Astronaut Nicole Stott, Expedition 20 flight engineer, participates in the STS-128 mission's first session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 35-minute spacewalk, Stott and astronaut John "Danny" Olivas (out of frame), mission specialist, removed an empty 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 laboratory module and installed them on Discovery's payload bay for return.