The crew of the International Space Station will have to wait a little longer for the arrival of an unmanned cargo ship, NASA said Sunday. The U.S. space agency said in a written statement that a scheduled data linkup between the station and the Cygnus spacecraft experienced a glitch Sunday, which resulted in an \"interruption of the approach sequence.\" The cause of the software problem was found and fixed by Orbital Sciences technicians; however, it will take 48 hours to get the orbiting Cygnus back on the precise course to link up with the station. With no Cygnus to deal with, the ISS crew was given an official off-duty day Sunday. But the station will soon get busy again. Cygnus arrives on Tuesday. On Wednesday, a Russian rocket will lift off carrying two cosmonauts and American astronaut Michael Hopkins on their trip to the ISS.