A defunct German satellite is expected to fall to Earth this weekend, with experts predicting that up to 30 big pieces of the junked spacecraft could hit the planet. But exactly when and where the satellite will fall remains a mystery. The 2.7-ton Roentgen Satellite, or ROSAT, will likely plummet to Earth on Saturday or Sunday (Oct. 22 or 23), according to the latest update from the German Aerospace Center. "Currently, the re-entry date can only be calculated to within plus/minus one day," agency officials said in a statement. "This time slot of uncertainty will be reduced as the date...