StarTalk Radio - Cosmic Queries: LightSail with Bill Nye

Episode Date: April 19, 2015

In May 2015, the Planetary Society will launch its first LightSail spacecraft for a “shakedown cruise” in Earth orbit. So who better to answer fan questions about the program than their CEO, Bill Nye, and comic co-host Chuck Nice? Subscribe to SiriusXM Podcasts+ on Apple Podcasts to listen to new episodes ad-free and a whole week early.

Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. Welcome to StarTalk. Bill Nye here, your guest host this week. I'm here with my colleague, charming associate Chuck Nice. Chuck, good to see you. Hey, Bill. Good to be here. And this week is Cosmic Queries, in which we answer your questions.

That's right. We call the questions from the Internet in all of our various incarnations. Twitter, Facebook. The social media that the kids use. All the social media. questions from the internet and all of our various incarnations twitter facebook uh the social media all the social media all the electric computer machines yeah exactly so uh this week our focus thank goodness chuck is me we're talking about the planetary society the world's largest non-governmental space interest organization based advancing space science The World's Largest Non-Governmental Space Interest Organization, Advancing Space Science and Exploration. And in the interest of full disclosure, you are the fearless leader. That's right. Of the Planetary Society.

I'm the CEO. And just so you all know, Neil deGrasse Tyson was involved with this. So I had Carl Sagan for astronomy back in the disco era. Took one classroom, but it redirected my life, changed my life. Wow. And so I joined the Planetary Society, which he and two other guys started. Lou Friedman, who's an engineer at JPL, and Bruce Murray, who was the head of the Jet Propulsion Lab during the Voyager missions, the Viking missions, the hey, hey days of JPL. Right.

And so I got on the mailing list. And then when Carl Sagan had this misfortune of getting this extraordinary, very difficult to deal with form of cancer, he died. And I was asked to speak at his memorial service because his kid, Sam especially, liked the Science Guy show. Yeah. And then I got on the board of directors. And then Neil was asked to be on the board of directors.

Okay. Because he was his rising star in astrophysics. Now he is, of course. Yes. Galactic glow. Galactic, right. Galactic overlord. Yes. So anyway, then we, the planetary side, because of the fame and accomplishments of Carl Sagan, we are recognized enough to give Stephen Hawking an award, the Cosmos Award.

Oh. And so we went to Cambridge. Oh dear. In the UK. Of course. It was quite lovely. And that's when you're with Neil, and I don't know how much time you spent. There's a lot of wine. Yes.

There's a lot of flowing wine. Neil and Bacchus are good friends. Yes, well acquainted. And now I'm the CEO. I don't really, I'm not sure how that happened. But I've been the CEO for over four years. And for the first time since the 1990s we're growing and the exciting thing is uh this goes back to carl sagan we're going to launch our own spacecraft first week of may wow a solar sail a solar sail. Which is an extraordinary thing, if I can use that noun. It gets pushed

through space by sunlight. Yes! Now that is... That seems crazy. It does seem crazy. It is really intriguing though. And you say Bill Nye, CEO of the Planetary Society. Yes. I thought light had no mass.

How can it possibly have momentum When I walk down the street Even if I'm John Denver And there's sunshine On my shoulders I don't I don't get high I don't get a push

Even if I'm walking on sunshine Yes Or Or you might as well be walking On the sun If I'm walking on sunshine. Yes. I don't. Or you might as well be walking on the sun. Okay, that's not going anywhere. So the thing is, whether in classical physics. Once you get to sting, the references stop, right? Yeah, they should, yeah. Whether in classical physics or through relativity, light has momentum.

Photons have momentum momentum and this is a fun little thing you can do in your head if you're out there and you're a physics person of any kind or just if you've ever watched u.s football okay momentum yes is the multiplicative it's when you multiply mass times velocity mass times speed. Right. And direction. So if you have a football player that is more massive and he's going faster, he has more momentum. Right. And so along this line, let's take E equals MC squared, which everybody loves. Now let's divide both sides by C in your mind's head.

All right. Then E over C, some packet of energy divided by the speed of light. Right, which is the constant. Equals some mass times the speed of light. So some mass times some speed is momentum. And that's it. So it's just something to think about. It's just, anyway.

So you get those two players coming together, concussion, basically. That's right, yeah. There we go. But unlike the NFL, we're not in denial. So this thing, we're going to have this very large sail deployed from this almost, you would almost describe it as tiny spacecraft. So it's like a sailboat, but in space. Yes.

It's a sailboat in space. And furthermore, you steer it by tacking the same way you steer a sail. A regular sail. Right. Oh, that's amazing. It really is. And so this goes, Carl, we have footage now on the website of Carl Sagan in 1976 on the Tonight Show with Johnny Carson describing solar sail.

