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OUTLINE:
0:00 - Introduction
0:48 - SpaceX rockets
21:26 - Falcon 9
25:37 - Starship
29:57 - SpaceX rocket engines
37:35 - Elon Musk
53:10 - Twitter
59:15 - How rocket engines work
1:04:07 - Rocket fuel
1:07:33 - Rocket engine cycles
1:19:57 - Rocket cooling
1:34:54 - Multistage rockets
1:38:27 - Single-stage-to-orbit
1:44:03 - Aerospike engine
1:51:48 - Greatest car engine of all time
1:56:57 - Starship
1:59:48 - Wet dress rehearsal
2:05:59 - Landing
2:20:17 - Seeing starship in person
2:29:24 - Starship orbital test
2:36:02 - Gwynne Shotwell
2:41:12 - dearMoon project
3:00:16 - Fear of death
3:08:42 - Everyday Astronaut origin story
3:34:33 - Soviet Rocket Engine History
3:53:20 - Russia, China, USA
4:07:49 - Starlink
4:15:36 - First human on Mars
4:18:34 - Moon landing
4:24:41 - Nuclear propulsion
4:32:21 - Bob Lazar
4:39:24 - Aliens
4:43:11 - Sci-fi books
4:46:29 - Long-term space travel
4:53:17 - SpaceX competitors
5:04:37 - Kerbal Space Program
5:11:02 - Advice for young people

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And the nozzle, so as you're saying, there's a bunch of different design options, but it's a critical part of this, how you do that conversion.

how much can you convert is really like the ultimate game.

How much pressure and heat can we convert into thrust?

Like that's really at the end of the day, that's what a rocket engine is.

The following is a conversation with Tim Dodd, host of the Everyday Astronaut YouTube channel, where he educates and inspires all of us with detailed but accessible explanations of rocket engines and all things space travel.

To support it, please check out our sponsors in the description.

Can you give a brief history of SpaceX rockets?

So we got Falcon 1, Falcon 9, there's different versions of those, Falcon Heavy, Starship, and also the Dragon capsules and so on.

Well, yeah, Falcon 1 is where it all started.

The original intent and the original idea of SpaceX was Elon wanted to try to get something to Mars.

He saw that NASA didn't have a current Mars plan and he wanted to go to Mars.

He literally wanted to at first purchase a rocket from Russia.

Then after a foiled attempt at doing that, he decided that he was going to try to develop his own rocket.

And the Falcon 1 is what came out of that process.

And he developed a pretty incredible team.

I don't know how exactly he stumbled upon the team that he stumbled upon that quickly, but the people that he assembled were amazing.

And they built the Falcon 1, which was a single Merlin engine followed by an upper stage engine called the Kestrel engine.

Pretty small compared to the things they're working on today, but that Merlin engine continued to evolve into being the power plant for the Falcon 9.

They went from a small lift launch vehicle up into the medium class launch vehicle so they could provide services for NASA.

That's 1 of the big things they first kind of hung their hat up was they got the opportunity to fly cargo to the International Space Station under originally it was called the COTS program, the Commercial Orbital Transportation Services for NASA, which evolved into the commercial resupply contracts.

And that's when SpaceX developed both their Dragon capsule, which is a uncrewed at first spacecraft that can dock to the ISS, and the Falcon 9 rocket that can take it to the International Space Station.

And then- The Dragon rides on, it's the thing up top that rides on the

big booster thing that launches it into orbit.

The Falcon 9's the semi-truck, the Dragon capsule's the payload.

You know, it's the thing being dropped off basically at its destination.

In this case, the destination is the International Space Station.

And yeah, so they developed those relatively quickly and became a commercial success before you know it.

They're now the number 1 launch provider in the world, launching more mass to orbit than anybody else, launching more frequently than countries, like the entire country of China who's going crazy right now with launches.

Granted, China beat them by 2 launches this last, in

but prior year, SpaceX beat the entire country of China.

