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Hey Daniel, you like the outdoors. You're an outdoorsy kind of person. Are you a fan of sailing?
Oh? Man, I love sailing. There's so much to appreciate, the wind, the quiet, but mostly it's because it's about applied physics.
That's the part you love the most about it is the physics of sailing.
Yeah. You know, you got the wind coming in one way, and the boat is pointing another way, and you have the you know, the keel underneath and the rudder. It's a it's a big complicated calculation, all happening in real time under you.
Yeah, and you might die or get stranded out and see if you if you mess it up, that's.
Right, that's ry. So physics can save your life. It's good to understand vectors.
But no, yeah, I always find it really confusing.
You know.
It's like, if you want to go one way, you actually have to point the boat the other way, but then you have to move the sail in line with the wind, and so there's like the Bernoulli effect. I just find it always really confusing.
It is confusing, basically.
You know.
All you need to know is if you want to go one way, make sure you point the boat a different direction, right, that's the only way to get there.
Never point to where you're going.
No, that's a classic rookie mistake.
Hi I'm orge I'm a cartoonist and the creator of PhD comics.
Hi I'm Daniel. I'm a particle physicist and the co author of our book together We Have No Idea, A Guide to the Unknown Universe.
And right now you're listening to our podcast, Daniel and Jorge Explain the Universe, a production of iHeartRadio.
In which we try to find weird, crazy, wacky, interesting, amazing things about the universe that will blow your mind and explain them to you in a way that makes you understand them and also laugh along the way.
That's right. We take you to all the corners of the universe, in rockets, in spaceships, in warp drives potentially, and all so maybe using sailboats.
That's right. We want to navigate your brain from here to there and all around, and we're willing to do it in any sort of mental capsule that's possible.
And so today on the program, we're going to be answering a listener question who was wondering if there are better ways to travel through space.
That's right, You guys might be familiar with the question of how do we get from here to there? Right? And if you want to fly from Earth to Mars, or Earth to Jupiter, or even to another star, you got to push yourself there, or you got to get your ship going at a certain speed, and that requires energy, and most of the technologies that we have currently are basically just like a fire spewing out the back, and that requires some sort of fuel.
That's right, you need fuel, And unfortunately, there are no gas stations between here and Mars, and so you kind of have to bring it all with you.
But there might be Tesla supercharger stations for all we know, Right, isn't that Elon Musk's plan?
How's that company doing these days?
Oh? I haven't really checked my stock portfolio, but you know, the guy thinks big, So probably as space goes to Mars, he's going to stop along the way and leave, you know, charging stations.
Yeah. So today on the program, we'll be talking about an interesting idea about traveling to the stars. We'll be talking about solar sales. How do they work? Do you really sail?
Our solar cells on sale? Right? How do what does this thing even mean?
That'd be nice if they're on sale, everyone can get one, that's right.
That's right, more than just our listeners in Delaware. Remember that podcast when we were going to cover the state of Delaware with solar cells?
Oh yeah, and do we get any feedback from delawareans.
Oh, actually we did. First of all, they commented that we need to also include Maryland, and they weren't offended at all. Actually, they were just glad to have any sort of Delaware shout out. They say that they don't often get mentioned.
Never happens. I guess exactly.
So we love you Delaware. Keep listening.
Yeah, so it's kind of an interesting idea that you can make a sale to sale the deep blue blackness of.
Yeah, it's really kind of an awesome idea. I mean, we're familiar with the wind, right, and the wind is a wonderful way to use a sailboat because you don't have to bring any fuel with you. Right, you go on a motor boat, you've got to bring all that fuel with you. It makes your boat heavier, it's loud, it's noisy, it's obnoxious. Right. One of the things I love about sailing is that it's quiet. Right. First of all, you don't have to fuel up because your fuel is just the wind. And then when you're sailing, there's no obnoxious motor sound to listen to. So the idea of traveling from one planet to another through space using something similar like being propelled without bringing along your own fuel. It's a beautiful idea.