And he had a model of it and so on. And this thing is visually very, very similar. I mean, as Mr. Scott would say. Well, you know, that's funny you say Mr. Scott, because the first time I learned or knew about a solar sail was from an episode of Star Trek. And I thought it was like so cool that they came up with this crazy idea. And then I read about it that they did not come up with that crazy idea. Well, it's consistent with the laws of physics.

Exactly. That they co-opted that crazy idea. So let's get to the questions. Okay. So what we have before us is a number of questions from our listeners and sometimes viewers if they're on YouTube. And they've submitted these questions specifically for you to answer, Bill, with respect to the light sail. And you do not have the questions, only I do. I have not seen the questions. You have not seen them. So just for the sake of disclosure, Bill does not know what I'm about to ask, but these are your questions.

Let's get to it. This one is from Joe Foster, and he comes to us from at Foss Do Nut or Donut. They're good donuts. That's a good donut, the Foss Donut. Let's just go with that. Exactly. Here's what Joe wants to know. What are you hoping to learn from this launch i mean what's

what's the purpose in terms of information so the big the biggest picture is if you had solar sailing spacecraft that were that were operated very well you could lower the cost of any mission to any destination in the solar system by, I don't pick a number, factors of tens of thousands because there's no fuel. So as we say, you can trade time for money. Gotcha. If you have time, you're a space agency. For example, Rosetta, that spacecraft took 12 years to get out to the comet.

right to get out to the comet if you have time the solar sail is fantastic system because it gets a when you think of a regular rocket the engine might run 20 minutes that's a huge rocket right engine might run nine minutes it's just full blast wow that was a smaller one I I'm pretty sure. Yeah, yeah. The first one was pretty big. Yes. But solar sail is just in space. And so day and night. Wait, in space there's no night. Ah.

So it gets a push, a tiny push continually, continuously rather, for as long as it's in space. And so we're improving this technology. And the big thing is NASA, well, the world, now has a standard called a CubeSat. A CubeSat? Cubicle satellite. Cubicle, oh, it's CubeSat. CubeSat.

CubeSat. 10 centimeters by 10 centimeters by hours is 30 centimeters, which is smaller than a loaf of bread. Okay. It's really weird. And when things get that small, the electronics have to be very small. The software has to be very efficient. Everything has to be really good.

And so we built this spacecraft, estimates vary, for about a fifth of what it would have cost a regular space agency to build. Wow. Because we just had passionate guys and we were supported by 46,000 members around the world. And so we hope to prove that solar sailing is practical on this scale,

which would enable universities, private corporations, everybody to participate in inexpensive cislunar spacecraft that's between the Earth and the Moon and out to destinations in the solar system. Unbelievable. I mean, very believable and extremely cool. Okay, so now let's touch on what you just said about getting up to speed and continual speed, because our next question is from Ben Shanker.

And Bill says, I mean, Ben mean ben says ben says you are bill it's a blur it really is it's just it's all a mush here uh up here that's my mind uh that's what your wife was saying at first she first she thought she were kidding and now she's now she's 17 years into it. That's right. You are absolutely correct, Bill. 17 years in. Well, she reminds me. She realizes that she's been tricked. She shakes her head. Yes, she does.

Here we go. Ben wants to know this. How long would it take for a light sail ship to get to a useful speed? And I'll put an addendum onto that. What exactly is a useful speed? Yeah. Okay. So the first thing is you got to get a chemical rocket.

That's our state of the art to get into above the atmosphere. And so we are a secondary payload on an Atlas V, a venerable rocket that is descendant of the rocket that launched John Glenn, for example. Oh, very nice. It's an engineering descendant. Nice lineage. Yeah, very nice. It's an engineering descendant. Nice lineage. Yeah, that's right. So once you're in space, see, the Planetary

Society tried to launch some solar sails 2005 on a Russian rocket. Okay. That was left over from the Cold War, and it didn't work very well, and our members would not, they would not let us try that again. No more leftovers. That's right.

So it's on a real Atlas V, brand new, smells new. Anyway, and you- It's got that new rocket smell. Gets above the atmosphere. And then if you, for example, wanted to go to the moon, it would take you about a month to get to the moon. Okay. And then if you want to go beyond that, you start computing years.

But the thing is you can go to destinations no one's ever thought of practically. Like catching up with a comet would take about the same amount of time as the, for example, the Rosetta mission because it's always getting a push. It's always getting a push. Always getting a push once you're out, out, out there. Right. But what we're going to do with light sail, as we call it, light sail, is go around the Earth,

show that the thing deploys, show that the antenna works. It's quite an important thing. You might not have thought about it, but when you're in low Earth orbit, if you are not a great big space agency with U.S. naval ships all over the world and the means to have stations on exotic coral atolls in

the middle of the ocean. Most of the time, you're not over the land. Right. Most of the time, there's nobody listening to your little beep, beep, beep, beep. And so these sort of things have to be carefully worked out. And then we're going to try steering. Can we twist the sail? Imagine this in your mind's head.