And just like you said, SpaceX still beats China even this year in terms of the amount of payload that was done.

That China had like 60 something, a couple more launches, but there was just like small CubeSat type of launches.

Exactly, some of them were literally like 100 kilograms or something, you know, like not large payloads.

And so SpaceX customers are different, so whoever wants to send payloads up into space.

Yes, but right now their biggest customer is actually themselves with Starlink.

1 of the biggest reasons they've launched so much mass to orbit is because Starlink is designed around the payload fairing and the payload capabilities of the Falcon 9 rocket.

So, you know, because they're vertically integrated, because they build their own satellites, because they're building their own rocket, they can literally design a system that's, you know, another manufacturer might have made a more square satellite that was heavier or something.

But SpaceX looked at it from a blank slate and said, here's our constraints, our payload mass constraints, our volume constraints.

Things like the size of a, you know, it's like a table folded up, which isn't anything I've, you know, really ever seen before.

So, but it's purpose built to fit as efficiently as possible inside their fairing and inside the capabilities of that rocket.

So therefore, because they're launching those like an insane amount, a dozen, 40, 50 times a year or whatever, they're just putting up insane amounts of mass like we've never seen before.

What about the different versions of Falcon

What are some interesting memories to you of the different developments in Falcon

The very first Falcon 9s had a square array of engines.

It had like a 3x3x3 grid of their Merlin 1 engines, the 1Ds.

I think it only lasted, I don't remember if it was 2 or 4 flights before they went into this octawave configuration where there's a ring of 8 engines with a center engine in the middle Still in the same diameter that the rocket was the fuselage was more or less the same 3.7 meter wide diameter But the the actual thrust structure changed and 1 of the big efficiency gains was you no longer have you know a corner engine and then like a edge engine and then another corner engine.

You can just make 8 of the same kind of part of the octa web, it's called, the same shape.

And then your interchangeability and your manufacturability becomes a lot simpler.

So that was kind of 1 of the bigger upgrades at first.

They kept stretching it every time they like touch this thing, it got longer and like, or taller and taller technically.

And then the next big feature that you saw in 2014 would have been they added landing legs to a Falcon 9 rocket, which was, I was at, that was the first launch I ever went to, was actually to see, it was CRS-3, so Commercial Resupply Mission 3, and it was probably their, God, I don't remember what that was, like, their 14th or 15th launch or something, like, pretty early on.

And people were literally laughing at the idea of them putting landing legs on it.

They're like, why are they wasting, why is this billionaire Elon Musk guy wasting his time trying to land a rocket?

So you said the Mars planet was there in the beginning.

I think reusability definitely, you know, it's a necessary part of making any kind of interplanetary mission, you know.

In order to actually do that just financially, you have to start reusing these things.

In terms of the development of the Falcon 1 and Falcon 9, how early on did the goal of reusing the rocket, having the rocket actually land, How early did that goal creep in?

I can't speak for Elon and SpaceX, but it was pretty, you know, immediately they wanted to try to recover.

very first 2 Falcon 9 rockets and Falcon 1, I think they even wanted to try to recover using parachutes to recover the first stage.

And now fast forward, you know, almost 20 years later and Rocket Lab is actually doing a concept like that where they're pulling a parachute after the first stage is reentering and they actually are trying to recover it with a helicopter, it's gonna try to snatch it out of the air.

They've actually done it successfully once.

it literally just grabs, snags onto the parachute.

So the rocket releases parachutes really high up.

There's so many interesting ideas and possibilities.

Like SpaceX basically just innovated a lot of different weird ideas just in the pursuit of making things more efficient, reusable, all of that.

So basically thinking from first principles how to solve this problem.

And so what you find is like you'll get all of these kind of crazy kind of solutions.

And with SpaceX, they weren't even getting to the point of the booster surviving reentry long enough to be able to pull the parachutes.

For instance, Rocket Lab uses carbon composite fuselage and tanks, or the same thing.

