Last-minute problem keeps SpaceX rocket, astronauts grounded

Last-minute technical trouble forced SpaceX to call off Monday's attempt to launch four astronauts to the International Space Station for NASA. The countdown was halted with just two minutes remaining until liftoff from Florida. SpaceX did not immediately say when it would try again. The next attempt could come as early as Tuesday. The problem involved the engine ignition system. Strapped into the capsule atop the Falcon rocket were two NASA astronauts, one Russian cosmonaut and one astronaut from the United Arab Emirates.