You have to go edge on toward the sun. Right. And then face away, going away from the sun. And that's how you build orbital energy. So we're going to run tests like that. Ah, that's fascinating. Very, very cool. It's built just by people, just by people who thought it was cool.

There you go, Ben. There's your answer. Let's move on to Sharon Smith Snodgrass. That's her name. Snodgrass. My dad was a prisoner of war with a guy named Snodgrass. Really? That's what he told me.

I don't know if it's a true fact or a false fact. Chuck, I wasn't there. He told me that. Grownups tell you stuff. This is true. I don't know. So go ahead. Okay.

How far away from the sun can the light sail travel before there's no further means of propulsion? And at that point, can it change direction, or is it on a one-way trip in the last direction that it was propelled? Well, nominally, it's getting a push indefinitely. I mean, that is to say, as a first cut, you're always getting a push. Consider, for example, that Pluto, which will be visited by a spacecraft in July, the word visited, flying by, except in space there's no sound, it just goes, yeah. Right. So it'll...

Let's hear that again, shall we? there you go the plutonian atmosphere grows when there's just the tiniest bit of sunlight on it everybody believes it's volatizing some melt um making some ice turn to a gas okay and then as it moves away from the sun that shrinks so even way the heck out there at pluto there's enough sunlight to influence a whole planet. So there will be enough sunlight to influence a spacecraft. And then if you want to go crazy, which is fun to do, we put a laser in your mind's eye on the moon. We launch a solar sail, and we have made an agreement with international governments

and the Federation is running things at that point. And we beam a laser on a spacecraft for, a solar sail spacecraft for 10,000 years. And it goes to Proxima Centauri, goes to the next star system. Right. Pushed by humankind's 10,000 year, nothing breaks. We all agree this is worth doing laser system.

Right. But if you think about it, it is the only known technology that could take us to another star system. It's quite cool because there's always a push. Always a push. Always a push. And we can, for Sharon's question, we could artificially, from what you're saying, we could artificially create that push if necessary. Yeah, so you'd have solar panels all over the far side of the moon running a laser that somehow redirects itself and is always aiming at the Chuck Nice Memorial solar sail spacecraft. I mean, these are some complex issues.

I'm not saying it couldn't be done. It couldn't be done. It's complex, but it's cool. But it's cool to think about. It really is cool to think about. Very cool. And it's related to light sail and the Planetary Society. Absolutely.

Okay. Well, we've got a couple minutes here. So let's go to John Thompson. And he's coming to us through Twitter. At Aviation is his handle. He says, with respect to the light sail, how are they built? And is there a top speed? Well, everybody's dream is to get to 100 kilometers a second.

But this spacecraft is not capable of that. So here's why. To get to those speeds, you'd have to get closer and closer to the sun. Right. And we don't have the materials that can take that right now. But this spacecraft, the sail itself- Ah, the Icarus syndrome. That's right.

It really is. But this spacecraft is made of mylar, aluminized mylar. It's inexpensive material. In fact, it's so inexpensive. How inexpensive is it? It's so cheap that they sent us a sample, which was big enough to make the first set of sails. It was so cheap. But anyway, set of sales. Like it was so, it's so cheap.

But anyway, the booms as they're called are often called tape measure booms because they resemble a steel tape measure that you use to get size your carpet or if you're a contractor sawing wood or what have you. Yeah. Okay. And they're extraordinarily stiff. They're made of this cobalt steel. Ours were made at the Air Force Research Lab in Kirtland Air Force Base in Albuquerque, New Mexico.

And we have a proprietary mechanism to wind these things, which are four and a half meters long. So they retract. Yeah. Well, they extend. They extend. But we have proposed retract and extending. So if you think about it, you ever had, when you have the tape measure extended and you let go of the lock, it goes back in. Well, what we do is push them into the thing.

So they're loaded. Like a spring loaded. It's spring loaded. Yeah. And they are extraordinary springs. They're really, they're just cool. loaded like a spring loaded it's spring loaded yeah and they are extraordinary springs they are really um they're just cool and they consist of two ribbons stitched welded together and stitch welding is a term they made up and it's just a laser it's very cool so it's a high-tech thing

that guys that have been working on for. And we have combined all these technologies, and we're hoping for a successful flight the first week of May. Fantastic. You're listening to StarTalk Radio. I'm your host sitting in this week, Bill Nye, with my co-host Chuck Nice. We'll be right back. Welcome back to StarTalk Radio. I'm Bill Nye, sitting in for Neil deGrasse Tyson. And this week, it's a big one for me.