And that's very, very lightweight, has really good mass fractions, and therefore their drag coefficients and things like that, they were able to survive re-entry of the first stage, which is something that SpaceX wasn't able to do at the time.

What's the big, I think, breakthrough for SpaceX with reusing the booster is they realized we had to basically slow down before we hit the atmosphere.

So they actually do what they used to call a re-entry burn, which I still think is the correct term because it is re-entering the atmosphere.

But now they call it the entry burn, and they light up 3 of the 9 Merlin engines, not only to slow it down, but actually even while those engines are firing, it creates like a literal force field as it's falling through the atmosphere.

But it also decreases the velocity by almost half, or around half.

And then that therefore decreases the amount of, you know, the biggest thing with the atmosphere is that as it gets compressed against the front of anything flying through the atmosphere, the compressed atoms just get hot.

And they can get so hot they turn into a plasma, and they get so hot they can just absolutely destroy anything.

So they slow down enough that the air molecules don't end up destroying the vehicle on reentry.

And then they realize, I think at some point it's probably a similar crossover.

They're like, well, if we're lighting the engines already to slow down in the atmosphere, we can just use that same engine to land.

And so like, well, what if we just stuck landing legs on it and just landed the thing vertically?

And next thing you know is December 21st, 2015, they did exactly that for the first time.

So you were there before that then, right?

So that, and for me, that was so fun watching, you know, that was like the peak of me just becoming obsessed with this idea.

I'm watching with, like back in the day, it was like months between launches, you know?

To watch this landing attempt or whatever, you know?

And every, you know, there's CRS-4 almost landed, CRS-5 almost landed, CRS-6, CRS-7 blew up.

I was watching that on, I think it was like a Saturday morning, or maybe a Sunday morning, and I remember watching that and watched it blow up, and I was like, oh my god, now what?

CRS-7, the upper stage, had 1 of the bottles inside the tanks that are filled with helium, and 1 of those bottles broke off on ascent and actually just completely overpressured the upper stage.

And the upper stage blew up and the whole rocket went kaboom in an uncontrolled manner.

And so then they came back with vengeance.

When they came back, the first mission back is the first time that they landed a rocket, which was awesome.

So the return to flight after the anomaly was, yeah, was landing a rocket.

So the first time you were there, what was that like?

Just, I was surprised at how much bigger the rocket was than I imagined.

I was, I originally when I was going down to Kennedy Space Center, I was disappointed that I wasn't seeing like a, you know, I didn't know a ton about rockets.

I knew enough to like know what a space shuttle was, what like the Saturn V was, you know, but that was probably about the end of my knowledge.

I just remember being disappointed that I wasn't seeing a big quote unquote NASA rocket flying.

I was thinking in my head like, oh, I'm going to see this launch.

It's probably going to be like 3 stories tall or something.

Just some little skinny little stick and some little firecracker and yay.

I think I'd almost been pitched that too.

I think the people that I was working for at the time, I think they kind of were downplaying it as like, well, it's not a big rocket, it's not gonna be that exciting.

But we get out there to the pad and I'm like, this thing's huge.

And I think people forget the scale of that.

It might look skinny and tall and all this stuff, but it's still a very, very large piece of machinery.

It's physically about as large as you can ship, the booster's about as big as you can ship across the country, period, without completely shutting down highways.

It is made within those exact specifications of having lane privileges and bridges and everything.

It's 12 feet wide, 3.7 meters wide, and it's 45 meters long.

So it's like exactly what you can fit with a pretty standard, you know, like before you start getting into crazy amounts of problems shipping the rocket.

And so when I saw it with my own eyes, I remember just being like, this is so much cooler than I thought.

Is it hard to believe that that thing is gonna have to lift off the ground and launch up into the air?

Maybe that's the most humbling aspect of it, that something that size, humans have come up with a way to take something that size and launch it up into the air?

Yeah, there's certainly a very humbling aspect when you watch it actually leave.

What were the different experiences you first remember?

Well, ironically, I didn't end up getting to see that 1 fly.

