#28 - The Father of Modern Rocket Science

The god of rocket science.

Who is that?

My name is Sam, your guide, and welcome back to The Tech Optimist.

So the whole thought for Impulse was, let's, let's develop in-space transportation to move those things around in space.

Boeing 747 example of, you know, great for taking people or cargo from New York to London. You're not going to park it in your driveway.

I'm super excited about what I call the true space economy developing. The Earth is finite and space is infinite, so we should start using the resources of space.

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Cool.

Welcome everyone. I am Drew Wonsalack. I am an investor with Alumni Ventures, and joining me today on this series of great founders, technologists, entrepreneurs is Tom Mueller, the founder and CEO of Impulse Space, and also founding employee number 1 at SpaceX. Thanks for being here, Tom.

Thank you for having me.

Yeah, so we're gonna jump into a bunch of stuff in the space economy. We're gonna talk about Impulse. There's a lot of great content out there about SpaceX, but we'll of course maybe spend some time talking about your time there. Let's kind of center the audience. These are people that maybe vary from, you know, heavily interested in space to maybe they're just curious about this market. I think a great place to start is actually with your SpaceX experience. Um, what was the environment like and kind of the interest from the market in space as an investment, as a technology, back when you started SpaceX, you know, about 2 decades ago?

When we started SpaceX, it, you know, there was a lot of naysayers. Like, most people didn't believe we could do it. Um, even I joining was like, this is high risk. Is this gonna go? I got to go try it, but have an exit plan because the chances were pretty low because most space startups, you know, launch startups that had tried had already failed. So it was definitely high risk, not hard to get investment until you've actually done a lot, right? Really, like, we didn't get a big investment until 2008 after we'd flown successfully after $3 billion. So really a whole different environment than it is now.

And a big part of that environment, at least kind of in our view, is as a result of the work that you and the team did at SpaceX is, you know, the rapid ability of launch, the low cost of launch. Something like Impulse, you know, wouldn't have existed 15, 20 years ago. It couldn't have, right?

Right.

Can you maybe share a little bit about kind of the final few years at SpaceX into the origins of Impulse and, you know, what kind of drew you to this concept and maybe a little bit of an overview of what Impulse is because, you know, we're excited about it.

Sure. Yeah. So for the last, basically the last 6 years since the time that I became propulsion CTO, I was working mostly on BFR, which became Starship. And having— which was fun. You know, I originally sized that spaceship and convinced Elon and others to change it from hydrogen fuel to methane fuel. A fully reusable vehicle that can be flown often, that can take at least 100 tons to lower orbit every time it flies. And realizing it was going to be a thing, I was just thinking the next opportunity is going to be in space. It's going to bring a lot of stuff to space. It's basically solved the problem of getting to low Earth orbit. Now the next problem is going to be moving it around in orbit because most cargo loads of 100 tons are not going to be a single object. They're going to be multiple things. Think of a big cargo ship coming into port, lots of cargo containers. They need to go to lots of different places. So the whole thought for Impulse was, let's, let's develop in-space transportation to move those things around in space.

More on Impulse Space with Drew and Tom right after this.

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I used the, you know, a Boeing 747 example of, you know, great for taking people or cargo from New York to London. You're not going to park it in your driveway, right? You're not going to pull it into your, you know, local town hall to deliver packages. And so that's really the mission of Impulse. There's 2 offerings kind of under the Impulse umbrella. There's Mira, which you guys launched your first one pretty recently. And then you have Helios, which was publicly announced a couple of months ago.

Right.

Talk kind of how those 2— what is Mira? What is Helios? And how do those 2 relate to each other and kind of this grand vision that you have for the company?

Yeah, um, I, I call MIRA the stay-there vehicle. It has storable propellants, it can stay on orbit for years, um, because the propellants can be stored at room temperature and, and don't go away. But it has limited amount of delta-v it can do. It can— in space, movement is, is delta-v, like how many meters per second you could add to a body to change its orbit. And MIRA can do something like on the order of 1 kilometer per second of delta-v, which, which is great for moving around in geo, but it won't get you to, to the moon or to high-energy orbits. Helios is the get-there product. It's, it's basically, um, adding a kick stage, almost like adding a 3rd stage to, to an existing vehicle like Falcon 9, or, or to— or actually several could fly on a Starship. And it can do, um, anywhere from 4 to 10 kilometers per second of delta-v. So now you're talking about— Able to escape Earth's gravity, able to go to high-energy orbits, able to go to the Moon, able to go to Mars, able to, you know, speed up getting to the outer planets. So it's definitely basically adding as much chemical energy impulse to a payload as possible. And it's just really about prime movement in space.

