https://techcrunch.com/2022/07/26/spacexs-cto-of-propulsion-retired-now-he-wants-to-go-to-mars/

Tom Mueller is a self-described race car guy. Upon retiring from his role as CTO of Propulsion at SpaceX in November 2020, he “mostly wanted to go racing and ride dirt bikes and travel,” he said in a recent interview. Mueller, who is 61, was putting behind him a storied career: while at SpaceX, he led the development of the Merlin rocket engine, which powers the Falcon 9 rocket, and the Draco engines that power the Dragon spacecraft.

Retirement was the plan — but plans don’t always work out as intended.