Rocket Scientists Answer Questions From Twitter

I'm Tiera Fletcher.

And I'm Myron Fletcher.

We are rocket scientists.

And today, we'll be answering your questions from Twitter.

[Both] This is, Rocket Support.

[upbeat music]

@BaitMasterOG.

Why do rocket ships launch straight up

instead of at an angle like a plane?

It's because, the way thrust is propelled out of rockets.

If you launch the rocket sideways,

you wouldn't have the counteraction of the ground

being able to push from.

The hardest part about launching a rocket

is truly getting off the ground.

So that's when you're experiencing

your greatest amount of gravity

and that's when you need the greatest amount of thrust.

A rocket takes off straight like this

but once it's in the air,

we can use thrust factor controls

to turn the rocket in any direction

that we would like for it to go in.

So it doesn't go straight out

of the Earth's atmosphere like this,

it actually comes in at an inclination like this.

Rotations are like this, they're not like this.

And so in order to get out of a rotation,

it's better to go with the rotation

than trying to go through the rotation.

And so therefore,

rockets will have an inclination

to go out sideways versus straightforward.

@polakowskig66 asks,

What is the skinny on Mr. Musk's new rocket engine?

So the Raptor 2 engine produces about

510,000 pounds of thrust.

And this is actually comparable

to the RS-25 engines that are used

for the Space Launch System.

They will be utilized for the Starship.

The Starship is a super heavy launch vehicle

produced by SpaceX.

And I know that for Elon Musk,

he has a huge goal of going to Mars.

So the Starship would be the vehicle

to achieve that goal for him.

It's predicted to have about 33 of these rocket engines.

So, looking at about 17 million pounds of thrust

that'll be produced from the Starship.

So that's a major difference from the Space Launch System,

which produces about 8.8 million pounds of thrust.

SOS only uses four engines,

where Starship would use 33 engines.

And so, if they can figure out how to get all those engines

to fire off at the same time every time,

they're gonna have a very, very

powerful rocket on their hands.

So the Starship could take the crown

for the most powerful rocket in history.

@somebodyhelloli, What are parts of a rocket?

Well, a simple rocket consists of a structural system,

which would include your nose cone and your fins.

As well as a propulsive system, right.

So a small engine that would go inside

of a model rocket for instance.

The reasons you have fins,

is because these fins causes the rocket to be stable.

And so this fin actually causes downforce to take place.

Now, when you're talking about a more complex rocket,

such as NASA's Space Launch System,

you are looking at a propulsive system

but your propulsive system is going to include these

solid rocket boosters here,

which includes solid propellant.

And those solid rocket boosters might look familiar.

They're actually from the space shuttle program,

just a little bit modified,

another section has been added to 'em.

And the solid rockets are important

because they provide about 90% of the thrust

needed to get spaceline system off the ground.

But then you also have a liquid propellant

in the form of liquid hydrogen and liquid oxygen.

But then here you're wondering where would the astronauts

or the payloads go?

Inside of the Orion capsule.

And that is where the Orion capsule sits

and together, you have your Space Launch System.

@Philip_Behn asks, May be a dumb question

but why are rocket engines that loud?

What exactly is making that sound?

So the thrust that these rockets are throwing out

is actually going past the speed of sound.

And because it's going past the speed of sound,

it creates these whiplashes, are known as shockwaves.

These shockwaves then cause rumbles to happen

and vibrations to take place and all of this together,

creates the noise and that's why it's so loud.

@Ianvincentscott asks,

So what fuel is powering the rocket ship

that NASA is sending to the moon?

NASA Space Launch System is using liquid hydrogen

and liquid oxygen.

Now, very, very cold liquid, normally known as cryogenic,

423 degrees Fahrenheit for liquid hydrogen

and -297 degrees for liquid oxygen.

When you combine those two with the fuel and the oxidizer,

you get combustion, called thrust

and you get about 2 million pounds of thrust

out of those systems.

The solid rocket boosters

are made up of proprietary material.

And that material is a hard material that is lit together

from the inside out,

which creates thrusts for those solid rocket boosters.

@ThePhysicsMemes asks, How do rockets burn fuel in space

if there isn't oxygen in space?

In the combustion chamber, you have the fuel

and a oxygen, when they meet each other,

that's called combustion.

That combustion causes thrusts.

In order for combustion to take place, you need oxygen.

A rocket actually has its own fuel and oxidizer on board.

Even though there isn't oxygen in space,

it brings its own oxygen source with it.

@Deelusi asks, What makes a rocket a rocket?

Is there a guideline?

Does it need to go to space?

A rocket is anything that is a structure

with a propulsive system and a nose cone.

A prime example of a great rocket would be a firecracker.

A firecracker is a rocket

because it has a propulsion system.

@Mo_Artwell asks, Why build the other parts

of a rocket ship if they are going to separate mid-air

and where do the remnants fall?

