Endeavor will launch at 3:39am Sunday, carrying massive parts including a seven-windowed panoramic room.
"Once this mission is complete, the space station from an assembly standpoint will be 98 percent complete."
NASA Spokesman Rob Navias says the 13-day mission involves complicated work for the six crew members.
"There will be a lot of work with the station and shuttle robotic arms to remove the large connecting node, this module called Tranquility, and the attached cupola robotics workroom from the payload bay of Endeavor to attach it to another one of the modules on the station."
After this mission, the remaining four shuttle trips will supply the space station with replacement parts, as well as environmental systems.
"To produce oxygen, to produce water, to process urine into water, to be able to do all the things necessary to sustain a permanent presence on board the station well beyond the retirement of the shuttle."
This mission will include three spacewalks and is likely the last night launch for the shuttle program.