StarTalk Radio - Things You Thought You Knew – Up, Up, and Away!

Episode Date: December 27, 2022

What is the rocket equation? How do airplanes fly? Neil deGrasse Tyson and comic Chuck Nice go through some things you thought you knew about how airplanes fly, x-rays, and how to fuel a rocket. NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free here: https://startalkmedia.com/show/things-you-thought-you-knew-up-up-and-away/Photo Credit: NASA/Joel Kowsky, Public domain, via Wikimedia Commons Subscribe to SiriusXM Podcasts+ on Apple Podcasts to listen to new episodes ad-free and a whole week early.

The wing is now pitched upward towards the moving air. Right. It's pitched upward. So air is flying straight into the wing. That's going to also add to the Bernoulli effect, and that plane is going to pop. Welcome to StarTalk. Your place in the universe where science and pop culture collide.

StarTalk begins right now. Chuck. Yes. You got one of your favorite kind of episodes coming up. All right. It's Things You Thought You Knew. I think you like those.

You like those. I do indeed. I'm glad you like, I like making you happy. It's because I know that I don't know. That is what I know. And so this is a way to remedy that. That's right.

It's a cure. All right. So Chuck. Yeah. You ever wonder how airplanes fly? You know. Have you ever walked up to one? And I sound like the guy in The Matrix.

You ever marvel at an airplane that 300 tons of metal. Mr. Anderson. No, he was talking to Morpheus at that time. Oh, Morpheus. That's right. Yeah, yeah, yeah. That's right, because he was talking about, yeah. He was trying to get him to reveal the codes for Zion. The codes for Zion, right. Yeah, yeah, yeah. That's right, because he was talking about, yeah. He was trying to get them to reveal the codes for Zion.

The codes for Zion, yes. Yeah, yeah, yeah. So anyhow, have you ever marveled at an airplane of all sizes? They just go fast forward, and then they fly. Do you ever pause and reflect on this? I'm not going to say I have, to be be honest i'd be lying it's just give me the scotch before we take off and i'm good all right i'll tell you what i marvel at what uh how sometimes i get a really decent meal in first class that's to me is a modern aviation marvel okay all right so so here you go so you may have

noticed that all airplanes have wings yes okay so i have wings are a good thing that's a good thing i will say they also have many wings on the tail okay right and then they have like a vertical wing, which is like the stabilizer wing. And so that prevents it from sort of a fishtailing. Right. Because if it's going quickly through the air and air parts on the left and right side of that tail fin, that gives the plane stability moving in one direction. Okay. Now, when I was a kid, I built model airplanes that flew gliders. And I tried making gliders without a tail fin, and it just fishtailed the whole time. It just didn't, it couldn't stabilize.

So I, so doing piece by piece, adding and subtracting bits to my, to my models, I was able to sort of learn early on in my life what role these were playing in the stability and the lift on an airplane okay interesting yeah just so i go back on that way back on this so now um you may have also noticed the shape of the cross section of a wing yes so if you take a cross section of a wing and sometimes you can see this oh yeah you know You can see it when you're on the, if you sit on the wing. On the wing. On the wing. When you're sitting in the wing seat. In the wing seat, right.

So, that's usually where the exit, there's usually an exit door above the wing so that you can step out. So, the top part is curved. Right. And the bottom is, it's typically flat. Right. So, you have a pocket of air that the moving wing is passing through. Yeah. And the air wants to stay as one parcel.

It wants to. Okay. Okay. So as you do this, the air on top to go that bigger distance has to travel faster to keep up with the air on the bottom so that when it reconnects, it's the same parcel. Gotcha. All right. So you have forced the air to move faster on the top than on the bottom and fast moving air has lower pressure. And I've done this before. I don't know who's going to be listening to this and who's going to be watching it, but you can take a ribbon. So I'm going to use my letterhead.

Okay. So here it is. I don't know if you can see. From the desk of Neil deGrasse Tyson. That's right. It's Hayden Planetarium. Right. American Museum of Natural History.

So not that it matters what paper you do use, but I'll get a nice long skinny strip from that. There it goes. And here it is. Just limp in front of me. And now I'm going to blow across it. Okay. There it goes. And here it is. Just limp in front of me. And now I'm going to blow across it. Okay, here I go. There you go.

