Workers preformed an unprecedented repair job on space shuttle Atlantis, replacing a balky 300-pound hydraulic unit in the spaceship's tail while the winged-orbiter stood on its exposed seaside launch pad. Photos: NASA/KSC.

New box The new Power Drive Unit (PDU) is attached to a crane at launch pad 39A.
Going up The new PDU, wrapped to protect it from the drizzlying rain, is hoisted up toward Atlantis' tail area. Perched more than 100 feet above the flame trench, workers in a "cherry picker" aerial platform, prepare to manoeuvre the PDU into position.
Into place The PDU, about the size of an office copier, is eased into place at the base of Atlantis' tail.
Job done With the complex repair job done, the gantry-like rotating service structure is rolled back in place around the shuttle.