I'm here with Chuck Nice. Yes. We're taking your questions, your cosmic queries, and it's a big week for me because we're talking about the Planetary Society, of which I'm the CEO, and uh our specifically our light sail spacecraft yes our solar sail spacecraft which we're going to launch we the nominal date is the 6th of may but these dates slip around it's by the way chuck i didn't tell you it's it's an air force payload an air force payload this is to say the primary payload is something that the Air Force is doing and they won't really tell us what it is. There's a lot of speculation that it's just a spy satellite or it's the X-37B lifting body, but no one's really sure. Anyway, so it's really cool, you guys, when you think about rocket science.

This part of it's not that hard. The primary payload or the thing where they've paid a lot right to load on is some air force thing and it's on top then below that is the secondary payload which is where we are and it's a it's seven of these very small satellites these cube sets right 10 centimeters by 10 centimeters by 30 centimeters, smaller than a loaf of bread. And so we're on there. And after the primary payload is off, then these seven little ones go spring, spring,

spring, spring off into space with these cool stainless steel sort of jack in the boxes. So it's very cool. But let's get back to the questions. Very exciting week for me. Very cool. All right. Let's go to Dan Owens. Dan, how have you been?

Dan's doing very well from what I can tell. And this is what he says. What is the top speed of a solar sail could feasibly reach before losing the sun's influence? Now, here's the real question. After that, could it be propelled by an onboard photon source, or would that be the equivalent of trying to blow your own sail? Yeah, it's trying to blow your own sail, exactly. That's trying to blow your own sail.

However. I can't say that I haven't done that. So think about, Dan, Owen. Yes. Think about it this way. Suppose you had solar panels and you soaked up sunlight and you powered a laser on board your spacecraft. Your solar panels are on a spacecraft, by the way, not like on your wristwatch or something. Which I have one, but that's not really, it's not the same.

It's not the same kind of solar space. It's not outer space, for example. Exactly. So then you'd shoot the laser off some way hoping, I mean, and expecting that you'd get a push. Like if you're holding the famous thing that will stand on roller skates and you have a bowling ball. Right. And you throw the bowling ball to somebody, you go off the other direction. You'll go left or right. Because of the conservation or momentum. bowling ball, and you throw the bowling ball to somebody, you go off the other direction. Right.

Because of the conservation or momentum. The momentum of the bowling ball going that way will be equivalent to your momentum going this way. Okay. All right. Well, imagine you did this. You soaked up sunlight, drove a laser, you shoot the laser. Well.

Back up, back up. It's simpler than that. If you have just a mirror in space, the photon bounces off the mirror and gives you a push. There you go. Whoa. And so that's what the solar sail is. And by the way-

You don't even need the old fan in the sailboat trick where you've got the electric fan in the back of the sailboat. All you need is a mirror. That's right. In space. In space. In space. That's all you need is a mirror. That's right. In space. In space. In space. That's all you need is a mirror.

Because you have a fan. Right. Which is the sun. Right. The sun is your fan. There you go. For your push-your-own-sailboat thought experiment. So it's, anyway, by the way, if you have just a black surface, there's an expression in

physics called a black body, a perfectly absorbent material. Yes. We have that saying in my family. was gonna let you do it anyway you get a push uh but you get twice as much push theoretically perfect if it was a perfect mirror you get twice as much twice as much push yeah and so this thing is made of super shiny mylar right and uh making out of mylar, it makes it a little cheaper than if you made it out of other better, fancier plastic, like aluminized, Kapton, polyimide, but the mylar, the thing is going to burn up in the atmosphere this first flight because the man is only taking our spacecraft. The man is only taking our spacecraft to The man is only taking our spacecraft

to 250, 400 kilometers. Okay. You know, 150 miles and stuff. And they're still up there, although you and I would suffocate in a few moments. Right. There's still a few air molecules, and so it will drag it down.

A little tiny bit of atmosphere that will... But we are going to launch a second light sail in May of 2016. Okay. That one on the mythic modern super Falcon 9 from SpaceX. Fancy. And so that one will be at a much higher altitude and we will get solar propulsion much more easily. Now, this first test is the first test.

Ha! That's right. And we're very hopeful that things will... See, NASA has tried deploying these sails on another spacecraft called NanoSail-D. Okay. And by the way, NanoSail, NanoSatellite, NanoSat, that's another word they like. Instead of CubeSat. But CubeSat is a standard that people have settled on. And by people, I mean mostly universities. And the Air Force is quite interested in CubeSats. Anyway, they tried this and it didn't deploy right.

The tape measure booms didn't boom. Okay. And so we believe we have solved that problem. Whoa. And of course, the guy who solved it is 12 years old. He's 26. Right. Of course.

