NASA Astronauts John Olivas and Nicole Stott, STS-128 mission specialists, during their mission's first spacewalk to construct and maintain the International Space Station. During the six-hour, 35-minute spacewalk, John and Nicole removed an empty ammonia tank from the Station's truss and temporarily stowed it on the Station's robotic arm. They 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.