Yeah, it's kind of cool to think that you can ride something out in space, right, Like there's something already going there and you can just kind of latch onto it and it will push it to where you want to go.
That's right. And you might be tempted to say, what's pushing the sail? Like obviously on Earth here it's air, But what's pushing your sail out in space? Because there's no air in space? And you're right right if we're not sailing in that same way. And then you might be tempted to say, what a about the solar wind? These guys have told us about all the particles shooting out from the sun. Is that the solar wind that a solar sail would be riding? But that's not even the case. It's not the solar wind that a solar sail works off of, though that would be some sort of poetic, beautiful parallel.
Wait, so it's not the solar wind that you would sail on in space.
No, it seems tempting, right, you'd like to have a solar sail boat using the solar wind for this beautiful analogy for our whiskey fueled adventures on the high seas here. But it's not actually the solar wind that pushes along a solar.
Sail, oh man, the solar wind does it give you a sunburn and chapped lips at the same time.
That's right, it gives you that solar wind tousled hair.
Also you have deep fried probably.
Exactly not recommended, folks, not recommended.
It's like a Brazilian blowout.
But Chris here, if you're listening to this podcast on the Space station, do not stick your head at the window to get a solar wind tousled look.
Yeah, instead riders, because that'd be really cool to hear from you.
Exactly exactly.
Yeah. So we'll be talking today about the solar sales, the idea that you can go between planets or stars or galaxies using a sale to catch something out there in space to take you there. And so, as we mentioned, this question came to us from Derek from Cleveland, and so here is Derek asking his question.
Hey, Daniel and Jorge, this is Derek from Cleveland, Ohio. My question is, how does solar sales work? If photons are massless, how can they impart momentum to a satellite, and how is the conservation of momentum upheld? I quickly want to say hi to my brother in law, Tim, who I'm sure will listen and discuss your answer with me later.
Thanks guys, All right, thank you, Derek. That's a pretty interesting question. I mean, it's sort of it sounds like he's heard of solar sales and he knows they work by catching light, but his question was how does that work if photons have no mass?
Yeah, so many good questions here, right, Like how does the solar sale work? He seems to understand that it catches light, but he doesn't understand like does light have momentum? Because he's probably thinking that momentum is mass times velocity, right, which is a case for slow moving massive objects. So he's wondering if the mass term is zero, how can you have any momentum? Like how do things with no mass have any momentum? And if they have momentum, if they don't have momentum, how can they push along a solar sale.
It's a great question, right, I mean I think it means that, you know, if light has nothing to it in terms of like mass, how can it push.
You exactly, that's the question. And so I was wondering what people thought about this. Are people aware of solar sales? Do they understand photons and momentum and all this kind of stuff. And so I went around and I asked people what they knew about solar sales. And before you listen to these answers, think to yourself, do you know how a solar sale works? Do you understand how light can have momentum if it doesn't have mass.
Here's what they had to say.
I feel like I've heard of it, but I'm not sure.
I mean, I've seen like fixed ones, but I haven't seen I know that they're.
Transitioning, like like Tesla's doing the roof tiles and stuff that have a solar day, but I don't know. I don't know if I've seen else A big I guess, kind of a sheet of sunlight. Yes, actually I have. A solar sail is basically a really big sail that doesn't get pushed by wind. It gets pushed by energy from the sun. So basically energy has a little bit of movement in it, and that big movement, a little bit of movement can push it because it's not too much movement, but it's a lot of energy in a big area that will push it.
I'm honestly not sure. I couldn't even.
I couldn't even yes.
Like maybe the stilted price on solar system or something like that. Sure, I like it all right. I love these answers or I feel like they're all correct. Like is it a boat powered by solar power? Yes, technically that would be a solar would.
That would be like a boat with an electric engine on it that's powered by solar cells. That's pretty cool.
