I’ll bet the impact tests were done with new, pristine RCC.
Downey Lab & Test Dept. first noticed microscopic craters in the RCC around 1995. They found that the craters were from CO outgassing. When the O2 was hot enough it diffused across the silica layer on the surface of the RCC.
We CAT scanned the RCC on Columbia and found that, although it looked OK, the de-densification had weakened it to the point where we could poke a hole in the test panels with a finger.
Fresh RCC is pretty tough.
I don’t think NASA replaced the weakened RCC because there was no funding in the budget.
Typical coverup, just like Challenger. You probably know, it was NOT the O rings.
Well, before I transferred to KSC I was the test conductor proof testing he LH2 tanks in NOLA/MAF. Our first thought was that the LH2 tank had popped. Reviewing the films showed that the leak in the booster joint burned a hole in the tank. A little relief for me but it was still a crappy day regardless. The location the “torch” was burning in to is/was one of the beefy-ist parts of the tank. Right around the 2058 ring and where the SRB lower attach points were.
I remember reading some of the reports on the RCC issues and no doubt the RCC test panels were more than likely pristine panels and a lot tougher than ones that had been up and down a bunch of times.