Expedition 15 was the 15th expedition to the
International Space Station (ISS). Four crew members participated in the expedition, although for most of the expedition's duration only three were on the station at any one time. During Expedition 15, the ISS
Integrated Truss Structure was expanded twice:
STS-117 brought the S3/S4 truss, and
STS-118 brought the S5 truss.