And he just wrote an app, and he's now a billionaire. Right, yeah. Right? That's how it works. No, no. These guys, they're young guys, and they're men and women, and they're passionate, and they've just done outstanding work. It's really exciting.

Well, Dan Owens, thank you for that great question, and your answer is, the sun is your fan. Always remember that. All right right let's move on and uh let's go to uh the sun is your fan the sun is your fan i don't want to forget this that's right that's it take it chuck sorry all right joey uh pirosco from uh and i love it uh that joey writes from green bay wisconsin here hey the LightSail technology is phenomenal. However, how will you prevent microscopic space debris from penetrating or completely destroying its fragile mirrors,

or as you called it, mylar, that it needs for propulsion? This is a really great question, Joey. I am interested right now. And, Bill, I love the look on your face. Let's have it. So two things, Joey. First of all, three things. First thing, thank you for your question.

That's an outstanding question. And many people have wondered that. But we'll start with, there's not that many micrometeorites. Really? I mean, we all worry about it. Yeah, because that's what you hear about when you take a look.

And space debris. It's serious freaking mess. It tore a hole in my suit. See, that's never happened. Get out. For example. Is that all Hollywood? No, it's all sort of common sense. But there's just not that much stuff. There's just not a lot of stuff out there.

With that said, the sale manufacturers have embedded this ripstop feature. And when you look at the, and by that i mean they're strands or fibers built into the mile into the fabric into the shiny plastic super thin stuff okay and if you look at an edge on a grazing angle you can see the lines and they're about two centimeters apart okay a little less than an inch apart, going this way and going that way.

And so to keep it from tearing mostly and just handling it with humans with those cool little white gloves on, when they fold it like origami in this clean room. Anyway, that's a great question, but we think we've addressed that. Micrometeorite going at 10 kilometers a second or 7 miles a second. We'll just go right through it.

Right. It won't. It's not like you're up there with a utility knife going, rah, rah, rah. Yeah, like the old pirate with the knife in the sail. That's right. There'd be just poke a hole. But there is ripstop built into it. So this ripstop weave, so to speak, actually

keeps it from like tearing. Like a run in a stocking. Exactly. Keeps it from continuing on. And this is an old trick and it's called a clay polymer. Mylar is a brand name, like tissue or Frisbee. A clay polymer and polymer's plastic and clay

means it has an alkaline. It has an oxygen hydrogen hanging off the end. And it does something to make this plastic have these wonderful properties. That's fantastic. Hey, Joey Perosco, that was a really great question, my friend. Love you, Joey. We do love you, Joey. Nice job.

Okay, let's see here. All right, this is a nuts. These people are thinking, man. This is Eric. Well, Chuck, you're choosing good ones. No, you know what? I'm kind of going, well, I am choosing good ones. This is Eric Shard.

Eric Shard would like to know, would light sails be a viable approach to deorbiting comets to aid in terraforming Mars. Excellent. Excellent. Piece of cake. Excellent, Clay. Nothing to it. Nothing to it.

Yeah. Come on. It would be ideal for changing the orbit of comets. Okay. Now, along this line, hold it. This isn't Chuck. Who's this? This is Eric Sharpe.

Eric. Eric. Along this line, Eric, keep in mind that there might be a shorter term, more important use of this closely related to your question. Instead of changing the orbit of comets, we might want to change the orbit of an asteroid.

That's what I was thinking. So it doesn't hit the Earth. That's what I'm saying. Like, for instance, Apophis is actually going to go through that keyhole, and we are doomed. God, you're down, Chuck. Exactly. Right? Apophis, name for the god of anxiety, is going to miss us.

The god of worry is going to miss us. But when it was discovered, it looked like it would not miss us. Exactly. And as we always like to say, it may be wrong. We may be wrong. There are probabilities here involved. But imagine this, Eric. You would have a solar sail that would catch up with an asteroid, which is not trivial,

catch up with it, and then, poof, you know, smother it. Right, right. Just get on top of it. And then the shininess would change the momentum, would take sunlight momentum and change the path of the asteroid just ever so slightly. And so then now to get back to the biggest picture of your question of taking comets, which might be full of ice, and smashing them into Mars so that we can terraform Mars. Terraform being a word that to you and me makes sense, but if you talk to Og, the cave guy,

he would think you'd kind of lost your mind. Okay, it's a whole planet. We can barely manage the planet that we live on. We have enough trouble with managing water here. And we don't do it very well, by the way. Okay, I went with enough trouble. You could go with suck. Yeah, we suck.

