Orbital Services stock falls in after-hours trading) Oct 28 (Reuters) – An unmanned Antares rocket exploded seconds after liftoff from a commercial launch pad in Virginia on Tuesday, marking the first accident since NASA turned to private operators to deliver cargo to the International Space Station, but officials said no one was hurt. The 14-story rocket, built and launched by Orbital Sciences Corp, blasted off its seaside launch pad at the Wallops Flight Facility at 6:22 p.m. EDT/2222 GMT carrying a Cygnus cargo ship for the space station.