I'm blowing on top of it. Top of it, but it straightens out, lifts up. Correct. So the faster air going on top has lower pressure relative to the pressure of the air on bottom. So the air on bottom presses it up. It's pushing. It's pushing. It's pushing it up.

You have an entire pair of wings doing this. An entire pair of wings. And the faster you move, the bigger the pressure difference is between the two of them. Period. Okay. The bigger the pressure difference is between the two of them. Period. Huh.

Okay. So, on the runway, where you're ready to take off. Right. And the plane accelerates, the pressure difference between the top and the bottom is becoming greater and greater and greater. And the plane's saying, I'm ready to do this. Okay? But you don't want to rely only on that. You ready to do this. Okay. But you don't want to rely only on that. You want to make sure this happens. So what, by the way, it's continues to accelerate through this.

What the pilots do is they, they, they up the flaps on the tail wings. Okay. Right. What does that do? That creates extra pressure to push the tail down, pivoting the nose upwards. Aha. When the nose goes upwards,

the upward pressure on the wings is no longer just this Bernoulli effect. Bernoulli is the guy who first decoded this phenomenon. Aha. It's not only that. effect where newly is the guy who first, uh, uh, decoded this phenomenon. Uh, it's not only that the wing is now pitched upward towards the moving hair, right? It's pitched upward. So air is flying straight into the wing. That's going to also add to the Bernoulli effect.

And that plane is going to pop. That's why it doesn't slowly gain altitude. That plane changes its angle to the air, and it flies high above the ground. And there's strong reason to do that because it also reduces the acoustic footprint of the takeoff. reduces the acoustic footprint of the takeoff the higher it can get the fastest the the less influence that sound is going to have on houses and other things that happen to be in the in the in the runway path right so these lowering your lowering property values everywhere everywhere and so this effect of pitching the wing so that the moving air just presses it upward is so effective that you don't even need Bernoulli to fly an airplane.

You know, you can have Johnson do it, or you can also, you know, Smith is cool, you know. You can have Ray J. Johnson do it, but you don't have to call him Ray. You can call him Ray J. Ray J can do it. Right. So that's an old timer reference there for people over 70. Um, so, so the upward pressure will do that. That's why, for example, if you've ever been to an air show, I highly recommend it. Even if you're anti-military, the air shows like display, not only military jets, but future of civilian jets, but you should see what your taxpayer money is going towards.

Okay. If you have the occasion to visit an air show, they're, they're big ones in the United States, um, in, in, uh, outside of Paris, uh, and outside of London. Uh, Farnborough is one. So these are major air shows. But anyhow, the F-16, as well as other planes, the last I saw was F-16 airplane can fly upside down and you can say, Oh yeah, I saw a top gun. I saw it. Oh, I remember that.

If this Bernoulli effect only pushes upwards with that orientation of the wing, how the hell do you fly upside down? You just angle the wings so that the air hitting on the front edge of it, the urge of that is to push it upwards rather than any other direction at all. And if you maintain that pitch of the wings, you can sustain a lift for the airplane. You can fly it at any angle for that. But if you're not otherwise in Top Gun or you're doing fancy things, you let Bernoulli do most of the work. Look at that. And there you have it.

So you're good. Yeah, just creating lift. Correct. Now, have you seen those little winglets at the tip lately in the last 10 years? Almost all planes have them. Yes. All the planes have a little wing on the wing. A little wing on the wing.

It's like a little wing hand. Hey, Sway, a little wing hand. What's up? All right. So they knew and learned that air moving over the wing. Oh, by the way, the wings get narrower as you get to the tip. Take a notice of that next time. They're very large as they attach to the airplane,

and then they get narrower. That's a very important feature for strength, by the way. Okay. Right. The strongest part of the wing is the nearest part to the plane. All right. That's a good fact. You don't want it breaking somewhere else.

