Following up on recent news of a NASA satellite falling from the sky and a German satellite that did the same, new submitter blais writes "NPR has an interesting interview about space junk falling back to Earth — and the odds of it possibly hitting someone. I thought it might be of interest to the other space nerds out there. Quoting: '... it's very difficult to know exactly when a satellite's going to come down. The Earth's atmosphere is hard to model. It's very thin up there, 100 miles or more up, but it exists. And sometimes it's a little bit denser, sometimes not, and the satellite might be tumbling, and so it makes it very difficult to know exactly when it's ... going to come down."