or after. Coming up in the east, we've got two planets, very bright Jupiter, and then to its left, dimmer but still bright, Saturn. And if you follow a line from Saturn to Jupiter, it'll lead you to the teapot,

asterism of Sagittarius. So it looks kind of like a teapot and forms part of the constellation Sagittarius. A couple hours later, if you're up later, we got Mars coming up. Mars is brightening. It is getting quite bright and it will get brighter and brighter until October when it's at opposition. Pre-dawn, you can still see Mars nicely over then in the south or the southwest. And then low in the east, we got Venus coming up, coming up, coming up, getting higher and higher, super bright. Depending on when you're getting this, you might be able to see the moon next to Venus on the 19th. Crescent moon, Venus still very low. You're going to need a really good view to the horizon in the east there. Time to let you know June 21st, annular eclipse whose path crosses Central Africa,

Saudi Arabia, Northern India, and Southern China. A partial eclipse will be visible throughout most of Eastern Africa, the Middle East, and Southern Asia. So for those of you out there in those parts of the world, enjoy. I'm a parsecs-wide teapot, short and sound. Oh, God, I just had this terrible image of you doing the dance like in the sky. Oh, that's going to haunt me. Had to do that once in high school. I will save that story for another time.

Oh, I look forward to it. And I hope some of you who will be under that annular eclipse will write to tell us about it. That'd be great. On to this week in space history. It was 1983 that Sally Ride became the first American woman in space. In 2009, Lunar Reconnaissance Orbiter as well as the impactor LCROSS both launched and LCROSS did its thing, slamming into the moon. And LRO still doing good stuff at the moon.

On we go to... I don't know, made me think of David Byrne for some reason. Same as it ever was. All right. So astronauts, this is an interesting little tidbit. Astronauts often experience a lessened sense of taste in space. So they often request spicy food or spicy condiments, for example, on the space station for long stays in space.

I remember reading that the sriracha sauce is pretty popular, if I remember correctly. That's actually what one of the S's stands for, I-S-S. I think sriracha sauce, I think sriracha sauce, I think sriracha, very hard to say. I think sriracha sauce actually probably originates from somewhere in space. That's mine. If they're aliens, they're definitely involved in the creation of that. All right. Take us to your sauce.

Yeah. We move on to, we try to move on to the trivia contest. We move on to, we try to move on to the trivia contest. Before Crew Dragon Demo 2, what was the last two-person orbital spaceflight launched from the United States? That was your question. How'd we do, Matt? You really have frustrated a lot of people who entered the contest with this one. It's my colon life. All right. So here's what we heard along this line of frustration from Mel Powell in California. Bruce was trying to trick us into guessing Gemini 12 with Jim Lovell and Buzz Aldrin. Wasn't he? Wasn't he? Don't even bother making him admit it. It's all so clear to us now. Can't take that guy anywhere. Can you, Matt? Now, can't take that guy anywhere.

Can you, Matt? I didn't do it. I wasn't trying to fool you. Here's our poem from Dave Fairchild, the poet laureate. Prior to SpaceX in May 2020, you have to go back to the 80s or more. That's when Columbia lifted for NASA a flight that was called STS-4. It left the launching pad in June of 82, mattingly Harsfield safely on board. Prior to that, it was Gemini 12 that had two crew aboard her, as records record.

I'm not sure that last line may not scan perfectly, but is that right? STS-4 Columbia is correct in 82. I also will note that STS-1, 2, and 3 also had two-person cruises. They were test runs for the space shuttle before they loaded them up with more people. Here's our winner, Perry Metzger. Perry Metzger, longtime listener in New York, New York, the town so great they named it twice. Who is it that says that? Anyway, Perry, he's a previous winner, but it has been over three years since he hit the jackpot. Perry, congratulations. You are the winner of that celestial buddy, Little Earth, our earthy plush toy, just like the one that is now up on the International Space Station.

And it's going to be brought home by Bob Behnken and Doug Hurley when they climb back in the Crew Dragon. They're going to bring Little Earth along with them. And I imagine it's going to end up in the Smithsonian. Well, yours won't go in the Smithsonian. It'll go to your house, Terry. So, again, congratulations. All right. We move on.

Now, this question, you've got to stick with me. It's definitely different, a little weird, but it takes you down an interesting rabbit hole if you follow through with finding the answer. So here we go. An ancient Greek analog computer used to predict planetary motions was retrieved from the sea in 1901. It dates from somewhere between 87 BCE and 205 BCE. Here's your question. What is this relic called? Go to planetary.org slash radio contest.

If I have a favorite computer in the entire history of Earth, this is it. I love this story so much. I just, I want to go to, I forget what museum it is, where they've actually rebuilt it, you know, based on all the x-rays they've done and analysis. And it's just, it's this anachronistic piece of technology that has no business existing 200 years BCE. But there it is. Anyway. And they found evidence of Sriracha on it. Yeah. And our friend Kim Stanley Robinson, the great writer, he wrote it into his story. I think it's in Galileo's Dream, that book of Kim Stanley Robinson. Enough of that. You've got until the

24th. That'll be June 24th at 8 a.m. Pacific time to get us this answer and win yourself an ancient Greek computing device. No, I'm sorry. You'll have to settle for a rubber asteroid. We're done. An ancient Greek rubber asteroid.

All right, everybody. Go out there, look up on the night sky and think if you were to put one thing in your house in the Smithsonian, what would it be? Thank you and good night. I would want to put two things in the Smithsonian, your microphone and my microphone, because they're such great historic value. And also, there are people who'd be very happy to hear that we no longer have microphones. We'd get more. We'd get more. Okay, he's Bruce. He's the chief scientist of the Planetary Society. You knew that.

And he joins us every week for What's Up, and you knew that too. Planetary Radio is produced by the Planetary Society in Pasadena, California and is made possible by its light-sailing members. Big thanks to those of you who have given us a rating or review in Apple Podcasts. I hope more of you will join them. Mark Hilveritas, our associate producer. Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. Stay safe and well.

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