All right. Uh, so, so what you have is a, a, a, a, so air not only moves over the wing, but it also moves off the wing horizontally. And what they found is the air going off the tip of the wing created little turbulent eddies. Gotcha. And anytime you have turbulence, you have a drag, a turbulent drag. Right. And they said, is there any way to smooth over these eddies? to smooth over these eddies.

And so they did this research under the umbrella of one of the A's of NASA. Recypher me the NASA acronym. I don't know, National Aeronautics. And Space Administration. And Space Administration, right. The first A in NASA stands for aeronautics. A big part of their budget is to study aeronautics. They discovered that if you put a little uptick,

a little up angle in the tip of your wing, you can boost the, you can reduce the drag, thereby increasing fuel efficiency, thereby enabling cargo planes to carry that much more and that much farther. Look at that. Overall, they saved between 10% and 15% of all the fuel costs the world has seen since that's been introduced.

And that is huge. Huge. Yeah. Huge. Yeah, I got to tell you. First of all, I look at it like great for the ecology. You know, that sort of thing. But if you're running an airline, you know, it's just good for the bottom line.

It's good for the bottom line. And you'll also notice that that little piece of the wing, if it's done in a modern design rather than the original designs, they just slapped something on there. They like glued it on with, I don't know. But the modern design… Chewing gum. Chewing gum. It's integrated to the shape and the form of the wing. You'll notice that the wing continues to get narrow. Yeah.

To that tip. Right. So it continues to get narrow, easing the air off of the tip so that you don't have this turbulent Eddie. So that's, that's how you have that. So now here's the thing. So that's how you have that. So now here's the thing. The plane wants to get airborne as quickly as possible. Right. So there's a speed below which it will stall in the air and just fall out of the sky. Okay.

If it's going faster than that, then all the upward forces are keeping it afloat. All right. Right. And like I said, less than that, you will stall and drop out of the sky. So when you hit that speed, okay. Which I believe is 88 miles an hour. I'm pretty sure.

Yeah. I'm pretty sure. It should be that even if it's not that right which is let it let it be yeah 88 miles an hour so um so there's the plane so so you want the highest possible air speed the air speed is what matters to whether you're going to stall right it's how fast is the air moving over your wings. So every plane, if it has the option, is going to take off into the wind. Uh-huh. Because what matters is not the speed relative to the ground, because a tailwind would give you high speed relative to the ground.

But once you're airborne, you want to stay there. And so what matters is the speed over your wings. Over the wing. That the air. aircraft carriers have at least two runways at an angle to each other. So that when the wind direction switches, they can change which runway you're using so that you will always take off into the wind. Nice. And the two, the, I forgot what the, is it 45 or 30 degree angle?

It's not, it's not at a 90 degree angle to each other. Okay. Because if you do, if you do the math and the geometry on this, you want it to be about a 30 degree angle because all combinations, what you do is you, if you, if the wind changes direction, then you just take off in the opposite direction of the, of the, all right. And you, it turns out many solutions are solved just by having two runways at that angle. And that's why aircraft carriers, you will see, um, just take a look at their shape,

but the World War II class aircraft carriers, you could, they had two angles you could land on their deck. Right. Yeah. There's, yeah. On it. And if you're going to land from the direction you're coming, they would turn around the aircraft carrier so that you're coming in against the wind.

So you want to take off against the wind. So this makes for a great bit of, um, for someone facing adversity in life. Right. You say to them that airplane achieves its greatest lift when taking off into the highest headwinds. And that notwithstanding, you are still screwed, my friend. You're still flucking this class. Go to the remedial class.

Too bad. Too bad you're not an airplane. Don't ever be a counselor, okay? Chuck Knight's worst life coach ever. Chuck, the fact that you even thought that. Oh, my gosh. There's some person who's got adversity in their life. Oh.

Too bad for not an airplane. There's some person who's got adversity in their life. Oh. And they're doing it right. Too bad for not an airplane. Oh, well. All right. So, also, they land into the wind. Okay? Because they want their slowest possible speed relative to the ground. Right.

And that way, when they reverse the thrust of the engines, they don't accidentally run off the end of the runway. Right. So that's why planes land and take off in the same direction, often on the same runway. That's why. Look at that. That's why. That is very cool.