So I don't know if you guys know this, but I am not an aerospace engineer. I am just the podcast editor for this show and the guide for this show. So I'm gonna leave the explanation to Mira and Helios up to Tom himself. So I did a little bit digging and I found this really awesome YouTube video by Ellie in Space. And what she did is she interviewed Tom in their facility. And it's a really awesome video. It's just under an hour. Obviously, I'm not going to share the whole thing, but I'm going to share a few snippets of it because I I think it's really impactful, uh, you know, to see how they operate, to see Tom, you know, sort of talk about his technology and everything. And so here are a few snippets from that video, uh, from Alien Space, which was posted just about a month ago. So it's still pretty recent, um, which is awesome. I thought that they were super cool and I thought you all would enjoy. So here's a little bit more about, uh, you know, the 2 projects that Tom was just previously talking about here.

And you can see that there's 4 thrusters on each side. Those are little SAFE thrusters, and there's 4 more on that side, so 8 total. And that structure on the back there is the mount for the solar cells. And out on the corner of the solar cells, those valves there are basically our cold gas thrusters. So they use ethane gas to point it, so like to point the antennas at the ground and point the solar cells at the sun. So the solar cells are pointing at the ground? And then when we want to do an orbit change, we point it in the right direction and burn, you know, and burn the engines for a given amount of time and move into orbit.

And when do you expect to launch this one?

This one's going up in October of this year.

Okay.

Yeah.

Wow.

So it's getting ready here, and in the next month it's going to go to system vibes. We send it out to a company and shake it to simulate launch. launch, and then it's kind of like hands-off after that.

Okay.

It's been, you know, tested.

And your first one was November 2023 on a SpaceX rocket, correct?

Yep.

Is that— did you want to have a full year almost in between, or have there been like delays?

I think we, we wanted to go on 11, but for some reason we just ended up on 12.

Okay.

Yeah.

Interesting.

Yeah. No, it's fine.

Very cool.

We're mostly working on Helios this year.

Yeah, right.

Last year was all about MIRA. This year is mostly about HELIOS.

Okay.

The demo launch in that is going to be in early '26.

Wow. Yeah.

Same timing as the lander, right?

Mm-hmm.

Okay.

Well, this will be late '26, but yeah.

Okay.

Yeah.

'26 is going to be a busy year.

Big year for you.

Yeah.

And if someone's never heard of MIRA or is not familiar, this is kind of like a space tug to transport from LEO to MEO, correct?

Yes. Well, just mostly this is made to move around in low Earth orbit. So it goes up on Transporter. It's optimized to fit in the Transporter lower spots.

Mm-hmm.

And Transporter dumps everybody at typically a 500-kilometer circular orbit, sun synchronous. And some people want to go to different timings or different orbits, different altitudes. And we can take 300 kilograms of things, CubeSats and stuff, to different You ready to do a burn, Kian?

Yes, sir.

So this is our test area back here. We have the vacuum test chamber for running the little 5-pounder here. We got shaker tables over here for— we simulate launch basically on like components. And over there is like hard vacuum where we pull down really, like, really like simulate space for like avionics and things.

You need this big of a vacuum chamber? You need a vacuum for a 5-pound thruster test?

Yeah. Here, I'll show you.

I guess this probably isn't that big then.

It's not that big.

It's about the right size, actually, for this. There's the thruster mounted on a thrust stand. You can hear the vents and the valves cycling. And so that line right there goes out to a vacuum pump out back. In this vacuum gauge, we're at 1.4 torr. So atmosphere is 760 torr, 760 millimeters of mercury is what a torr is.

Okay.

So we're at 1.5 torr, so we're at 1/500th of atmosphere basically in there. So it's a vacuum. So the plume, you know, it has a high area ratio. It's like got a 100 area ratio, so it'll expand the plume completely. So we're measuring thrust.

