Akhir 04, 1432 H/March 09, 2011, SPA -- Astronauts on board the space shuttle Discovery, NASA's oldest spaceship, fired their ship's braking rockets on Wednesday to leave orbit and begin an hour-long glide back to Earth on its last flight, according to Reuters. Touchdown at the Kennedy Space Center in Florida is planned for 11:57 a.m (1657 GMT).