The Space Shuttle

So I am waiting with a worry that I can't express for the space shuttle to return.
I don't really know how to say why I'm so worried, or why I let it consume me like this. We all remember where we were or how we heard about Challenger, and Columbia (with Columbia the irony was I didn't turn on my TV for quite a while that morning - I thought stupid AOL had failed to mention their return). I woke up my husband, shook him from a sound beer induced slumber sobbing about the shuttle and that he had to wake up.
Why did I do that? I still don't understand it, except that maybe I didn't want to be that sad and all alone.
And why do I care now? Maybe it's because I feel like these people have been put into harms way for no good reason. Soyuz could go up and transfer goods to the International Space Station. Crappy old Soyuz works just fine. We watched the lift off at my work, and it was just so moving. Everyone watching on the TV then suddenly everyone ran outside because apparently on a clear day you can see the launches, even from Tampa. And while it was exciting I wasn't really all that worried about lift off. They figured out the O ring problem and conclusively their fix has worked over the last decade.

But this foam thing, and now the string hanging off the wing thing, and now the window curtain thing (are they going to fix that one?) I feel like the shuttle is falling apart, and their are PEOPLE on it.
When I was little, first and second grade, the WEEKLY READER would have stories about how some day we would fly to space on these ships that would land like airplanes. It was fantastic and so exciting for the future. I can remember taking my WEEKLY READER home and showing that picture to my dad, what the new space ships would like like. And he would tell me about how the day the men landed on the moon was his birthday - and he held me on his lap and it was
an exciting wonderful day.

Why did we pull the string out? WHY? The string, if I understand it, is like a fibrous grout between the tiles. It is made of some "able to withstand the heat of the sun" fabric that keeps the air and heat from getting between the tiles and melting the shuttle during re-entry.
AND WE PULLED IT OUT.
Is there more string under there? Do we now have two tiles with less than enough fiber between them to withstand re-entry.

NASA YOU BETTER KNOW WHAT YOU ARE DOING BECAUSE I AM LOSING MY MIND.