At night from the 1st to the 2nd September, 2009 American astronauts J.Olivas and N.Stott performed the first of three STS-128 spacewalks. The EVA began at . It lasted 6 hours and 35 minutes. The spacewalkers completed all of their major objectives.
The astronauts removed an emptied the ammonia tank from the station’s truss and temporarily stowed it on the station’s robotic arm. Olivas and Stott also retrieved the European Technology Exposure Facility (EuTEF) and Materials International Space Station Experiment (MISSE) from the Columbus module and install them on Discovery’s payload bay for return.