And what is this one called?

That's SAFE.

That's—

SAFE.

Okay.

I just wanna make sure I knew how to pronounce it.

Yeah.

This is the one that we have. There's 8 of these on Amira.

Gotcha.

And there'll be 48 of these on the Vast Space Station.

Wow.

Yeah. Hence the name Impulse. And I think, you know, your focus on propulsion, that's the key here.

Yeah.

For those listening that didn't, you know, at least take a couple summers of aerospace engineering classes like I did, explain the kind of the importance of that density and even delta-v, some of these terms that you're using that are so crucial, I think, to what you guys are doing.

Yeah.

Someone hears that and, you know, a kilometer a second, that's pretty fast, right?

Yeah.

What does that mean kind of in actuality?

So orbital velocity is 7 kilometers per second at low Earth orbit. And then to get to higher energy orbits, that potential energy to get out of the gravity well takes, like to get from low Earth orbit to geosynchronous, orbit, which say 300 kilometers at some inclination to 36,000 kilometers at the equator, is about 4.2 kilometers per second nominally. So that's— Helios can add that much delta-v to a 4-ton payload in order to get it to geosynchronous orbit. And the rocket equation, the very simple rocket equation, only really has 2 factors, the performance of the engine and the mass ratio, empty to— I'm sorry, full to empty, which basically means how much propellant you can store compared to your total structural and payload mass. So you want to make your spacecraft as light as possible, hold as much propellant as possible, and have as high a performance rocket engine as possible. It's just, it's that simple. So we just try to make the spacecraft extremely light and try to make the— the performance of the engines as high as possible.

Yeah. And you need that trade-off to get these larger payloads to GEO or geosynchronous orbit. Again, I'll kind of ask, like, we're talking about LEO, we're talking about GEO. Why is it so important that we get to GEO? Why does there even have to be this infrastructure that provides that? And again, for people listening, I mean, a lot kind of operates in LEO right now.

I mean, if you go back before Starlink and LEO constellations became a thing, I mean, they were tried back in the late '90s and early 2000s and failed the first time around. And that's why a lot of people were kind of naysayers that Starlink would be successful. But before that was GEO, like your DirecTV dish is pointed at a geosynchronous satellite. The fact that you point, you point to the south because it's at the equator, which is, you know, south of North America. Um, and, and geosynchronous means it has a 24-hour orbit, so it stays at the same spot in the sky relative to the surface of the Earth. So super important, um, orbit. Um, and it has been, you know, Hughes Aircraft's been flying geosynchronous, um, spacecraft since the '60s and really proliferated in the, in the '70s. So that, that was the main way to do worldwide telecommunications was, was through GEO until Starlink came along, which now set up, you know, on the order of a second of transit time. Now you're talking just milliseconds. Um, so, so LEO becomes super important for if you want low latency, like instant internet or communications. But still, the, the cheapest way to, to move bits through space is through the GEO circuit because, because you could cover the whole globe with 3 satellites.

Yeah. And that's why it's so special and so important. And there's obviously a massive market there. Do you see GEO with what SpaceX has done and will continue to do and what Impulse is doing now, open up GEO to new markets that, you know, we're not thinking about that isn't just, you know, kind of moving bits around? What does this unlock?

Like, if you look at the predictions for GEO, they know, like the Euroconsult numbers that we looked at, or there's geo including MEO, um, medium Earth orbit, like, you know, you know, like, um, the, uh, the GPS orbits and above, things well above, you know, many, many times higher than LEO. Um, the— they're, they're talking about 30 a year. We think it's actually less than that, but it's, it's flat. It looks pretty flat. We think by, by reducing The cost of access to these orbits by a pretty large amount. Certainly when Starship starts flying along with Helios, we're talking about, about getting the price down by at least a factor of 2, maybe even a factor of 3. And, and we think that will increase the number of things going there. And certainly the government missions want to go there. There's, there's a lot of interest by the government.

Fantastic. That was helpful.

Great.

