Fossum and Sellers on the P1 Truss during EVA1 on STS-121 / Expedition 13 joint operations

S121-E-06073 (8 July 2006) --- Using Space Shuttle Discovery's Remote Manipulator System/Orbiter Boom Sensor System (RMS/OBSS) for maneuvering, astronauts Piers J. Sellers (red stripes) and Michael E. Fossum, STS-121 mission specialists, work on the S0 Truss of the International Space Station. The 7 hour 31 minute spacewalk was the first of three scheduled EVA sessions for the STS-121 mission.