Why We Should Put Rockets On the Moon Warum wir Raketen auf den Mond schicken sollten Por qué deberíamos poner cohetes en la Luna Pourquoi nous devrions envoyer des fusées sur la Lune Perché dovremmo mettere dei razzi sulla Luna 月面にロケットを設置すべき理由 달에 로켓을 띄워야 하는 이유 Kodėl turėtume paleisti raketas į Mėnulį Waarom we raketten op de maan moeten zetten Porque é que devemos colocar foguetões na Lua Почему мы должны поставить ракеты на Луну Neden Ay'a Roket Göndermeliyiz? 为什么我们应该把火箭送上月球 為什麼我們應該把火箭送上月球

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Hey smart people, Joe here.

I'm here with Don Pettit you probably recognize this guy.

He's my favorite astronaut that I know.

Hold on Joe, you only know one astronaut.

That's not important,

you're still my favorite.

Last time that I was here, we were hanging out, we were De laatste keer dat ik hier was, waren we aan het rondhangen, we waren

talking about how to drink coffee in space and the cool invention that you

made to do that, and and when we were done I walked over here to this building hecho para hacer eso, y cuando terminamos caminé hasta aquí a este edificio

to check out this thing.

This is a Saturn five.

It made me think when I was sitting in here looking at the size of

this thing, because until you're standing up next to this thing, you just do not

have a sense of how massive the Saturn 5 is.

It took all of this to get just this little bit to the moon and back.

That's the command module. Ese es el módulo de mando. Dat is de commandomodule.

So why did it take all of that to do this. Entonces, ¿por qué hizo falta todo eso para hacer esto?

That's called the rocket equation.

Oh I was told there would be no math. Oh, me dijeron que no habría matemáticas.

So there's a famous saying: the dinosaurs went extinct because they didn't have a Así que hay un dicho famoso: los dinosaurios se extinguieron porque no tenían un

space program.

But we do!

Half a century ago, astronauts got in a rocket a lot like this one to send this tiny little

bit up here on a 384,000 km trip to the moon and back.

And they were able to do it because a lot of extremely smart and dedicated people pushed

engineering and chemistry to the limits to create a 36-story tower of carefully-controlled ingeniería y la química al límite para crear una torre de 36 pisos de

space fire powerful enough to escape this… fuego espacial lo suficientemente potente como para escapar de este...

…this is Earth's gravity well.

This is a way to visualize how anything in the universe with mass causes spacetime itself Esta es una manera de visualizar cómo cualquier cosa en el universo con masa causa el propio espaciotiempo

to warp, bending or attracting any other thing with mass. deformar, doblar o atraer cualquier otra cosa con masa.

The more massive the object, the deeper the gravity well, and… well, if you don't Cuanto más masivo sea el objeto, más profundo será el pozo gravitatorio, y... bueno, si no

expend enough energy, you're trapped inside the well, unable to escape.

Fortunately, rockets are excellent energy-expending, gravitational well escape devices. Afortunadamente, los cohetes son excelentes dispositivos de escape de pozos gravitatorios que gastan energía.

But the ability of a rocket to escape a gravitational trap–or not–depends on some basic rules

of physics and chemistry.

And these rules…

…are written down in the Rocket Equation.

The rocket equation deals with moving from point A to point B in a gravitational

field.

And it tells you how much propellant you need in order to do that, compared with how much

your total rocket weighs.

Let's explain this idea of “mass fraction” real quick.

Take a typical gas burning car.

You don't need very much gas in the tank, compared to the total mass of the car, to

get from point A to point B down here on Earth

I'm on my way to Houston to talk to Don the astronaut… but you already knew that

because you're watching the video right now… but the point is, this car, its total

weight is only 3-4-5% fuel.

But that airplane… that's 30-40% fuel.

JH: What percentage is this thing fuel? JH: ¿Qué porcentaje es este combustible cosa?

DP: A rocket, per the rocket equation, is 85 to 90 percent propellant, which means everything DP: Un cohete, por la ecuación de cohetes, es 85 a 90 por ciento de propelente, lo que significa que todo

you see here as this rocket, is only 10 to 15% of the mass of the total vehicle.

And that 10-15% is the entire structure of the rocket.

The people, life support, and all the cool science stuff we want to carry into space?

They're only 1% of the mass of the total rocket, propellant and all. Son sólo el 1% de la masa total del cohete, con propulsor y todo.

JH: So it takes 99% of the mass of this thing to get the 1% of cool important space stuff

up there.

DP: That's correct.

So this is the Rocket Equation, a simplified version of it anyway.

It was figured out by a Russian rocket scientist named Konstantin Tsiolkovsky.

Don't be scared by how mathematical this looks. No te asustes por lo matemático que parece.

It's actually pretty easy to understand.

e is just a mathematical constant, it's roughly

2.72 or so.

And what this means is that when there's an explosion here, how much of that energy

is directed to the rocket going this way.

We lose some of that explosion energy to things like friction, heat, engine efficiency and,

most importantly, gravity.

And since this is all an exponent, it means that if we increase the strength of the gravity En aangezien dit allemaal een exponent is, betekent het dat als we de zwaartekracht vergroten...

field we're in, this number goes up really quickly.

Like compound interest.

And that means the ratio of your rocket that has to be propellant goes up really quickly.

The stronger the gravitational field, you pretty quickly find that you need a lot of

rocket to get a little bit of stuff out of your gravity well and up into space. cohete para sacar un poco de material de su pozo gravitatorio y llevarlo al espacio.

So, if you're in the business of engineering rockets, what can you do?

DP: To get off the planet Earth, you've got the gravity of Earth… and we're not

gonna change that.