Yeah, sure, yeah, that's like a solar boat for sure. Or like a discount, I don't presume it. Is it like a discount on solar panel? I think like a solar sale.
I think that guy might have thought I was actually trying to sell him solar panels, like he looked kind of wary. He's like, hmmm, are you another one of those shady solar salesman discounts?
They are pretty shady.
Quote unquote that's right exactly.
Their business wouldn't stand up to sunlight.
You had to be pretty bright. And there was one folk, one guy who actually had a pretty solid answer.
Was this your physics student saleash sale? Instructor.
No, it was not. Actually, that was my eleven year old son, who I think overheard me talking about solar sales to somebody else before I asked him, so he had a preview of the answer and just wanted to sound smart.
You're saying your son cheated.
I'm saying I asked him the question, and he knew the answer, and so he answered.
It all right, that's right. It wasn't a test.
Yeah, he had a bit more of a head start than the rest of the other folks that we asked.
So it's not something that a lot of people seem to know about or recognize the name of.
That's right. It's not a common concept, and that surprised me a little bit because I thought that people had heard more about, like how to move through space or the kinds of engines you might use. But I guess not, which makes an excellent topic for today's podcast. Yeah.
Well, I have to admit my only reference to a solar sail powered spaceship is from Star Wars.
Do they do solar sales and Star Wars? I don't even remember that. I thought they all had ion engines and stuff.
Yeah, I know, kind I mean if you've watched the prequels, which I'm sure we can get into a whole episode about. But count dookou what that character has rise around in a ship that has solar sales or what looks like what looked like solar sales?
Oh my gosh. Why you have like an encyclopedic knowledge of all the ships in every science fiction movie ever? That that's impressive.
I have an encyclopedic knowledgeable in nerd movies.
So that's what you do it four in the afternoon when you're not feeling in the mood to do cartooning. It's like, turn on some science fiction movie.
Yeah, isn't that what everybody does?
Yes, yes, that is exactly what everybody does in the middle of the afternoon. No, but you're right, these things are in science fiction. I've read lots of books with solar sail powered hips in them. It's a pretty common idea in terms of like how to get from here to there? And you know what, we don't have that many ideas for how to get from one planet to another or one star to another, and so it's on a pretty short list.
Well, this is how it kind of worked in Star Wars, so kindt dooo, get on this ship. He takes off, he flies up into orbit or space, and then he like unfurls this huge giant sail, this like giant sheet that looks kind of like it's made out of gold, and then then he starts going. So it's like it's like you opened a giant umbrella and then that pushed them forward.
Yeah, that's basically it. Solar sales are giant umbrellas. Podcast over, you nailed it, Star Wars for the wind. Yeah, let's get into it, Daniel. What is a solar sale? So a solar sail is an enormous flat sheet, just like a sail on a sailboat. And the thing that it captures is not wind like in air, because there is no wind in space, and it's not the solar wind because the solar wind member is protons being shot out by the sun and those could push a sail, but there's just not that much of them. There's just not that many of them. There's not enough of them. What it's capturing is light. So the light from the sun is zooming out from the sun and it's carrying energy with it. And we'll dig into that in a moment. But photons have momentum, and so what happens when they hit the sail is that they give it a little push, and you get enough little pushes and you can actually get going somewhere.
So this is a real thing, like people have built these, Like there are functioning solar wind sailboats out there in space.
Yes, this is a real thing. It's like physics says, there's no reason why I shouldn't work. People have big plans to make huge solar sails that can go all around the Solar System or maybe even to other stars. And somebody has actually built one of these things and made it work. The Japanese they launched one several years go and show that it actually worked, Like the physics isn't just theoretical, Like there is one thing out there that's solar sailing right now.
Oh that's pretty cool the Japanese.
