They started PRA of Shuttle after Challenger [1]. I got that number from the SLS PRA and Reliability people, and might have read it in a report too, but I don't remember many more details about it. There's a lot that goes into PRA [2].
Shuttle size was dictated by intended cargo and maneuvers, so it's not really possible to say how changing size would affect it since you'd have completely different design constraints and objectives.
Shuttle size was dictated by intended cargo and maneuvers, so it's not really possible to say how changing size would affect it since you'd have completely different design constraints and objectives.
[1] https://ntrs.nasa.gov/citations/20150002964
[2] https://www.nasa.gov/pdf/293261main_62868main_1_pmchallenge_...