NASA Astronauts John Olivas (left) and Nicole Stott, STS-128 mission specialists, in the mission’s first spacewalk as construction and maintenance continue on the International Space Station. During the six-hour, 35-minute spacewalk, they removed an empty ammonia tank from the Station’s truss and temporarily stowed it on the Station’s robotic arm. They also retrieved the ESA experiments European Technology Exposure Facility (EuTEF) and Materials International Space Station Experiment (MISSE) from the Columbus laboratory module and installed them in Space ShuttleDiscovery’s payload bay for return.