The Japanese, nice job. But the thing about solar sales is that it's gentle, right, it's not really really powerful winds of light out there for you to capture with your sales. So if you have like even a really big sale like eight hundred meters by eight hundred meters, which is you know, enormous, right then, that only gets five newtons of force. Five newtons is not that much. It's like how much you know a force there is on like a one pound object on Earth. So like a one pound rock, you know, think about how much that feels in your hand. That's the force of the Earth's gravity on a one pound rock. That's the same amount of force that the Sun would push on a eight hundred meter by eight hundred meters sail about the distance from of the Earth.
Which is huge, right, I mean it's like several city blocks.
Yeah, that is not a small thing to build and to unfurl and to keep from getting shredded right by like micro meteorites and whatever.
But you're saying, if I made a tarp there was about a kilometer on each side over Manhattan, it would get pushed down not just by the weight of it, but also by the sun that's hitting it.
Yes, exactly, And every time a photon hits you, you're getting pushed. Like photons are actually pushy.
They're kind of rude, aren't they.
They just like zoom along wherever they want to go. They don't ask questions, they don't take turns, or they just go in straight lines wherever they need to. No photons care momentum, and every time they hit something they give it a little push. So when you turn, when you flip the switch and turn on the light, you get pushed down a tiny little bit and you might think, what, I can't feel it, and you're right because it's a small effect, which is why solar sales are very gentle and you need a huge one to add up to any measurable force.
Well, it step us through a little bit of how this works. I mean, so you're saying, if I take a flashlight and I flash it at you, I am technically kind of pushing you with it.
You're basically punching me in the face with light. Yeah.
Yeah, that's really mean because we don't think of light as having substance to it, right like you. I mean, we know we sort of associated with energy and heat and warmth, but not forced that's right.
We don't think of photons as having mass because they don't, but they do have energy, right. Photons are energy. There's just pure energy, and if you have energy, that means you have momentum. And it's complicated because we're only used to thinking about things having momentum when they have mass. We think about you give something momentum because it's heavy and it's hard to get going, and once you've pushed it, it keeps going. It has momentum. Right, So something that's like light and fluffy and you know, weighs nothing, it's hard to understand how that can have momentum.
Well, I think I think we're all pretty familiar with like if I shine a flash light on you or a laser, like your body's going to absorb that energy or you know, warm up a little bit or something. But you're saying that if I have an atom on my skin and you're flashing a flashlight on it, the photons actually sort of hit it and the atom wants to go the other way.
Yes, exactly. Think about what happens with a mirror, right. It's a little bit more complicated when the light gets absorbed. So let's think about a mirror where the light gets reflected, the light suoming in one direction, it hits the mirror, and the light's going in the other direction. Right, How does the light change direction? Right? What changes the direction of the light. It's the mirror. Instead of thinking about a light in a mirror, think about a ping pong ball and a paddle, right if you get hit. If a ping pong paddle gets hit by the ball, then the ball bounces the other direction, but the paddle gets pushed back a little bit, right, That balances the momentum mirror momentum is conserved, so in the same way, when the light hits the mirror, it gives that mirror a little push, and the mirror pushes back, and that's what turns the light the other direction. And so when light reflects off of something, it's giving it a little push.
So pure energy can push you basically exactly. It can resolve in something wanting to move the other way.
That's right.
And this is what the cool things in physics when you learn that a concept you thought you had a firm grasp on, like momentum, is actually just a special case of sort of a larger concept. Like we're familiar with, momentum is mass times velocity, but that's not its definition. That's just how you calculate it for slow moving things with mass. You can calculate momentum for things that don't have mass, because momentum is a larger concept. It's just it captures like the quantity of motion of something, not just it's mass times velocity.
It's just it's more like the total energy.
Yeah, but it's fascinating because energy is just a number. It doesn't have a direction, right, And physics energy is a scaler, not a vector, like it doesn't have a direction, just a magnitude, or its momentum has a direction, like you know, pointed in one direction is different from pointed in the other direction.
Right.
See, so light has momentum.