I left my camera out there, like a remote triggered camera.

My first images as a launch photographer at the time was CRS-3, but I went home, it scrubbed too many times.

This is back in the day, they were scrubbing like often, and they'd be like a 3 day, 5 day, 7 day, you just never knew.

So I go home and I watch the live stream of it.

So I didn't even get to experience my first launch.

Anyone that's ever tried to go to a launch can probably empathize because, yeah, scrubs are very common in the spaceflight world.

So That 1 I didn't get to see, but since then, obviously, I've been able to attend very many launches.

How much do you understand the control involved in the landing?

I couldn't tell you a single thing about the code and the avionics behind it, but I can tell you all the hardware that makes it happen, if that helps.

Well, I mean, to me, it seems like whenever I talk to people, they say it's not that big of a deal in terms of the level of intelligence and the control.

But to me, it's just like when you observe it, it seems incredible, because all the variables involved, all the uncertainties involved, all the, because there's aerodynamics.

I mean, like there's different temperatures.

There's so much going on with the fuel, with the burning, the combustion, just everything that's going on to be able to perform control at such high stakes effectively, that code is probably not written in JavaScript, I guess is what I'm saying.

Actually, no, I don't, if I remember, again, this is well outside of my domain, but they're coding in a common language.

And that was 1 of the things that was weird is that Elon, when he started SpaceX, was like, we're just gonna code in the most common language so that we don't have to have people learn this archaic, weird thing.

And we can just literally pull people off the streets and be like, here, write it,

I mean, it'd be epic if it was like Python or something, but I don't, I think like reliable systems have to be written in C, C++ probably, which is a common language, which is something, I imagine like NASA engineers would probably have to use some kind of proprietary language in the olden days for security, for privacy, all that kind of stuff.

Oh, in the olden, old, old days, like they were inventing code and language from scratch.

It's just still incredible that it's able to do that.

Like just the feat of engineering involved is truly, it's like 1 of the marvels to observe about these rockets coming back to Earth that they're able to land.

Like the drama of it is just incredible to see.

Yeah, well, 1 of the fun things to remember too, with specifically the Falcon 9 and the Falcon 9, or Falcon Heavy boosters, I mean it's the same thing basically, they shut down all but 1 of the 9 engines.

And even with that 1 engine at its minimum throttle setting, it's still too much thrust to hover.

So as this rocket's coming down, if they start a little bit too early, if they light that engine too early, it will actually stop above the ground and will not be able to lower itself.

It will literally stop, say it stopped 200 feet above the ground, their only option is to kill the engine and then it's just gonna fall those 200 feet.

So it's what we call a suicide burn or a hover slam, kind of interchangeable terms, because your thrust to weight ratio is never below 1.

So they have to actually literally be riding the throttle.

So what you do is you kind of start, ideally you kind of start in the middle of your window of throttle range.

So let's pretend your engine can throttle down to 40% of its maximum rated thrust.

You might start at like 70% of thrust in the middle of that window of where it could burn.

So if all of a sudden it's kind of coming in too hot, you have room to throttle up.

you're coming in a little too early, you throttle it down.

And it's just amazing how smoothly and how perfectly they're able to still control that thing, even though they're down to 1 engine out of the 9, and they're still riding the finest margin of what's possible.

And they're continually playing with that to try to get it, because every bit of fuel they're using and propellant they're using to land is propellant they weren't using to put something into space.

So, they want that to be as efficient as possible.

So, they're really watching them hone that in and just continue to evolve and edit that and just get it to be the workhorse.

We're coming up on 100 consecutive landings, perfect landings, 100.

I think they've done like 150 something landings altogether, 160 altogether.

But we're talking like in a row without blowing up, which, you know, 5 years ago was completely experimental and insane, and now we're coming up to the point where we're 100 in a row.

It's like this is becoming more reliable.

And the landing, which is not the primary mission, this is purely for SpaceX's gain, is to recover the booster.

