We were doing a program at our local Science center and we had a 6" refractor pointed at the Andromeda Galaxy. The Astronomer at the time was also pointing out when The Hubble Space Telescope would be able to be seen as a satelite overhead. As he finished pointing it out and given a brief talk about some of the recent things Hubble had imaged, one patron asked "what are the chances of hubble crashing into any of the objects it is looking at?