How about that? Yeah, you could do that. Let's not sugarcoat it. Right, but with that said, you guys, about terraforming Mars, there's a reason Mars doesn't have much of an atmosphere, and that's the solar wind scrapes the atmosphere off. The solar wind are these particles that stream off of stars, and in our case, the sun,

and they've scraped the Martian atmosphere away because Mars isn't quite big enough to have a magnetic field, to stay molten, to create a magnetic field, which makes the charged particles come streaming into the poles instead of sideways tangentially across the surface. So you guys terraforming mars that's it no but i mean it's not gonna happen it's just not that easy okay there's nothing to breathe there's nothing to eat and it's freaking cold you guys we live in this

world on on this world where humankind uh has migrated all over the place. Everybody's from East Africa. Chuck, your people much more recently than my people. Went north. Yeah, my people, East Africa is Detroit. It's like that. It's like that. But actually, well, we can get a whole digression on skin color, but it has to do with ultraviolet light.

You go north into Mesopotamia, then you migrate across Eurasia. Then there's this ice age. All the snow is frozen up in the mountains. So we can just walk to Sarah Palin's place in Alaska, then south, killing everybody. By everybody, I mean all the big mammals and eating meat. And then we just migrate all the way down into South America. It's cool. But we're running out of places to which to migrate. That is so true.

You're not going to be able just to leave the earth and go to Mars. It's a very complicated and long distance. However, if you want to send spacecraft to Mars to study its environment, and I recommend that we all do that, I cannot help but recommend solar sailing as a means of inexpensive propulsion for, let us say, citizen research. For people who are interested in interplanetary missions, you could embrace a solar sail spacecraft, not unlike the light sail, which the Planetary Society is going to launch the first week of May. Did you see that circle of life there? Brought it back around, Eric. Did you see that, Eric?

That was fantastic. Oh, great. Well, there you have it. Forget about Mars. Not going to happen. The solar wind comes strolling in across the atmosphere. All right.

Take it, Chuck. The musical stylings of Chuck. Thank you very much. Please avail yourself of some of the mints here in the Stardust Lounge. Tip your servers. Try the chicken. Let's go with a real quick question because we have just a little bit of time left here. With Logan, I guess it's keeps.

Logan says, all the talk is about propulsion of solar sail. My question is, how does it stop? Make flight path corrections, et cetera. Standard rockets? Wouldn't that defeat the purpose, though? Yeah, so you seldom stop in space. Oh. Yes, when you land on the surface of Mars, you stop.

But mostly, you go into orbit around things. Got you. And by that, I mean you start out in orbit around something, Chuck. The big thing you start out in orbit around is? Earth. The Earth for our solar system. For our solar system. Yeah, but everybody actually.

It's the sun or the star. Even when we're on the Earth, we're in orbit around the sun. Even when we're orbiting the Earth, rather, we're in orbit around the sun as well. Correct. So you seldom stop. You go out there on just the right trajectory to get captured by, let us say, Mars's gravity or the moon's gravity.

Right. That's the most, it's a much more common thing in a spacecraft mission. And light sail is ideally suited to that. It's ideal for that. So it's going to be an exciting launch. It's supported by Planetary Society members around the world.

And we don't stop, basically. We don't stop. But the light sail will, sorry, burn up your membership dollars at work. But it's going to be a fantastic mission, and we're going to learn a lot about it. And not only that, I'm Bill Nye, your guest host this week on StarTalk with my co-conspirator Chuck Nice, and we'll be right back. Welcome back to StarTalk Radio. I'm sitting in as your host, Bill Nye. I'm here with my co-conspirator Chuck Nice. Yes. And it's cosmic query time where we take your questions. But this week, I am very excited as the CEO of the Planetary Society to take questions that all have to do with our solar sail spacecraft, our light sail spacecraft. Light sail.

Which launches the first week of May on an Atlas V. And the Planetary Society, everybody, is the world's largest non-governmental space interest group. We advance space science and exploration so that citizens – enabling citizens of the world to know the cosmos and our place within it. And so we advocate in U.S. Congress for good space policy and a limited extent in Europe and a very limited extent in Israel. space policy and a limited extent in Europe and a very limited extent in Israel. The meeting this year is in Israel. A very limited extent in India and in Japan. But we have members around the world who have a great interest in advancing space science and exploration. And that's why we built this very cool solar sail spacecraft. Chuck. Yes, sir. You've got questions. I've got great questions so far.

I have to say that our audience has been thinking quite in depth about this light sail. And we've had some really, really interesting questions. You don't have to sound so surprised. They're your fans, okay? They're smart people. This is true. They are. So let's, well, I don't know if this person's actually

screwing with me. This radio, Chuck, just don't give them too much information. All right. So it's Derrick Iswig Chaya. Okay. That's it. I did my best. Well, it's using Roman characters to

describe a language that they weren't made for. Absolutely. But we're doing our best. Go for it. Okay. How big of a sale is required for this project? And does the size of a sale actually matter? In other words, bigger the sale, faster the boat?