Light has momentum, has energy, and it has momentum, but it has no mass. One way that some people like to think about it is you can think about momentum is sort of the difference between the energy and the mass, right, because in relativity we think of the total energy as the energy stored in the mass plus the energy of the momentum. So you can sort of invert that equation and say the momentum is the difference between the total energy and the mass. And in the case of the photon, there is no mass, so the momentum just comes from the energy, whereas in the case of another particle, right, it has a bunch of energy. Some of that is in the mass and some of it is in its motion. But for the photon, the energy is just in its motion, so it just has momentum and no mass.
All right. Sales are a real thing, and they work by taking the momentum that's in light, absorbing it and then using that to push you along in space.
That's right. And it's the light from the Sun that's doing this, not the protons from the solar wind. And everybody actually can see this if you just have seen a comet. You know, comet is just a big ice ball and it falls towards the Sun and as it does so it gets a big tail, right, and that's the tail of it, like the stuff melting and dripping out the back, and the tail points in a specific direction away from the sun direction of motion. People think, like, you know, it's like a fuzzy lines behind something that's moving fast, But the commet actually always points away from the Sun, and that's because of this effect of light. That's light pushing the tail of the comet.
Really, it's not like a trail of a dust that you leave behind.
No, because as the comment is moving towards the Sun, the tail is behind it. But as the comet goes around the Sun and then leaves the tails in front of it.
Wow, so it shouldn't be called a tail once again?
Yeah, I guess. Or maybe it's like backing away from the sun as it leaves. It's like whoa, that was close.
All right, let's get into will it work and how can we make it work? But first let's take a quick break.
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All right, so that's solar sales, Daniel. That's pretty cool. The question now, I think is does it work? If you build it, will it take us to other planets and maybe other galaxies?
Yeah, it seems like it will. And you know, we know a lot about it. We can do these calculations. We know how much light there is we can calculate how it will reflect and how much will be absorbed, and we know all the numbers we need, and so people have plugged all this stuff into calculations and they said, if you build a solar sale that's like a kilometer by a kilometer and you have a really light ship, you know, not too heavy, how long would it take to get to Mars or to get to Jupiter. And the thing you have to understand is that the string that the light, of course, gets weaker as you get further from the Sun. So the solar sale is very powerful close to the Sun because it's capturing more light, and then as you get further and further away from the Sun, it gets weaker and weaker. So solar sales are great for navigating around the inner parts of a solar system.
Well, the question I have is, you know these sales are catch the rays from the Sun, right, they catch the light from the Sun and push it get pushed away from the Sun. But what if you want to travel towards the Sun or perpendicular to the Sun. How would you do that?
If you want to move towards the Sun, It's not hard, right, You just need to use gravity. Right, the sun is going to pull you towards the sun, so that part's not hard. But the only way you can use the sale to build energy is moving away from the sun. So you can play this game of gravity versus the solar sail depending on which way you want to go.
If you're facing the sun, can you go side? Can it push you sideways? Because gravity's pushing me towards the sun and the solar sales pushing me away from the sun. How do I gain speed sideways?
