Great share. I knew a few SR-71 crewmembers because the FB-111 was a stepping stone to the SR program. It made sense, both aircraft were in SAC so there wasn't much culture shock and FB crews routinely flew Mach 2 missions so could deal with high speed scenarios. The stumbling block was one needed to pass an astronaut physical to qualify for the SR program. Taking that physical was a you bet your wings scenario if you failed, so many were reluctant to try.