Your powerful rockets that are heading into space,

they are actually multi-stage.

So once a stage is completely depleted of its fuel,

you no longer need it,

so these two particular solid rocket boosters,

they're the first to fall off for the Space Launch System.

And then you have the core stage,

the liquid hydrogen and the liquid oxygen.

Once those are completely depleted,

you no longer need this entire core stage.

Where do those pieces fall?

Typically into the ocean.

Anything that's close to the coast

was the best place to shoot off a rocket.

Most parts that land into the ocean,

there aren't reusable parts.

But now they're actually landing those parts

on space barges, which are reusable.

@DeeKooi_23 asks, How to rockets land

like, don't they just go straight up and down?

Yeah, there are a few companies right now

that are using reusable rockets

that are causing them to land back on the earth.

Blue Origin and SpaceX are two prime examples.

Their rockets will launch off into the atmosphere

and then they'll send their payloads off into deep space

and then the actual booster parts will come back down

to Earth safely and they'll actually cause thrust

to come out of the rocket right before it lands,

causing it to slow down and give it a cushion.

It's a very complicated process to make that happen.

Very, very.

It's like causing a pencil to land on its eraser.

@Real_MarkRidley, How do rockets get built?

For large rockets such as the Space Launch System,

it truly is a nationwide effort

and also even international.

Where it takes thousands of suppliers coming together

in order to get this one rocket built.

You gotta start at the component level.

That the parts that you can physically see and touch

and some that you can't physically see and touch.

Those parts are built at suppliers all over America.

Once they're tested, they're all shipped down to

Michoud Assembly Facility in New Orleans.

And in New Orleans you have a group of test engineers

and production engineers,

who actually put the parts together.

And once they're put together,

we then send it over to Stennis in Mississippi,

where we actually hot fire the rocket.

And that's where we run a full duration test,

with liquid hydrogen and liquid oxygen.

Once that test is completed

and the NASA engineers are happy,

we then shoot it over to Kennedy Space Center.

There we actually put it on a launch stand and from there

we actually cause the rocket to go into space.

And those are the steps to how you build a rocket

@sid_thinketh asks, What will be the next huge

revolutionary advancement in rocket propulsion?

Warp drive?

Nuclear propulsion?

Go ahead propulsion guy.

We currently have nuclear propulsion systems.

Nuclear propulsion sounds great

but let's just wait until we start shooting a bunch of nukes

in the air

and figure out if other countries don't get mad about it.

So based on the theoretical limits

that we've studied so far, there is a possibility

that one day we might be able to travel at light speed.

We possibly can with fusion technology.

So there are technologies that are out there

that are currently still being developed.

They're on very small scales right now.

But one day they'll be commercially available

and we might have warp drop in our own lifetime.

One thing that's critical here,

that you have to counter for, is human factors.

Body can only withstand so much gravity.

And so when you start exerting that amount of pressure

and that amount of energy on the body,

the technologies might be there to propel us

to go light speed but can our bodies withstand that speed?

That is an interesting handle.

I'm gonna try, @dvanremortal, Can rockets be used

to intercept asteroids and redirect them?

NASA actually completed a mission called, DART.

Double Asteroid Redirection Test.

To test and see if we can actually defend our planet.

And we successfully did.

When that probe hit the asteroid,

it actually caused the momentum to change of that asteroid,

which caused its orbit to slow down by 33 minutes

There could come a day

where a super huge asteroid comes our way.

So now we can use all of the momentum transfer data,

so we can figure out how big that spacecraft needs to be,

how fast it needs to go,

compared to whatever asteroid is coming our way.

@hulagangster asks, What's the difference

between rockets and ballistic missiles?

Rockets and ballistic missiles are built very similarly.

The only difference, is the payload.

The different payloads is, one is carrying humans

and the other one is carrying warheads.

@BlakemBand, What is harder,

rocket science or brain surgery?

Coming from a rocket scientist,

I think it's rocket science.

[both laugh]

Listen, brain surgery is difficult.

You are dealing with one of the most important organs

of the human body, so just one small centimeter

or even smaller than that,

you can literally disable someone.

You know with rocket science,

if you're off by one centimeter, by one micrometer,

you can cause catastrophic failures to take place.

Yeah, I do rocket science every day

and it is quite difficult,

so I just can't choose between the two.

They're both just hard.

@sheapayne14 asks, Like, why can't I just be like

Jimmy Neutron and just build rockets

in my backyard and stuff?

Well actually you can.

There's an entire society,

National Association of Rocketry,

all around the United States.

Amateurs are building rockets in their backyards.

And we ourselves, we actually build rockets

in our backyard all the time.

Now, if the rocket happens to go above 3,218 feet,

you're gonna have to get a regulatory agreement

from the NAR society or these other societies,

to say that you can fly that rocket.

Otherwise, you might interfere with

somebody's passenger flight.