Yeah. Is that the deal? Yes. And it's more, it's not just the bigger the sale exactly. It's the bigger the sale relative to the mass of the whole thing. Gotcha. Right? Right.

So this sail is 32 square meters. It's quite large compared to this thing, which the spacecraft, the bus, as it's called, is smaller than a loaf of bread. And this will be the highest acceleration spacecraft, solar sail spacecraft launched. It'll have the most oomph for its mass. The Japanese Aerospace Exploration Agency, JAXA, launched this very cool Icarus spacecraft a few years ago that was a demonstration that they could do it, and it worked fine.

But it was intended, the whole spacecraft was intended to end up in orbit around venus but it missed and so now it's in a in an orbit about the same distance from the sun but uh not around venus about the same distance as venus is from the sun so we are we are close uh we're close friends with our buddies at jackson who got a lot of uh got a lot of experience by deploying this thing. It worked really well. It worked really well. But because of the 600-kilo spacecraft, 600-kilogram spacecraft, it didn't get as much acceleration, strangely enough, as light sail will get here the first week of May. That's interesting.

Now, here's the follow-up to that question from the same person. It'll be several weeks after that when the sail is deployed, and atmospheric conditions have to be just right, and so on. Gotcha. Those are some disclaimers. So, I'm not sure if Deichrich is trying to express a disbelief in light sails, but says, in addition, how much funding is put into figuring out an efficient fusion reactor? That's a separate issue.

That's what I was going to say. Like, are you saying, like, light sails aren't going to work, so we really need a fusion reactor? Actually, the light sail does work on a fusion reactor. That might be his tie. And where is the fusion reactor. That might be his time. Maybe that's what his time is. And where is the fusion reactor, Chuck?

Take a shot. Take a shot. Where do we have a fusion reactor at a safe distance? I'm going to say that would be the big plasma ball in the sky. The sun. There you go. That's right. The sun is our fusion reactor.

Chuck, he's the real deal. Chuck's the real deal. The sun is our fusion reactor. Chuck, he's the real deal. Chuck's the real deal. So the sun provides the hydrogen, the protons combined to make what we normally call helium atoms. Right. And in that process, release a tremendous amount of energy, photons, which will push the light sail. But investing in a fusion reactor is something we do here in the United States as taxpayers all the time.

And fusion reactors are always, in my experience, 40 years away. They're always 40 years in the future. But that doesn't mean— No matter what time it is that you're thinking about them. That's right. My whole life, 40 years. But that doesn't mean somebody won't figure it out. I'm not being dismissive. Right. But the Planetary Society's not really into building fusion reactors.

We're into taking advantage of the natural fusion reactor, which we call the sun. Very cool. Let's take another question, Chuck. All right. Let's take another question. All right. This is from Denard Springle coming to us from Google+. And Denard says, The first attempt at the light sail by TPS was sadly a tragedy.

TPS, everybody, means the Planetary Society. Okay, thanks. In 2005, Cosmos 1 crashed in the Barents Sea, which I had not really noticed before. It's in the Arctic. It's part of the Arctic. It's an area of the Arctic Ocean. Lead on.

He says, and this is not instilling a lot of confidence there, Denard, will there be a third attempt if the same should befall the second attempt? So if the same fate befalls our... Light sail A. Our light sail A. We have light sail B, which launches in May of 2016. Okay, so there you have it. So yeah, we have two spacecraft.

We got two. See? And if you're a Planetary Society member, thank you, because one of the things that my predecessor did do was get everybody, by sending letters to people, get everybody to build a second spacecraft. Once you have the design, building the second one isn't nearly as difficult as you may imagine.

That's how you mass produce cars, for example. Right, exactly. And it's, making the hardware is one thing, but it's really, it's the software, man. That's what just takes people a long time to get it to really actually work actually you can get it to almost work right away right but almost work is a lot like not working but we gotta work it and so everybody's very excited so that's a great question almost work is a lot like not working so there you have it. That was a good question. Way to go there, Denard. I appreciate you. Pardon me for that.

Will the lights... Oh, sorry. Let me back up here. This is from Andy... That gets me every time. I don't care. And we're showing our age. I mean, you don't really... Rewinding now is not a mechanical thing yeah that's true and click on a click of it just yeah exactly um andy bracken wants to know

uh will the light sail be used in the future for missions to the planets just our outer planet. Is this basically the future? The future. Well, we claim it is. Can you make this the future? Yeah, we claim it is. So as we say, if you have time, you can trade that for money. In other words, light sails will go wherever you want. Well, as long as you don't get too close to the sun with our current materials.

