International Space Station (ISS)

The STS-121 patch depicts the Space Shuttle docked with the International Space Station (ISS) in the foreground, overlaying the astronaut symbol with three gold columns and a gold star. The ISS is shown in the configuration that it was during the STS-121 mission. The background shows the nighttime Earth with a dawn breaking over the horizon. STS-121, ISS mission ULF1.1, was the final Shuttle Return to Flight test mission. This utilization and logistics flight delivered a multipurpose logistics module (MPLM) to the ISS with several thousand pounds of new supplies and experiments. In addition, some new orbital replacement units (ORUs) were delivered and stowed externally on the ISS on a special pallet. These ORUs are spares for critical machinery located on the outside of the ISS. During this mission the crew also carried out testing of Shuttle inspection and repair hardware, as well as evaluated operational techniques and concepts for conducting on-orbit inspection and repair.