And then you have the energy in your rocket propellant, and once you max out what is possible Y luego tienes la energía en el propulsor de tu cohete, y una vez que maximizas lo que es posible

with chemistry, then there isn't anymore. con química, entonces ya no la hay.

That's it? ¿Eso es todo?

That's it.

You max out the energy density, and you plug it in the rocket equation, and you have Si maximizas la densidad de energía y la introduces en la ecuación del cohete, tendrás

to abide by what it says. para cumplir lo que dice.

Think about that.

A rocket is basically a way to take the energy stored inside chemical bonds and use it to

crawl out from the bottom of our gravity well. salir del fondo de nuestro pozo gravitatorio.

So rocket science isn't just physics.

We have to fiddle with chemistry too. También tenemos que jugar con la química.

We have 4, maybe 5 classes of rocket propellants to choose from these days, just a handful

of chemical options to try and nudge the rocket equation in our favor.

So the universe has set the rules, and we're just playing the game.

That's one of the best ways of describing it.

I call it the “tyranny of the rocket equation”.

Now I love talking to Don because I like how his brain works.

He understands the rocket equation in precise mathematical detail.

But he's also able to engage his imagination, and use this knowledge to answer unexpected Pero también es capaz de utilizar su imaginación y sus conocimientos para responder a preguntas inesperadas.

questions, like what would our space program look like if we lived on a slightly different

planet.

Say you increase the size of Earth, so Earth's gravitational constant increases.

If Earth were about 10 percent, maybe 15 percent bigger, we would not be able to make a rocket

to carry any useful payload into space. para llevar cualquier carga útil al espacio.

In essence, we could not get off this planet.

This is shocking news.

Huge new developments.

This makes me think of something: Do you think there could be alien planets, extraterrestrial

civilizations, who just live on planets that are too big for them to get off of?

The sky's not the limit! ¡El cielo no es el límite!

Whew. Uf.

Gravity is.

The tyranny of the rocket equation is also the main thing separating us from making x-wings La tiranía de la ecuación del cohete es también lo principal que nos separa de hacer alas x

and Enterprises in real life.

As long as we're using chemistry for our rockets, we're engineering rockets at the

edge of what is possible in order to escape Earth's gravity well  But what if we could

find somewhere else nearby with a smaller gravity well we could fuel up? ¿encontrar otro lugar cercano con un pozo gravitatorio más pequeño donde repostar?

Hmm… what could that be? Hmm... ¿qué podría ser?

There's a lot of talk about going back to the moon.

You wanna go?

Oh, I'd go the moon in a nanosecond!

It would take you a little bit longer than a nanosecond.

Yeah, it takes 3 to 5 days to get to the moon.

But it's an enabler for allowing humans to expand into other places in our solar system. Pero es un medio para permitir a los humanos expandirse a otros lugares de nuestro sistema solar.

A rocket scientist named Krafft Ehricke Un científico de cohetes llamado Krafft Ehricke

made one of my favorite quotes:  “If god intended man to be a spacefaring hizo una de mis citas favoritas: "Si Dios quiso que el hombre fuera un astronauta... maakte een van mijn favoriete citaten: "Als god de mens als een ruimtevaarder had bedoeld"

species, he would have given us a moon” If Earth had no moon, next stop past Earth

would be Venus or Mars, both very difficult to go right out of the box. serían Venus o Marte, ambos muy difíciles de salir de la caja.

The moon, 3 to 5 days away, there are resources we can use,

What kind of resources?

Primarily propellant.

Imagine if you could make your rocket propellant from resources you find on the moon.

What can you make rocket fuel out of that you can find on the moon? ¿Con qué se puede fabricar combustible para cohetes que se pueda encontrar en la Luna?

You can't make it out of rocks.

Water!

There's water on the moon?

There's water on the moon!

We didn't know this during the Apollo era, but now we have verified there is water on

the moon, significant quantities of water on the moon.

Water is found throughout the rocky planets where human beings would be interested in

exploring.

So if you make rocket propellant systems based on hydrogen and oxygen, you will at least

in concept be able to refuel your rockets almost anywhere you want to go in our solar

system.

So right now, would we have the ability

to launch a rocket from Earth with people on it and point it directly at Mars?

Or is that just really really hard?

Yeah, it's tough to do that.

It would take a lot of propellant to go from Low Earth Orbit straight to Mars and back

again, would require 8-12 Saturn V launches just to stage one mission. de nuevo, requeriría de 8 a 12 lanzamientos del Saturno V sólo para llevar a cabo una misión.

Wow.

That's basically the whole Apollo program for just one mission to Mars.

And here's where a little bit of imagination,

combined with the science we've just learned, can show us a solution to another interesting

problem.

Now remember how different vehicles require a different fraction of propellant compared

to their total mass to go from point A to point B?

A car is a few percent, an airplane is 30 to 40 percent, and a rocket is more than 80

percent.

This number is so high because…

…Earth is a really hard gravity hole to get out of.

But the moon is a much smaller gravity hole to escape from.

Launch your rocket from lunar gravity, and according to the rocket equation it only has

to be about 30 to 40 percent propellant…

…and 30 to 40 percent propellant is less like the Saturn V, and more like the aviation

industry here on Earth, and we're already pretty good at engineering planes.

The dinosaurs got stuck down here.

To explore the rest of the solar system, like centuries of explorers before us, we need Para explorar el resto del sistema solar, como hicieron siglos de exploradores antes que nosotros, necesitamos

to cross over this one tall hill so we can see what's on the other side.

And we've got a much easier climb ahead of us if we start from the moon. Y tenemos una escalada mucho más fácil por delante si empezamos desde la Luna.

Sounds like a pretty good reason to go back, and even stay for a while.

And you'll get to see some cool rocks while you're up there too. Además, podrás ver algunas rocas preciosas mientras estás allí arriba.

You'll see some cool rocks.

Stay curious.