CAPE CANAVERAL, Fla. (AP) – A space shuttle left the International Space Station for the very last time Tuesday, heading home to end the 30-year run of a vessel that kept U.S. astronauts flying to and from orbit longer than any other rocketship.Atlantis slipped away after performing a partial lap around the space station. Ten pairs of eyes pressed against the windows, four in the shuttle and six in the station.All that remains of NASA's final shuttle voyage is the touchdown, targeted for the pre-dawn hours of Thursday back home in Florida.In keeping with tradition, Atlantis' departure was marked by the ringing of the naval ship's bell aboard the space station. The undocking occurred nearly 250 miles above the Pacific."Atlantis departing the International Space Station for the last time," space station astronaut Ronald Garan Jr. announced, ringing the bell three times.