NASA chooses rocket for Orion launches

NASA says it will modify an existing and proven Delta IV rocket second stage to launch an Orion spacecraft on an unmanned test flight in 2017. A manned flight to lunar orbit is planned for four years after that, the agency said. The Boeing upper stage is "the only means available to support the immediate in-space propulsion needs" for the excursions, NASA said in a statement. An internal study of in-space propulsion systems available in the United States, Europe and Japan determined the Delta IV upper stage "is the only known in-space stage requiring relatively minor modifications" to meet mission requirements as well as the launch schedule, NASA said. The Delta IV second stage is powered by a single Pratt & Whitney RL-10B2 engine fueled by liquid hydrogen and liquid oxygen. Both Orion missions will be launched from complex 39B at Kennedy Space Center on early versions of NASA's new heavy-lift Space Launch System, Florida Today reported.