And you know how they know which way the wind's blowing? They look at the windsock. Oh, I thought you, I was going to say you licked your finger. Oh, then they roll down the window of the 747. Yeah, and you roll down the window of the plane, you stick your finger, okay, there we go. That's it. Maybe Lindbergh did that, I don't know. Right.

But you look at the windsocks, and I look at the windsock every single time, and I confirm that we are indeed taking off in the direction of the wind because it's the opposite direction the windsock is pointing. We'll see next time. And the windsocks will are. You want to go against the wind. So wherever the windsock's blowing,

that ain't the way you want to do it. That ain't the way. Real simple. Yeah, but you can reaffirm that the traffic controllers are doing the right thing. Right. By making this observation.

Yeah. They're not just up there drunken partying. You know? They actually are paying attention. They're also paying attention. Well, that's exactly also. The way you said it, they're not just drunken partying. They're just.

They're also looking at your ass. Right. So all this is going on on the runway. And I got more to talk about airports. I mean, I just, there's so much going on. You know why they're called- Quick thing about- You know why they're called gates?

You know why they're called gates? Uh, no. They used to be literal gates. Oh, okay. Airports, you'd go up to the gates and they'd open the gate. And then you'd walk onto the tarmac and get on the airplane before they were right jetways day when they had you had to climb the stairs to get on the plane well the president still does that when he lands in different countries but and small airports you

would do that but i'm just saying they were literal gates and then we move them indoors and now you have these jetways you don't't even see when you're, are you, am I indoors? Am I outdoors? Where am I? Yeah. Well, just a reminder that it's a real object that's really flies.

And thanks to engineering for this, the people that say, I don't trust science and say, we made a 300 ton hunk of aluminum fly at 550 miles an hour across country, serving you hot food and giving you the internet while you sit in your comfortable chair. And at the end of that, you're going to complain that the salad had too much salt. That's how you know you're living in the future. But see, the salad did have too much salt, Neil.

I mean, I wasn't just nitpicking okay i know i might seem demanding but there is a reason behind my complaints you know you're in the future that's all i'm saying yeah man anyway planes that there's more to talk one day we'll talk about the pressure difference between inside the cabin and outside that's a fun thing i do experiments on. But one day we'll do more. When you have more appetite for airplanes and airports, you can take this up again. I like it. Chuck, we got to take a quick break.

But when we come back, more of the things you thought you knew on StarTalk. Hi, I'm Chris Cohen from Hallward, New Jersey, and I support StarTalk on Patreon. Please enjoy this episode of StarTalk Radio with your and my favorite personal astrophysicist, Neil deGrasse Tyson. Welcome back. We're in the middle of things you thought you knew. Let's continue. Chuck, when was the last time you were at an airport?

I don't know. A couple weeks ago, a few weeks ago, maybe. All right. I want to give you things to notice on your next trip, because otherwise it's just a drag to go through and TSA and everything. Just some things to notice. You mean things like we've become a slovenly country that looks like we're going to the damn bathroom in the middle of the night when we travel?

Put some clothes on, people. Real clothes. Okay? No, they got their pajamas on because they want to sleep on the plane. No, no. All right. So, here you go.

So, the first thing, you know, at the TSA, you got the, the x-ray machine, right? You got the x-ray machine. I just want to alert you of something. If there was a day and I'm old enough to remember before anything got x-rayed, you know why? Because nobody had an x-ray machine to do it. And in the 1960s, there was a spate of hijackings. Many of them were to Cuba because we didn't, we, our diplomatic ties had been broken off. Uh, and because the Cuba were like, they were commies, right?

They were sympathizers with the Soviet Union and they were in our hemisphere. And so we didn't have planes to Cuba. So if someone wanted to get, fly to Cuba, they had to hijack a hemisphere. And so we didn't have planes to Cuba. So if someone wanted to get fly to Cuba, they had to hijack a plane. So I don't mean to laugh, but the hijackings to Cuba were like, so Congress said, we got to stop this. The only way we can do it is maybe we can x-ray your luggage. Okay. So does anyone have an x-ray machine that we can just drag into here and do this, right?