Well, if for those listening couldn't understand by now, Tom is, you know, the guy to talk to about this stuff. I pulled together some of the comments or reviews on posts, and Tom has been described as the leading spacecraft propulsion expert, founding father of the new space economy. I even saw, you know, an X reply the other day called you the god of rocket science. So with those titles, you know, with great power comes great responsibility. You kind of have this, I think, better than most perspective on the space economy. When you look out at other space innovations kind of outside of Impulse, what's really exciting to you? What do you feel like maybe isn't getting the attention or even investment that it deserves?

I'm super excited about the what I call the true space economy developing where we're manufacturing and assembling in space and then eventually using the resources in space, using the water that's on the moon. There's probably at least a billion tons of water ice on the moon. There's metal and minerals on the moon and near-Earth asteroids that can be used way more efficiently, like more than 20 times more energy efficiently to get that matter from the surface of the Moon into low Earth orbit than it is from the surface of the Earth because of the much more massive gravity well of Earth. So I think I'm pretty excited about companies like Varda and others that are doing manufacturing and assembly in space. I think once that really— that's kind of the first step. Once that really takes off, I think pretty soon these companies are going to have enough capital to realize that getting that material from like the surface of the moon or asteroids, that'll become important. That'll just be the way to do it. And that basically offloads the resource drain on Earth because, you know, the Earth is finite and space is infinite. So we should start using the resources of space.

Yeah, absolutely. I mean, there's so much opportunity out there and stuff like Impulse is going to I think unlock a lot of these markets that we wouldn't even be thinking about. Coolest space tech you've seen. So, I mean, we've like, I feel like 20 years ago we were talking about potentially hover cars or like teleportation. When you look out there, what's kind of the coolest thing that like might fit into a Star Trek episode but actually is closer than people would think?

It's got to be Starship. Starship's so exciting. It's going to transform access to space. It's hard to beat that one.

Yeah. And I think people— and when I first heard about Starship, you know, a long time ago, you think of this kind of step function above in size compared to, you know, a Falcon 9, which I think people are used to seeing now. Can you like quantify the scale of like How big Starship is and then just really what that means. We touched on it earlier, but really what that means and why it is this kind of like big breakthrough that you're mentioning it is.

More about Starship right after this.

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Really quick, before Tom tells us how big of a milestone and how big of an achievement Starship is, Starship recently put out kind of like a hype video for their, uh, 4th flight test. They put out this video a week ago as of you know when I'm editing this episode. It already has a million views, and I watched it myself because I was curious, and it gave me goosebumps. Just the way that it's edited and produced, and you see like all the reactions from the crew within you know Starship and in SpaceX that have worked on this for so long and have put you know blood, sweat, and tears into this, and it just makes you root. For them, you know, as like engineers and designers and technicians. It's just, it's just really cool. So I'm going to share that first to sort of prep you for, uh, Tom's response to Drew's question about how impactful that is. So I'm hoping, you know, that you guys get goosebumps too, because I did. Um, and then it'll sort of help you really understand what Tom is saying after this, after you see this. See slash hear this again. If you want to see the video, we'll have a link to it in the show notes. But also, the video is on the video version of this podcast if you want to hop over to YouTube or any of our socials to find it that way. But yeah, so here's that video from SpaceX of Starship from their fourth flight test from about a week ago.

Attention all operators on countdown one. This is the final go no go poll for Starship Flight Four. Stage 1?

Go.

Stage 2?

Go.

Stage 2?

Go.

Flight director is go for launch. We have liftoff.

Vehicle is pitching downrange.

Ship chamber pressures are nominal.

Max Q.

Vehicle is supersonic.

Booster engine cutoff.

Ship ignition.

Stage separation confirmed. Hot stage confirmed.

Ship under its own power. Please confirm startup. View of the jettisoned hot stage.

Booster, the primary goal today is to do a landing burn and a splashdown in the water. You can see those grid fins on your left-hand screen rotating and turning to guide the booster.

And there's that landing burn. And we have blastoff! Ship engine cutoff.

Our primary Goal is to get through the extreme heat of Starship reentry.

Starship is approaching entry interface.

Starship is passing through 100 kilometers altitude.

Good attitude for entry.

Vehicle is passing through 85 kilometers altitude.

Flaps have control of the vehicle.

Vehicle is approaching maximum entry dynamic pressure. External temperatures are dropping.

