I was surprised at the post-launch press conference that NASA said they saw no debris. I was watching the launch replays of the cameras posted around the launch site before the news conference, and on two of the replays there was what appeared to be the same large piece of white debris, over two feet in diameter by my reckoning. Watch the first 30 seconds or so of cameras UCS-15 (TV-21A) and KSC DOAMS (TV-16). In the first video, just as Atlantis emerges above the plume of vapor on the launch pad, the debris comes from somewhere on the external tank, approximately adjacent to the left side of Atlantis' cockpit and falls down behind the left wing. The other camera is looking at the back, or underside of the left wing, and on that video, a piece of debris appears behind and at the top of the wing and falls down and out of sight into the rockets' exhaust. By stopping the action, I could measure the diameter of the piece in the latter video and compare it to the diameter of the SRB body in the same frame. The piece of debris was about 1/5 the (12 foot) diameter of the SRB. Hence my guess that the piece was about 2 feet in size. It didn't appear that the piece hit the wing, and the event occurred so early that the shuttle wasn't going very fast. But still, I was a little dismayed that NASA hadn't seen it. ljg