That's not so large like you find in the hospital. Astrophysicists of the early 1970s had just miniaturized X-ray detectors to put into satellites to observe the universe in the X-ray part of the spectrum. into satellites to observe the universe in the x-ray part of the spectrum. Because black holes and matter swirling in down the throat of a black hole just before it goes to die radiates x-rays. And we calculated this and we knew this and we said, we're going to find black holes in the universe. We need an x-ray telescope.

Well, the x-ray machines are huge. We need an X-ray telescope. Well, the X-ray machines are huge. Then we got to make them smaller to fit into the orbiting satellite. Get them in space, right? And so a company called American Science and Engineering, based in Cambridge, Massachusetts, okay, pioneered small X-ray detectors. And then they got tapped by the government and say, will you bring those into every airport in the country, every international airport? And thus was born X-ray detectors at airports because of astrophysicists. Now, were any of these astrophysicists also hijacking planes?

Because I can see a connection. Oh, the conspiracy theories. Okay. And one of the leaders of that was a guy named Ricardo Giacconi. And he was also a professor, a scientist up at the Harvard College Observatory, the Smithsonian Astrophysical Observatory. Today, it's just called the Center for Astrophysics. And when I was an undergraduate there, I worked in his group, the X-ray group.

We did some things. All right. And he would later be given the Nobel Prize for pioneering X-ray, opening up an entire new window on the universe, X-ray astronomy. So, and another cool thing is I would later be tapped by the White House to serve on a committee to give out the Presidential Medal of Science. Okay. Oh.

And this is under the George W. Bush White House. So I'm there and we get invited to the ceremony. So I'm ready to enter the White House. And he's, oh, we awarded it to him. He'd already gotten the Nobel Prize. Dude, give him the Presidential Medal of Science. Exactly. So. A little bit of a letdown. Into the Nobel Prize. Dude, give him the Presidential Medal of Science. Right, exactly. So he's coming into the...

Right, I know, I know. But so he comes in, and he's going through this, there's this house you have to walk through before you get to the White House, and that's where all the security measures are. So he's walking through, and I can't help but notice the White House is using an American science and engineering X-ray detector. Wow.

This guy invented it. It was his company. It's his company. That's pretty cool. And I tell you what, we have come full circle here. That's so funny. It's like the guy who made the thing that you're using for security is the ultimate security risk. Because he knows all the back doors if there is any. Because he would know what...

Because he knows all the back doors if there is any. Because he invented, he knows what... Yeah, exactly. That would be the case. If he's using his machine... He'll know how to get around anything in his own invention. If he had come to the White House when I was head of security, I'd be like, no, get that guy up against the wall,

full pat down, full pat down. That's right, everything, we got to make sure sure this guy knows how to hide stuff believe me so anyway so when you go through they're not asne detectors anymore but that was the birth of that entire movement and it was astrophysicist serving our needs happen to also serve the needs of the government by the way i retell that story uh in my book um accessory to the war the unspoken alliance between astrophysics and the military and more broadly it's between astrophysics and security but anyhow so you go through there and a lot of airports i'd like they have mosaics in the floor i just and i thought i have a little photo essay i might might publish it one day. And it's the birth of flight. It might have some rockets. It's got the night sky and it's usually

some interpretation of it. So I look down as much as I look forward when I'm walking through airports just to see what the mosaics are. The only time when you'll hear Neil deGrasse Tyson say, keep looking down. So, Chuck, so the interesting thing about x-rays, we think of them as penetrating through objects, right? Special kind of light energy. But it's not as weird as you think. Okay.

Okay? You realize visible light penetrates glass. Okay. Okay. That's why windows are made of glass. Okay. I mean, listen, I know that that was a scientific stretch, but. Okay.

But wait a minute. But let's keep going here. Do you know that glass blocks x-rays and high-energy light? Okay. All right, now we're doing something. So not all substances are transparent to all bands of light. Okay. That's all I'm trying to say.

I got you. Okay. So microwaves, which is what your phone use to communicate. Right. They clearly pass through walls. Yep. Because when you go indoors, you can still use your cell phone. I mean, unless, of course, you have Sprint.

I mean. No. Stop. I mean, then, you know, give it up. Stop. You know what I mean? Like, oh, my God. How would I?