@tbieberbelieber asks, I'm confused!

What's the difference between a spaceship, space shuttle

and a rocket?

A shuttle, for instance is something that's gonna carry

humans into space and back down into earth.

That's why it's called a shuttle.

It literally carries humans in and out.

A spaceship could be used interchangeably

with the space shuttle but if you're talking about

a specific spaceship, you're usually talking about

something that's going in between different orbits.

A rocket is simply a structural body that you can launch,

it has a propulsion system.

So it can be your fireworks

or it could be the Space Launch System.

@nomanali7147, How do rockets or moon missions

get back to earth from the moon?

Let's say you have a spacecraft orbiting the moon,

then you reach a point where you want to return to earth.

You then need to understand what is the amount of thrust

or what is the amount of drag that I have to overcome

in order to escape this orbit?

When you come out of the moon's orbit,

it has its own gravitational force.

In order to come outta that orbit

you have to slingshot yourself out of that orbit.

So you use thrust in order to slingshot

out of the moon's orbit to get into Earth's orbit.

So you go from a lunar orbit

to a geosynchronous orbit, is what we call it.

And once you get into the geosynchronous orbit,

you decrease your speed so that you can come back to earth.

You slow down a spacecraft by using reverse thrusters.

Spacecrafts normally have thrusters

on the front and the back.

And so when you're going into these different orbits,

you will actually fire those reverse thrusters

to actually slow you down.

You then want to deploy parachutes so you can have as soft

of a landing as possible.

@angelyuqi asks, How do rockets know exactly where they

have to go?

Guidance, navigation and control.

And all those system coming together

and that's called control torque.

And that's also known as, gimbaling.

The gimbals are located at the front of the engines here.

These are RS-25 engines that are located

for the Space Launch System.

And by using gimbaling, we're able to slightly

move those engines on the order of about 10 to 12 degrees.

And we're able to slightly adjust the rocket

in such a way, to correct this trajectory as we see fit.

Just like a ship, right.

A ship is a really, really big object

and has a little bitty rudder,

that causes that ship to steer left and right.

It's the same way with the rocket.

320 feet tall and 10 degrees,

can cause a rocket to steer left and right.

@MikeSparreo asks, Who was Katherine Johnson?

Katherine Johnson was an amazing woman.

And she was one of the first African American women

to work work for NASA.

She was a mathematician.

She was responsible for doing the trajectories

for the Freedom 7 mission,

as well as the Friendship 7 mission,

as part of Project Mercury.

And those were actually our first human flights

for the United States of America.

@Space_science73 asks, So what is the coolest

rocket launch ever?

A little biased but NASA Space Launch System

is the most powerful rocket ever launched in history.

So it's my favorite.

What about you Myron?

I would say NASA Space Launch System as well.

The reason being, we had a very, very powerful rocket launch

and take a capsule as farthest we've ever sent it.

We've never sent a capsule that are gonna carry humans

as far as we've sent that capsule.

To me, that's the coolest thing that you can do

as a rocket scientist.

@AlectheDestroyr asks,

Yo how you become a rocket scientist?

So for us, it starts with a degree.

You go to school to become an aerospace engineer.

In this degree, you're gonna have to go through

calculus one, calculus two, calculus three,

differential equations, a lot of math.

And then you have to have the science part,

physics one, physics two.

But then you're go into orbital mechanics.

You're gonna have to study aerodynamics.

You're gonna have to study dynamics, statistics, statics.

And then you're also gonna study different things

like propulsion, computer aid and design

and different fields like that,

with aerospace engineering degree.

@LionelMedia asks, What was Operation Paperclip?

So Operation Paperclip was an intelligence operation

that took place to get a bunch of German scientists

over to the United States.

We got to pick their brains,

understand how they were building the V-2 rocket.

One of the German scientists that we brought over

was actually called Wernher von Braun

and he was the director of the Marshall Space Flight Center.

Now, he was a visionary.

He really wanted us to get to Mars.

And so the Saturn V was a bit overly built.

You can read more about it in The Mars Project

one of the books that he published in the 50s.

But he was definitely one of the founding fathers

of our space program.

@Interrobang_2 asks, Will humanity ever leave

the solar system?

Really, really good question.

So we've actually had spacecraft that actually have

left our solar system, Voyager 1 and Voyager 2.

Now Voyager 1 and 2 were launched back in the 70s

and they just now made it outside of the solar system.

So you can imagine, putting humans on a rocket

for 30, 40 years, how that'll turn out.

But, the possibility is definitely there.

Current propulsion technologies could expedite

that 40 or 50 year journey

but it's still a long way to go and those probes are

out there learning more about that environment

before we put a human into that space.

So those are all the questions for today.

Those were a lot of great questions

and if you're interested in learning more

about rocket science,

we definitely encourage you to pursue it.

Thanks for watching, Rocket Support.