As far as the satellites colliding, I'm really, really surprised it doesn't happen more often. I don't think anybody realizes how crowded it is up there. Here's a CGI picture of all the junk up there.....
The submarines colliding is ridiculous that it even happened and I'm sure somebody is in big trouble for it.
The fireball is weird because nobody found a piece of it, I mean that thing would have to be huge to cause a fireball like that. Like the article said, it would have to be the size of a truck!
There's no way that metal piece came through a wood chipper, it would have jammed that thing up solid, plus it wouldn't be hot, and it would have been all scraped up. It almost looks like a part of a motor mount which doesn't make sense either.