It has nothing to do with the effect of getting the payload on orbit, you know, most of the time.

And the landing is really only for their benefit and their gain.

Long-term gain, like it's a long-term investment in being able to recover the boosters.

Can you believe All this was done in basically 10 years.

So we've seen this development over a period of 10 years.

So like where we started commercial spaceflight at scale to today where it's almost starting to be mundane.

I mean, obviously, even just in the, I think I'm a fairly fair weather fan, really didn't start paying attention to like 2014.

And just seeing what it was like back then to what it's like.

I don't watch every launch at all anymore.

But back in the day, I, like I said, would wake up in the middle of the night to catch these streams, or catch these launches and watch them, because they were such a big deal, and there's maybe only 5 of them a year.

Nowadays it's like, oh yeah, there's literally like 2 a week on average now.

Let alone, you know, United Launch Alliance, Rocket Lab, any of the Chinese missions, you know?

It's hard to, really, really, really hard to keep up with.

I wonder at which point in the future, the number of launches to orbit will exceed the number of launches of airplanes, like on the surface of Earth.

have to admit, I kind of have a hard time extrapolating out that far.

You know, there's a lot of people that are like big futurists and really do think about like interplanetary stuff and think about colonizing Mars and stuff.

I have a hard time predicting like when Starship's gonna fly, the orbital launch, you know, and That's like imminent-ish, like month or 2 scale time frame.

And yet I'm still like, I can't tell you anything about when we're gonna land on Mars or what that economy and what the scale of launch operations is gonna look like in order to do that, because it's just so hard.

I wouldn't have predicted where we're at today 5 years ago.

Yeah, but it's funny because there's so many new companies starting up trying to predict that and it's a really exciting startup culture right now.

I think when you make certain engineering decisions and hiring decisions and like what you focus on in terms of both business and engineering, it's good to think on a scale of 10, 20, 50, 100 years.

It's 1 of the things that Elon is exceptionally good at, which is asking the question, okay, this might seem impossible right now, but what's the obvious way to do this if we look out 20 years?

You start to make decisions about robotics, about brain and computer interfaces, about space travel, they make a lot of sense when you look at the scale of 10, 20, 50, 100 years.

And don't make any sense if you look at the scale of just months.

But of course, the actual work of day-to-day is focused on the next few months because there's deadlines, there's missions they have to accomplish.

Anyway, returning back to the brief history of space rockets, the Falcon Heavy.

So we talked about Falcon 9 and the rapid development there.

What other flavors of Falcon is there and how does that take us to Starship?

Yeah, realistically, the Falcon 9 evolved more or less, kind of like just got more powerful and a little bit longer and more capable.

But nowadays they fly what's called the Block 5, even though it's like the eighth or ninth iteration of the Falcon 9, but they call it Block 5.

It's the 1 that has the black landing legs, the black interstage.

They have a fleet of roughly 10 or so that are doing the majority of the legwork these days, and they're flying up to 15 times, I think, right now as the current booster leader.

They're also recovering the fairings, so the nose cone of the rockets are frequently, if not every time, being recovered.

And the only thing being expended is the upper stage, And that's kind of where the Falcon 9 is ending.

It really doesn't make sense to develop that infrastructure any longer.

So they went with the next step, which is go even bigger physically.

So they have more margin for upper stage reusability.

And that's what we see with Starship and Super Heavy.

So the Super Heavy booster, the whole system is confusing.

The whole system is kind of considered Starship, but technically the Starship is just the upper stage, which is also like the spaceship, which is also the upper stage.

And then the booster itself is considered the super heavy booster.

as the, at the time it was the ITS, the Interplanetary Transportation System.

Later, and I think about 20, By the end of that year, 2017, it kind of became known as the BFR, the big Falcon rocket.

And then I think it was about end of 2018, they started calling it Starship.

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Tim Dodd: SpaceX, Starship, Rocket Engines, and Future of Space Travel | Lex Fridman Podcast #356