Well, that's a really good question. I hadn't even thought about that. How do you steer it? Because the photons are only coming out from the sun, So can you move in a direction that's not out away from the sun. My first thought is, let's think about how a sail works on a sail boat. Right, on a sail boat, you can move in a different direction than the wind if you put the sail sort of across from the wind. But the problem is a sailboat has a keel, right, it has something underneath it. It keeps it from sliding sideways, and so it can only use the part of the wind that it wants by pointing in the right direction. A solar sail. Of course, on a spaceship doesn't have a keel, so at first thought you might think, oh, a solar sail can only take you in the direction the photons are going. Right. Well, let's think about it for a moment. What happens if you tilt the sail so that it's not pointing flat away from the sun right, if it's at an angle with respect to the photons. You might think, well, it doesn't really matter because the photons hit it and bounce off, and they're giving a push the direction they were going. Right. It's actually a tiny bit more complicated. If the photons hit it at an angle, then they also bounce off at an angle right. So if the photons are coming directly out from the sun and they hit flat on the solar sail, then they bounce back the opposite direction, and the momentum they've given is in the direction they were going. But if they come out from the sun and they hit the solar cell at an angle right, then they reflect off. Think about light hitting a mirror right, It doesn't come back the way it was going. It reflects off at an angle, and so the push that it gives is actually in the direction that the solar seal was facing. So I think that means that you can steer a solar sail. You just turn it through the way it wants to go, and it will catch that part of the photon's momentum that pushes it in the direction it's facing. You can't just point in that direction and drive the way you can with your car. You have to take an account all these limitations. But you can do it, and you can take a pretty heavy load, you know, a few tons to Mercury and it just takes a few years. If you want to go to Venus, it takes you know, about a year. If you want to go the other direction, it starts taking longer because the radiation from the Sun drops, right, So if you want to go to Mars, it takes like a year and a half maybe two. It takes like two years to get to Jupiter, three to get to Saturn, and then like six years and nine years to get out to the outer planets.
Wow, that's a lot of whiskey drinking on board.
That's your fuel after all, right, there's no solar whiskey.
You'd be using it up. You could have burned it to evade that asteroid. But no, you had to drink it.
Yeah, well, you know it depends on how well you get along with your crewmates. Depending that determines how much whiskey you have to drink.
Can you imagine being stuck in a spaceship with your physics student for nine years?
Danum No, But I also can't imagine being in a spaceship by myself for nine years, right, Like, what do you think would be easier to handle? Total isolation or being stuck with one person in a tin can for nine years?
For me, would definitely be by myself.
Yeah, you and a big stack of science fiction movies, right.
That's all you need. And a cartooning pad obviously, so I can document my descent into madness.
That's your further descent into madness you mentionedly my fur.
That's thank you for reminding me. But yes, but what about beyond the solar system? Could you use the solar sale to leave the Solar system?
You could a little bit. I mean what you can do is try One strategy is to just try to get going as fast as you can using solar sales and gravity and then zoom off in the direction of another star. So you like you sling shot around the Sun to get some speed up, and then as you're leaving the sun, you unfurl your sales and it pushes you away from the Sun as hard as you can. But then once you leave the solar system, it's really going to stop pushing you very much, and so your speed doesn't pick up anymore. But you know, if you do it right and you have a light enough object, you could get up to a reasonable speed and head off in that direction.
Yeah. I mean, at some point when you leave the solar system, it's like the there's no wind. It's like being on a sailboat with no wind. There's nothing to push you anywhere.
Yeah, and you know there is radiation out there and there are particles, but it's very low density. It's not enough to really boost you. One idea people have, and I love this idea because it's so crazy plus ambitious, which is my favorite combination, is to basically beam light at these things. Like if you're in a solar sail boat and you're leaving the solar system, maybe we could like build a huge laser and beam the energy at your solar sale to give you a push.
What if you punch a hole through the cell with your laser.
Yeah exactly. It can't be too intense. But you know these these sales will be very reflective, right. They are essentially the big sheets of aluminium or maybe plastic that's covered with aluminum so that they're super reflective. So if it's reflective enough, then even a really really powerful laser won't punch a hole, right, because punching a hole means the energy gets absorbed and so it like melts and destroys the sale. If it's reflective enough, then you should be able to shoot even a really powerful laser and have all the energy to be transferred into the momentum of the sale.
It's like a blowing on a little sailboat.
Yeah exactly. Or I'm sure I've seen some science fiction movie where somebody like reflects a laser blaster with a mirror.
Right, Oh, you just have like a pure mirror shoot at it and then that pushes you forward.
Yeah. If somebody shoots you with a laser blaster and you have a mirror, you can just reflect their energy pulse or whatever back at them.
All Right, Well, let's get into how you would actually build a solder sail even if it wasn't on sale. But first, let's take a quick break.
