STS-120 was a Space Shuttle mission to the International Space Station (ISS) flown by Space Shuttle Discovery. The mission launched on October 23, 2007, and was the eighteenth shuttle mission to visit the ISS. The primary objective of the mission was to deliver and install the Harmony module, which would provide additional living and working space for the ISS crew, and to rotate the crew of the ISS.
The STS-120 crew consisted of seven astronauts, led by Commander Pam Melroy. The crew also included Pilot George Zamka and Mission Specialists Scott Parazynski, Doug Wheelock, Stephanie Wilson, Dan Tani, and Paolo Nespoli.
During the mission, the crew of Discovery successfully delivered and installed the Harmony module to the ISS and rotated the crew of the ISS, bringing back the Expedition 16 crew and delivering the Expedition 17 crew to the station. The mission included three spacewalks to perform maintenance and repair work on the ISS.
The STS-120 mission was considered a success and helped to further the construction and expansion of the ISS. It marked the thirteenth visit of the Space Shuttle to the ISS and the first time that the ISS had a total of three modules.