U.S. spacecraft readies for fiery plunge into Saturn after 13-year mission

By Ian SimpsonWASHINGTON (Reuters) - The U.S. space agency's Cassini spacecraft will end its 13-year mission to Saturn in mid-September by transmitting data until the final moment before it plunges into the ringed planet's atmosphere, officials said on Tuesday.Cassini, the first spacecraft to orbit Saturn, will make the last of 22 farewell dives between the planet's rings andsurface on Sept. 15.The spacecraft will then burn up as it heads straight into the gas giant's crushing atmosphere.