They go Sprint as a sponsor of StarTalk. Yeah, yeah, exactly. I'm roaming in the kitchen, but not in the living room. What? Okay.

So, so microarrays pass through walls that are otherwise opaque to you. So the fact that x-rays go through like luggage and things and human flesh, you know, you know what x-rays don't really go through? They don't really go through your bones. I was about to say, why don't you, if you really want to fool an x-ray,

just make everything out of human bones. No, no, no, no, no. So it does not go through bones, so bones cast a shadow on what it is they're trying to view. Ah, so really you're not seeing the bones themselves. You're not seeing the bone. You're seeing the fact that the x-ray went everywhere else except the bones. Right.

Exactly. So it's like when you stand in front of the sun and you do a puppet, you know, on the ground, a shadow puppet. It's really just the, you know, it's not the image of your hand. It's the absence of your hand. Correct. Right. of your hand, it's the absence of your hand. Correct. It is it is you're giving meaning to the absence of sunlight. Right.

Where your hands had blocked the photons. Exactly. From hitting the sand. Right. So that's what's happening. Yeah, yeah. That's cool. That's cool. When Wilhelm Lutzen discovered x-rays and he put his hand in front of it and he saw that there are the, he saw the bones. He could barely see the flesh because it went right through his flesh.

Right. Okay. When you're looking out a window, you're not looking at the window. You're looking at what's beyond the window. Okay. So he's looking at, he doesn't see the, he sees the bones because the x-rays were absorbed by the bones and he also think i saw his wedding ring or something which absorbed even more x-rays and it was like pitch black and rather than sort of grayish please do not ask why his wedding ring was made out of human bone

he's a weird kinky man that bill hem in fact in all the rest of the world they call run engine rays rather than x-rays um but yeah yeah yeah so uh point is uh x-rays are useful for looking through your luggage and finding things that you might make a weapon out of typically out of metal but they will not find weapons made out of things that are not metal and are otherwise transparent to plastic, like, um, a plastic gun, right? If you make a plastic gun, it's not, it's not gonna find it in the same way. It would reveal a, a, um, a metal gun.

So here's what you can do now. Big time controversy on that too about printable guns. Correct. Correct. So here's an interesting thing you can do. Like you said, like I noted, the bone does not completely block the x-rays. It just blocks more x-rays than your flesh does. So it casts its own mild shadow in the photograph. Okay. If you have

different frequencies of light and you interplay them, you can see what the trend line is in the thing's attempt to absorb it or not. And once you do that, you're better at detecting what could be in the suitcase if you move the frequencies back and forth. But what they also do is they attach color. This is the literal use of false color, where you attach a color to the edges of signals that are shown up in the image, in the X-ray image. Because your eye picks up color much better than it picks up tiny changes in a grayscale shading. Right.

All right? So if I say anything grayer than this level, make it red, and anything less gray than that, make it blue, your eye, boom! I see red and blue as two completely separate things rather than as the continuum that it is. So the folks back there, the TSA, they have a fascinating task ahead of them to identify objects and shapes and, and, and, and highlight them in ways that it makes it easy for the person looking through person looking at your luggage rather than harder.

Right. And so, yeah. Yeah, that's super cool. And I wonder, do they assign a special color to sex toys? Because they tend to somehow find them all the time. I've never seen this ever happen. Is this you trying to pull sex toys through the security? I'm just saying, I don't know how every time it, you know.

You heard that this happened. This is what I heard. That somehow they're just like, got to check that one. And it's just like, nope, just another sex toy. Sorry, everyone. Everything's great. Okay. This guy here.

No reason to be alarmed this guy right there's another tech sex dog so you're free to go with your sex toy and by the way those the those flappy things at the entrance where your luggage into the machine yes they're like have heavy metal particles in them so the x-rays don't come out so don't reach in there

because it's trying to shield you from the x-rays don't come out so don't reach in there because it's trying to shield you from the x-rays that would otherwise leak out of that hole nice there you go well that is super i have to tell you i will never look at the x-ray machine again the same way that's what i'm saying and i want you to think of astrophysicist when you do and And I will now, which I have never done before. I can say that with a... X-rays are just another band of light that comes to us from the depths of space

that humans on Earth with excellent engineering has exploited for all manner of social, cultural, geopolitical purposes. Look at that. Thank you, Wilhelm.

