ROUGH CUT - NO REPORTER NARRATION Friday's the day when what's left of NASA's defunct Upper Atmosphere Research Satellite is expected to come crashing down to earth. NASA says most of the the satellite, now space junk the size of bus, will burn up in the atmosphere on the way down. But about 26 pieces weighing around half a tonne in total will survive. The scientists say it will miss North America but the the final destination of the wreckage is not entirely clear. NASA says the chances of a person being hit by the falling debris are about 1-in-3, 200. The satellite's return to earth is being closely monitored by NASA and the U.S. Air Force. The 10.6 metre-long satellite was launched in 1991 aboard a space shuttle to study ozone and other chemicals in the planet's atmosphere. Its mission ended in 2005.
