Uneasy does it

I think I'd feel a lot better if NASA had decided to fix the damaged heat shield on the Endeavor space shuttle before attempting re-entry, which is planned for today. The ship was struck by debris on takeoff, leaving a deep gouge in the heat shield, but NASA managers decided, not unanimously, that the shuttle could return home safely. I hope this was the right decision, and that the brave crew, including a schoolteacher, make it back to earth with no difficulty. But it's very hard to forget that a similar team of NASA managers decided 21 years ago that the shuttle Challenger could return safely despite similar damage, and we remember how badly that ended. It does seem a bit strange that after the Challenger disaster, NASA devised a way to fix heat shield damage in orbit but decided not to use this technology in the present situation. I hope they're right; it just seems strange.