(04/11/2000) -- United Space Alliance technicians at Launch Pad 39A look at the site of the power drive unit (PDU) for the rudder/speed brake on Shuttle Atlantis. From left are Mark Noel, Tod Biddle and Bob Wright. Shuttle managers decided to replace the faulty PDU, about the size of an office copy machine, at the launch pad. If successful, launch preparations will continue as planned, with liftoff targeted for April 24 at 4:15 p.m. on mission STS-101. The mission is the third assembly flight for the International Space Station, carrying logistics and supplies to the Space Station, plus the crew will be preparing the Station for the arrival of the Zvezda Service Module, expected to be launched by Russia in July 2000. The crew will conduct one space walk to perform maintenance on the Space Station