Arguably, a mechanic who is literally performing maintenance on exceptionally mechanically dense and complex parts of a rocket, say the rocket engine plumbing or wiring harnesses... is figuratively performing rocket surgery.
Now, that one does have its place. I either it in an ironic sense that you dont need multiple degrees to do something. The flip side is that the people we send to space tend to be the most qualified people in multiple fields, a medical surgeon with a stem degree does not sound too far outside the realm of reason.