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That would be a pretty awesome idea for merch like Solar Sale Daniel and Jorge Solar Sale explore the universe instead of explaining the universe. That'd be pretty cool.
What do you mean, what will we sell sale sell.
We'd sell the solar sale like we have a shop where we sell t shirts and coffee mugs with you know, Daniel and Jorge explain the universe on it. We should add to our Internet merch account a solar sale that you can buy.
Okay, cool, done, let's do it. And then you just get a sheet of aluminum foil? Is that the idea?
That sorry a one kilometer by one kilometer square of illuminifoil with your picture on it.
There you go, and you can sail away into bankruptcy.
Right, and you can shoot a laser at that picture from Earth.
Dual purpose aluminum foil. You can wrap your leftovers and go into space exactly.
But that's basically what a solar sail is. Right. You want it to be really really big, but you also want it to be really really light. You want your solar sailboat to be as light as possible so that all that momentum gets turned into speed. The more massive your sailboat, the slower it's going to go for the same amount of momentum. So you want it really big and really thin.
I mean, does it matter in the long run how much your solar cell weighs.
Sure it does. Yeah, I mean you want to get up to like half the speed of light or a quarter of the speed of light or something, it's going to take a lot longer. And if you don't have a laser push, then you have a limited amount of time to get energy from the sun, and so you want to get up to as high as speed as possible.
Oh, I mean, but that's just in general, all the same for any acceleration, right, absolutely. Yeah, the lighter you are, the faster is to go faster.
Yeah, exactly. And that's like why people who you know, climb mountains on their bicycles remove every tiny little thing that's not necessary because they don't want to carry that mass up the mountain. You know, I met a guy who was climbing Matripeach you, and he like sawed his toothbrush in half because he didn't need the bottom half of it and didn't want to carry that thing up the mountain. So, yeah, you want to use your spaceship to be as light as possible so you can translate all of that momentum into speed.
So basically that's all you need is just a thin aluminum foil. But usually they show show them in movies and pictures as gold. It looks like gold foil. Does that give you a better advantage if it's gold or golden?
No, you can't just have aluminum foil because aluminum is too brittle. Like you try to make a huge sheet of aluminum foil. I mean, I can't even get like a one foot square of aluminum foil to stay together without tearing. And so you try to like fold and then unfurl a one kilometer square of alumine foil, It's not going to work. So usually what they do is they have some sort of plastic and they spray aluminum coating on it, and so sometimes that plastic is gold. But I don't think there's a reason why that's gold. I think that's just to look cool.
All right. Well, where are we at then, in terms of projects that are trying to use solar sales to get us out there?
Yeah, So the best solar sale ever so far is the Icarus project launched in twenty ten by Japan, and they had a fourteen by fourteen meter solar sale, And that sounds small compared to what we're talking about, like eight hundred meters by eight hundred meter but fourteen meters is not small. That's like, you know, the size of an apartment.
Can I just comment under choice of names, like, have they read the whole story of Icharis? Do they know how that story ends?
I don't know.
I love the hubris in choosing the name Icarus for a solar sale project, right, it's they chose a story about Hubris, and they did it kind of hubristically. They're like thumbing their nose at history.
I love it. That's not going to happen to us. We're gonna fly really close to the sun and nothing bad is going to happen to me.
Maybe they're trying to regain the name Charis. They're claiming it back, you know, the way some people claim back bad words. Said, we're going to turn this into a positive stereotype. Now.
They want to redeem Charis himself.
That's it exactly. Maybe they're like the descendants of Charis himself.
Yeah, so they're billing it. They build it, They're going to build it.
They built it, they launched it. It worked. It's solar sailing. It's zooming around the sun right now.
Really, it's out there sailing weight.
It's out there sailing away it's sipping whiskey and looking down on us. And that's the most successful solar sail so far.
But it's not like a ship, right, it's like a satellite or a little vessel.
