Has the space junk in Earth orbit really reached a dangerous tipping point?

Space is a vast and often empty place, but within our own orbit, things are getting pretty crowded. There are millions of pieces of debris, from busted satellites to lost chunks of rockets, encircling our planet. Some say it's a deadly menace. But just how dangerous is this space garbage, really? » 9/02/11 11:16am 9/02/11 11:16am