Jun 4, 2026 · 43m · sourcery
Tom Mueller: SpaceX's #1 Employee Built the Merlin Engine. Now He's Building Impulse Space · Sourcery with Molly O'Shea
Tom Mueller · 30m spoken Molly O'Shea · 6m spoken Test Operator · 7s spoken Test Controller · 1s spoken
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gold bands on the timeline = statements, start to end. Hover to read, click to jump. CC turns on captions
Host Molly O'Shea tours Impulse Space with founder Tom Mueller, SpaceX's first employee, exploring the cutting-edge manufacturing, 3D printing, propulsion testing, and orbital transfer vehicles shaping the future of in-space logistics.
How this conversation actually went
Every chapter scored 0–10 on four independent dynamics. Hover any point for the reasoning behind the score. Molly holds 16.9% of the talking time here. How this is scored →
Molly as informed peer 2.0 Guest teaching 5.6 Guest disagreement 0.1 Molly pushing back 0.1
speaking balance: gold is Molly, purple is the guest (3 minute bins)
Sharpest disagreement ▶ 38:51 Hot take on space-based data centers
Mueller aggressively dismisses skepticism regarding orbital compute, declaring data centers in space an absolute no-brainer due to earthbound power constraints.
Hardest push from Molly ▶ 43:21 Proposing photonic chips against copper scarcityWhen Mueller argues that earth is running out of copper and must mine celestial bodies, Molly introduces photonic computing as an alternative technical solution.
Biggest teaching moment ▶ 9:47 Masterclass on staged combustion physicsMueller provides a masterclass on oxidizer-rich staged combustion, explaining turbine horsepower, pre-burners, regenerative cooling channels, and expansion area ratios.
Molly holds their own ▶ 43:21 Photonic chip counter-inquiryMolly demonstrates technological awareness by prompting Mueller on whether optical interconnects and photonic chips could bypass the copper bottleneck.
the scores for every segment, with the reasoning behind each
| Chapter | Topic | Molly as informed peer | Guest teaching | Guest disagreement | Molly pushing back | Why |
|---|---|---|---|---|---|---|
| Facility Tour: Avionics Clean Assembly & Tour Overview | 2 | 5 | 0 | 0 | Molly guides the facility tour with introductory questions about Mueller's background and vehicle specs. Mueller thoroughly explains the Mira vehicle, thruster configurations, and orbital rendezvous capabilities. | |
| Facility Tour: Helios Vehicle & Impulse Space Origin Story | 1 | 6 | 0 | 0 | Molly prompts Mueller to explain the origin story of Impulse Space. Mueller explains the transition from SpaceX launch capabilities to the necessity of dedicated in-space transportation systems like Helios. | |
| Facility Tour: Deneb Engine Deep Dive & Staged Combustion | 2 | 7 | 0 | 0 | Mueller gives a detailed engineering breakdown of the Deneb oxygen-rich staged combustion engine cycle and high-expansion carbon skirts. Molly listens and asks open development questions. | |
| Facility Tour: 3D Printing Mechanics for Rocket Engines | 2 | 6 | 0 | 0 | Molly inquires about manufacturing techniques and COPV tanks. Mueller details why 3D printing acts as a rocket engine cheat code and breaks down composite overwrapped pressure vessels. | |
| Software, AI, & Generative Design in Space Systems | 1 | 4 | 0 | 0 | Molly asks about software integration in hardware development before a mid-roll sponsor ad read. Mueller explains the role of AI coding, generative design, and IT tooling. | |
| Machine Shop Tour: CNC Milling, Lathes, & Copper Liners | 2 | 6 | 0 | 0 | Mueller walks Molly through the machine shop, explaining mill-turn operations, 5-axis milling, and copper combustion chamber liners. Molly observes and asks brief observational questions. | |
| Metal 3D Printing Lab & Raptor/Merlin Engine Evolution | 3 | 5 | 0 | 0 | Molly mentions the public comparison charts between iterations of the Raptor engine. Mueller explains why metal 3D printing with proprietary burn-resistant alloys is essential over casting. | |
| Propulsion Cleanroom & Saiph Thruster Live Hot-Fire Vacuum Test | 2 | 6 | 0 | 0 | Mueller hosts a live hot-fire vacuum chamber test of the Saiph thruster, explaining radiation cooling skirts, pulse-width modulation steering, and flight telemetry data collection. | |
| Electric Propulsion & Nuclear Space Exploration | 2 | 6 | 0 | 0 | Molly asks about electric and nuclear propulsion applications. Mueller contrasts Hall thrusters for geo station-keeping with nuclear electric power requirements for deep space exploration. | |
| Sponsor Segment: VCX, Public, Merge, and Deel | 3 | 5 | 1 | 1 | Following the sponsor read, Mueller defends his thesis that compute must move to space to solve terrestrial power constraints, while Molly offers a smart follow-up regarding photonic chips to offset copper shortages. |
Statements from this episode (14)
Mueller met Elon Musk through amateur rocketry projects in his garage
“In fact, that's how I met Elon was through the amateur rocket stuff that I was doing.”
Impulse Space's Helios vehicle can boost Mars payload capacity 5x
“This can take a large satellite, like a four ton satellite from low earth orbit at a couple hundred miles up to geosynchronous orbit at 22,000 miles. That's so basically escaping most of the gravity well over very high energy transfer. It can take, you know, f…”
SpaceX's Merlin is the most reliable, highest thrust-to-weight engine ever
“My, probably my proudest development was the Merlin engine, which is currently flying on Falcon nine, the most reliable rocket engine ever developed, and also the highest thrust of weight of any rocket engine ever developed.”
Mueller says launch is solved; in-space transport is the next frontier
“Launch mostly being solved or is being solved. It's like the next big opportunity is to move all that payload, all that cargo around in space. So I started impulse space to do in space transportation as opposed to from earth to space transportation, which was …”
Mueller predicts Deneb will be the highest-performing hydrocarbon engine ever
“This engine will probably be the highest performing hydrocarbon engine ever flown because it's, it has a very high area ratio.”
Mueller calls 3D printing a "cheat code" for rocket engines
“For rocket engines, it's almost like a cheat code. It's so easy to make a high performance rocket engine with three D printing. Because the rocket injectors and the cooling passages are pretty small and complex. So to make a rocket engine by machining and asse…”
Properly designed composite pressure vessels weigh half as much as titanium
“So a properly designed COPE will be about half the mass of a state-of-the-art, all metallic tank, like a titanium spacecraft sphere. The carbon's so much stronger, it'll actually be about half the weight.”
Impulse Space provided the complete propulsion system for Vast's space station
“We provided the whole propulsion system for VAST, including the thrusters.”
Impulse Space machines 700-pound copper forgings down to 25-pound liners
“We start with these forging that weigh about 700 pounds and the final slotted product weighs about 25 pounds.”
Rocket engines take three major iterations to become mature products
“And I always said it took three versions of Merlin to get it to be really tight. And it took three versions also of Raptor. I always say it takes really three, three iterations to get to a really, really tight product and Raptor's there.”
Solar electric propulsion will outperform nuclear on cost for near-Earth missions
“Nuclear electric NEP propulsion is going to be important for going out to the outer planets. If you're staying near earth or even between earth and Mars, probably solar electric is, is, is, is going to outperform it on, on cost and performance just because sol…”
Mueller predicts large-scale nuclear rocket stages are decades away
“I think it's pretty far in the future. I mean, you know, and maybe, maybe a few decades away before we're really doing big nuclear stages.”