A close-up view of Space Shuttle Discovery's tail section is featured in this image photographed by an Expedition 13 crew member on the International Space Station (ISS) during the STS-121 Rotating Pitch Maneuver (RPM) survey. Visible are the space shuttle's main engines (SSME), vertical stabilizer, orbital maneuvering system (OMS) pods and a portion of the aft cargo bay and wings. The Marshall Space Flight Center (MSFC) has management responsibility for development of the SSME.