James Webb Space Telescope

The delays worry me, but then I think "at least they're catching them early". And it doesn't look like they are design errors.
I suppose when you have absolutely zero margin for error, this is what you have to do (note: to me, their ability to “shake” the craft and spin it does not qualify as creating a margin for error).

Even as a childhood space geek, the high level of excitement I feel about this project is surprising to me. I really, really hope this thing works - not least because a failure is going to damage the cause for future space projects pretty severely.