Part 6/12:
Mueller led the design and development of the Merlin engine, the powerhouse behind every SpaceX launch. Drawing on his experience with pintle injectors, Mueller engineered a simple, reliable, and cost-effective engine that used liquid oxygen and kerosene. A key breakthrough was making the Merlin engine throttleable, enabling it to be efficiently shut down and restarted—an essential feature for reusable rocket stages.
The development process was fraught with setbacks. In October 2003, the first Merlin engine test resulted in melting metal and potential catastrophe. Mueller’s team persevered through months of troubleshooting, refining their design to withstand extreme conditions.