Time for a break. But when we come back, we will continue stuff you thought you knew on StarTalk. We're back. One of my favorite segments, things you thought you knew.

Let's continue. Chuck, I got some more explaining to do. Oh. Okay. I feel like that's it. I feel like, I don't know. Lucy. Lucy.

Lucy, you got some explaining to do. Yeah, yeah. So, some long ago sometime, I think we talked about the rocket equation. I want to talk about that again, but then take us into space with it and talk about some other stuff as well. Okay, so you ready? All right. Blast off.

There you go. All right. So, if you're going to drive from New York to California. Right, which I'm never going to do. And you have an internal combustion engine car. Right. They're called ICE cars in the lingo, by the way. Internal combustion engine.

You fill up the tank with gas until it's empty. Right. And then you fill it up again. Correct. And then you fill it up again until you get to California. Right. You have convenient filling stations along the way. All along the way.

Just little daggers in the heart of the earth all along the way. Now, if you didn't have those, you would need a single tank big enough to get you to California. A single tank. Right. Okay. So, we have to ask, what does that tank weigh? All right. Now, if that tank weighs as much as the car, and then some maybe, then the fuel you're burning in New York, part of that is just simply to move the car that's filled with fuel you haven't burned yet.

Right. Exactly. Such is the challenge with rockets. Because we don't have filling stations in space, every ounce of fuel you burn is to get the next ounce of fuel higher up so that it could then burn afterwards. Okay? Right.

So let's run a quick mathematical example. You ready? Okay. Okay? If I tell you it takes one pound of fuel to put one pound of payload into orbit, you ready? Okay, you got that? Right. Okay?

You with me? Okay. Stay with me. One pound of fuel for one pound of payload. One pound of payload into one pound of payload. One pound of fuel to put one pound of payload into order. All right. Suppose I want to put two pounds of payload. I'm going to need two pounds of fuel.

No. You're going to need a pound of fuel for each of those pounds. Damn. I need the fuel for the fuel. I need fuel for the fuel. Damn. You need fuel for the fuel. I need fuel for the fuel. Damn, you need fuel for the fuel. So I need a pound of fuel for the pound, a pound of fuel for the fuel.

For the fuel, okay. So now that's three pounds of fuel. Fuel, right. To get one. Two pounds into orbit. Two pounds, right. Now let's go three pounds of payload. Okay?

Right. So there's a pound each for each of those. That's three pounds. Right. Okay. Plus a pound of fuel for each of those three pounds of fuel. So I need six. Okay. But wait.

Then, am I saying this right now? Then you need a pound of fuel for the fuel that's going to get the three pounds of fuel into orbit. The point is, whether or not I even explained that accurately, you get the point here. explain that accurately. You get the point here. The point here is that the amount of fuel you need for every increment of payload grows exponentially. And it's a famous equation called the rocket equation. Right.

That's why if you saw the launch of either the Apollo missions, if you're an old-timer, or the recent Artemis missions, you see this huge rocket. And way at the top is the Orion capsule, the service module and the capsule. It's the little thing at the top. And everything else is fuel. Because that has to go not only to Earth orbit,

but to the moon and back and the astronauts or the payload plus whatever the hell else they've taken up there. So the rocket equation, you need calculus to do that correctly. So the, so a more realistic calculation would be 10 pounds of fuel for one pound in orbit of payload, right? more realistic so now two pounds is one is you need 10 pounds for that extra pound of fuel plus 10 pounds of fuel for the 10 pounds of fuel they got the other pound of fuel crazy so it's crazy it's completely Okay, so now here's an interesting fact. Okay. When you burn your gasoline, okay, how does it turn into energy? Do you remember? There's a small spark.

It turns into an explosion. It pushes a piston. It's a spark. Right. Correct. And the explosion is the gasoline plus what? They infuse it with air or something. Like, it becomes a fuel.

