Interview, Fireside Chat, Product Demonstration
Tom Mueller: SpaceX's #1 Employee Built the Merlin Engine. Now He's Building Impulse Space
- Tom Mueller, a founding employee at SpaceX, led the development of Falcon/Dragon propulsion and the origins of Starship before departing six years ago to focus on in-space transportation.
- Mueller's primary achievement at SpaceX was the Merlin engine, described as the most reliable and highest thrust-to-weight rocket engine ever developed.
- Impulse Space was founded to address the "next big opportunity" of moving cargo and payload within space, rather than from Earth to space, with a strategic focus on lunar transportation and landers.
- The company's current fleet includes three spacecraft, with two having successfully executed a rendezvous maneuver within 1,200 meters of each other last year.
- The "Mira" spacecraft is a highly propulsive orbital transfer vehicle equipped with eight thrusters generating a combined nearly 50 pounds of thrust.
- Mira features steerable, unfurling solar panels, a vault containing avionics and reaction wheels, and a chassis housing three propellant tanks capable of remaining operational in orbit for five years.
- The upcoming "Helios" vehicle is designed as a propellant tank containing 12 tons of liquid oxygen and liquid methane.
- Helios utilizes a high-performance engine producing 15,000 pounds of thrust to move four-ton payloads from Low Earth Orbit to Geosynchronous Orbit.
- Helios can potentially increase payload delivery to the Moon by 50% or improve payload to Mars by a factor of five compared to standard two-stage launch profiles.
- Impulse Space is conducting a bid for a Lunar lander contract and views the Moon as a critical near-term destination for infrastructure and resource extraction.
- The company's propulsion engines are named after stars, including the "Deneb" (a blue supergiant), "Rigel," and the "Saiph" thrusters used on Mira.
- The Deneb engine utilizes an ox-rich stage combustion cycle, burning liquid methane and liquid oxygen to achieve a projected specific impulse (ISP) of 385 seconds.
- Deneb is designed to be the highest-performing hydrocarbon engine ever flown, featuring a large carbon-epoxy nozzle skirt that can operate at temperatures exceeding 3,000 degrees Fahrenheit.
- The Deneb engine's main injector and combustion chamber are manufactured via metal 3D printing, a method Mueller describes as essential for creating complex cooling passages and injector elements.
- Impulse Space employs proprietary "Nova Light" alloy, which is burn-resistant in hot oxygen environments and possesses the strength of Inconel, for printing turbo pump parts and main injectors.
- The company maintains a vertically integrated manufacturing strategy, producing Composite Overwrapped Pressure Vessels (COPVs) in-house to reduce tank mass by approximately 50% compared to traditional metallic tanks.
- Helios COPVs are designed to withstand pressures up to 5,000 psi, a capability that traditionally requires long lead times and high costs from external vendors.
- Impulse Space utilizes generative AI and advanced software for spacecraft design, coding, and 3D printing processes, integrating these tools across a large software department.
- The company employs 5-axis milling machines and CNC lathes for hydroforming and machining critical components, including 700-pound copper forgings reduced to 25-pound slotted combustion liners.
- Impulse Space recently completed a successful vacuum chamber test of a Saiph thruster, demonstrating the ability to operate via pulse-width modulation for precise spacecraft steering.
- During initial operations, the fleet successfully performed an automated collision avoidance maneuver prompted by warnings from Air Force Space Track and LEO Labs.
- The company is developing electric propulsion (Hall thrusters) running on Krypton to handle north-south station-keeping for geosynchronous satellites, preserving chemical propellant for primary transfers.
- Mueller advocates for Nuclear Electric Propulsion (NEP) as the future solution for outer planet exploration, citing the New Horizons Pluto flyby as a precedent for the utility of nuclear power for long-duration science.
- He predicts that data centers will eventually migrate to space to overcome terrestrial energy constraints, projecting that compute power demand could match total Earth-based power usage within 20–30 years.
- Impulse Space aims to support the lunar economy by extracting infinite resources, such as copper from the Moon or asteroids, to meet Earth's growing industrial demands.
- The company plans to launch a fourth spacecraft later in the fall, continuing its rapid iteration cycle characterized by frequent testing and development.
- Mueller identifies the CTO role as his preferred function within the organization, citing a deep passion for designing rocket engines, avionics, and radio systems.