[Paul Ross]

90-degrees orientation of the shuttle athwart its flight vector is not a normal roll reversal. The S-Curves programmed into the flight computers don't call for anything approach such a radical yaw.

[Cold Heat]

The first roll occured as they were approaching California. It was 80 degrees. The roll reversal occured at 13:56.15 GMT and initiated over Utah/NM. The craft never got into a 90 degree attitude until destruction.