<As the shuttle descended across the Southwest, it was flying normally, and the seven astronauts showed no awareness of anything amiss -- even as ever-larger pieces of the shuttle were apparently peeling off. "There's a lot of stuff coming off this orbiter, and nobody's saying anything," said the board official, most likely because the shedding was obscured by the glowing plasma, superheated gas that builds up around the shuttle as it enters the atmosphere at hypersonic speed.

More likely because there is no way for the astronauts to see behind them. The rear windows are inside the cargo bay. The films of the reentry show several shots through the top cabin windows of flickering plasma, but since as far as anyone knows, nothing was wrong with tiles at the nose end, nothing unusual would have been seen.

I look forward to someone finding those pieces near California and Nevada.