Right. We'll go a long way over a long time. But yes, missions to Mars and Jupiter have been discussed at length. And there's guys who are people who are into this and they run the numbers. They do calculations on this. And yes, it's all quite doable. But the longest journey, Chuck, starts with but a single step. And so that's why uh we're

doing light sail a here in may fantastic so uh so basically all of your unmanned missions this could be oh yes this could be the thing for all of your unmanned yeah yeah if you're but the big thing is the cost is so much lower than a chemical rocket that cubesSats, as they're called, whether or not they're light sails or not, are made by universities, by small companies. And now, which has really helped things, the Air Force is quite interested in CubeSats and they want to fly an armada of them, a flight of them. I guess in the Air Force, we don't have armadas. We have flights.

a flight of them, I guess, in the Air Force. We don't have armadas. We have flights. Right, right. Things in formation, CubeSats in formation, and they would look for, they'd be used as a wide aperture radar or what have you. And along this line, in May, we are going to have a companion mission.

CubeSat is going to be part of a Georgia Tech proximity mission where the spacecraft keep their stations relative to each other, like ships at sea. So it's very cool. But Chuck, we're coming up on four minutes left in the show. Yes, we are. And I think you know what that means. I believe

that means it is time for our lightning round. Where we take your questions, we answer them very quickly. Here we go. The first question for our lightning round. Where we take your questions. We answer them very quickly. Here we go. The first question from the lightning round. Chuck Nice. How easy would it be to repair the light sail if micrometeoroids peppered it like a shotgun shot?

So this isn't just one tear like we talked about earlier in the show. This is a shotgun shot. Like, pop, pop, pop, pop, pop. Well, it'll still have a little bit of propulsion with the shreds of sail that are still there. But that shred, that ripstop feature, I think, will keep that shotgun eventuality from eventuating. Sweet. Okay. What is the ideal...

Oh, oh, oh. First of all... It's lightning round, Sean. I'm sorry. Sweet Okay What is the ideal speed Oh First of all It's lightning round I'm sorry I'm screwing up the lightning round Because I did not give the last person's name Which is Gabe Zabato Gabe Zabato

Thank you But next question Okay This is from Jesse Robinson Coming from Google Plus What is the ideal speed of travel And how long will it take to achieve that speed Well first of all With your lower It doesn't matter You can go ideal speed of travel and how long will it take to achieve that speed?

Well, first of all, with your low Earth orbit, you can go, you know, the ultimate goal, by the way, is to get to 100 kilometers a second, where you're going very close to the sun and get slung way the heck out of the solar system. But in the meantime, we're in low Earth orbit. So in nautical miles, you're going seven miles a second. Seven miles a second just to get started. There you go. Aaron Kelly, who is coming to us from Twitter, says, Ocean sailing ships use a keel and a rudder to leverage the wind on the sails and steer.

Is there an equivalent for the light sail? I love this question. Yes. So what we do, two things. We have, first of all, we have torque rods. These are twist rods that react against the Earth's magnetic field. There's electromagnets. They're about this long, Chuck.

Okay. 20 centimeters. 20 centimeters. And the very fine wire one. So electricity comes onto solar panels, which are part of the spacecraft, and you twist against the Earth's magnetic field, then the other thing is there is an old technology, which we love, gyroscopes, which in spacecraft often go by the expression momentum wheels.

They run electric motors, keep them spinning, and they twist, twist against gravity and orbital motion? That is awesome. We are steering and tacking the light sail spacecraft. Steering and tacking. I love the whole gyroscope thing. Oh, and that's sexy. Sexy!

Okay. Nelson is amazing. That's the name. Nelson is amazing. Nelson is amazing. How would you predict a solar sail could revolutionize life on Earth? In other words, how does it change international travel for us down here as opposed to travel up there? Well, what it would do, if practically, you wouldn't get on a light sail and fly around. You are too massive.

You can't breathe in space. And so you can't breathe in space. And so you can't breathe in space. But what could practically happen is the future of, let us say, air traffic control could involve CubeSats flying in formation to make excellent, high-quality, inexpensive, high-reliability radars. Could happen. Okay. All right.

I think we have time for just one more, and this is Brett Shock. He wants to know, can the sail be revved up in orbit for a few years and then hitch a ride? Well, yeah. We're going to run for about a month, which is very traditional because so little of the time are you over land to get telemetry. We're going to run for about a month before we deploy the sails. And we are also planning to run tests of extending and retracting the sails the same way you furl and unfurl sails on ships

at sea. You have been listening to StarTalk Radio with your guest host, me, Bill Nye, and my co-conspirator, Chuck Nice. Thank you very much for your excellent questions. They were good. Consider the Planetary Society, our light sailsail spacecraft, the first week of May. Keep looking up.

This is StarTalk Radio.