Starship is in landing. Starship landing burn shutdown. It's slightly bigger than the, you know, as far as just, you know, height and volume, it's slightly bigger than the Saturn V moon rocket. It's got twice the thrust of the moon rocket. It can lift more to LEO than the moon rocket. The next version of it will be able to lift more than than the Saturn V, but it's— the Saturn V was completely expendable. It was all thrown away, whereas Starship can be flown again. Elon talks about the cost of flying Starship to be less than the cost of flying Falcon 1, the original rocket, the single-engine rocket that we flew, first rocket we flew, which we sold for $6 million. So he's talking about doing what, you know, $10 billion vehicle could do for like $6 million. So it's quite an advancement over the last 50 years.

Yeah, I don't think, you know, I would say easily most people don't understand the impact, right, that that's going to have. And then also just the increased cadence, um, what we— what SpaceX is going to be able to do with, with just the Falcon 9 and, and Heavy. And so, um, you know, it's going to be a, you know, a pretty interesting trajectory over the next couple years to couple decades.

I talked to an investor the other day that didn't even know what Starship was, and I was kind of surprised. My thought was, you shouldn't be investing in space if you don't even know what Starship is.

No, no. I think what I've learned over the last half a decade or plus, kind of just like looking at this market more deeply, is if you don't know as intimately as you can what SpaceX is doing, You don't know what's happening in space.

It's all dependent on SpaceX right now. SpaceX got it started and they're launching, I don't know what, 90% of the mass in the free world to space. Yeah.

Yeah, fantastic. And then as you kind of, again, look at this broader space economy, what's missing? I mean, what are you waiting to see be developed? Whose mind are you waiting to be changed? You know, what's kind of that unlock or kind of overlooked piece of—

I think, you know, manufacturing in space, compute in space, you know, like if you look at just energy usage, which is driving, you know, climate change and a lot of pollution on Earth, And then you look at the growth of energy needs for AI and crypto. We're going to be at, you know, by, you know, some estimates, by 2045, just compute will be using as much energy as electrical energy generated on Earth right now. So, you know, and then everything else is growing also, you know, the use of energy for everything else.

Yeah.

Even if population stays— goes flat, per capita use of power is still going up. So, at some point, it's going to make sense to move compute into space. And I've been talking about it for a while. People say it's not affordable. Now I see a lot of people talking about it because it just makes sense. You can build giant solar arrays in orbit. You have limitless energy, and you can just run compute in space and just beam down the results. So I think that's something that's going to happen that, that's great. And I think just manufacturing in space in general and just using the resources that are in the inner solar system is just the next step.

Yeah, I'm glad you brought up energy. A little birdie told me the other day that you, like myself, are a kind of pro-nuclear energy.

Absolutely.

I think both terrestrially and then also, you know, for in-space applications.

Yeah.

And just, I think, important when you talk about kind of the energy requirements moving forward. I mean, like, just ChatGPT alone is, I think, uses the energy of 17,000 homes or whatnot in a day. So the demands will be there. How much can we bring compute into space where energy is resourced differently? Or how do we create cleaner energy here on Earth?

Yeah.

This was great, Tom. I appreciate you joining. One final question is a little bit less on space and more about you as an entrepreneur. You joined SpaceX. I consider you, you know, co-founder practically, right? You were there at such an early time that you saw all the stuff that, you know, anyone else would have seen, right? You were, you know, Elon's right-hand man. Now you're in the driver's seat. Kind of Difference in your mind between those early days at SpaceX and the early days now? You obviously have this kind of wealth of experience, but things maybe you didn't foresee being, you know, the guy, the founder and CEO here.

Well, certainly, I, you know, I was head down developing propulsion rocket engines and stuff. I wasn't involved in investor relations or—

You weren't doing podcast interviews with—

Right.

I wasn't doing business sales or business development, you know, so that's as the founder and CEO of this company. And I'm CTO too, which is really probably most of what I do is still technical, but there's just a lot more that I had to learn that I'm getting better at, certainly.

Yeah, absolutely.

Cool.

Well, thank you so much for joining us, Tom. We're big fans of you guys and Impulse. I just caught up with Eric earlier today and You guys are crushing it. So we're excited to be on board, and thank you everyone for listening.

Thank you. Cool.

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