The launch of the Shuttle carrying the Spacehab logistics double module was the third launch in the assembly phase. The Double Spacehab module was not going to be a part of the ISS, it is a module built in Europe and is often used by Nasa on it's shuttle flights. It is used to carry out experiments, but has also been used to carry supplies to the Mir space station when a new U.S. member was to join the Mir crew. This flight to the ISS carried supplies just as on the Mir missions. It carried equipment to further outfit the Service module (due to launch later this year), and the rest of the station. The reason the equipment was brought up on this flight and not with the Service module is because the Proton rocket could not boost more than the Service module already weighs into the desired orbit.
Module information:
Read about the shuttle mission to outfit the station and see pictures from it on my STS-96 page.
accommodate powered payloads.
the exterior of Russian station segment and will be used to
perform spacewalking maintenance activities.
