[Bartweiss]

I think equating "best engineers" with "superstars" means you might be bringing your own associations to the topic. (Not unfairly, that's a standard association in the Valley, but still.)

The few NASA engineers I've known have been superb as NASA employees. They weren't grand innovators solving problems on their own, but they were knowledgeable and intelligent. They had deep understanding of the tools they worked with, were rigorously careful and formal, and understood the problems and tradeoffs of their work far beyond any spec they were handed.

To me, that counts as being one of the best engineers in the world. These are people who know what they need to do, why they need to do it, and how they can best accomplish it. In the case of NASA, that generally means doing something radically different than you would at a tech startup, but these people are still brining enormous ability and great care to their work.