Comment by mrandish

Yeah, I was wondering if it was FTS. I guess it doesn't really matter as FTS is just designed to intentionally cause the same kind of RUD that happened anyway. The main criteria is a RUD sufficient to ensure pieces small enough to burn up on reentry. From the looks of the explosion from the videos helpfully captured from the ground, the RUD certainly looked sufficient. Given it was 146km up at >13,000 mph, rolling down a window would trigger a sufficient RUD.

At those speeds, temps and pressures exploding into tiny pieces isn't just easy - it's the default. NOT exploding is much harder!