Yeah, it's a little vessel. It's basically just two experiments, like, can we do this thing, Let's see if it actually works, because you know, sometimes in physics, you do the calculations, they sound great, and then you know it doesn't actually work the way you expect it because you forgot to account for something. But in this case, it's pretty much worked as they expected. And that's it's a huge boost for all the solar sale enthusiasts.
I didn't know that was such a thing.
I'm a solar sale enthusiast. I'm a big fan of First of all, I love sailing, but I'm a big fan of anything that's going to take us to other planets or take us to other stars and isn't going to require a huge ridiculous amount of fuel.
Cool. Well, and then you were telling me there's another cool project called the Breakthrough star Shot project.
Yeah, they have this awesome idea. They say, let's not send one big solar sale, let's build one hundred, like a thousand nanosales, so there'd be a bunch of really small ones and they would push them along with lasers between here and Alpha Centauri. The problem with building a laser that pushes a big solar sales you need a big laser. So they were like, okay, well, let's just have a small solar sale that can be pushed by a small laser and then just have like a tiny little craft. And so they imagine that it would take twenty years to get to Alpha Centauri with these little nanosailors.
And so they would have a giant laser gun on Earth shooting at these things, pushing them along.
A thousand laser guns pushing on them.
Oh, each one has their own little laser gun.
Yeah, exactly. Each one needs its own little boost. But the cool thing about solar sailing is that, you know, it's a small effect, but it just adds up, and if you're traveling for a long time, it's just like more and more acceleration. Eventually these things can get up to a respectable fraction of the speed of light, you know, so they can cross the distances between stars.
And then they would communicate back what they find. But they can't come back, can they?
They cannot come back. No, because there's no laser system over there for to shoot them back. I mean that we're aware of. Maybe we'll get there and find Elon Musk has built some you know station over there for recharging your solar lasers or something. But no, they it's just it's a one way trip.
Well, that's cool. It's like instead of building a giant boat, you build a whole bunch of little rubber duckies into the river.
Kind of, that's exactly that's gonna be. Humanity's first contact with an alien species is the equivalent of a rubber ducky. Look at us, we're so impressive. This is a little squeeze toy.
Nni allies are like, this is a sign of war.
That's sorry. Maybe the rubber ducky is like holy to them, and it's offensive that we like threw them in their face. Plus we probably all our lasers be like burning their eyeballs out for twenty years while the while the nanocrafts are getting there.
But if we fill them up with whiskey, maybe they'll they'll like it, you.
Know, they'll either love it or hate it. They'd be like what Scottish whiskey. I only drink.
Irish disneeds war.
Wars have been fought over less, I'm sure.
All right. So that answers Derek's question, who wanted to know? How do sold our sales work? And hopefully you guys enjoyed that and are inspired to maybe think about taking off sailing.
That's right, and you know, maybe someday we'll go out there and we'll sail among the stars. I think it's really beautiful and poetic to imagine using the LFE from the stars themselves to push ourselves from one to the other. I really wish that could happen.
All right, Thanks for listening, guys, see you next time.
If you still have a question after listening to all these explanations, please drop us a line. We'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge That's one word, or email us at Feedback at Danielandhorge dot com. Thanks for listening, and remember that Daniel and Jorge Explain the Universe is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact. But the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. How with US dairy tackling greenhouse gases, Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's last sustainability to learn more.
California has millions of homes that could be damaged in a strong earthquake. Older homes are especially vulnerable to quake damage, so you may need to take steps to strengthen yours. Visit strengthen your House dot com to learn how to strengthen your home and help protect it from damage. The work may cost less than you think and can often be done in just a few days. Strengthen your home and help protect your family. Get prepared today and worry less tomorrow. Visit Strengthen your House dot com.
There are children, friends, and families, walking, riding, on paths and roads every day. Remember they're real people with loved ones who need them to get home safely. Protect our cyclists and pedestrians because they're people too. Go safely, California From the California Office of Traffic Safety and Caltran