And what's in the air? Oxygen. Yeah, yeah. So the air, what's in the air? Oxygen. Thank you. So you have gasoline plus oxygen makes energy, okay? When it burns.

Gotcha. You got the oxygen for free. It's just sitting there in the air. Right. Okay. If I have a rocket, I want it to leave the air. If I'm leaving the air, I don't have oxygen. Oh, no.

I have to bring the oxygen with me. Well, this is getting more expensive all the time. Okay. So, here you go. So, do you remember the Artemis and the space shuttle has two solid rocket boosters on the side? Right. Okay. The two boosters, and then it releases them.

Right. Those two boosters on the side. Right. Okay. The two boosters and then it releases them. All right. Right. Those two boosters burn air with their mixture. When the rocket gets high enough, they're done. We can't have them trying to work where there is little air because what's the point of that? So you get to use the free air to launch the rocket at its lowest level through the atmosphere where there's plenty of oxygen. Right. Then they drop away and anything that happens after that needs its own oxidizer.

And the fuel tanks that not only started burning at the base on the launch pad but continue in orbit is the larger tank that has two tank containers. One of them holds hydrogen. The other holds oxygen. And the hydrogen tank is twice as big as the oxygen tank. Okay. So when I mix them, what's the mixture? That sounds a little bit like h2o oh well yes so when i mix hydrogen

and oxygen it is highly exothermic meaning it releases tons of energy and the and the and the And the exhaust is water. Oh, wow. Water. Water. So we have this incredible, you know, propellant that the byproduct is water. Yes. Why doesn't everything run on that? I love the gears are going in Chuck's head. I'm just saying. Okay. Okay.

There isn't hydrogen just laying around. I got you. But it's everywhere in water, but pure hydrogen is just so you have to get the hydrogen. So you're going to get it from the water to begin with. And guess how much energy it takes to separate the H2 from the O? More than it does to put a rock in it.

So the energy it takes to separate the hydrogen oxygen is slightly more than you're going to get back by recombining the hydrogen and the oxygen. I see. Yeah. So, it's not quite an equal thing, but that's how you get your hydrogen fuel. It sucks. It totally sucks. That sucks. And where are you going to get that energy from?

Is it an oil plant or whatever? Right. You can use solar power to do that, by the way. But I'm just saying, there's no such thing as a free lunch. There you have it. That's all. Wow. There you have it.

So, by the way, they use liquid hydrogen and liquid oxygen because it's much denser. You get way more fuel than if it's just gaseous hydrogen and gaseous oxygen. But liquid hydrogen is liquid at like four, is that? I forgot the number, but low single digit Kelvin temperature. Oh, wow. Okay. We got a whole other explainer on Kelvin. Low single digits.

So the whole thing is chilled and that's why you look at some launch um videos of of the saturn 5 rocket you see this ice oh yes the sides yes it's florida where the hell's the ice come from right because this stuff is cold all right keeping liquid oxygen and liquid hydrogen so that when they combine you have the maximum number of molecules to do it, get the maximum amount of exothermic reaction, and you get the maximum thrust. And according to Newton, you cannot move forward unless you spew something else back out the other side. Normally, for me, it's hatred.

Hatred. I'm glad you said that instead of flatulence. Otherwise, you could have... That was was my first thought but I was like let's go a little deeper let's be a little more mature so the point is unless you have friction to help

propel you forward if you're just trying to move through space or through the air something has to come out the back so that you propel forward for every action is an equal and opposite reaction and that's why you have this huge plume coming out the other side and so this that's the rockets 101 for you that's very cool just saying Just saying. Very cool. And all that began like in the early 20th century.

So the Russian who did this early 20th century is Tsiolkovsky. I always mangle the name. Tsiolkovsky. There we go. I think I did that right. He first wrote down the rocket equation and Russia didn't look back. And so the Russians had the rocket equation.

They had Sputnik they had Laika the first mammal they had the first astronaut so they beat us at everything except for landing on the moon

you know we land on the moon say we win of course they beat us at everything else all right so this has been

another Star Talk a Things You Thought You Knew edition I thank my co-host Chuck always a pleasure I'm Neil deGrasse Tyson. As always, I bid you to keep looking up.