.. so, now the fix has gone wonderfully, and as always hats off to the outstanding STS114 crew who do such great work, all the more so when at the back of their minds they must be wondering if they'll make it back OK. The right stuff is alive and well ..

however I'm trying to figure out these questions:

Gap fillers are evidently essential during launch but not during re-entry. It's apparently more dangerous to have something sticking out and thus disrupting the laminar flow of across the underside heat shield, that's why we needed them removed. Fine; but what about the remaining 2 gaps now left by having removed the fillers? Why do these NOT pose a risk? If these (and gaps between tiles generally) are not a risk during re-entry, then why ARE they a risk during launch (hence necessitating the gap fillers in the first place?)

I've searched around for answers, but without getting into textbooks and journals, I haven't been lucky .. comments from those in the know (Gary, Larry et al) would be most welcome