S121-E-06388 (8 July 2006) --- The shadows of astronauts Piers J. Sellers and Michael E. Fossum, two STS-121 mission specialists who are anchored to the Space Shuttle Discovery's Remote Manipulator System/Orbiter Boom Sensor System (RMS/OBSS) foot restraint, are visible against the port pod for the Orbital Maneuvering System on the shuttle. Photo credit: NASA